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Waste Heat Capture Study -State Of Alaska 1978
WASUS ltl aa CAP UO BRD SU bw FOR: S@TaAtTE OF ALASEA DEPT. OF COMMERCE & ECONOMIC DEVELOPMENT DIVISION OF ENERGY & POWER DEVELOPMENT PREPARED BY: Ww ROBERT W. RETHERFORD ASSOCIATES W Ml Sores CONSULTING ENGINEERS. She | RECEIVED SEP 51978 ALASKA POWER AUTHORITY WASTE HEAT CAPTURE STUDY for STATE OF ALASKA Department of Commerce & Economic Development Division of Energy & Power Development Prepared by Robert W. Retherford Associates Consulting Engineers Anchorage, Alaska June 1978 CONSULTING ENGINEERS TELEPHONE 344-2585 P. O. BOX 6410 ANCHORAGE, ALASKA 99502 TELEX: 626-380 bn (| ROBERT W. RETHERFORD ASSOCIATES June 28, 1978 603-717 Ms. Clarissa Quinlan, Director State of Alaska Department of Commerce and Economic Development Division of Energy and Power Development’ 7th Floor, McKay Building 338 Denali Anchorage, Alaska 99501 Dear Ms. Quinlan: Transmitted herewith are 150 copies of the report entitled "Waste Heat Capture Study", as well as bound single copies of numerous reports, catalogues, magazine articles, etc. which served as valuable input for the study. In view of comments we received during the final review process, it ap- pears that your office would have preferred less "background" information and more specific information for "nuts and bolts, Btu's, dollars, and gallons" applications. Within the available time and budget constraints we have added some such information, but the study remains relatively general. It has been our intention in this study to identify locations, systems, and methods to help determine the advisability of performing detailed analyses at specific places for particular systems. This study offers a number of general guidelines which can be applied to individual situations to allow one to get a "feel" for the amount of waste heat generated, the amount which it is feasible to capture, and the costs and operating problems associated with capturing and using it. If such a preliminary analysis indicates a strong possibility that a particular waste heat installation would be economically feasible, then detailed engineering estimates should be performed for that specific installation. The gross amount of heat available for capture in small villages is consid- erably less than that available in more populated areas. However, con- sidering the relative ease with which such energy can be captured and utilized in some of the smaller villages and the potential individual impact of such savings, there is very good reason for specific followup action. For the smaller villages, we recommend: is Some method of control be instituted so that various agencies such as PHS, BLM, schools, etc. do not go in separate unco- ordinated directions. If the various agencies (including AVEC) can begin thinking, planning and operating as a unified group in A DIVISION OF ARKANSAS GLASS CONTAINER CORPORATION Ms. Clarissa Quinlan June 28, 1978 Page 2 603-717 designing and locating facilities, it is highly probable that fuel consumption in particular villages can be reduced by an amount equal to 25% of the fuel burned by the engine-generators. 2. Ata few select locations, perform a detailed analysis of waste heat capture possibilities, including first cost, operating costs, and potential fuel savings. 3. Assist in obtaining demonstration grants for several concepts which promise to produce a measurable increase in fuel efficiency of diesel-electric generators. For instance, organic bottoming cycles, multi-engine generators, two-speed engine-generator units, and the constant-frequency variable-speed generators. For larger power plants and industrial installations, one can reasonably conclude that if an economic use existed for the waste heat, it would be used. There are exceptions, of course, and conditions do change. It is our desire that this study serve as an educational tool to direct attention to those areas where waste heat capture possibilities, using to- day's technology, are being overlooked and to make us aware of the strong and weak points of emerging technology. By raising the general level of awareness, perhaps we can help to favorably influence future decisions in the energy field. This has been a challenging and educational project, and it seems that we have only begun. We express our thanks to the many agencies and indi- viduals who contributed to the project and in particular to you and to Mr. Dale Rusnell of your office. Sincerely, ROBERT W. RETHERFORD ASSOCIATES LO pI Key Dwane L. Legg, P.E. Executive Assistant DLL:ngU Encl. Section |: Section ||: Section III: TABLE OF CONTENTS Introduction General Comments Conclusions & Recommendations General Conclusions: Conversion Efficiency Building Losses Waste Heat Market Economic Proximity Heat Recovery Equipment Diesel Engine Heat Recovery Time Coincidence of Supply and Demand Factors Affecting Energy Decisions Improving Energy Utilization Recommendations: Section IV: Existing Facilities Modifications To Existing Facilities New . Installations Development Grants Waste Heat Distribution General Background District Heating In Rural Alaska Initial Feasibility Analysis Interpreting the Results Section V: Production of Waste Heat Thermal Electric Machines Other Sources Calculation of Stack Heat Losses for Major Contributors Commercial Buildings 11 11 12 12 a2 13 14 15 15 15 17 18 18 20 22 22 23 24 29 38 38 43 45 47 Table of Contents, continued Section VI: Capturing and Using Waste Heat General: Cooling Water Exhaust Heat Heat Wheel (or Rotary Regenerator) Heat Pipes Heat Pumps Combined Cycle Plants Limitations To the Capture Of Waste Heat Section Vil: Uses For Waste Heat Space Heating Of Offices and Dwellings Greenhouses Aquaculture Bottoming Cycle Turbines Driving Generators Other Uses Section VIII: Utilization of Waste Heat In Alaska General Comments Historical Waste Heat Utilization Projected Waste Heat Utilization Potential Waste Heat Utilization Section |X: State Of the Art - Heat Recovery Equipment Heat Exchangers Exhaust Gas Boilers Bottoming Cycles Combined Cycle Turbines Metering Heat Heat Pumps Section X: Alternative Energy Sources Solar Heating Wind Power Residential Total Energy Systems (Home Diesel Furnace) 49 50 50 51 51 53 54 58 59 64 66 66 70 71 71 71 73 74 80 80 80 80 81 81 82 85 85 85 88 Table of Contents, continued Page Unorthodox Efficiency and Life Improvement Methods for Engine Generator Sets 94 1. Two Speed Gear Box 94 2. Two Engine Generator Set 96 3. Roesel Generator 101 Hydroelectric Potential 103 1. Small Hydro 103 2. Hydraulic Turbines for Small Hydro 105 3. Induction Generators for Small Hydro 108 Tidal Power 110 Hog Fuel 112 Fuel Cells 113 Turbo Compound Engines 114 LIST OF TABLES Table No. 1 Determination of Average Annual Heating Load 30 2 Estimated Installed Cost per Foot for Pipe 36 3 Energy Conversion Efficiency 43 4 Some Major Waste Heat Sources In Alaska 46 5 Bottoming Cycle Summary 67 6 Possibilities for Waste Heat Capture . At the AVEC Villages 75 iz Allowable Hydroelectric Investment vs. Fuel Cost 105 8 Summary of Tidal Power Projects In Alaska | 9 Economic Comparisons of Fuel Supply Options in 1985 115 LIST OF ILLUSTRATIONS Figure No. 1 Available Waste Heat vs. Generator Capacity 26 2 Required Heating Btu's vs. Building Volume 27 3. Pipe Size vs. Transportable Btu's 28 4 Economic Waste Heat Transmission Distance vs. Heating Load 31-35 List of Illustrations, continued Figure No. 5 Jacket Water Waste Heat Recovery System 60 6 Jacket Water & Exhaust Waste Heat Recovery System 60 7 “Bootstrap" Building Heat 63 8 Typical Bottoming Cycle Installation 68 9 Community Total Energy System 78 10 Residential Total Energy System 93 11A Standard Generator Set 97 11B Generator Set With Two Speed Gearbox 97 12 Parallel Twinned Generator Set 99 13. Coaxial Twinned Generator Set 99 14 Allowable Hydroelectric Investment vs. Fuel Cost 106 GLOSSARY BIBLIOGRAPHY APPENDICES - District Heating Feasibility Analysis - Available Waste Heat from Exhaust Gas Heat Recovery Calculations for Kodiak Electric Association - Young Radiator Company Heat Exchangers - Heat Recovery Silencers mMOoOoWwD ' Page 1 SECTION | INTRODUCTION This study has been conducted at the request of, and funded by, the State of Alaska, Department of Commerce and Economic Development, Division of Energy and Power Development, Clarissa Quinlan, Director. The focus of this study is that present use of fossil fuels (coal, gas, oil) in Alaska (as elsewhere) to produce more useful forms of energy (heat, electricity, motive power) is less than 100 percent efficient. As a general statement, we can state that the inefficiencies of conversion are made manifest as heat in one or more forms. For example, if a machine burns a certain quantity of fossil fuel and produces useful output (shaft horsepower, electrical energy, steam, hot water or air for space heating) equivalent to 30% of the fuel burned, the energy repre- sented by the remaining 70% of the fuel will appear as unused or "waste" heat. Such heat most often appears as hot exhaust gas, tepid to warm water (65°F-180°F), hot air from cooling radiators, or direct radiation from the machine in question such as a furnace, steam power plant, diesel engine, etc. Within the above setting, we can consider any machine as a waste heat source if it does not convert 100 percent of the fuel it consumes into useful energy. Such wasted heat is an energy resource and this study examines methods of using that resource. Under certain conditions such heat can be one of the main products of a thermal machine, but as a general rule that heat is a secondary or byproduct generated as a result of the primary operation, such as electrical power production. This study has two main thrusts: (1) Consider ways to capture and use heat which is the by-product of some other operation, and (2) Consider alternate ways of energy conversion which produce lesser quantities of heat as a byproduct. The end result of successful inno- vations in either area will be a reduced consumption of non-renewable resources. Page 2 There are several reasons which may cause a given set of conditions to remain as they are or to change: The state of technology limits what can or cannot be done; human preferences influence selections, and economic considerations price the alternatives. This study presents the economic factors relating to the use of fossil fuels in Alaska and the re-capture or reduction of wasted heat. It touches upon other areas such as technological limitations, personal preferences, and regulatory constraints, but only as such issues are helpful in understanding the overall issue of "wasting" heat. Con- siderable emphasis is placed upon utilizing waste heat as a resource in small rural Alaskan "bush" villages. The overall magnitude of recover- able heat is small in bush communities as compared to that available in the larger towns, but the economic impact is much greater in the bush villages. In the smaller villages there is often less disposable income than in larger population centers; a larger portion of this disposable income is spent on such basics as heat and electricity which are often produced by diesel oil; and the cost per gallon of fuel is considerably higher in rural areas. As a consequence, this study has the potential of providing greater impact upon individuals within the smaller commu- nities. With the foregoing thoughts in mind, one objective of the study is to identify and catalog sources of heat presently being dissipated into the environment and suggest constructive uses of such heat. Another objective is to provide a listing of the technologies which exist, are presently being developed, or are theoretically possible along with a discussion of the technical, financial, lifestyle, and governmental lim- itations of the most available or promising methods of heat capture and utilization. In one sense, the waste heat under scrutiny is analgous to the small amounts of gold, silver, copper, or other minerals present in the tail- ings of old mines. The minerals present in the tailings (or in natural state in low concentrations) have considerable value, but to separate Page 3 and recover the marketable material requires an expenditure greater than the worth of the recovered product. However, as world conditions change and the value of the resource rises at a faster rate than does the cost of recovering the resource, a point is reached when it is economical to mine or reclaim the "low grade" resource. This same situation exists with waste heat. When additional heat can be produced by burning more fuel, and at a lower cost than required to recover waste heat, economics dictate that the "waste" continue. However, as the cost of producing energy rises at a faster rate than does the cost of capturing this low grade waste energy, economics will rule and the waste energy will be captured. If more fuel is not available at any cost, necessity will override economy and man's ingenuity will allow more efficient machines to be produced, but at higher cost. This study attempts to give a broad overview of the entire matter of capturing and utilizing waste heat. It is not intended to be a compre- hensive evaluation of the entire field. The only area receiving a com- prehensive and through evaluation is that of, in essence, squeezing more benefit from each gallon of oil burned, especially in the smaller communities. These same principles will, of course, apply equally as well to situations within larger communities, but at a different scale. Page 4 SECTION II GENERAL COMMENTS The thought of capturing waste heat is not new or unique. Since the cost of producing heat is many times the largest single cost in pro- ducing a product or service, waste is not welcome and never has been. However, economics dictate what is "waste" and what is not economically recoverable. if the effort and facilities required to enable one to eliminate the waste represent a greater cost than the resource saved, one cannot afford to save. A number of comments follow which could be interpreted as "negative", if taken out of context. It is not the intent of these comments to indicate that heat is not being wasted, or that it is not practical to capture waste heat. These thoughts are presented to counter the idea that tremendous quantities of heat and fuel are being wasted merely because we are unlearned, careless, callous, or irresponsible. Large amounts of heat and fuel are wasted; portions of it can be conserved, and technological advances are being made. Savings can be and are being realized, but there is not a limitless supply of heat “gold mines" just waiting for us to claim their wealth. We do find increasing economic incentive to apply existing technology to existing installations and find some very promising and exciting new and emerging technology which is deserving of very serious consideration. The body of this study addresses in detail many of the limitations, possibilities, costs, etc., connected with waste heat capture. A re- lated, almost inseparable area of discussion is that of increased effi- ciency of converting fuel to heat. If a particular machine converts a larger percentage of fuel into useful power (becomes more efficient), it obviously will convert less to heat. For purposes of this study, cap- ture of waste heat or production of less heat by increasing the effi- ciency of conversion will be considered as having equal end results. Page 5 The heat required to make a modern home comfortable is in one sense wasted as surely as the heat from the aborigine's open fire. All heat from both escapes to the outside atmosphere. The heat from the open fire is not waste to the aborigine as he cannot afford the facilities to make more of it useful to him. His only practical action is to burn more wood. A modern house can easily contain 20,000 cubic feet of air space. The people in it do not displace more than about 14 cubic feet. Looking at this, we theoretically waste 99.93% of the heat, as we heat 1400 times more empty space than occupied space. Most people, however, do not view heating 20,000 cubic feet while occupying only 14 as waste, but as money well spent. It would be possible to cut most home heating fuel requirements in half by simply lowering the temperature and wearing more clothes. We arrive at the balance of light clothing and warm houses because we do not view such action as waste. Dad is quite willing to work a little harder so Mom and the kids can be comfortable. Taxi cabs sit with their engines idling between fares, which could be considered as wasting fuel. However, the cab company views this “waste" as money well spent because patrons would not be attracted to cold cabs in the winter or hot cabs in the summer. Drivers would be attracted to the company that pays the same union wage but allows them to idle their engines for the comfort of the driver and passengers. Added home insulation is usually well worth its cost if one owner keeps the house for its useful life. Some houses change owners every two or three years and none of these short term owners can get back his added cost in fuel saved. Thus a true saving to the long term owner is a "waste" to the short term owners. It could be viewed as cheating the short term owner to require him to pay for insulation he cannot realize a true worth from. Even in this area, though, we see local and national energy policies emerging which encourage better insulation in all homes. The end result will be more expensive but better homes. Page 6 Much attention has been paid in recent years to the fuel economy of the new automobiles. Presently improvements are being made in fuel effi- ciencies and we could argue for replacement of the older vehicles with more efficient ones. However, a man who has a three year old paid for gas hog would have to keep his brand new gas miser about.15 years for the savings in fuel cost to equal its purchase price. He cannot "afford" to spend $5,000 to $10,000 for a new car in order to save a few dollars a week in reduced fuel consumption. However, as the price of fuel climbs ever higher or as fuel becomes limited in supply, "fuel economy" becomes ever more valuable. As another example, a truck engine has an efficiency of perhaps 25%. If an added mechanism can improve efficiency by 10% to an overall efficiency of 27.5% but costs the operator 1% in load capacity, the trucker cannot afford to save fuel. 4 The term efficiency has been used above. This generally used term is often misunderstood. The above creature comfort examples could be rated by efficiency. The modern home is more efficient than the ab- origine's open fire. The modern home produces more comfort with less fuel and fuss. The idling taxi engines are more efficient than the dead taxi engines as idling the engines produces more profit than the cost of the extra fuel. The insulated house is more efficient than the non- insulated is because it requires less fuel to maintain a given level of comfort, but is less efficient to the short term owner because his total cost is more for the same comfort. Efficiency relating to engines, turbines, boilers, generators, motors and heat exchangers means many things. The constructive use of heat has many absolute limits. For instance no diesel engine can ever be "100% efficient" but heat exchangers are always "100% efficient" as all heat delivered is rejected. if even a small portion of the heat delivered did not leave the heat exchanger, it would eventually melt or burn. Page 7 The diesel engine even if "perfect" and using a "perfect gas" is limited to less than 60% efficiency by the physical laws of thermodynamics. Since real diesel engines must use real gases and real machinery, efficiencies of 33% are real efficiencies. About 33% of the heat energy from the burning fuel becomes mechanical energy in the rotating shaft. Heat exchangers however, have a different real measure of "efficiency". There is a temperature loss through the exchanger which in effect lowers the grade of the available heat. The hot fluid may lose 1000 Btu per gallon as the exchanger cools it from 200° to 190°F. The cold fluid may gain 1000 Btu per gallon as it is heated from 170° to 180°F. No heat exchanger can raise a cold fluid to the temperature of the hot fluid. Most practical heat exchangers have a 10°-20°F temperature loss which means that the heat leaving is lower grade or "less available" than the heat entering. There is no loss of heat, only its availability is lost. An example each of us has experienced is our auto heaters here in the arctic. High fan speeds may produce a high volume of relatively cool air even with a hot engine. Lower fan speeds produce a lower volume of warmer air. Much greater heat was being transferred to the air at the high fan speeds, but the availability of this heat was too low to warm us. The problem of availability of heat is the reason diesel engines are about 30% efficient, gas turbines about 20% efficient, and large coal- fired steam plants nearly 40%. It would seem that this over 60% "waste" heat energy should be easily captured and put to use. However, to squeeze the 20% to 40% of the heat into useful mechanical energy the availability of the remaining 80% to 60% has been pushed so low that it — just cannot be utilized. Once a big steam plant gets through squeezing a lump of coal into kilowatt hours of electricity all that waste heat (60% of the lump) is really in cool water and moderately warm stack gas. The heat is there but like the cool air from your auto heater it just can't be economically used. Page 8 A great disservice to rational popular energy concepts has been done by enthusiastic reporting of research predictions and in some cases inventors' claims as if these were really functional systems. Carburetor patents have been written about which could allow autos to go 450 miles per gallon. These supposedly have been kept secret by the big oil companies so more gasoline could be sold. This is of course impossible, as all patents are public. Anybody can get a copy of any patent and see all the details. Patents are non-renewable and after 17 years anybody can make and sell any patented device, yet such claims have been made for at least 40 years. If there was any substance to such claims, these carburetors should be old hat by now and 450 miles per gallon would be commonplace. Considerable progress is being made in improving automobile fuel efficiencies, but it truthfully appears that no astounding breakthroughs are just around the corner. Other reports give glowing accounts of the use of sewer gas or garbage to create fuel. The gas from everybody's sewage in town can heat the sewage plant and perhaps even run the treatment pumps by means of added equipment. In the case of very big towns sewer gas could even generate some excess power. Garbage has energy in it. We should try to utilize this energy. However, to heat your five-gallons-a-day house on garbage, your family would have to produce more than 150 pounds of garbage each day. The low heating value and contamination in garbage make it an expensive fuel if its heat must pay for its collection, preparation, and conversion installations. However, if the cost of collection, preparation (sorting and drying) and incineration facilities can be charged off to "garbage collection fees" then the useful heat can be economic. In larger population centers such recycling of garbage is being done successfully and economically. Heat pumps are widely proclaimed as having "performance ratios" of three to one. This means that the pump delivers three times as much energy in the form of heat as energy used to operate the pump, which is an apparent great saving. A fact often not understood by those presenting this as a saving is that the mechanical energy to run the Page 9 pump possibly came from fuel burned at, say, 33% efficiency. Thus three times as much fuel energy was burned somewhere else (at the power station) as energy used by the pump. The total fuel burned is usually more for equivalent heat in your home when using heat pumps than if you heated directly with gas, oil, or coal burned in your own home furnace. As cold climate becomes more severe, heat pumps be- come less and less useful. On a straight energy basis heat pumps are of course more efficient than electric resistance heating. Electric resistance heating using electricity generated by coal, oil, or gas combustion uses three to four times as much fuel as your own local fur- nace would use. It is thus a disservice to present heat pumps as the ultimate "energy savers". However, in certain applications such as space heating in mild climates, where hydroelectric power is available to drive them, they probably have no equal. The above has been written to provide a feel for the problem of "Waste Heat Capture". Perhaps it gives an appreciation of the fact that while it is true most heat is wasted, much of this "waste" is necessary to give us heat that is usable. To capture this great amount of waste heat we must have uses which can utilize low grade heat. Jacket water heat from many large diesel engines is not hot enough to directly substitute for your household hot water furnace. The machines which can extract useful energy from sources of low grade heat are expensive. This is why designers of all types of thermal machines constantly strive to work at higher and higher temperatures. High temperatures mean more available energy; therefore, the machinery to use it can be less expen- sive. The cost of thermal machinery varies more directly with the amount of working fluid handled than with the heat energy utilized. Thus a plant of 1930 design utilizing 640,000 Ibs. of steam per hour and producing 115,000 HP is not much different in size from that of 1900 design producing 40,000 HP from the same amount of steam. The difference being that the newer plant uses steam at 727°F, and 615 psi; the older 373°F and 180 psi. Truly modern plants use 1150° steam @ 5500 psi. Rather than try to capture the heat "wasted" in cooling water and stack gas the increase in realized efficiency comes from "extending the top end". Page 10 This is an indication that there are presently real limitations to capture of the heat wasted at the low end of the process. All three of these plants exhaust cooling water and stack gas full of equal amounts heat at the same low availability. Page 11 SECTION III CONCLUSIONS & RECOMMENDATIONS GENERAL CONCLUSIONS Conversion Efficiency Nearly any industrial or power generating process in use today or likely to be used in the near future produces heat that is wasted into our environment. This heat is a basic product of any conversion process. It is not produced due to ignorance or carelessness, but because under the existing circumstances it is a reasonable way to proceed. Technological advancements continue to make small-scale improvements in conversion efficiencies of engines, boilers, etc., but the basic laws of physics prevent us from making quantum improvements in basic efficiencies. As a general guideline only some 20 to 50% of fuel input is converted directly to the desired electrical or mechanical energy using existing or projected equipment. Increases of overall efficiency above this level are achieved by capturing and using a portion of the heat which is generated in the conversion process. In general, machines which operate at 20% efficiency or less are highly mobile and "handy". A gasoline powered chain saw is very inefficient, as is the vacuum sweeper. The more efficient a machine becomes, the more complicated, bulky, and costly it becomes. Were a chain saw made as efficient as a large diesel electric plant, it might be easier to move the forest to the saw. In other words, we sometimes trade efficiency for some other desirable feature such as convenience or first cost. Any contemporary design thermal plant wastes heat because the de- signer did not know how or could not afford to get more power from it. The designer has in effect said, "I've squeezed all the juice from the lemon that it is practical to do. If someone can use the rind, seeds, and remaining juice, they are most welcome to them." In effect, waste Page 12 heat capture is concerned with using heat of such low grade that it has very little value and is not economically recoverable. Building Losses One hundred percent of the energy used to heat our buildings is "wasted" in that it is eventually dissipated into the surrounding en- vironment. Some of this heat is capturable with presently available equipment. Examples of capturable building heat are the Btu's con- tained in the ventilating air exhausted into the atmosphere and in the hot water that is discharged into the sewer. The remaining heat, that lost through the walls and roof, is best not "wasted" than captured. This can be best addressed by building structures which, because of their construction features, have less heat loss. Waste Heat Market For captured "waste heat" to have a value, there must be a market for it. Such heat has a marketing area which is quite restricted when compared with the market for the basic product (usually electricity). This is because the waste heat is of such low grade that it can be transported only relatively short distances. If a market does not exist, the heat has no value. For instance, isolated power plants such as those powering the trans-Alaska oi! pipeline or proposed for the gas pipeline produce waste heat, but for the most part there is not a near- by market for the heat. Economic Proximity The market for waste heat must be in economic proximity to the source of heat. In other words, we must be able to capture, transport, distribute, and meter the heat at less cost than would be required to Produce an equivalent amount of heat by some other method. To illus- Page 13 trate an extreme example, the heat from Mt. Augustine could possibly heat all the homes in a number of Alaskan bush villages, but there is no reasonable way of transporting it. Therefore, it is cheaper to carry fuel oil and burn it in stoves in the Alaskan homes. However, this should not discourage us from searching for other more practical ways of conserving heat. The "grade" of the energy influences economic proximity. Electricity is thought of as a highly transportable energy, but depending upon the distance to be transported, its transportability may be far less than coal, gas, or oil. Economic proximity to the end use for coal, gas or oil usually occurs at greater distances than for electricity. The energy in Arab oil could not get here by electric transmission lines but the oil can. One of the limits on "free" hydroelectric energy is its economic proximity to its users. Distance often allows costly coal, gas, or oil to be of higher economic proximity than "free" hydroelectric energy, because of the cost to build facilities to transport the "free" hydro- electric energy. Waste heat, being of lower grade than any of the above examples can be expected to be even less transportable. Heat Recovery Equipment Almost without exception, the additon of heat recovery equipment to any installation increases the complexity of that installation. Such increase in complexity can be very slight, requiring few additional operating precautions, or they can add considerable complexity and the requirement for full time attention, such as required by a waste heat boiler. Increasing the efficiency of a reasonably efficient machine generally increases the complication greatly. In any particular situa- tion, an analysis should be made to determine if the value of the heat that can be recovered is more than the cost in both dollars and com- plexity required to recover it. Page 14 Diesel Engine Heat Recovery Diesel engine cooling water waste heat can be utilized for process use or space heating if the use is in the economic proximity to the engine. Section !V offers some guidelines for determining if economic proximity exists. Diesel engine exhaust heat has very limited use as a power source but can generate useful process or heating steam, again subject to the limits of economic proximity. Near, but future, O.R.C. systems may make diesel exhaust power a reality in selected locations such as base- loaded plants. Until now exhaust heat power has not been practical in the 100 HP range and below. However, Thermo Electron Corporation, and Robert W. Retherford Associates are presently attempting to obtain financing through a demonstration grant to install a 40 kW O.R.C. system in one of the AVEC villages. Typicaily heat energy equivalent to one third of the fuel supplied is dissipated into the air through the engine radiators and one third goes out the exhaust. Practically all the heat in the cooling water and approximately one half that in the exhaust is capturable. This means that roughly 50% of the fuel buried in a diesel generator is converted into waste heat. If a power plant burns 50,000 gallons of oil per year, recoverable heat equivalent to 25,000 gallons is produced. If that heat could all be captured, oil consumption for heating could be reduced by 25,000 gallons. For instance, an AVEC power plant with a 100 kW peak load, 50% load factor, and 9 gallon/kWh fuel rate would require 48,000 gallons of fuel per year. If all the recoverable heat were used, it would reduce oil requirements for heating in that village by 24,000 gallons. Because much of the heat is produced in the summer when it is not needed, it is not practical to use all of it, but this does give the reader a feel for the scale of waste heat production at such plants. Page 15 Time Coincidence of Supply and Demand The coldest part of the day is typically in the early hours of the morn- ing. At this time electric demand is least. The waste heat from en- gines, turbines, or condensors would be minimum when the tempera- tures are lowest. Hot summer nights cause maximum air conditioner load. Waste heat produced by this generation is certainly not needed. Time coincidence of supply and need of engine waste heat must exist or heat storage must be provided. Normally the period of peak electrical demand does not coincide with the period of peak heat demand. in this case heat must be stored during the period of peak electrical demand and distributed during the period of peak heat demand. Factors Affecting Energy Decisions Economics and lifestyle preferences invariably have a strong influence on the energy decisions we make. If energy can be captured at less cost than it can be wasted, it will be captured. If it costs more to capture energy than to produce it by another method, it will not be captured. In practically every case, total power requirements could be reduced ‘if dwellings and commercial buildings were clustered closely around the power plants and other heat sources. it would then be relatively inexpensive to transport waste heat to the buildings. How- ever, the typical person does not care to live or work adjacent to the power plant and is willing to pay more for his energy requirements for the privilege of being removed from the power plant. Improving Energy Utilization There are several areas which should be examined when trying to identify methods and places to improve energy utilization of thermal electric machines. Page 16 1: Plants using out dated technology which are "wasteful" compared to today's best. 23 Plants using machinery of low efficiency (compared to today's best) because of low first cost tradeoff. Such an example is the modern simple cycle gas turbines which has a relatively low efficiency, but low first-cost, operating simplicity, and high reliability. 3. Plants intended to deliver heat and recovering electrical energy "ahead" of the heat (common in many large universities for many years). Such a system will typically pass steam through a turbine which drives an electrical generator, and then will use the turbine exhaust steam for heating purposes. This is commonly called co-generation. 4. Diesel engine exhaust and cooling. 5. Transportation of recovered heat to a point of use. The governing factor is one of economic proximity of recovered energy to the proposed point of use. This transportation of recovered heat is an oft missed link. Transporting the captured waste heat is far more difficult than transporting the energy made while producing the heat. Transporting low grade waste heat is one of the more critical elements in its use. Appendix C includes specific calculations for Kodiak which help put the transportation costs into perspective. If the school, water system, sewerage disposal plant, etc., always need heat equal to the engine's output and are next door to the engine, it is surely wasteful to not fully exploit waste heat recovery. When the need for heat is separated from the engine in space and time, variables enter which need careful technical and economic consideration. The charts and graphs included in Section 1V show some idea of these relationships. However, each installation needs to be evaluated upon its own merits. The critical point of any efforts to evaluate waste heat Page 17 recovery is that point at which the equivalent annual cost of recovering heat will be less than the cost of generating heat by other means. Low grade waste heat cannot be transported very far for its actual resale value. The price of delivered timely heat to a user at his radiators, water system, etc., must be less than his heating fuel cost. RECOMMENDATIONS Existing Facilities The recommendations included in this paragraph are those that can be done now with only technical guidance and nominal expense, simply by taking advantage of presently available equipment and technology. hs In bush village power plants cooling water should be piped to replace or supplement heating fuel in schools, community centers, city halls, water systems and sewer systems where economic prox- imity exists. In smaller communities where it is practical, consid- eration should be given to moving the power plant nearer other public facilities so that waste heat can be used to advantage. By doing this, we could conservatively expect to reduce heating oil requirements by an amount equal to one fourth of the oil consumed by the power plant. es Larger city power plants and industrial heat sources should reduce or eliminate heating fuel requirements by using cooling water to heat all facilities within economic proximity of heat source units. It is usually possible to accomplish this at least in the plant shops, offices, etc. Page 18 Modifications To Existing Facilities It is recommended that the following can be done with some engineering and modification to existing facilities, but using established machinery and designs: ae Bush Village Power Plants a. Exhaust heat recovery boilers should be added to engines where practical to increase available heat for distribution to nearby facilities. b. In locations where it is economically feasible to heat adjacent facilities with waste heat, consider addition of heat storage tanks to give a steady heat source regardless of engine load. 2. Larger city power plants and industrial heat sources should install exhaust heat boilers and heat storage to furnish hot water or steam for residential commercial and industrial needs which may be in economic proximity to plant. New _Installations It is recommended that the following can be done in new work using established knowledge and innovative engineering. ds Bush Villages a. Bureau of Land Management, Public Health Service, and the electrical utility cooperate in the siting of facilities in such a manner to obtain maximum utilization of waste heat produced by the power plant. Page 19 b. Village design be predicated on utilizing powerplant and industrial waste heat. Attention should be given to developing more effective exhaust silencers so that there is less reluctance to living near a power plant. c. Multispeed, variable speed, or two engine, generator drives be designed and built to increase engine life, reduce fuel consump- tion, and lower first cost of equipment. d. In areas where the home diesel furnace can possibly be competitive with conventional power supply, perform specific tech- nical and economic analyses for each location to determine if this concept would have advantages over central station power. e. Hydro power should be substituted for thermal power where it is available, cost effective, and ecologically acceptable. Ts In selected locations bottoming cycles should be applied to diesel powerplants and gas turbine plants (if economical). City Power Plants a. City power plants should be located in the center of pur- posely concentrated industrial and residential areas so normally wasted heat can be used. Ecological and esthetic ideals would have to be considered secondary to fuel economy. b. The areas near powerplants should be opened to industry and residential concentration attracted by cheap heat. Cc: Bottoming and combined cycle systems should be added to new design and existing plants. Page 20 d. Coal and diesel plants should be built in lieu of gas turbine plants. Diesel plants should have bottoming cycles or heat re- covery exhaust systems or be turbo compounded. Development _ Grants It is recommended that engineering and development grants be made available to aid in instituting some of the above recommendations. Specific suggestions are as follows: 1. Trial installation of the home diesel furnace concept in one or more smali villages. 2. Design, production, and installation of variable speed or twin engine generator sets. Such units can appreciably improve the efficiency and life span of both the home diesel furnace and the small central power plant. 3. Design and production of a multi-engine single alternator plant. 4. Design and production of an optimized diesel bottoming cycle for both large and small diesel engines. 5. Design and construction of show-case coolant heated marine life farms; exhaust and coolant heated agriculture. 6. Design and production of "run of the stream" induction generation units. 7. Design and production of turbo compound diesels in the automotive size and in the multi-megawatt size. 8. Page 21 Detailed analysis of waste heat capture possibilities in specific AVEC villages which appear to have the most favorable conditions. Likely candidates are Chevak, Shishmaref, St. Mary's, and Wales. Page 22 SECTION IV WASTE HEAT DISTRIBUTION General Background District heating has long been popular in northern and eastern Europe and the Soviet Union as well as in the northeastern United States. These systems generally consist of a transmission and distribution system of pipes which carry hot water or steam from a centrally located heating station to the buildings it heats. Once the heat has been removed from the water, it must be returned to the heating station for reheating. This means that the system is a continuous loop. The heat stations in a district heating system generally are designed in conjunction with a coal-fired or nuclear steam generating plant. This economizes on the capital investment involved in such stations and reduces the use of fuel by utilizing waste heat for water heating. Portable heating units may be used where co-generation is not feasible, or for load balancing. Several economic factors influence the feasibility of district heating systems. There must be sufficient population density to justify the capital costs involved. Labor and material costs and the insulation and size of the buildings heated must be considered as well as the cost of other heating methods. The costs of district heating can be segregated into those which vary with the length of the system (primarily the cost of pipe) and those which are independent of the systems length, (such as heat exchanger and waste heat boiler). These costs will vary between locations depend- ing on labor and transportation costs and the required capabilities of the system. ‘ aa = Gn Page 23 The cost of heat exchangers, waste heat boilers and associated equip- ment depends on the generator installed at the location. These costs can best be determined by contacting the generator's manufacturer and obtaining the price of the specific models of waste heat recovery equip- ment specifically designed for that generator. Some typical catalogue prices are included in Appendices E and F. Using these as a guideline, we can estimate that the component price for a heat recovery silencer will range from $2800 for a 55 kW engine-generator set to $12,000 for an 850 kW engine-generator. These units would allow capture of waste heat equivalent to approximately one sixth of the fuel supplied to the engine-generator. To these prices must be added the cost of installa- tion and auxiliary equipment. A heat exchanger for the jacket water system will range from $430 for the 55 kW engine-generator set to $2,900 for the 850 kW engine- generator. These theoretically can capture waste heat equivalent to approximately one third the fuel supplied to the engine-generator. For a complete installation, including labor and auxiliary devices, the above prices should be multiplied by a factor of 3 or 4. District Heating In Rural Alaska The high cost of heating with diesel fuel may make some district heating feasible in rural Alaska utilizing jacket water and exhaust heat from the local power plant. Before the economics of district heating can be considered, it must be determined that the available waste heat is sufficient to meet the heat- ing demand of the area under consideration during various conditions of heating and electrical load. ‘This is particularly important where an electrical generator produces sufficient waste heat at peak load, but does not on an average basis. Page 24 The largest cost of the district heating system is often the cost of distribution piping which connects the waste heat source to the heat user. The location dictates the type of pipe that can be used. Espe- cially in Alaska there are many variables such as transportation cost, subsurface conditions, and availability of skilled labor which cause installed costs to vary widely. The interest rate is another important factor in determining the feasibility of a district heating system. A district heating system will typically last for 30 years. In that time the system's owners would have paid $1.42 in interest charges on each dollar borrowed at 7%. At 12%, they would have paid $2.73. The feasibility of district heating in a community in rural Alaska can be roughly determined with the graphs and tables included in this section, which are based on estimated 1978 labor and materials costs for rural Alaska. These graphs are based upon using village labor for all con- struction work except plumbing and supervision. Both the Alaska Village Electric Cooperative (AVEC) and the Public Health Service (PHS) have used village labor for installing their electric and water systems in rural Alaska with satisfactory results. These costs may vary widely from location to location, so an engi- neering feasibility study should be done if the graphs indicate that district heating is possibly feasible. They assume that both the jacket water and exhaust heat will be utilized as heat sources and that waste heat will provide all the heat to the system. Transportation of pipe and other construction materials is by barge to the location. The system is assumed to be financed for 30 years at 7% interest rate. Initial Feasibility Analysis The analysis which follows is based upon a number of approximations and simplifying assumptions which will be explained within the text. It is not intended to be decisive or all inclusive. {it should serve only as a general guide to determine if a detailed individual analysis is warranted for a particular location. Page 25 The first step is to determine the Btu's available from the generator. From available records determine the system peak load and the system load factor. Then use Figure 1 to determine the Btu's per hour avail- able at the system peak (100% load ) and on an average basis. Next, using Figure 2, determine the peak Btu's per hour demand for each building to be heated by the district heating system. This does not include the losses in the hot water distribution system, but they are of such magnitude to be masked by other approximations. This analysis should also consider the time-of-day relationship between the peak electrical load and the peak heat load. In all probability they will not occur at the same time. If the heating peak Btu's demanded are less than the average Btu's available from the generator, then district heating is definitely possible and the analysis should be continued. If the heating and electric peaks are not coincident or if the heating peak's duration is greater than the electric peak's, it will be necessary to drop buildings out of the pro- posed district heating system or provide for heat storage. If it is decided to eliminate some of the buildings from the heating system, it usually will be best to drop the buildings which are farthest from the power plant. If the engine-generator does not provide enough waste heat but it still seems best to install a district heating system, this analysis should be dropped and a separate analysis performed using a separate heating station with waste heat being used to supplement the main heating station. If it has been determined that sufficient Btu's are available to meet the heating demand, the system must then be sized. From Figure 3 select the pipe size which corresponds to the peak heating demand; then select the type of pipe which the system will require. This is a very subjective decision as the pipe must be sufficiently durable to endure its environment and must be insulated sufficiently to prevent excessive BTU/HR. X 105 AVAILIBLE FROM WASTE HEAT Page 35.0 30.0 25.0 20.0 15.0 10.0 5.0 Ke) ° 400 800 1200 GENERATOR CAPACITY (KW) AVAILABLE WASTE HEAT VS GENERATOR CAPACITY FIG. | - ® BUILDING VOLUME @ (ft. 3 Wp dG BTU/HR HEATING REQUIREMENTS BUILDING VOLUME VS BTU/HR HEATING REQUIRMENTS 1,000,000 -4 - Fig. 2 Page 28 € ‘Old = a S,N1G@ IWVLNOdSNVYL SA 3ZIS Jdid = 90! X ‘YH/NL€ JIWVLYOdSNVYEL w sI 7 eI 2 " ol 6 8 Z 9 s » € z ! = 7 a a | + eo + + ~ ut t “wea | 4 + + t + { f ug + + + ta we + | + { { + + $7] + | ars + + + + + + + + + ug + 4 4 + —+— + : ud - - ung + ue | uy ¢ uy Page 29 heat losses. For instance, asbestos pipe is inexpensive, requires less installation labor than heavier pipe, and has good insulation features. However, it must be buried in a fine gravel and sand base. Shifting permafrost would quickly destroy asbestos pipe. Using Table 1 select an average heating load per building and multiply by the number of buildings intended to be heated, using the average heating load for the locality nearest the study location. Now, using the graphs in Figure 4, select the Heat Load vs. Distance curves for the particular pipe to be installed. If the distance obtained from the graph is greater than the distance of the proposed system, the project is probably feasible. If the distance obtained from the graph is less than the distance of the proposed system it is probably not feasible. In this case the length of the system must be reduced or the project abandoned. Table 2 lists estimated installed costs of various types and sizes of pipes. These costs are based on 1978 estimated labor and materials costs. Pipe installation is assumed to be by village laborers with a plumber and supervisor from outside the village. Installation is assumed to proceed at the same rate as installation by a contractor's work crew. Interpreting the Results Waste heat utilization is not free even though there may not actually be a direct charge for the heat. The equipment for utilizing this "waste" usually requires a sizeable investment. The waste heat recovery system is feasible only when the annual cost of the equipment to do so is less than the cost of the fuel savings involved. The graphs in Figure 4 depict that relationship. Page 30 Table 1 District Heating Feasibility Analysis Determination of Average Annual Heat Load Average *Average Annual Degree Temperature Heat Load Location Days (°F) (Btu x 108) Anchorage 10,814 35.24 2.958 Barrow 20,174 9.73 5.128 Bethel 13,196 28.85 3.501 Cordova 9,764 38.25 2.702 8 Fairbanks 14,279 25.88 3.754 Juneau 9,075 40.14 2.541 King Salmon 11,343 33.92 3.070 Kotzebue 16,105 20.88 4.180 Nome 14,471 26.18 3.729 * Based on a "standard" 20,000 ft.3 building, 40 x 40 x 12.5 ft. Walls of 2"x4" construction on 16" centers, with R-11 insulation, U factor .07. Roof and floors 2'x8" or 2"x12" on 16" centers, unheated attic, 6 inches 4 of insulation, U factor .07. Two 24"x40" windows, 1% air changes per hour. ‘ ( atu LOAD HEATING ANNUAL FIG. 4 ANNUAL HEATING LOAD VS ECONOMIC WASTE HEAT TRANSMISSION DISTANCE AT VARIOUS FUEL OIL PRICES THE FOLLOWING GRAPHS DEPICT THIS RELATIONSHIP: Page 31 Pipe Size Pipe Type A, 4 AsBesTos B. 6" AsBestos C. 8” AsBEsTos D. 4" DucTILe IRON E. 6" DuctiLe IRON F. 8” DucTILe IRON 6. 4 Insucated DucTiLe IRON H. 6" Insucated DuctiLe IRON I. 8” Insucatep DucTiLe IRON 4" ASBESTOS PIPE Po T 7 ' 610 Ble + | + +— | | 4.88 + if + fe +0 | 40¢ i 4 meek | | | t FUEL OIL ARICE i 50¢ CENTS. 60¢ 244 . + — 1 70¢ | : PG | putt | | | ‘ — | L2z : : * i ee | Ss | \ 4 6 7 8 9 lo TRANSMISSION OISTANCE (1,000 f1.7 FIG. 4A Page 32 FIG. 4c 6" ASBESTOS PIPE 2 2 2 Ps ev 2 3 ° ¢ 3 8 e 8 Scere 1 | : | =e ¢ { 1” s : 4 oe ooo ei pe 2 | 3 3 | 5g Ja Biden as | cccnraennaamaal | eos —3¥-—- nl oe gna rm Sa 2 az $8 « ei al oe phe ° °Q w fe Seas lable } wie eS ze a 0 6 es le = g °° « ° a : at aaa = = w oe a < fj cs “ IE a ” ° = n ee GEE Cee PE a gece ea ae Tein a n < eter] nak paces asesh ° ‘o L + cl I 2 8 8 ¢ N 2 8 8 t 8 © ¢ nm Nn = o < a a = (g0! * Mig) GvO1 ONILV3H = VANNY (601 * M48) QVO7 ONILV3H VONNY (1,000 ft.) DISTANCE TRANSMISSION » 10%) ( atu Loao HEATING ANNUAL (eTu «x 10%) LOAD HEATING ANNUAL 4° DUCTILE IRON PIPE hae Page 33 [ \ 6.10} + + | - + 50¢ | | | 4.88} 4 + + | eoy i TOE 2.66|- + 1 ny \ | 7 { | | | 244+ 1 a 1 —— | | arte | | 1.22 ++ - ! i A. a d. 3 ' 2 3 4 5 6 s 9 10 TRANSMISSION DISTANCE (},000 ft.) Fig. 40 6" DUCTILE IRON PIPE 40¢ 50¢ T 60¢ 6.10 | | | a ae “| TOE 488 80¢ { 2.66 i | 2.44 ' | | 1.22 | | \ | ° ‘ 2 3 < s 6 6 3 io TRANSMISSION oistance (1,000 ft) Fig. 4€ » 10%) Load ( eTu HEATING ANNUAL x 10% ) ( Btu LOAD HEATING ANNUAL Page 34 8" DUCTILE IRON PIPE aoe ~ a Be ao 6.10 | + | i al 1 X 2.665 Fuge on pric \ NTS/GAL. | | | 244 4 + 1 | ae h22 | a SEE i A | | | | Pe | i I | ce UN LB 1 j S t 2 3 ‘ 5 6 7 8 9 10 TRANSMISSION DISTANCE {1,000 ft.) FIG. 4F 4" INSULATED DUCTILE IRON PIPE so, s0¢ 60¢ 70¢ 80¢ 610+ sal t _ i 2.66 4 i i | 244 | | : | | j | a. ue se i i ° ‘ 2 3 4 5 6 v 8 3 iG TRANSMISSION DISTANCE (1,006 #1.) FiG. 46 « 10%) LOAD ( Btu HEATING ANNUAL s 10%) LOAD ( 8Tu HEATING ANNUAL Page 35 TRANSMI 4 DISTANCE (1,000 ft.) 6" INSULATED DUCTILE IRON PIPE oe 70¢ a0¢ u Bd¢ 6.10 me + - + ri ' 1 assy [ T + 1 ra Oil PRicg ' NTS/GAL. : 1 2.66}— + 1 i: + 1 | 244 ie 1 | | | | | zal L mi of om Fs { 1 | | ' , | ! ! | ° ' 2 3 4 8 6 T 8 9 ie TRANSMISSION OisTaNce (1,000 ft.) Fig. 4H 8" INSULATED we ae ae a DUCTILE IRON PIPE | | 6.10 + 4 [ i | ass} L = eo | zoe! fee 1. pd | 246 +——_}__| 4 ! | L | 22 4 ere ier tele eeT af | ae ee \ ' | \ | Se s Page 36 Table 2 Estimated Installed Cost Per Foot* For Pipe in Rural Alaska Various Types and Sizes (1978) Interest Pipe Size Rate Material (Percent) 4 inch 6 inch inch Asbestos 7 $ 36 $ 42 5 ac 9 44 50 63 12 56 64 80 Fiberglass ip 43 50 70 9 52 60 85 12 66 77 108 Ductile Iron Y 65 82 121 9 78 99 146 12 101 127 187 Carbon Steel Zi 70 99 125 9 85 119 150 12 108 152 193 Insulated 7 94 na 149 Fiberglass 9 Aas) 134 129 12 145 Vil 230 Insulated 7 121 152 209 Ductile Iron 9 146 182 251 12 187 234 322 Insulated id 127 168 216 Carbon Steel 9 153 202 260 12 196 259 334 * Median cost for coastal locations, using village labor. Page 37 Finding that the system is feasible does not mean that materials should be purchased and construction started. The system still needs to be engineered for the particular location and situation. The previous analysis has merely justified that study. The study should compare the fuel savings from the district heating system and the annual cost of the district heating system. If the cost is less than the savings, the project is feasible and the system should be installed. If not, the costs of the proposed system should be reduced or the project abandoned. The costs of conversion to the district heating system for individual consumers is one important factor to remember in the analysis. The graphs do not account for those costs. If the buildings to be heated are already heated by hot water baseboard units, the cost of conversion should be relatively low. If the buildings are heated by forced air, there may be very high conversion costs. If new facilities are to be heated by this system, there will be little or no additional equipment costs for individual consumers. No maintenance costs have been included in the analysis. The exhaust heat recovery unit will require frequent cleaning. This is particularly true if the engine to which it is attached frequently operates at less than full load. The Anchorage Water Utility experiences about 4% leakage in its system. The district heating system will also leak re- quiring some maintenance. No attempt has been made to accurately calculate such maintenance costs. Appendices A and B are programs and instructions for performing the above analyses with the HP-97 desk calculator. Page 38 SECTION V PRODUCTION OF WASTE HEAT Before waste heat can be distributed for heating as discussed in the previous section, or for any other purpose, there must be a source of waste heat. This section gives a brief discussion of sources of waste heat. These sources have been divided into the categories "Thermal Electric Machines" and "Other". Thermal Electric Machines The main thermal electric machines in use are the steam turbine, gas turbine, and diesel engine. This discussion considers the losses which occur in converting fuel to mechanical or electrical energy and the limitations to capturing that "lost" energy. With every increase in price or decrease in availability of fuels , engi- neers and scientists renew their efforts to squeeze more benefit from each unit of fuel. For 200 years since Newcomen's first vacuum engine, the technology has been primarily concerned with increasing efficiency of engines. This has required reduced production of waste heat or improved means to recapture it. The jumps in efficiency which have been made over these 200 years are the result of technical and financial incentives to compete with preceeding ideas and developments. James Watt's engine utilized fuel 20 to 300 times more efficiently than did New- comen's, and Corliss's engine was much better than Watt's. DeLaval's steam turbine represented another magnitude jump in converting fuel to mechanical energy, with Dr. Diesel making perhaps the most recent and significant improvement to efficiency. Each improvement came as a result of better understanding of basic technical principles and the application of innovative skills. Important technical limits on fuel conversion efficiency are the real restraints of the basic method by which energy conversions are made. Page 39 These conversion methods are described by the names of important contributions to the use and understanding of each method. The con- version methods are further labeled as "cycles" -- hence, Otto cycle, Carnot cycle, Rankine cycle, Diesel cycle, Brayton cycle. Each of these cycles has a limit to the efficiency of conversion beyond which it is not possible to improve. These limits are related to the range of temperatures within which the "practical" engines of the world can operate. The ability of structural materials to remain stable and safe under maximum operating temperatures places absolute limits on the conversion efficiencies of today at about 40%. Typical high temperatures in the conversion cycles are represented by the temperature of steam in a steam plant, combustion gas in an engine or gas turbine, etc. Typical low or "bottom" temperatures are repre- sented by the condensing water temperature of a steam turbine or the exhaust gas of an engine or gas turbine. The highest temperature found is typically about 1100°F for diesel engines and 1600°F for gas turbines. The related lower temperatures are 60-80°F condensing water, 350-600°F engine exhaust, and 800-1000°F turbine exhaust. As the high temperature is pushed upward with no appreciable increase in the bottom temperature, or as the bottom temperature is reduced ever lower with no appreciable decrease in the upper temperature, there is a corresponding increase in cycle efficiency. The technology of materials that can adequately survive these temperature restraints is the key to improved efficiency of these cycles. Other cycles such as MHD! and the fuel cell are the subject of intense research and development, but are not yet available. Fuel cells with higher efficiencies of conversion than diesels are tech- nically possible, but are not as yet commercially practical or economical. Current development work with fuel cells holds strong promise of the ability to produce first generation fuel cells that convert 35-40% of fuel 1 MHD is the abbreviation for Magneto-hydro-dynamics which uses a jet of ionized gas particles flowing through a magnetic field to produce electric current. The theoretical efficiency appears to encourage hopes for a substantial gain in cycle efficiency. Page 40 into electrical energy and second generation units which are nearly 50% efficient. ? The fuel cell is under intensive research and development by both private industry and government. Progress is encouraging. In the abstract of a paper presented by L.R. Lawrence of the Energy and Research Development Administration (ERDA) at the July 1977 meeting of the IEEE Power Engineering Society in Mexico City, it was stated, "Clean, quiet, highly efficient power generation from a variety of fuels at a lower cost is the major objective of ERDA's fuel cell program ... It is presently projected that fuel cell technology can save at least 275,000 barrels of oil per day and over $1,000,000,000 of taxpayer money per year by 1985 ..." The Rankine Cycle steam electric plant has had the most development and can be the most economical. It can be powered by the full range of fuels from peat through municipal refuse, waste wood products, oil, gas, coal, and nuclear energy. Such plants, depending upon size, approach 40% efficiency. The 60% of the energy not converted to useful energy is in extremely low grade heat such as condenser cooling water with a temperature typically lower than 70°F and in stack gas with a temperature typically at about 300°F to 800°F. Approximately 15% of the input fuel energy appears in the exhaust and 45% in the condensing water. This stack gas has had the practical recoverable heat returned to the combustion air. Nuclear power is really steam power where the heat comes from a “nuclear fire". There is no hot exhaust, only tepid condenser cooling water. Such plants are presently operating at about 33% efficiency according to Dr. Kingsley Grahm of Westinghouse Nuclear Division as reported in a telephone conversation with Conrad Hilpert. Most of the waste appears Luecker, William J., Jr., and Casserly, James R.; "Fuel Cells for Utility Service", United Technologies Corporation. Page 41 as tepid condenser cooling water. This indicates that the best nuclear plants are less efficient than the best steam plants but are more effi- cient than the "average" steam plant. Diesel engines are one of the most efficient simple cycle means of con- verting chemical energy to electrical power. in theory the diesel cycle will burn any combustible material: coal dust, sawdust, animal fat, and all petroleum products. This idealism has been a popular subject for discussion, but as a practical fact diesel engines burn only high grade liquid petroleum or gas. Large multi-thousand H.P. engines can burn residual oil (almost tar, heated to fluid form), but smaller and smaller engines require better and better fuel. The waste heat from diesel engines is very low grade heat which appears in the exhaust and cool- ing water. The cooling water normally is in the 160-200°F range but it can be 250°F or higher with slight engine modification. Engines today are usually run at the cooler temperatures because of design simplicity, simpler operating routines, and first cost economy. The exhaust heat in a diesel is of higher temperature and more easily used than the cooling water heat, but higher initial costs and increased operating complexities are encountered when attempting to recover energy from the exhaust. Typically 30% of the fuel supplied to a diesel-electric set is converted to electricity, 30% is transferred to cooling water, 303% is exhausted as hot gas, and 10% is radiated directly from the engine block. Diesel engine developments in Europe (where incentives are more compelling) have produced the largest diesel engines in the world in stationary power generation service. Dr. Conrad R. Hilpert visited several such European installations in April, 1978, and reports equip- ment operating at approximately 47% efficiency. The equipment was operating in a combined-cycle (diesel and steam) mode with a steam turbine "bottoming cycle". These plants operates at approximately 47% thermal efficiency. Appendix C includes calculations of heat produced at the Kodiak power plant. According to the "Final Environmental Impact Statement - Proposed Trans-Alaska Pipeline" prepared by the United States Department of the Page 42 Interior in 1972, the pipeline's twelve pumping stations total to 648,000 HP. Each station contains four 13,500 HP units, with one on stand-by. According to literature supplied by the Cooper Bessemer Corporation, Mt. Vernon, Ohio 43050, these units have an efficiency of 27.7%. The "wasted" 72.3% of the fuel represents some 1,500,000 HP. This could heat 200,000 homes for six months per year at five gallons of oil per home per day. Obviously a market for such quantities of heat does not presently exist along the pipeline. An interesting concept advanced by Robert W. Retherford for the proposed gas pipeline could have a similar application here. (See "North Slope Natural Gas Transport Systems and Their Potential Impact on Electric Power Supply and Uses in Alaska", prepared for the United States Department of Interior, Alaska Power Administration, March, 1977.) If the oil pipeline were powered by electrical energy from hydroelectric or coal-fired plants, 5,800,000 barrels of oil per year could be saved. Such a system would obviously require an expensive electrical transmission system, as well as generating plants. The idea is worthy of serious consideration from the standpoint of making more oil available to sell, reducing waste heat production, and coincidentally providing a strong electrical tie through the rail-belt area. Gas turbines, widely proclaimed as able to burn “anything" are actually practical burning only gas or oil. The simplest form of the gas turbine (open cycle) makes no use of the hot exhaust gasses which typically are in the range of 1000°F. Efficiencies of such plants are usually in the 16-35% range. Improved efficiencies can be obtained using regen- erative turbines which use a heat exchanger to transfer a portion of the exhaust heat to the combustion air. Efficiencies of regenerative turbines are typically 10% better than the open cycle turbines. In spite of its improved efficiency, the regenerative turbine is not as popular as the open cycle turbine. If some alternate use of the exhaust heat is possible, that is usually preferable to operating a regenerative cycle. Page 43 Combined cycle plants can increase the efficiency of diesel engines and gas turbines to the extent that they are competitive with large steam plants. Combined cycle plants make use of the best technology of the steam cycle to produce electrical energy from the hot exhaust of diesel engines and gas turbines. The gas turbine or diesel engine is then used as the "fire" for a steam or other fluid Rankine Cycle system. Table 3 is a listing for comparison purposes of the conversion efficien- cies of a number of energy conversion processes. This can be used as an approximate guide for selecting machinery for a new installation. We must realize, however, that fuel cost and availability, first cost, and environmental considerations for a particular location must often receive as much attention as conversion efficiency. TABLE 3 ENERGY CONVERSION EFFICIENCY ULTIMATE DISPOSITION OF FUEL DESIRED EXHAUST COOLING WATER SYSTEM OUTPUT % % TEMP . °F % TEMP. °F Oil or Gas Turbine 16-35 65-84 800-1000 - - Diesel Engine 30 35) 300-600 35 160-200 Nuclear Fired Steam 33 - - 67 60-80 Coal Fired Steam 30-40 15 300-800 45 60-80 Home Furnace 60-70 30-40 350 - - Fuel Cells 35-40 - - 60-65 180-220 Regenerative Turbine 25-45 Soet3 700-900 = Other Sources Other places In our society discharge heat into our environment in addition to that produced by power plants. All the heat which heats our living quarters is wasted in one sense, but there are some addi- Page 44 tional "forced wastes". Public buildings often require two complete air changes per hour. Heating this fresh air can be a great part of heat- ing the building. Private homes usually have enough air leakage (which contributes to total heat loss) to supply normal combustion air and ventiliating requirements. Industry generates heat in processes such as making glass, brick, bread, ice, steel, and transportation, etc. If a user for this low grade waste heat is in economic proximity, waste heat capture is practical. Sewage contains waste heat. The average person contributes about 100 gallons of sewage flow per day. Much of this is waste hot water which is several degrees hotter than the sur- rounding environment and might be considered a waste of heat. How- ever, this heat is so low grade that its recovery is economically imprac- tical. In addition, warm temperatures help the bacteria digest the organic matter contained in the sewage. Especially in the arctic cli- mates this heat serves a useful purpose and probably should not be considered to be wasted. Mr. Thomas Hanna of the Alaska Department of Environmental Conserva- tion (ADEC), Juneau, supplied a printout of the ADEC Emission Inven- tory. Copies of the printout may be obtained from the above agency. Over six hundred pages of computer printout contain about every source of emission in Alaska except for homes and automobiles. Stack gas waste heat is not really useful below 300°F as heat will not flow unless there is a temperature gradient, so only sources with tempera- tures above 350°F were extracted. Over 200 sources had emissions over 350°F and of these, 31 had gas flow rates listed. These were totaled to present an idea of a "waste heat resource". Again, it must be pointed out that unless these heat sources are within economic proximity of a need for the low grade heat available, it is perhaps not really waste. Page 45 Calculation of Stack Heat Losses for Major Contributors: By use of the following equation, the number of recoverable Btu's per minute can be estimated. (Stack Temperature-300°F)(Specific Heat)(Flowrate)(Density )=Btu's/min. The specific heat of air at constant pressure is 0.241 Btu/Ib.-°F. The density of the exhaust gas is assumed to be 0.073 Ib/ft.. The flow- rate is given in cubic feet of exhaust gas per minute. The stack temperature is assumed to be the average temperature in the stack in degrees Fahrenheit with three hundred degrees as the minimum usable temperature for the stack gas. Example: Determine the heat loss in Btu's/min. under the following conditions: Stack temperature, 1000°F; Flowrate, 20,000 ft?/min. Solution: (1000°F - 300°F)(0.241 Btu)(20,000 ft*)(0.073 Ib) = 246,302 Btu/min. 1b-°F min ft A total of 31 locations reported a stack temperature above 350°F as well as providing a flowrate for their exhaust gases. These 31 locations represent a total of 6,075,713 Btu/minute which is equivalent to 569,435 barrels of oil per year. This figure, however, is anly based on a presumed use of 569,435 barrels of oil per year for heating in economic proximity to these 31 sources. It would be an error of thought to consider any of this lost heat a "waste" unless by individual study of each case it could be shown that there is some possible use for the heat. For these 31 locations, the Btu loss per minute is tabulated in Table 4. It must be noted that this list is not of THE sources of waste heat. It is only of those who had given useful data. There could be many times more sources, each of which could be of greater potential heat recov- ery. The list is a representative sample only. Page 46 TABLE 4 Some Major Waste Heat Sources In Alaska ‘Listed by Stack Temperature Stack Temp. Flowrate Recoverable Heat Location (°F) (Cfm) BTU's/MIN Ak. Lumber & Pulp, Sitka 355 76,000 75,537 Mun. Power Plant, Anchorage 360 28,700 30,295 Mun. Power Plant, Anchorage 360 33,600 35,467 Mun. Power Plant, Anchorage 360 29,500 31,140 Ward Cove Pulp Mill, Ketchikan 360 277,000 292,396 Collier Carbon & Chem., Kenai 370 40,972 50,457 Eielson Air Force Base 385 296,000 442,640 Adak Naval Communications Station 400 . 15,310 26,936 King Salmon Airport 400 2,900 5,102 U of A Physical Plant, Fairbanks 400 29,170 51,319 Lathrop School, Fairbanks 400 3,400 5,982 Murphy Dome Air Force Station 410 2,080 4,025 Collier Carbon & Chem., Kenai 420 204,000 430,677 Cape Newenham Air Force Station 440 2,020) 55714 Ak. Wood Products Mill, Wrangell 450 61,700 162,823 Ak. Wood Products Mill, Wrangell 450 49,000 129,309 Batch Plant, Adak Naval Station 500 25,000 87,965 Ft. Wainright HQ 500 15,355 54,028 Chugach Electric Assn., Anchorage 550 61,600 270,932 Phillips Petrol. LNG Plant, Kenai 500 15,500 81,807 Ak. Wood Products Mill, Wrangell 650 41,850 257,693 Anchorage ML&P, Ship Creek Facility 750 15,460 122,394 Collier Carbon & Chem., Kenai 800 31,620 278,145 Gilmore Data Acqu'n Facil., Fairbanks 850 400 3,870 Alyeska Terminal Camp, Cement Plant 930 28,000 310,340 Municipal Power Plant, Anchorage 970 120,000 1,414,477 Alyeska ACI Unit 3, Fairbanks 1,000 20,000 246 ,302 Alyeska ACI Unit 4, Yukon River 1,000 20,000 246 , 302 Alyeska ACI Unit 1, Gulkana 1,000 20,000 246,301 Fluor, Valdez City Incinerator 1,000 35,000 431,028 Alyeska Terminal Camp 1,000 20,000 246,302 Total: 6,075,713 Page 47 The other 200 "hot" sources which did not give flow rates, of course, could contribute more to the above, but no attempt was made to cal- culate their contribution to the total. The private industrial sources in this list are perhaps the most eager ones to accept suggestions as to how their waste heat could save money as their livelihood is based on economy. However, each case is unique. A fresh look at a source might point out a missed but lucrative saving to be made but on the contrary it may also waste valuable money and manhours in determining that there is no saving possible. Commercial Buildings A start was made to determine waste heat attributable to commercial, governmental and institutional buildings. This part of the study was not completed due to redirection by the initiating office. It should be mentioned, however, that if heat conservation is really of concern, the beautiful glass buildings so very popular might be out of place in any cold climate with long heating seasons. They perhaps are equally out of place in climates needing air conditioning. The loss through modern insulated walls can be 1/5 to 1/10 that which exists through glass construction. However, considering the quantities of heat required just to heat the ventilating air of public buildings, the wall heat losses of even a glass building are reduced in significance. For instance, a windowless building in Hershey, Pennsylvania uses ten times the amount of heat to heat ventilating air as is lost through the walls according to a letter dated April 7, 1978 from Mr. R.A. Zimmerman, President and Chief Operating Officer of Hershey Foods to Conrad R. Hilpert. However, the issue of how much glass a building should have is far from settled. According to Mr. Zimmerman, and Mr. Emil Zeller, Manager, Physical Facilities of the Woodward Governor Company in Rockford, I|linois both are completely satisfied with their windowless buildings. They state numerous advantages including very low heat cost. Mr. Zeller's comments are included in a letter to Conrad Hilpert dated April 17, 1978. Page 48 Material accompanying but not considered a part of this report includes listings of Anchorage's buildings by square feet area and number of stories. This listing was extracted from the files of the Anchorage Fire Department through the courtesy of Mr. Jack Steele, Fire Inspector/Public Education Officer. It could be used to approximate a waste heat source in Anchorage or other Alaskan city. Page 49 SECTION VI CAPTURING AND USING WASTE HEAT This discussion assumes that the system being considered is not already up to today's best technological efficiency limit. Cooling Water. Cooling water can be used in two ways: 1) The hot coolant from the engine or industrial process can be piped directly to radiators in the space to be heated, or to other process which can use the heat; or 2) the hot coolant can, via a heat exchanger, heat a medium, probably water, which will be used for space heating or other processes. Most engine manufacturers are very adamant in their "NO" on No. 1. A leaking radiator can destroy the engine, whereas in the second system the engine will be unaffected. Engine water must be soft and free of impurities that could reduce the heat transfer in the engine. This can be controlled in a small system using the same water over and over, but is much more difficult in a system where engine water is circulated through the heating system. No. 2 causes an additional inefficiency because heat exchangers lose up to about 20 degrees while transferring the heat from the heat producing loop to the heat using loop. This loss and the low temperature of cooling water from most processes force such waste heating systems to require about twice the radiators for space heat as would be required for an equivalent furnace in the cellar producing hotter water. Page 50 Exhaust Heat. 1. The stack gas or flue gas from combustion can be piped directly to gas-to-air exchangers to heat space or processes. This technique has been used in air-cooled automobiles for many years and in "stack robbers" which extract heat from the flue of a space heater. However, a leak from the exhaust into the "heated" air can be dangerous and therefore this system finds limited applications. Gas is hard to pump distances unless at high pressures. Exhaust gas is normally of relatively low pressure, and engines and tur- bines lose efficiency rapidly as exhaust pressure increases. Five ounces per square inch is a practical limit. Direct heat by exhaust gas is thus limited by two considerations, back pressure and contamination. 2. The exhaust gas can be used as the "fire" in a boiler or heat exchanger. Flue gas contains water, with each pound of liquid fuel burned producing over a pound of water which appears as superheated steam. Cooling this gas to the condensation point produces liquids which allow high temperature corrosion to take place. Most boiler designers place a low limit of well over 300°F on the flue gas outlet temperature. Simple cycle plants with high temperature exhaust can supply good amounts of heat. An exhaust heat boiler on an up to date coal fired steam plant is pointless as the whole plant is the most efficient "exhaust heat boiler" known. Heat Wheel (or Rotary Regenerator). Recently the "Rotary Regenerator" has been popularized by the various automotive gas turbine attempts. It is an old device which while very efficient and compact has a high contamination factor. The basic prin- ciple of operation is quite simple. A wheel with good heat (and pos- sibly humidity) absorbing capability is continuously rotated with one half of the diameter enclosed in the "hot" air and the other half in the Page 51 "heated" air. The wheel continuously absorbs heat and possibly humid- ity from the exhaust or "hot" portion of the system and transfers it to the incoming air or "heated" portion. Used to transfer heat in a gas turbine it is near ideal. Used to recover ventilating heat in a theater, it will be near ideal in conserving heat and humidity and also near per- fect in returning everyone's exhaled breath and perspiration. However, such devices are receiving increasing attention in applications for commercial buildings. Heat Pipes. Heat pipes are a simple, passive, highly effective device for trans- ferring heat. They basically consist of a highly volatile fluid such as Propane contained in a sealed container at a critical pressure. Heat applied to one end will vaporize the fluid, with the heat required to vaporize the fluid being absorbed from the medium surrounding the heated end. As the vapor thus produced rises to the cooler end of the heat pipe, it radiates sufficient heat to condense the vapor to a fluid which trickles back to the hotter end of the heat pipe. This process continues indefinitely without the addition of external power. These devices are variously known as heat pipes, frost tubes, thermal piles, or Long piles after their inventor, Erwin Long. They find such di- verse applications as transferring heat from internal components in compact electronics packages to supporting sections of the Trans-Alaska oil pipeline, or to prevent thawing of permafrost adjacent to utility poles. Where their unique characteristics are needed, their cost is reasonable. However, they generally cannot compete economically with simple heat exchangers such as hot water radiators. Heat Pumps. These are very common, the most familiar application being the refrig- erator found in most kitchens. The refrigerator removes heat from the Page 52 butter and bacon and pumps it into the kitchen. A heat pump can just as well pump heat from "cold" water or the "cold" outside into the home. However, using a warmer heat source causes such devices to be more efficient. Heat pumps today are commercially practical in mild climates where seasonal heating and cooling of approximate equal amounts are neces- sary. In severely cold climates where no real need for air conditioning exists, home furnaces nearly always show good fuel saving compared to good heat pumps. However, heat pumps can be fuel efficient when compared to resistance electric heating and are first-cost efficient when compared to a furnace and air conditioner.?’4 Commercial units are not fuel efficient for heating only when compared to a "furnace in the cellar", and initial cost is many times the price of a furnace of equal heating capacity. Using warm water as the heat source, the heat pump becomes more fuel efficient, but not appreciably. A heat pump of modern design, having a coefficient of performance (C.O.P.) of say 3, produces a heat output of 3 units for an equivalent unit of input. In other words, one unit in equals 3 units out. However, if the source of electrical energy for the heat pump is a fossil-fuel plant having 33% efficiency, we have about a breakeven situation. Three "units" of fuel will produce one unit of electricity. This one unit of electricity, by operating a heat pump can produce 3 units of heat. The original three units of fuel, if burned in a typical home furnace can produce over two units of heat. The above mentioned C.O.P. of 3 for a heat pump can be realized if a relatively "warm" source is available. If hydro power generates the electricity to drive the heat pump, heat pumps can heat a home with less fuel than a furnace of equal capacity. Dervin, Ronald; Popular Science, September 1976, p. 92. General Electric Co.; Publications 25-6516-02, 22-3047-3, 25-6240-75. Page 53 Combined Cycle Plants Combined cycle plants have been mentioned above. Generally speaking, the Rankine thermal cycle can accommodate the greatest temperature range. It is the thermal cycle steam locomotives used. The steam locomotive exhausted to the atmosphere and was doing very good if it obtained 6% overall efficiency. The condensing steam turbine plant refined to its utmost is almost seven times as efficient. It is more efficient than the reciprocating steam engine mainly because it can profit more from exhausting into a high vacuum in the condenser. If a gas turbine or diesel engine is allowed to be the heat source for a boiler feeding a condensing steam turbine the steam turbine is able to capture some of the waste heat. Combined and binary or trinity cycles are not new. Long before World War |i the heat from coal was used to boil mercury which blew down through a condensing mercury vapor turbine. The mercury condenser was the boiler for a condensing steam turbine. These plants were the most fuel economical of the period. Present technology allows systems to operate at such pressures that steam can be raised to the temperatures formerly practical only with mercury cycles. As a result, the mercury cycle is no longer attractive. Fluids which boil at lower temperatures than water are often used in "bottoming" cycles. These fluids are usually organic compounds; thus the name Organic Rankine Cycle has come about. Any exhaust with a temperature of greater than 500°F is a possible heat source for these systems. These systems are new and in "preproduction" or in field trial production. They are expensive and can only be justified because of their use of free heat. However, they do exist now and we are seeing increasing interest in their future development. Page 54 LIMITATIONS TO THE CAPTURE OF WASTE HEAT Since anything manmade can be improved by man, it can be truthfully said that we waste more heat than we absolutely have to. However, it is one thing to point out a heat waste (that was probably well known to the system designer) and another to find something in economic proximity that can use the waste heat. The capture of the waste heat from a modern steam electric or nuclear electric plant is quite simple, but not often practical. Some use within a few hundred yards of the condenser outlet must be found for water at less than 100°F. A 50 MW station could condense 400,000 pounds of steam per hour. This would require about 40,000,000 Ibs. of condenser cooling water per hour. This would be a stream of water at 88°F, 20 feet wide, and one foot deep running 6 miles per hour. This amount of water could make 45 square miles of desert as well irrigated as Juneau, Alaska. The stack gas of such a station is very low (250°F) in temperature. Opportunities are limited to use it effectively through heat exchangers to heat anything because it is at too low a temperature. However, it might be used to heat a hothouse garden directly when not populated. Gas turbine waste heat is mainly in the exhaust gas with outlet temper- atures of around 800° to 1000°F being common. This exhaust can be used to power the steam portion of a combined cycle plant or to power an exhaust boiler used to produce process steam or hot water. The amount of heat available will vary depending upon the particular machine characteristics. Even if a nearby use is found for such steam or hot water, only about half of the available heat can be captured. As stated previously, if the exhaust is cooled below about 300°F corrosive conden- sates are formed which cause new problems. Page 55 Diesel engines generally stated produce 30% shaft power, 30% cooling water heat, 30% exhaust heat, and 10% radiation. All of the cooling water heat, about 4 the exhaust heat, and all of the radiation can be usefully captured if space heat needs are in economic proximity. Section 1V discusses methods of determining if economic proximity exists. Appendix C includes waste heat calculations for the Kodiak power plant. Industrial process heat can be captured in about the same manner as described above for power plant exhaust. Stack gas at 1000°F is about the same whether from a glass furnace, diesel engine or gas turbine. Recovering heat from hot process water of an industrial plant is faced with the same limitations existing in recovering heat from cooling water in power plants. The waste heat from buildings is better not wasted than captured. Better insulation and heat exchangers in the ventilating air are about all that can be done. It becomes futile to consider waste heat capture efforts in a building whose glass walls lose ten times the heat a well insulated wall might. The original design was hopefully based upon the premise that in one way or another the glass walls were worth the added first cost and the added cost of heating and cooling, as compared to well insulated walls. Waste heat capture from processes which do not have heating as a primary goal must deal with the problem of the heat load requirements being non-coincident with the requirements of the main process. If an electric power station was intended to power only resistance heaters in homes, the waste heat would be available exactly when the heat load was greatest and there would be no coincidence problem. If the electric plant is intended to power non heating loads there will be times when the waste heat is not available but heat is needed and vice versa. in the summer down South, air conditioners present peak electrical loads to electrical utilities, but at this time waste heat is not needed. In other words, electrical demand is at its highest level which causes Page 56 maximum waste heat to be produced, but a market for the waste heat does not exist. Time-demand curves for a typical electrical utility show peak electrical load from 11 a.m. to 6 p.m. and minimum load at 3:30 a.m. This is almost exactly out of phase with the outside temperature. Thermal plants in general do not supply waste heat to outside loads because of the necessary commitment to supply heat even when it is not being made and the user demand being low when heat is available. Depending upon individual circumstances, use of supplemental electric heating can sometimes partially offset this disadvantage. A very successful diesel engine waste heat system is in use at a mine in Arizona. Steam is needed for industrial processes and enough diesels are run to make the required quantity of steam. The electrical load is so great that several thousand HP can be absorbed anytime the plant and mine are working. Even here direct fired boilers are being installed as a more economical method to produce steam during periods of low engine loadings. Low engine loadings can be experienced during slack periods in the mine, etc. Efficiency and per unit cost of waste heat systems suffer drastically when operated at less than full rating. For instance, a waste heat boiler might provide only 25% of rated output when the exhaust gas source is operated at 50% load. Also, an investment of say $800 per kW in waste heat recovery equipment represents $3200 per available kW when operated at 25% load. When heat supply and demand are not coincident, some method of stor- ing heat can contribute to improved overall efficiency. Such storage of heat is not a new idea. Locomotives called "fireless cookers" have been employed for many years in plants where fire hazard is great, such as explosive plants. These locomotives contain a large insulated pressure tank in which hot high pressure water is stored and allowed to boil off to steam each time the throttle is opened. In such applications one charge of the boiler often lasts up to eight hours. Page 57 A single tank of water 16' x 16' x 16' could store one hour's jacket cooling water waste heat from the largest diesel engine in Alaska. A small "bush" type 135 kW unit could store radiator and exhaust heat generated in an hour's running in a tank 9' x 9' x 9'. A whole day's running would only be a tank 25' x 25' x 25'. In areas where freezing is a problem, antifreeze costs and special antifreeze measures must be taken. The technology of heat storage is simple, but storage is not free, and the cost of the heat storage must be paid for by the fuel it saves. The capture of waste heat is limited by three considerations. Ae Can we capture the waste heat? 2s Do we have a use for the heat within economic proximity of the heat source? 3. Can we afford to capture the waste heat, or is it cheaper to burn the fuel in a home furnace? Each of these questions must be answered in the above order. Every heat producing installation has had these questions answered satisfactorily in light of the limitations in effect when designed. Tech- nology advancements continue to reveal some new possibilities, but economics, regulatory policies, or lifestyles may prevent implementation of available technology. For any given set of circumstances, a period- ical review should be made to determine if economic factors or tech- nology have changed enough to reveal new possibilities for utilizing waste heat. Page 58 SECTION VII USES FOR WASTE HEAT The U.S., following the 1973 oil embargo, found itself awakening to a new era, the energy awareness era. The previously always available supply of fossil fuels can no longer be taken for granted. Alternate forms of energy must be investigated and made readily accessible. However, because oil and gas will not be substantially replaced by these alternate sources of energy before the early part of the next century® and because of the ever increasing costs involved, it behooves fossil fuel users to obtain maximum utilization of these fuels. In utilizing the energy stored in fuel, for heating or to produce work, losses occur. In diesel engines, these losses are manifested in several ways, namely in friction losses, in heat rejected to the exhaust gas, and in heat rejected to the cooling water. Due to the laws of thermo- dynamics, some of these losses cannot be recovered. However, because of the ever increasing price of fuel, it is worthwhile to periodically investigate the economics involved in converting the recoverable part of what would normally be losses to useful working energy. Several methods are available to utilize the energy present in waste heat. Among them are space heating for offices or dwellings, space heating for commercial greenhouses, water heating for aquaculture or public water facilities projects, fish farming operations, and bottoming cycles to generate electricity or shaft horsepower. These methods are investigated in greater detail below. Herman, Stewart W.; Inform, Inc.: Energy Futures. Ballinger Publishing Co., 1977. p. 661. Page 59 Space Heating of Offices and Dwellings The lowest capital investment for return currently possible can be achieved through the use of wasted heat for space heating of a nearby facility without resorting to any form of heat storage. One method for using the waste heat for space heating is to take the heat from the ceiling of a high temperature area and transfer and distribute it to a cold area. Ceiling temperatures have been recorded as high as 190°F according to Robert Curl in a technical paper, "Prac- tical Applications of Heat Recovery Systems" presented to SME in 1976. This method could be implemented in a generating facility in order to capture the radiator heat from the engines. It is interesting to note the increasing frequency with which advertisements are appearing in the trade literature for overhead fans which are designed to mix the air and thus equalize the temperatures at the various levels in a room. Many of these devices are the open-bladed slow-speed fans so common in commercial establishments before refrigerated air conditioning became so commonplace. Though those fans were designed primarily for cooling during the hot months, they can also be very effective during the heating months by distributing the hot air near the ceiling to the lower areas. An additional plus for such an installation is that with lower ceiling temperatures there is less loss of heat through the ceiling. Jacket water heat and exhaust heat are available for space heating of offices and dwellings. Many of the manufacturers of generating equip- ment provide methods for efficient use of these sources of waste heat. This use is accomplished by connecting a series of devices which con- trol and monitor the flow of heat through a system such that this heat may be most effectively used for the above described purpose. Figure 5 shows a system presented by Donald Dehn of Dehn Engi- neering Sales, Seattle, Washington, and Figure 6 shows a system pro- posed by the Caterpillar Company. Both these were presented at a Northern Machinery Company Waste Heat Seminar in Anchorage in 1978. ifs. ENGINE. SPACE HEAT — hump THEEmMOgTaTic : (?) i FAvIATCR. THERMU STATIC VALVE @ENERAIOM | -——v. ites FAN MoToR. a | 14 | ENGINE 4 { in | Sr SS Le O— - 1! ean v TMeemostanic a SN JACKET- WATER WASTE HEAT RECOVERY SYSTEM FIG. 5 TO REMOTE HEAT LOOP rh FROM CEMUTE / WEAT LOOP EXPANSION che TANK THERMOSTATIC. VALVE | “ a es A o |, atA tle ole or | - c ° w \ THEM OsTaTIC. BoosTes ContactoR TYPICAL FLOW RATE = 295 GPM auld JACKET- WATER AND EXHAUST WASTE HEAT RECOVERY SYSTEM FIG. 6 Page 6( Page 61 In the case of transferring heat in steam to water, the water may be stored, maintaining a constant volume and a variable temperature. This method, correctly designed, can help to prevent peak loads from being imposed on the system. This can be accomplished by designing the system such that when hot water is drawn off to service, cold water rushes into the tank, usually through a ball valve, striving to maintain the water level. The jacket water heat in a generator is almost totally recoverable and about 60% of the exhaust heat is recoverable. In the case of a 600 kW generator, this represents a thermal output of 31,300 Btu/min (jacket water) plus 22,500 Btu/min (exhaust to give a total output of 53,800 Btu/minute) according to information supplied by Caterpillar at the N.C. Machinery Waste Heat Seminar. From the relatively simple system discussion above, it is possible to extend the concept to very sophisticated district heating systems. The following excerpt from Sweden Now, 1972® describes the level that has been achieved in Sweden. One big power station [serves each] community instead of one furnace per house. An underground network of pipes conveys hot water to heat all the buildings connected to it. This is district heating -- so far the cheapest, most practi- cal and laborsaving method of heating large areas, and which results in a dramatic reduction of air pollution in the cities ... One major city in Sweden can boast a complete advanced district heating system: Vasteras, 70 miles west of Stock- holm. it has 120,000 inhabitants, 90% of whom have been connected to a district heating network which has blessed the town with "Sweden's purest city air..." Sweden Now; "District Heating by Underground Network is Clean and Cheap", Vol. 6, No. 3, 1972, pp 42-43. Page 62 The power station, which is oil-fired, produces both elec- tricity and heat. The energy which cannot be used for the generation of electricity, and would otherwise be wasted, is now removed by the water circulating in the closed district heating circuit. The water has a temperature of 175-265°F (80-115°C) when it reaches the subscribers, while in the return pipes it is down to 130-150°F (55-70°C). Each household pays a fixed annual fee plus an energy charge based on its actual consumption. The grand total is lower heating costs than in traditional heating systems. An additional advantage is that the return heat is used to keep streets in the center free of ice and snow in the winter through a pipe system just under the street surface. All space heating systems should be designed to consider other possible internal sources of heat gain. The term "bootstrap heating" is used to describe those heating systems which are able to derive their heating requirements from waste heat generated within the building. The charts of Figure 7 describe graphically the common sources of "boot- strap heat" in buildings. To approximate the amount of heat produced by a particular source (we will use lights in this example) proceed as follows: 1. Determine the lighting load in kilowatts and the gross square footage of the building. es Locate the intersection of these two values on the appropriate graph. 3. _Interpolate within the family of curves "Btu/sq.ft./hr." to determine the heat produced by lights in this building. 4. Multiply this value of Btu/sq.ft./hr. by the gross square footage of the building to determine the approximate total heat generated by lights in the building. FANS & PUMPS BHP. INSTALLED 4H.P. INPUT Kw o 1+ 2% 8% 4 se GROSS SQ.FT (100,009) | 2 BS 4 5. e GROSS SQ.FT. (100.000) UNIT HEAT PICK-UP FROM ELEVATOR EQUIPMENT ROOM ° 1 2. os s 4S © GROSS S@FT. (100,000) UNIT HEAT PICK-UP FROM TRANSFORMERS Kw. INPUT OF USEFUL LIGHTING (100) ny oO ny ° ) a erg uve pews ee OT whe tere EXHAUST (i000 crm) uw GROSS SQ.FT. (100,000) UNIT REAT PICK-UP FROM NECESSARY EXHAUST e000 400} 200 KW. INPUT AT WINTER DESIGN y ° (ir 3 4 5 e GROSS 3$Q.FT. (lOQo0E UNIT HEAT PICK-UP FROM INPUT TO WHEAT PUMP ’ 2 _ eS GROSS SQFT (roqood) 6 UNIT HEAT PicK-UP FROM LIGHTS "BOOTSTRAP" BUILDING HEAT Fig 7 Page 64 This same procedure can be followed to determine the heat available from fans, pumps, elevators, exhaust air, etc. Greenhouses Air temperature, relative humidity, and air circulation are carefully controlled in modern greenhouses. Because of rapidly alternating heating and cooling requirements, greenhouses are difficult structures to heat. With current techniques, heating is usually accomplished by radiators heated with steam or hot water. The energy for heating is usually derived from coal, gas, oil, or electricity. Cooling require- ments are met by ventilation, or ventilation in combination with evapora- tive cooling pads. Ventilating air is drawn through a water soaked curtain or pad with the air being cooled by providing energy to evap- orate water from the pads. Warm water can conveniently be used to provide the energy for heating greenhouses. The design of the heating system would depend on the temperature of the warm water. If the temperature is sufficiently high, conventional finned-tube heat-exchangers can be used. This tempera- ture should be about 40°C or higher. At lower temperatures the size of the finned-tube heat-exchanger rapidly increases and a more expen- sive installation results. Warming the greenhouse soil can also be accomplished by circulating warm water through a network of underground pipes’ Estimates are that the waste heat from a 1000 megawatt power plant would heat sev- eral hundred acres of greenhouses.® This heat per area factor means that in a typical Alaskan arctic village the two 300 kW generators might heat a greenhouse 70 feet square by use of auxiliary storage, radiation, Boersma, L. and Rykbost, K.A.; "Soil Warming With Power Plant Waste Heat In Greenhouses", HortScience 10:28-30, 1975. Public Utilities Fortnightly; March 16, 1978, p. 57. Page 65 and pumping equipment.® The soil is maintained at a desirable temper- ature and the heat escaping through the soil would be available for warming the greenhouse air. Theoretical considerations and experi- mental measurements indicate that the heating capacity would not be sufficient to keep the greenhouse air temperature more than a few degrees above the outside air temperature during the night and auxil- iary heating would be required. This application has the advantage that it allows a rapid warming of the soil in structures which are not in use during part of the winter. Increasing the soil temperature by this method has been demonstrated to increase production. ’ In areas such as Alaska where the growing season is short but the days are long, a well balanced waste heat agricultural complex might allow for more products, which are now imported from the lower 48 states, to be produced locally. The usual "hot house" start for Alas- kan vegetables could be aided by.waste heat, but even this would only use heat for a few weeks of the year. Heat storage costs and hot house costs are unable to compete with freight. For example, bananas are relatively inexpensive in Alaska even though they must be trans- ported great distances. Assume "several hundred acres" = 625 acres. Assume 1 generator running constantly @ 60% load -6 x 300,000 watts = 180,000 watts 180,000 watts T,000,000.000 watts x 625 acres/1000 MW = .1125 acres > > , -1125 acres x 43560 sq.ft./acre = 4,900.5 sq.ft. 4,900 sq.ft. plot 70 ft. x 70 ft. Page 66 Aquaculture Aquaculture is the growing of fish under controlled conditions. It has been practiced for centuries but its commercial value has only recently been recognized. The most highly developed aquacultural operations are in Japan. Many fish species of commercial value have a limited optimum tempera- ture range. The benefit of temperature control with respect to produc- tion capacity is great. Shrimp grow 80 percent faster in water at 27°C than in water at 20°C.!° The energy required to heat open-air water basins for fish culture would be very large and the cost of energy would be prohibitive if it had to be produced locally for the specific purpose of heating the basins. However, reject energy might be advan- tageously used for this purpose. The basins would be heated by pumping the warm water through submerged pipes or external heat exchangers. The temperature of this water should be about 35° to 40°C. The size of the heating system is determined by climatic condi- tions and temperature of the warm water. A potential for the development of aquaculture lies in the use of the fish product for cattle feed. Fish meal has long been an important component of animal feed. Aquaculture would be an important com- ponent of an integrated agricultural production scheme. Bottoming Cycle Turbines Driving Generators Bottoming cycle systems differ from other methods of waste heat utiliza- tion in that they generate either electricity or additional shaft horse- 10 Yarosh, M.M., et al; "Agricultural and Aquacultural Uses of Waste Heat". Oak Ridge National Laboratory Report, ORNL-4797, July, 1972. Page 67 power from the rejected heat of another engine. The term "bottom" comes from the idea that these heat engines are running off bottom temperature heat, or heat which would normally have been discarded. Virtually all the systems commercially available today are Rankine cycle engines. A simplified diagram of a Rankine bottoming cycle,?? illus- trating several possible sources of waste heat, is shown in Figure 8. As the diagram indicates, waste heat (Q) from a source is exhausted through a vapor boiler to vaporize a working fluid. The working fluid is used to drive a turbine. It is then condensed and returned to the cycle. As is noted in the diagram, approximately 20% of the energy available in the heat can be converted to work. According to a survey made by Inform, Inc., there are four organiza- tions currently involved in the design and construction of bottoming cycle equipment. The summary from Energy Futures by Herman is shown in Table 5. TABLE 5 Bottoming Cycle Summary Company; Business Major projects and objectives J. Hilbert Anderson designed and built 10-Mw organic-fluid engineering firm turbine for Magma Energy; hopes for other geothermal-related work. Barber-Nichols Engineering has designed and built small organic- engineering firm fluid systems to drive air-conditioners; wants to design and build custom bottoming cycles for industrial clients. Sundstrand designed and built 100-kw organic-fluid diversified industrial "total energy" systems in program with manufacturer the American Gas Association; hopes to produce 600-kw bottoming cycles. Thermo Electron sells 500-5000-kw steam bottoming cycles; producer of heat- is designing and building 500-kw organic- transfer equipment fluid bottoming cycle for ERDA and hopes to produce such systems commercially. 11 Sundstrand Energy Systems; "600 kW Organic Rankine Cycle", Rockford, Illinois, December 1977. GAS TURBINE BOTTOMING CYCLE WORK = 20% Q TURBINE VAPOR BOILER CONDENSER COOLANT INCINERATOR TYPICAL BOTTOMING CYCLE INSTALLATION FIG. 8 (SUNSTRAND, 1977) ) eBey Page 69 In addition to the firms listed by Inform, Inc. another company, Mechanical Industries, Inc. is also involved in this area. The obvious advantage of a bottoming cycle is more electricity or shaft horsepower output for the same fuel input. However, there is also a not-so-obvious advantage. By recovering waste heat from fossil fuel generation systems, the thermal pollution per kW generated will be reduced and air pollution will possibly be reduced as a result of burn- ing less fuel directly. Thermo Electron Corporation is in the process of writing bottoming cycle waste heat utilization proposals for several Alaskan sources. When the definite numbers costs and figures in these reports have been evaluated, an accurate economic analysis can be made. However, even before actual costs have been proposed, several observations can be made: 1. The economic justification for any equipment purchased comes from the fuel saved. In the Alaskan bush where, because of load fluctuations, generator units cannot be base loaded, the output of the waste heat generator cannot always be maximized. Not only does this increase the payback period required, but close attention must be paid to running the primary diesel engine at its optimum maintenance efficiency. 2s For new generator installation, cost comparisons must be made between: a. more expensive generators with equivalent fuel/kW output, and b. less expensive generators with added bottoming cycle equip- ment. Page 70 Other Uses A number of other uses (limited perhaps only by one's imagination) exist for waste heat. Without attempting to discuss the advantages, disadvantages, or limitations, we list several below: Product Preheating Absorption Refrigeration or Air Conditioning Drying Operations Preheating of Process Air or Fluids Sidewalk Snow Melting These are highly industrialized uses. Heat has most use in industry for other things than comfort space heating. The most highly indus- trialized and technological societies use heat most efficiently simply because they have use for low grade heat. Page 71 SECTION VIII UTILIZATION OF WASTE HEAT IN ALASKA General Comments The current "energy awareness" popularity has called forth a number of Alaskan projects which utilize waste heat in an effort to conserve fossil fuels. However, at least three rural Alaska utilities utilized waste heat prior to the onset of the "energy crisis". The military in Alaska has long co-generated electricity and steam for heating at rural and urban bases. Fairbanks has for many years provided heating steam in the downtown area as a by-product of electrical generation. The University of Alaska at its Anchorage and Fairbanks campuses has installed electric and heat co-generation facilities. The UAF facility is intertied with the Golden Valley Electric Association, Inc. and has an energy interchange agreement. The UAA facility has not consumated such an agreement with Anchorage Municipal Light and Power. How- ever, negotiations for such an agreement continue. Historical Waste Heat Utilization Perhaps the most successful waste heat utilization is at Kotzebue. The Kotzebue Electric Association (KEA) has installed exhaust silencer/waste heat boilers on four of its generators. The original installation on two generators occurred in 1969. Three of these units and the generators' jacket water provide heat to the city water system and the KEA office. KEA charges the city for the heat required to heat the city water supply. This charge originally was 63% of KEA's annual $11,500 oper- ating cost. KEA has recently recomputed its annual costs, including current maintenance and fuel costs. This amounts to $123,600 with the city's share, $88,635, twelve times its original cost. The City of Kot- zebue has not accepted the new cost estimates and is negotiating them Page 72 with the utility. It is our understanding that the utility's records are not detailed enough to establish accurate incremental costs. A greenhouse at Sport Lake near Soldotna on the Kenai Peninsula was originally intended to optimize the gas flow from the well which supplied the Consolidated Utilities, Inc. power plant according to Sam Matthews, Chief Engineer of Homer Electric Association. While the greenhouse directly burned the gas for heating, it reduced waste by increasing the total gas recovery from the well. Ironically, with increased market for natural gas, the greenhouse opera- tion became less desirable. Consolidated Utilities, Inc. went bankrupt in 1972 and the power plant ceased to operate at that time. Mr. Gordon McCormick, General Manager of Naknek Electric Association, furnished helpful information about that utility's waste heat operation. Naknek Electric Association, Inc. (NEA) has supplied waste heat to the Naknek elementary and high schools for ten years and also heats its own offices with waste heat. The schools are about one quarter mile from the NEA plant. NEA originally utilized both water jacket and exhaust heat. However, the exhaust heat silencer/waste heat boilers corroded and rusted away after two years as a result of condensation which occurred after the engine shut down. This occurs frequently at NEA, because of typical variations in electrical demand during the day. Presently only jacket water heat is used to heat the school. NEA recently rebuilt its waste heat recovery system for an estimated cost of $52,000. The schools will repay this investment in about three years. The system uses "lightly insulated" four inch iron pipe and a heat exchanger in the plant and the school. The heat exchanger at the school heats the hot water supply. Apparently operating costs of NEA are not broken down in such detail to permit a determination of added costs caused by waste heat recovery. Page 73 Alaska Commercial Company, formerly Northern Commercial Company, uses "total energy" package generators to provide heat and electricity to its stores at various rural locations around the state. The Chugach Electric Association, Inc. (CEA) in Anchorage has sold process steam from its Knik Arm power plant since its acquisition in 1959 according to Mr. G. Stromberg of that utility. Prior to that time the Alaska Railroad, the former owner, had sold process steam. The steam was used by the railroad, Anchorage Cold Storage Co., the Alaska Native Hospital, and several warehouses in the area. Recently, the Knik Arm plant has become inefficient to operate due to increases in the cost of fuel and labor. Contractual committments require CEA to continue supplying steam to the railroad or CEA would shut down the plant. CEA has terminated steam sales to its other customers. It is of note that co-generation, even with on-hand facil- ities and heat customers does not guarantee ar: economical operation. CEA also selis steam to Standard Oil from its Bernice Lake power plant. Projected Waste Heat Utilization There are several projected and potential waste heat utilization projects around the state. Information concerning an installation presently being installed by Anchorage Municipal Light & Power (AML&P) was provided by Mr. Miles Yerkes and Mr. H. Nikkels. AML&P has a combined cycle steam turbine under construction which uses high quality steam from a waste heat boiler attached to two simple cycle gas turbines. The process steam exiting the turbine is used to heat the city water supply and is cooled in a water tower. AML&P estimates the cost of this equipment to range between. $205/kW to $260/kW. They presently have no estimate of the total project cost. Page 74 CEA expects to complete a combined cycle turbine installation at their Beluga plant in 1979. The total project cost is $40 million or $606/kW. This installation is very similar to the AML&P project, except that its Beluga location precludes the use of process steam for water heating. - The North Slope Borough plans to install a waste heat boiler on a new gas turbine located at Barrow. The heat would be utilized for district heating. Higher than anticipated construction costs have precluded installation of the waste heat boiler. Presently the borough has sus- pended installation of the waste heat boiler indefinitely according to Mr. John Howell, Consulting Engineer. The Golden Valley Electric Association, Inc. has installed two "regen- erative cycle" gas turbines at North Pole. These turbines are more efficient than comparable simple cycle turbines, thus increasing output and reducing fuel consumption. Potential Waste Heat Utilization The technical capability for utilizing waste heat is well established. The primary constraints for utilizing waste heat are economic. Waste heat becomes more feasible when the heat load is proximate to the heat source and evaluation of potential utilization should center on this rela- tionship. Most Alaskan utilities generating with fossil fuels can utilize waste heat for office and plant heat. Institutional buildings close to power plants should be evaluated for waste heat utilization. Where city water pump stations are close to the power plant, utilization of waste heat for water heating should also be considered. Table 6 shows potential waste heat applications for several AVEC vil- lages. These and all waste heat utilization projects are justifiable when the fuel cost savings are greater than the cost of waste heat utilization equipment and operating costs. Village Chevak Elim Emmonak Goodnews Bay Kiana Lower Kalskag Kivalina Nunapitchuk Quinhagak Scammon Bay Selawik Shageluk Shishmaref Shungnak St. Mary's St. Michael's continued... TABLE 6 POSSIBILITIES FOR WASTE HEAT CAPTURE AT THE AVEC VILLAGES Heat Load(s) School Armory or School School School Primary School PHS Pump House Community Hall School Health Clinic Community Hall and Health Clinic Primary School and Health Clinic PHS Pump House and Community Hall PHS Pump House and High Shcool Store and Warehouse PHS Pump House PHS Pump House, Community Hall Use Space Space Space Space Space Water Space Space Space Space Space Space Water Space Water Space Water Water Space Heating Heating Heating Heating Heating Heating Heating Heating Heating Heating Heating and Heating and Heating Heating Heating and Heating Page 75 Notes Long transmission distance School has 3 buildings Power plant may be too smail Power plant may be too small Power plant may be too small Power plant may be too small Possible with adequate load factor Next door to pump house, fairly close to school Construction camp a possibility Power plant isolated Page 76 Village Heat Load(s) Use Notes Toksook Bay Primary School Space Heating Wales PHS Pump House, Space and Power plant may be Post Office Water Heating too small Page 77 Figure 9 shows another potential method for utilizing waste heat. This method takes advantage of one of the most important items controlling the economic viability of a waste heat project, proximity of source to load. By constructing the schools, the power plant, the health clinic and all other community service facilities in one building, optimum use can be made of the available waste heat from the power plant generators. An artists conceptualization of a practical community total energy system is included. !t can be seen that several forms of waste heat recovery are being utilized. Convection heat from the engine block, when required, can be drawn into the gymnasium by hot air circulating fans (4). When the gym- nasium no longer requires heat (midsummer) the same engine block convection heat can be vented through the waste heat louvers (6). Heat is also recovered through engine heat recovery silencers and jacket water heat exchangers. A hot water storage tank is shown for heat storage during instances of greater heat production than demand. Because the waste heat available will not always meet the heat load required, as when all diesel generator sets are down, an auxiliary heating boiler is shown. A power plant expansion can be accomplished by expansion into the community hall, city office, court house and jail area (12) with a simul- taneous addition to the building to house the displaced office. This scheme, as most any other, has disadvantages as well as advan- tages. Some of the more obvious disadvantages are the noise of the engines and the smell of fuel which can be present in the complex if proper design, installation, operation, and maintenance precautions are not taken. A more pressing disadvantage is the fire danger. A prop- erly designed, installed, and maintained system should pose very little UNITY KEY TO PRACTICAL Cons: TOTAL ENERGY SYSTEM O1AGRAM iy A 1 -2 2 | me ae ‘a s | / 4 g 8 Pee i z Pelt Ee i i ee ‘y « = Sy eile é Qi ills 3 | z . . | Bs 5 3 re Fe mee WANN le . | eee eile a SESS ER ye ey 2 ee ee Ce eles o edie s PS2h 528 gis - Sis SSS sig © Elis 6 F eles 6 ieee eis esl 88 = i OQOO©CHOOS SO A PRAGPFZCAL commuUNITy POTAL LYLAGY S¥YaTuM Ss ~IM~ WES CRA TATA -NEW* bx) soncey e ntretsroag FIG. 9 “9mMI--~ jses = sis Ee iss < re ls = iba A) Re Page 79 fire danger, but in Alaska we know from experience that power plants do burn down. If the power plant in this proposed complex were to burn, it would most likely destroy the total complex. That fact alone should not prevent us from building such installations. With proper design the power plant can be built to be practically immune from burning down and at only slight additional cost. However, to maintain that immunity, strict operating practices must be adopted and adhered tO; Page 80 SECTION IX STATE OF THE ART HEAT RECOVERY EQUIPMENT Heat Exchangers. These are mass-produced and are available commercially for nearly any need. Gas to gas, liquid to liquid, gas to liquid exchangers for any temperatures, sizes, and pressures are usually catalog items. Heat recovery units are pre-engineered and stocked by engine suppliers. One does not have to go to unique types for any recovery need. This is especially true for the automotive engine sized generation units. See, for example the Young Radiator Company literature and prices in Appendix D. Exhaust Gas Boilers. These are commercially made by several companies. There is much more competition in large units which are fired by multi-megawatt engines and gas turbines than for the automotive engine sizes. Exhaust boilers require certain operational procedures as is true of any fired boiler. They can blow up, burn out, plug up, soot up, scale up, and crack. As a consequence the waste heat recovered by small exhaust boilers has not been valuable enough to pay for this type of operator attention, whereas in large units it has been for many years. See, for example, the Maxim Silencer literature and prices in Appendix E. Bottoming Cycles. These cycles are becoming of more interest as fuel costs rise. They are available, simple, relatively inexpensive, and devoid of new tech- nical problems. Bottoming cycles using liquids other than water do, Page 81 however, introduce new operational problems. Leaks may be fire haz- ards, toxic hazards, or corrosion hazards besides being expensive. (Water is pennies per thousand gallons, bottoming cycles' fluids may be dollars per gallon.) Bottoming cycles can recover waste heat. They are not yet (1978) a commercial reality for diesel engines but are for multi-megawatt gas turbines. However, one company, Riley-Beaird, Inc., P.O. Box 1115, Shreveport, Louisiana, is interested in putting heat recovery exhaust silencers on engines as small as 1-2 HP (if a market exists). They now make and sell exhaust boilers for automotive sized diesels. Even these small exhaust boilers need periodic service to remain operable and efficient. Should they be ignored for days at a time they will at least soot up, run cold, and put back pressure on the engine which lowers efficiency and burns valves. Combined Cycle Turbines. These systems are actually a form of the bottoming cycles discussed previously. Combined cycle operation, where gas turbines fire a steam boiler feeding a condensing steam turbine, can make a major contribu- tion to increased turbine efficiency. These are a commercial product with suppliers ready to supply multi-megawatt sizes. Kilowatt sizes are not yet marketed. Metering Heat. The sale of waste heat involves metering heat. This involves measuring two other things: the volume of flow of the fluid must be measured as well as the temperature change. Heat meters have been used for many years in industry. A common type measures the flow of steam with the customer paying for the number of pounds of steam used. Since the Pressure is constant, the available heat in each pound of steam deliv- Page 82 ered is fixed. Other systems measure the condensate return. Again, since the delivered steam quality is known, the amount of returned condensate is a measure of the heat delivered. A simple water meter can be used to measure the heating water delivered to a customer if the supply temperature is maintained. At present there is not such a choice of Btu meters available on the market as there is watthour meters. A Btu meter can be engineered from stock :instruments, but.they are not as readily available as electric watthour meters. Everybody's house needs, and has needed, a watthour meter for 50 years; consequently such units have been mass-produced for many years and are readily available for $25.00. As yet, nobody's house really needs a Btu meter; there- fore, they are low-production-volume, expensive items. We would expect to pay several hundred dollars for a Btu meter equivalent to the $25 kWh meter. Heat Pumps. As pointed out previously, the common refrigerator is a heat pump. The heating of things by heat pump is as old an idea as the cooling of things. The idea that the coefficient of performance (COP) of a heat Pump allows more heat to be realized than energy supplied conveys the delightful possibility of something for nothing. The heat pump almost makes this true, but not quite. The heat pump is analogous to a steam power station running back- wards. We supply electrical energy, add it to the energy from the "boiler" (in this case heat from the cold outside air or cold water) to increase the "grade" of the heat, and then reject the heat from the condenser into the house. A COP of 3 means that for every Btu of electrical energy used driving the pump, 3 Btu's of heat are delivered, which appears at first to give a gain of 3 to 1. However, the single Btu of electrical energy may have come from a powerhouse and distri- Page 83 bution system which used 3 Btu of fuel to deliver the equivalent 1 Btu of electrical energy to your heat pump. In that case it is clear that no real "something for nothing" has been accomplished. It would be good to look at some real figures. One of the largest makers of heat pumps is General Electric Company, and their data is used because it is realistic and their machines work. Heat pumps are commercially practicable and profitable if their unique characteristics are valued high enough. Often the decision to use heat pumps is also a decision to place a rather low value on overall fuel efficiency compared to other heat pump features. The user has decided to waste fuel and have his air conditioner and heater in one unit and let someone else worry about oil delivery or ash hauling. The General Electric company, in their bulletins 25-6516-02, 223047-3, and 25-6240-75, quote performance at 45°F outside temperature. As the temperature falls below 0°F the heat pump becomes no more overall energy efficient than electric resistance heating. However, if the heat pump can use 45°-60° water as its heat source, it can beat electric resistance heating at any outside air temperature, but it cannot really outperform a good home furnace. Assume that the powerhouse uses 10,447 Btu thermal!? to produce 3413 Btu's (1 kWh) electrical energy. Assume an optimistic 5% distribution loss and a 2.5 to 1 coefficient of performance of the heat pump. The heat pump is putting out 8,532 Btu for 10,997 burned at the power- house. The total system from fuel to heat pump output is 77.5% effi- cient. This is only slightly better than an oil-fired boiler of home heating size which costs much less. A G.E. 60,000 Btu/hour "Weather- tron" costs $1,650.00 while a similar gas furnace of 67,200 Btu/hour capacity costs $211.84, making the initial cost of a heat pump $27.50/ MBtu/hour and of a gas furnace $3.15/MBtu/hour. The first cost of a 12 U.S. Department of Commerce, Bureau of the Census, Statistical Abstract of the United States, Washington, D.C., 1976. Page 84 heat pump is nearly 9 times the cost of an equally rated furnace. (MBtu/hour = 1,000 Btu/hour. ) Should we observe the GE unit at -18°F outside temperature, the heat pump performance is considerably below the home furnace. Using 2.5 kW the pump is delivering 8,400 Btu per hour. It is using 8,532 Btu to deliver 8,400 Btu. An apparent 98% efficiency. Resis- tance heaters would be 100% efficient. The fuel efficiency of the heat pump is much different. Each kWh of electric energy needs 10,447 Btu plus 5% distribution. The pump is consuming 27,492 Btu/hour at the power station to deliver 8,400 Btu/hour in the home. This is a fuel efficiency of 30%. No home furnace is this poor. Benjamin Franklin's iron stove was better 200 years ago. If a source of warm water is available heat pumps can be more useful. The heat in the water, however, must be "free", either geothermal, or other natural heat or waste from some thermal process and transported for "free". Sugaestions are sometimes heard to use waste heat from thermo power stations. This is very possible if the thermo station is not penalized. The heat pump shortcomings compared to a furnace are not really a fault of the "state of the art", but rather fundamentals of the laws of nature involving heat flow. It is about this simple: 1: A heat pump powered by fossil fuel will not normally be as fuel efficient or economic as burning the fossil fuel in a furnace. a5 A heat pump powered by hydroelectric energy or nuclear electric energy can be more economic than a home fossil fuel furnace if fossil fuel is expensive enough. Se Heat pumps waste fuel in thermo plants compared to home fur- naces, but heat pumps do not normally waste as much fuel as straight electric resistance heating. Page 85 SECTION X ALTERNATIVE ENERGY SOURCES Solar Heating. Solar heating systems are possible and various research demonstrations are encouraging. It appears that all shortcomings are truly the result of the "state of the art". There are no fundamental limitations other than the amounts of solar heat available which varies with location, date, weather and area. Today it is not a question of whether a sys- tem should be installed in lieu of a furnace, as it is true of heat pumps or whether it would save fuel. There is no real confidence as to when commercial units could be available so a buyer could choose either solar or gas heat as he can today with electric, heat pump, gas, oil, or coal heating units. Solar heating in Alaska appears to be farther off than solar heating in Arizona. The reason Alaska is colder than Arizona is because we get less solar radiation when it is needed most. Thus our solar heating systems will be larger than Arizona's for two reasons: we need more heat and it must come from a weaker and more intermittent source. It seems the solar heat will not be used in appreciable quan- tities for some time, especially in Alaska, no matter how intense our desires, needs, or governmental regulations become. More and more individuals and companies are taking an active interest in solar heating. However, most solar heating systems are still "one of a kind" and tailored to each special installation. Wind Power. Wind power is too old and too well proven to be shrugged off. "“Wind- charger" was the power for many thousands of farms in the depression. Today each of those farms could theoretically go back to windpower if they were also willing to revert to handmilking, cold cellars and spring houses. There are no commercially available wind electric generator Page 86 systems that could power a modern farm even if the cost was bearable to the people who buy milk, meat and bread. The shortcomings of wind power are not caused by "state of the art" considerations but by mech- anical principals. A 100 mph wind can push about 40 pounds?!? on every square foot of surface. This is a terrible and uncommon wind. A modern steam plant can continuously utilize steam at 792,000 pounds per square foot. A modern diesel engine produces 37,440 pounds on every square foot of piston head. A hydroelectric station utilizes water at 27,450 pounds per square foot. Chicago, "the windy city" averages 10.3 mph (Statistical Abstract). This represents a wind pressure of only about 4 pound per square foot. Comparing working fluid pressures allows a concept of the relative sizes of prime movers. Wind turbines are gargantuan machines compared to steam turbines, and only run when the wind blows, so power storage systems are needed. Steam turbines can be made to run when people need power. The depression-spawned Windcharger used common lead cells. Every auto has one. If the bush inhabitants can be satisfied with the electric service of a 1936 rural lowa farm, wind power is a realistic possibility. If electric space heaters, irons, TV, deep freezes and refrigeration is desired, wind power becomes a wish. Machines of such power are not economically feasible and the storage system is expensive, complicated and in need of technical management and main- tenance. The lowa farm which used wind power in 1936 uses REA or private electric power today because they cannot afford windpower in the large quantities necessary. Were wind power systems economic they would be used. Present technology is entirely proven in both function and cost. 13 Kent's Mechanical Engineers’ Handbook. Power, John Wiley & Sons, Inc. New York. Page 87 It is a cost failure. For wind power to become economic, there must be an "invention" similar to Dr. Diesel's engine or other power must rise to costs which even the pessimists do not predict. However, progress is being made in developing wind-driven generators which would be connected into a utility network. For instance, a machine capable of producing 200 kilowatts has recently been installed at Clayton, New Mexico.!4 This unit can supply up to 15% of the city's power needs, thus saving diesel fuel. A recent "exciting" wind power proposal (as reported by Helen Gillette in the Anchorage Times of 15 June, 1978) suggests 650 windmills to deliver 1300 Megawatts of power. The design requires each to be 330 feet in diameter. These are to be in a canyon eight miles from Palm Springs, California. Windmills cannot be concentrated like trees in a forest as only the ones on the edge would get much wind. The 650 windmills would be at top efficiency if spaced in a line across the prevailing wind. If they were placed in a less efficient arrangement, even more than 650 would be needed. This line of 650 windmills would be 50 miles long assuming the 330 ft. blades need 60 feet of clearance to the next machine. To put this in local perspective, the line of windmills would run from downtown Anch- orage to ten miles beyond Portage Glacier. The power from all this would, when the wind blows, would equal the output of one steam turbo generator which would give power when needed, or a small hydro dam which could give power all the time even if not needed. Some ecologists paint a picture the serene Dutch windmill solving all our energy problems. Were wind power to replace the "dirty coal steam plant", one cannot help but wonder at the consequences the forest of whirling blades, pumped-storage reservoirs, propeller crippled birds, 14 Public Utilities Fortnightly, March 16, 1978, p. 58. Page 88 and defoliated wind runs would bring, if enough windmills were in- stalled to produce an appreciable portion of our power requirements. However, that should not prevent us from carefully considering wind- power installations of more moderate proportions. Residential Total Energy Systems (Home Diesel Furnace). This is a term we apply to a system in which each individual home, duplex, multiplex or business building burns fossil fuel in an electric power and heat producing unit. The entire town or at least the dis- trict would have no central power. Each residence and business would have its own electric power and heating installations. The idea is not new and has been suggested continuously since the distribution of power was first considered. The technology has always been present, but the economics have never generally been in its favor. A typical growth pattern begins with a few small individual power plants providing lighting and heating to businesses and very few homes. After that, small local utilities are usually taken over by bigger, more efficient power companies bringing the customer even lower rates. It is possible, however, that geographical isolation, high fuel costs, and local construction problems can favor the residential total energy system. In small communities the central power station is not large enough to be much more efficient than the diesel of a residential total energy system. Low-density housing causes the economic proximity factor to be non- existent. REA borrower utilities have a national average net utility plant per customer cost of $1,155.00.15 Chugach Electric Association's net utility plant per customer is $3,060.00.15 Alaska Village Electric Cooperative, Inc. has a net utility plant per customer of $3,293.U0.15 Home space heating and domestic water heating equipment could add about $700.00 more. 15 United States Department of Agriculture; REA Bulletin 1-1: 1975 Annual Statistical Report, Calendar Year ending December 31, 1975. Page 89 It is now seen that if a home diesel furnace, which could take the place of the central bush village utility and the present home heating systems, could be assembled for about $4,000.00 per home, total first cost would not be penalized. During the "non heating" portion of the year, the home unit would have a somewhat lower efficiency than a large central plant, but during the heating season, the efficiency of the home unit would be considerably better than a central plant without heat recovery features. Maintenance costs of small engines and their systems is usually greater than an equivalent central plant. Small diesels of 1-5 kW are not targeted to 80,000 hour life as are large medium speed diesels (8,000 kW). High speed diesels of 300 kW have target lives of 5,000 to 10,000 hours between heavy repair but always can be returned to new condition for far less than new cost. The home diesel furnace size engine are "throw away" units usually designed for intermittent service of a few hours duration. These are targeted at 5,000 hours total use. Though their first cost is relatively low, the long-term cost of major repair is very high. A central utility, if large enough to have a full time operator will probably have better care than the worst cared for diesel home furnace, and care equal ‘to the best maintained home unit. If the céntral utility is allowed to deteriorate, the entire system falls to the level of the worst, and individual home diesel furnaces in the homes of people who cared would always be better. ‘If the home diesel furnace system exists, some people in town will always have light and heat while the poorly maintained central utility will turn out everybody's lights when a malfunction occurs. In a system using the home units, indiv- iduals have the option of stopping the home diesel furnace when it is not needed, thus realizing even greater economy of operation. As is true of nearly all waste heat capture efforts, the decision to use low-grade heat depends on the economics of the particular application. The equivalent annual cost of the heat saving installation must be less than the cost of the fuel it saves. Page 90 The relationship of these costs is interesting. A typical small cheap diesel generator set is the Yanmar.'® A 2 kW unit costs $1,995.00 without any home heating modifications. It is thus clear that first cost of a home diesel furnace can compete with an average REA utility in Alaska. AVEC type systems need close study to determine the economy of the home diesel furnace. The cost of the diesel engine generator is only half of the AVEC per customer system cost. In some locations this cost could be very favorable to the home diesel furnace. Current data on bush village electric service costs are of interest and are considered below. Mr. Horace O. Simmons, Executive Director of the KANA Housing Auth- ority has recently obtained some numbers on bush village central power system costs which are very encouraging to the Home Diesel Furnace concept. (Mr. Simmons originated this name.) Mr. Simmons has also been doing some very good investigation into the means to create the Home Diesel Furnace. The costs, however, are of overriding impor- tance. Recently opened bids for central station electric systems in bush villages of from 36 to 50 houses have ranged from $6,000.00/ house to $16,000/house. Considering that to these costs can be added the home furnace and water heating, it is quite obvious that a detailed design and cost study should be made. If $6,000.00 per house is a limit, the home diesel furnace may easily beat a bush village central power system. Mr. Simmons points out some real advantages to the home diesel furnace. A central 50-300 kW power station in need of service requires a field service representative who works in field conditions. This causes extreme expense and many times "field fixes" which are less than best. A home diesel furnace can be picked up by two men and shipped back to a well-equipped shop, fixed right and cheaply by experts with good facilities. The home would be lighted and heated by one of several 16 Power Genny II; Marine Diesel Engine Headquarters, Inc., 2834 N.W. Market Street, Seattle, WA 98107. Page 91 spares carried to the home by the same two men. As mentioned before, nothing could kill the whole system. Schools, churches, hospitals and larger buildings could be lighted and heated by one or more of the standard home diesel furnaces which would be run only as needed. Local emergencies would not have power outages as a consequent trouble. The home systems being simple would need no experts; anyone able to keep an outboard engine or snow mobile running would easily accomplish his own normal operational service. Since his family's light and heat depended on what he did by himself, the home diesel furnace would get the service needed to keep it running. Expansion of the system would be continuous. No large bond issues or block expenditures would be required to add several new customers. Each house finished would have light, heat and power as the last nail was driven home. As an "ideal system", the home diesel furnace is not lacking in good features when compared to any present central utility. The technology is old hat; the machinery is on hand or being manu- factured now. Cost is the governing factor. Actual use will possibly reveal a fuel efficiency even greater than calculated, as each home owner can tailor his "on" time to exactly meet his needs. By slight changes in life style or some additions to the basic home total energy system, it would be possible for each homeowner to operate his system much less than a full 8760 hours per year. A central electric plant or individual units being discussed here normally operate at very light load many hours per year. Basic electrical load during the "sleep- ing" hours is always only a small percentage of the peak load. Central stations handle this situation by shutting down part of their units during low-load periods. An individual home could easily shut down its power plant completely during the sleeping hours for that portion of the year when it is not needed to produce heat. The main or perhaps only requirement for power during this period would be the refrigerator or freezer. Modern well-insulated units should be able to hold their temperature for the time the generator is shut down if the door is not being opened. If the Owner is willing to endure a slight inconvenience Page 92 for the sake of economy, he can even shut down the plant for periods of time during the day. If this concept can be coupled with a constant- frequency variable-speed generator as discussed elsewhere in this report, even more favorable operating economies are possible. The system could operate at idle speed during light load conditions. One scheme to allow the generator to be shut down during periods of light load would be to install a battery bank and possibly an inverter to operate a minimum number of lights and low-load appliances for limited periods of time when the generator is not operating. Another possibility would be to provide some manner of heat storage so that perhaps the generator could be turned off at night even during colder weather. A system such as this would have supplemental electric heating, pos- sibly in the form of a standard domestic hot water heating for adding heat to the heating loop during periods when the normal electrical load is not large enough to produce the desired amount of heat. This would add heat to the system in two ways. The electric heater would heat the water but would also add load to the generator which would cause the generator to produce more heat. The net effect would be a highly efficient conversion from fuel to heat. Figure 10 is an artist's rendering of such a residential energy system containing all the features discussed. Such a "gold plated" system can Probably not compete with central station service except in unusual circumstances. This is only a conceptual presentation and is not pro- posed as a working model. The system does appear to have consider- able merit. It should be closely evaluated, possibly in conjunction with the two-speed drive or the Roesel Generator discussed elsewhere. Aeeene eENcnaron rest. ENae THERMOSTATIC SENSOR MEAT RECOVERY SILENCER BOILER THERMOSTATICALLY CONTROLLED S-WAY VALVES FO" MADIATO® & MOT WATER STORAGE CIRCUITS THERWOSTATICALLY CONTROLLED 3-WAY VALE FOR MOT WASH WATER CIRCUIT CD) rwenwosrarie sevson @) oc rawee (0) mor wesw waren rane (a) wvenren (9) WASH WATER MEATING ELEMENT (13) Mouseworo ovrier (0.¢.L040) (10) Mor waren SPACE MEATING CIRCUIT (20) MEATING CIRC. PUMP (0.¢.L040) (IN) SPACE WEATING WATER STORAGE TANK (UNDER FLOOR) (71) LIGHTING [0.6.L040) “ (it) waren mearime ELEMENT (AC L040) (7) Poraece waren pur (0.6.L040) "HOME DIESEL FURNACE 19) ENGINE AAQIATOR W/FAM @ WOTOR LOVER (5) POraece waren rane “HOUSEHOLO CO-GENERATION” (ia) 4.6. Paner (4) AEE LER (46 LOO) “RESIDENTIAL TOTAL ENERGY SYSTEM” (13) #4rrear ewaneer (25) WASNER @ DRYER (46.1040) i (is) #arrenr nace ——emecrion oF FLow ‘ my aii 7 Ky : ral ae Gat) sect: [ResioenTiAL TOTAL FNERGY SYSTEM a = FIG. 10 i a Br a Tele =| ae I t00 eeee) a £6 e6ed Page 94 Unorthodox Efficiency and Life Improvement Methods for Engine Generator Sets. Te Two Speed Gear Box One proposed system will not capture any waste heat, but will just waste less. It can cut low-load fuel consumption by 25% to 50% and can extend engine life in some (but typical) operations by 200%. The operation of diesel engine generator sets at extremely low loads for an extended period is detrimental to the engines. In general these units should not be operated at less than 25% load and more prudently at not less than 50% load. A 300 kW set operated 16 hours a day furnishing 12 kW or perhaps only a few hundred watts of station power and street lights is being abused. The manufacturers of such sets advise the use of artificial load resis- tors to keep the engine in a proper load range. This, of course, is today impracticable, being an unreasonable waste of fuel. One solution would be to shut down the big unit and startup a small unit to be run during the low load period. This requires an "automatic device" or a person to do this shifting of units, and incurs the cost of an additional engine generator set, its services, switchgear and synchronizing con- trols. A possible economy could be achieved by some mechanical methods of matching the "big engine" to small loads. In general diesels can idle at low speeds with minimum wear and "hot end" problems (carboning up, slobbering, etc.) and will use relatively little fuel at these lower speeds. The engines will produce little power at these lower speeds without being "lugged" but can produce small power efficiently at these lower speeds. "High speed" diesels can be good low speed diesels if not lugged. Page 95 It is now easily seen that if an 1800 RPM 300 kW diesel could be slowed to 600 RPM to furnish 30 kW, it could do so quite effectively and at reasonable cost. One means to do this is a two speed gear box between the engine and alternator. The gear box, by means of a simple clutch, would allow direct drive for high load and a lower engine speed for part load, with the alternator always running 1800 RPM. A timer and or load sense relay would "clunk" the gear box to "direct" or "over- drive" for high or low load. Space would cause no severe size limitations, so the gear box could be a cheaply made counter shaft design and could be, by changing gear sets, tailored to each application to keep the engine in a "best range". The low load gear sets could be changed in the field in a few hours to get the most from the engine. Estimates of added life are difficult to obtain because engine makers simply advise that it is abusing an engine to run it full speed at near zero load for a great part of its life. However, it seems safe to opine that an engine loaded 0% to 10% full power but running 600 RPM for 5000 hours and 50% to 100% power at 1800 RPM for 1000 hours would still be a reliable working machine, whereas a similar engine supporting the same loads but kept at 1800 RPM for all 6000 hours would probably have been overhauled twice. Life increase due to "not-turned-revolu- tions" is 24 times for the slowed down engine. Added to this is the reduced wear from the reduced dynamic loads which could be eight times better, and the reduced "hot end" problems of high speed low load. Two similar engines called upon to produce 5% of their full power full speed rating but one doing it at 600 RPM (near idle) and the other at 1800 RPM (full speed) will have a large difference in life expectancy. The low speed engine will be in good shape when the high speed engine will become unserviceable. Fuel efficiency at 5% load and at this lowered speed could be up to three times as good as for the higher speed engine running at this same load. Page 96 The two speed gear box would enable these advantages to be obtained in a simple, cheap, original equipment or field installed unit. The installation would be about as seen in Figure 11 where a standard generator set is compared to a two speed gear set. The added section is the gear box. 2 Two-Engine Generator Set A second method to get simplicity and economy advantage over the case requiring a complete smaller engine-generator set is to utilize two engines to drive one alternator. During periods of high load, both engines would be used. As the load fell, the larger engine alone would be used and during periods of very low load the small engine alone would be operated. This system lends itself to very simple "brute force and stupidity" automation. Since the alternator is always running (never switched), a simple three level load relay would clutch, declutch and shutdown the engines as necessary. The inertia of the running engine-alternator would provide cranking for the "dead engine". Engine power ratios would be fixed by the low load demand. Ina situation where the extended low load period would be less than 10% full load, one engine could be 60 HP, and the other at 240 HP for a 300 kw total. A 30% low load period could use one engine of 120 HP and an- other at 180 HP for 300 kw. Cost advantage over a two engine-generator setup would be substantial. Automation would be simpler. Manual operation would also be simpler, and the "idiot proof" factor is better in the clutched engine system. The engines can be "slammed in" without regard to synchronizing, phasing, or switching. Friction clutches are very forgiving and the inertia of the running engine-alternator eliminates the need for elab- orate starting procedure. When the load requires more capacity than present with the running combination a relay turns the fuel on and Page 97 STANDARD GENERATOR SET FIG. IIA GENERATOR SET WITH TWO-SPEED GEARBOX Fig. 1B Page 98 drops in the clutch on the idle engine which will then be pulling its load in about two seconds. The customers would notice only a slight "bump" in the power. This two engine, one alternator, setup could be applied to single bear- ing alternators as shown in Figure 12. This would have the advantage that the smaller engine could be run at its optimum speed via the offset drive train. A two bearing setup could be as shown in Figure 13 which is self explanatory. First cost, fuel use, reliability, simplicity, and ease of operation all are enhanced by the two speed drive or the two engine drive when com- pared to two separate gen-sets each with its own switchgear and syn- chronizing equipment. The Cummins Engine Company!” presents some interesting data. An NT-855-C310 engine producing 290 HP at 1800 RPM has a fuel rate of about .38 Ibs/BHPH. If unloaded to 20% load (58 HP) at 1800 RPM , it is using about .70 Ibs/BHPH. A two speed gearbox allowing this engine to produce 58 HP at only 600 RPM brings the fuel rate to .40 Ibs/BHPH. The VT-1710-C635 producing 600 HP at 1800 RPM has a fuel rate of .379 Ibs/BHPH. At 100 HP 1800 RPM the fuel rate is about .690/Ibs/ BHPH. Slowed to 800 RPM, the engine produces 100 HP at a fuel rate of .40 Ibs/BHPH. The engine is not in a "slobbering" operating range as it is running at 55% of its full power capability at this lower speed. Either of the big and little engine systems allow a similar improvement, but at greater first cost. Assume that the powerplant requires a peak loading of 634 kW and an eight hour minimum between 50 and 100 kw. This would require a single engine to operate for eight hours between 8% and 15% load, with a fuel rate of perhaps over .8 Ibs/BHPH and in a very detrimental operation range. Using a Cummins N-855-C220 and a 17 Cummins Engine Company, Inc., Columbus, Indiana 47201; "Applica- tion Engineering Bulletin #11.01", February 1977. Page 99 PARALLEL TWINNED GENERATOR SET FIG. 12 COAXIAL TWINNED GENERATOR SET FIG. 13 Page 100 VTR-1710-C700 driving a single alternator and a single set of switch- gear, when peak power is needed both engines would be working. Both in proper ranges giving about .40 Ibs/BHPHR. When the eight hour minimum was the load, the smaller N-855-C220 would be working between 32% and 64% load giving between .42 and .38 Ibs/BHPH a fuel saving of about 100%. The smaller engine would also be working in its best range. Shifting from one to the other or from either to both engines would be by the simplest "Brute Force and Stupidity" mechanism of turning the fuel on or off and kicking the clutch lever in or out. This could be by a person or an automatic control. Neither need be highly knowledgeable. A further economy measure made possible by the use of the gear boxes of Figure 12 is the possibility of using 2, 3 or more engines on a single alternator. The economy here is one of controls, simplicity, mainte- nance, repair, wear and fuel. In all plants two items contribute most to the failures. These are engines and controls. Human error is also present. The alternator usually runs on and on. Adding or removing generators from the line is a simple "push the button" act if all the little black boxes work. Done manually, it requires skill and know- ledge, or a serious outage or damage can exist. A four engine installation with four engines driving a single alternator eliminates these problems. The addition or reduction of capacity: is best described by the crude terms "dumping an engine on" or "dumping an engine off". Should an engine need repair, it can be removed and a spare added by anyone capable of simple plumbing and nut and bolt mechanical work. Such repair can be done without interruption of power, no switchgear needed, no synchronization necessary, and no electrical power connections undone or remade. The economics of such systems are economics of "faith". It is nearly impossible to calculate a favorable payoff period using fuel saving alone, but if one of these systems prevents one major overhaul during Page 101 the life of the engine generator, it has paid for itself and shown a profit. Depending on the operation, these systems can save several major overhauls and prevent the hazardous conditions created by full speed low load operation. (Slobbering engines are exhaust system fire hazards.) The use of jacket water and exhaust heat recovery equipment is also improved by running engines at speeds where the load present is a high percentage of the permissible output. Both jacket water and exhaust temperatures are high. There is no increase in waste heat, but it is made more recoverable. Conventional low load operation almost immediately will soot up an exhaust boiler. This will prevent it cap- turing waste heat when the load comes on. High coolant pump speeds when at conventional low loads force jacket temperatures down in usual installations. The systems described here will return conditions very close to the design ideals. Power stations where operators are skilled and always on duty with Proper supervision and have many units to share load perhaps may find only Figure 13 of interest. In bush plants where rugged simplicity and durability are paramount, the other systems hold promise. There is no new technology involved. Clutches, gearboxes, and drive shafts are ~ simple designs. Most parts are "off the shelf". The package needs only sizing and assembly. Getting such systems on the market is one of creating a customer demand. When such systems are proven in operation, the economic factors will create the demand. 3. Roesel Generator!8 A recent invention, the "Roesel Generator", U.S. Patent 3,521,149, July 21, 1970, may be the exact answer to slow speed operation at light load of diesel engines. This generator produces a constant 60 Hz 18 Precise Power Corporation, Box 1905, Bradenton, Florida 33506, John F. Roesel, Jr., President. Page 102 output with varying shaft speeds by the process of magnetically im- printing the proper number of poles within the generator to produce the precise output frequency desired over a widely varying range of rotational speeds.19’ 2°’ 21 Presently this generator is available in single and three-phase models from 1.5 to 50 kVA at approximately $1,000 per kVA in smaller size and $500 per kVA in the larger sizes according to sales literature supplied by the Precise Power Corporation. According to the manufacturer, whose claims are supported by numer- ous articles in trade periodicals, this unit is gaining rapid acceptance as a precision power supply for computers. The potential applications for this generator in bush power generation are exciting to consider. Such units could be driven by wind, small stream hydro, the "home diesel furnace", etc. This generator holds great promise as a means to allow small power plants to operate at normal RPM, normal load conditions, and also at low RPM, light load conditions with no gears, clutches, etc. Dr. Conrad R. Hilpert of Robert W. Retherford Associates has con- ceived other alternators which allow 60 Hertz constant frequency power at any variable shaft speed. These are presently being studied for patent application. The Roesel or Hilpert generators would allow the engine to operate at its most fuel efficient speed regardless of electrical load. The gener- ator facility could be optimized as never before possible. 19 Philip J. Klass, "New Technique Offers Regulated Power." Aviation Week and Space Technology. February 26, 1973. 20 E.F. Lindsley, "New Alternator Delivers 60-Cycle Power At Any Speed." Popular Science, July, 1973. 21 L.R. Herman, "The Roesel Generator." IEEE. Paper A 76 035-6. Page 103 Hydroelectric Potential. ae Small Hydro Until recent years, the relatively low priced fossil fuels and the low installation cost of fossil fueled thermal plants constrained the devel- opment of most small hydro plants. Today, however, with the realiza- tion that "Fools Paradise" cannot last forever, our nation is frantically searching for new energy sources and ways to recover waste energy. The economic impact of these increasing fuel costs requires a reeval- uation of small hydroelectric potential previously not considered eco- nomic. Unfortunately, nothing in life is free, and the initial cost of a hydroelectric plant is relatively high. The purposes of this section are (1) to determine an approximate amount that may be invested in a hydro plant compared with diesel fuel replacement, and (2) explore methods and means to reduce the initial cost. A comparison with diesel fuel is made as most small Alaska utilities generate their electrical needs with diesel-electric units. Many of these are located near swiftly falling streams where the utilization of the power of the falling water should be investigated. Table 7 and Figure 14 showing the allowable hydro investment per kW for fuel cost were derived using the following assumptions: a. A 20-year amortization period with quarterly payments at 6, 8, and 10% interest. b. Diesel fuel escalation at 5% per year during the 20-year period. Gs Diesel engine-generator sets producing 13 kWh per gallon of fuel. Page 104 d. Hydro installed capacity for 50% load factor. The 20-year amortization period was selected as the best probable financing period for a private utility and the range of interest rates chosen were those that may be expected from State loans or private financing. When considering other diesel costs such as lube oil, glycol, maintenance, and higher depreciation, the hydro may be installed under this criteria with little or no rate increase during the first few years. When using this criteria for an REA loan at 5% for 35 years, an invest- ment of $7,167 per kW could be made where present fuel cost is $0.50 per gallon. An escalation rate of 5% per year for diesel fuel is considered very conservative. Many economists prefer using a 7% escalation rate. A fuel rate of 13 kWh per gallon of fuel is much better than most Alaska diesel plants achieve. Again, this figure was used to be on the conservative side. If any potential hydro site investment readily appears to fall below the break even point as determined from Figure 14 for a present fuel rate and probable interest, the hydro should definitely be investigated if a better alternative does not exist. A distinct advantage of the hydro is that it will still have a long and useful life after the initial investment is paid off, whereas, the diesel unit will be worn out and replacement cost at escalated prices may be greater than the initial investment of the hydro. Page 105 TABLE 7 ALLOWABLE HYDROELECTRIC INVESTMENT VS. FUEL COST 20-Year 20-Year Ave. Annual Fuel Fuel Cost Maximum Hydro Investment Diesel Cost/Gal For 8760 kWh Per kW* - 20 Year Amortization Fuel (5% Assuming 6% 8% 10% Cost/Gal Escalation) 13 kWh/Gal Interest Interest Interest $0.30 $0.496 334.23 $1,938 $1,661 $1,440 0.40 0.661 445.41 2,584 2,214 1,918 0.50 0.827 SSTiaet 33200 25/10 2,400 0.60 0.992 668.61 3,878 35323 2,879 0.70 1.157 780.02 4,523 34875 33395. 0.80 1.323 891.43 5,171 4,431 3,840 * Based on a 50% load factor. Example: If a utility is paying $0.50 a gallon for diesel fuel and can borrow money at 8% interest on a 20-year loan (quarterly payment), the annual payment of $557.27 would allow for an investment of $2,770 per kW installed capacity for an installation with a 50% load factor. Additional credit should be allowed in the above table for the peaking capacity which in 1978 is estimated at $200 per kW. és Hydraulic Turbines for Small Hydro Hydraulic turbines are divided according to their hydraulic action into two main classes: impulse turbines and reaction turbines. In an impulse turbine, all the available head is converted into kinetic energy or velocity head in one or more contracting nozzles by which the water is formed into one or more free jets before acting upon the runner. In reaction turbines, the entire flow from headwater to tailwater takes place in a closed conduit system, being laterally constrained on all sides. Only a small part of the available head is converted into kinetic (1) ALLOWABLE HYDRO INVESTMENT PER KW (FUEL REPLACEMENT ONLY) (1) Based on 20-Year Amortization (Quarterly Payments) (2) Based on 5% Escalation for 20-Year Period 1 (3) Based on 50% Load Factor (4) Add Peaking Capacity Credit to Investment 0.60 0.70 0.80 SESS BBL COST (2) pm i ;. PER GALLON sh es es oaoe bp ALLOWABLE HYDROELECTRIC INVESTMENT VS FUEL COST FIG. 14 Paae 106 Page 107 energy and the large remaining part is pressure head which varies throughout its passage through the turbine. Since this is the type of turbine most commonly used in heads under 1000 feet, our discussion will be limited to the reaction turbine. Typically, hydraulic turbines are designed and manufactured for each installation with few so-called "package" or "off-the-shelf" units. Off-the-shelf units are limited to approximately 25 kW and heads under 50 feet which is not compatible to most villages in Alaska. Since it has been found that a good centrifugal pump will perform well as a turbine in reverse direction of rotation, but a good Francis tur- bine will not perform satisfactorily as a pump, the impeller runner of a reversible Francis pump turbine is designed essentially as a pump impeller rather than as a turbine runner. A conventional Francis turbine runner, because of relatively short blades, is not well adapted to efficient deceleration of flow in its water passages, or to the cavata- tion requirements, when it is operated in the reverse direction for pumping. Since there are only a few hydraulic turbine manufacturers in the world that are interested in small hydro developments and literally hundreds of pump manufacturers producing pumps of standard design within the horsepower and head range of most Alaska communities, it is illogical that this source has not received recognition. The reason for this neglect or oversight is unknown, but Mr. Carl H. Steeby of Robert W. Retherford Associates is attempting to rectify that situation by pur- suading suppliers to install a demonstration project. Not only are these pumps already designed and, with the possible exception of the im- peller, standard manufactured components, replacement parts are also standard and readily available for maintenance. Preliminary contacts with pump manufacturers and recent quotations indicate costs for such pumps may be less than one-half of similar turbine costs. Page 108 The use of centrifugal pumps as hydraulic turbines will necessitate some variation from the typical hydro design. The pivotal action of the wicket gates on a Francis turbine maintains an equal radial flow into the runner under all load conditions, whereas, the centrifugal pump con- tains no wicket gates. In order to maintain constant radial pressure on the impeller during changing flows to meet the varying load demands, a governor controlled valve on the discharge side of the turbine would regulate the flow and maintain a full and equal lateral pressure in the volute. i. Induction Generators for Small Hydro A Squirrel Cage Induction Generator is similar in appearance and design to a squirrel cage induction motor. Because of its simplicity and low cost, the induction generator merits consideration in certain applica- tions, such as small unattended hydro stations. A standard polyphase induction motor connected to a voltage source has a rotating magnetic field of constant speed set up in the machine air gap. When the rotor is driven mechanically by an outside source at exactly the speed of the air gap rotating magnetic field, no voltage is induced in the rotor cage bars. However, motor action occurs when the shaft resisting torque causes the rotor to run at a speed less than the constant speed of the rotating air gap magnetic field. Current induced in the cage conductors slipping in the air gap causes a motor or driving force. During motor operation power is drawn from the electrical supply lines. By external means, such as with a water turbine, it is possible to drive the rotor forward, or against the air gap magnetic field. Current is then induced in the rotor conductors. Because the rotor conductors must slip forward in the rotating air gap magnetic field, the rotor must, therefore, be above synchronous speed for generator operation. Page 109 The induction generator has no internal excitation or magnetizing cur- rent source of its own to establish the main air gap magnetic field. Hence, the generator must draw its excitation or magnetizing current from some external source. Therefore, the induction generator cannot generate as an isolated unit. It must be connected to a system having synchronous machines on line to establish voltage and frequency condi- tions. The induction generator may be increasingly loaded by increasing the driving speed, but an increase in speed does not influence system frequency or voltage. Thus system frequency or voltage cannot be changed arbitrarily by any induction generator adjustments. One of the principal advantages of the induction generator is its sim- plicity and ruggedness which contribute to low operating and main- tenance costs. Furthermore, unattended hydroelectric plants in remote locations may be simply designed, installed and economically operated to produce low-cost kilowatthours by using induction generators. Such equipment as exciter, governor, rheostat, voltage regulator, synchro- scope, direct current volt or ammeter, direct current bus and accom- panying switching can be eliminated. During start up of a hydraulic unit, the gate opens a small amount allowing the turbine to accelerate the generator. When the waterwheel generator unit reaches synchronous speed, the generator breaker may be closed by means of a speed switch, thereby connecting the generator to the system. By means of suitable timing devices, gate openings may be automatically timed to regulate generator output. In normal shutdown, as the gate closes, breaker operation is initiated at the time the generator drops to synchronous speed. Emergency shutdown may be occasioned by one of the protective devices, such as a differential relay. Breaker operation occurs immediately and the gates begin to close. Some overspeeding may result but can be tol- erated in the interests of simplicity. Page 110 An induction generator is well adaptable for generating "by product" energy into a large power system in conjunction with a throttling tur- bine. The turbine serves the purposes of reducing natural gas, steam or other fluids from a higher to a lower utilization pressure. The distinctive advantage of using the induction generator is its economy and simplicity of control. Tidal Power. From time to time the mass media and technical publications proclaim the virtues of tidal power. This power would be produced by low-head hydroelectric turbines operated by tidal flow of various bodies of water. One of the main advantages of tidal power is that, for the locations normally proposed, it is dependent only upon the action of the moon on a particular body of water. It is not subject to seasonal flood peaks, or periods of drought. Table 8 is a summary of potential tidal power projects in the United States. Proposed applications of tidal power in the Anchorage area have been discussed for a number of years. Mr. Roy W. Johnson, Consulting Engineer, has proposed a tidal power system for Anchorage which would produce 1.2 to 2 million kilowatts of electrical energy and would provide as a side benefit vehicular access from Anchorage direct- ly to the Kenai Peninsula and to the Susitna River Flats.22723 22 Anchorage Daily Times; "Cook Inlet Tidal Power", September 19, 1974, p. 24. 23 Johnson, Roy W. Consulting Engineer; "Harnessing Cook Inlet's Tidal Activity", Presented at Project Independence Hearings, Federal Energy Administration, Anchorage, Alaska, September 9, 1974. TABLE 8 SUMMARY OF POTENTIAL TIDAL POWER PROJECTS IN ALASKA * Mean Gross Annual Equivalent Tidal Energy Power Continuous Installed Annual Proj. % Mean Area Range Potential Production Output Capacity Capacity No. of Ref. Location Sq. Miles Et: gwhr/yr gwhr/yr in MW Megawatt Factor Units Scheme Al Knik Arm 80 26.0 12,200 2,870 330 750 0.44 50 1-Pool A2 Turnagain Arm 291 24.5 42,300 9,000 1,030 2,600 0.40 170 1-Pool A3 T&K Arms 111 (Upper) 24.5 58,440 10,950 1,250 2,600 0.48 170 2-Pool A4 T&K Arms 402 24.5 58,440 12,400 1,420 3,550 0.40 230 Comb. Pools A5 Angoon (Indian) 11.6 10.6 315 80 9 30 0.30 10 1-Pool *Tidal Power Study, ERDA/Stone & Webster Engineering Co., January, 1977. LLL e6eq Page 112 This study did not attempt to establish cost estimates for such projects. It can be stated in general, however, that such projects would be quite costly and only begin to become attractive as the cost of fuels continues to climb and other alternatives are exhausted. Hog Fuel. Alaska has a resource in "hog fuel". This is waste forest products and sawmill waste. In the logging areas hog fuel (so named because it is reduced to chips by a machine called a hog) is abundant. Hog fuel is clean burning relatively and non-polluting. In many cases the forests would be benefitted by removing the diseased and fallen trees and dead brush. On the shores of Southeast Alaska, the washed up logs are another potential fuel source. At first look it would appear that we are "wast- ing" such resources by not burning them as fuel for power generation. However, preliminary investigations by our firm, including discussions with personnel at Louisiana-Pacific Facilities in S.E. Alaska, indicate serious problems with processing and burning such fuel. It is costly to gather, transport and process the logs, even to fire an existing boiler. To build a boiler, gather, transport, and process the logs, and burn the fuel specifically for production of electrical energy cannot be eco- nomically competitive with hydroelectric, diesel engine, or even turbine operation. As a general rule, even if the power production facilities already exist, operators find it uneconomical to harvest and process the washed-up logs for boiler fuel. In addition to the economic problems there are also technical problems. Logs that have soaked in salt water produce corrosive sodium and chloride compounds which damage the boilers and add undesirable pollutants to the air. Page 113 Many installations do make beneficial use of hog fuel and others can no doubt be found. However, we do need to recognize that use of hog fuel is not the cure to our energy problems. Fuel Cells. The fuel cell is a device for directly converting fuel into electrical energy, heat, and water. Like a normal storage battery, they function by virtue of electro-chemical reaction. Fuel cells have been known since the late 1800's?4 but have not previously been produced of such size or such cost to receive serious consideration as a source of elec- trical energy to displace conventional power sources. The Energy Resource and Development Administration (ERDA) is actively engaged in building, testing, and reducing costs of fuel cells of such size to provide or supplement central station service.25 A 4.8 MW installation is presently being constructed. A typical fuel cell will convert 40% of fuel input into electrical energy and 60% to heat. With proper config- uration beneficial use of 85-90 percent of the fuel input can be obtained. This makes the actual fuel cell one of the most efficient energy convert- ing devices available. However, the fuel cell requires pure gaseous hydrogen for operation and the overall system efficiency must take into account the energy expended in converting any fuel into a form usable by the fuel cell. The present short-term goal is to produce a fuel reformer with a thermal efficiency of 87%.2° 24 Fickett, Arnold; "Fuel Cells: Versatile Power Generators", EPRI Journal, April 1976, p. 14. 25 Lawrence, L.R., The ERDA Fuel Cell Program, Division of Conserva- tion, Research, and Technology, Office of Conservation, Energy Research and Development Administration, Washington, D.C. 20545; IEEE Paper A 77 688-5. 26 Handley, L.M., Grevstad, P.E. and McVay, D.R.; "Improvement in Phosphoric Acid Fuel Cell Power Plant Technology", United Tech- nologies Corporation, Power Systems Division, South Windsor, Conn. 06074, p.9. Page 114 First generation fuel cells operate at a constant temperature between 350° and 400°F. They produce as by products hot water at about 200°F and can, if desired, produce steam at pressures of 15 to 60 PSIG.27 The same problems are encountered in capturing and using this heat as are encountered in capturing heat from other sources. Table 9 gives projected economic comparisons of fuel cell supply options vs. central station coal in 198528 If these goals are achieved, it is obvious that fuel cells will be on the verge of economically competing with conventional power sources. Turbo Compound Engines. The diesel engine has an advantage over combustion turbines in that the extreme combustion temperatures are contained in water jacketed steel. Melting, erosion, and burning of these parts is well controlled and without the use of exotic materials. The compression ratio of the diesel is much greater than that of combustion turbines, thus the theoretical efficiency is very high. These concepts have been combined to use the diesel cycle to generate high pressure gas which is expanded through a turbine from which useful power is obtained. The extremes of these designs are seen when the diesel cycle produces gas only to drive the turbine, and no shaft power; through a midrange where both diesel engine and turbine power drive the output shaft; to the common turbo supercharged diesel where only the engine powers the shaft, with the exhaust-driven turbine only ramming combustion air into the diesel. Turbo compounding holds promise of producing engine efficiencies which cannot be improved upon by bottoming cycles. 27 Bolan, P. and Handley, L.M.; "First Generation Fuel Cell Character- istics", Power Systems Division, United Technology Corporation. 28 =Fickett, p. 17. Page 115 TABLE 9 ECONOMIC COMPARISON OF FUEL SUPPLY OPTIONS IN 1985*! (1975 dollars) Fuel-Cell System Fuel- Fuel Heat Capital Cell Cost*? Rate*$ Cost*4 Figure Option Fuel ($/10®Btu) (Btu/kWh) ($/kW) of Merit*> Dispersed fuel cell Low-sulfur using distributed distillate 2.49 7500 205 30.3 petroleum product Naphtha 2259 7500 205 21.0 Dispersed fuel cell Synthesis using distributed gas 4.38 8200 145 44.1 coal-derived fuel SNG 3.98 7500 205 41.4 Hydrogen 5.84 6500 180 48.2 Methyl fuel 4.70 6500 235 41.9 Central station coal Coal 1.47 ~7800 ~400 ~24.0 gasifier-fuel cell power plant *1 Data abstracted from EPRI 318, Assessment of Fuels for Power Generation by Electric Utility Fuel Cells. Final Report prepared by Arthur D. Little, Inc., October 1975. *2 Delivered to fuel cell power plant. *3 Fuel-cell fuel to ac power. Conversion of fuel-cell fuel to ac power (not including interest during construction or installation). *5 Lower values are more favorable. Glossary Page 1 GLOSSARY of Terms Bootstrap Heating -- There are many sources of heat in each home, office, factory, etc. These heat sources could easily heat the occupied area. The early American Farm home was heated by heat releases from: the wife's kitchen stove while she was cooking meals. For many years, well up into the 1930's, many people utilized gas lights in the winter to save on both light bills and heat. The light needed to read by could also heat the room. Today this same concept is possible. Homes heated by electric resistance heaters need never turn the lights off to save money if the heat- ers are demanding power. Lights are good resistance heaters. In many offices the lights can heat the whole place if air is circulated through the fixtures. A perfect application of waste heat capture. Brayton -- See "Cycles". Btu -- A British Thermal Unit (Btu) is the heat needed to raise one pound of water one degree Fahrenheit. 1 Btu = 3969 calories. Calorie -- A calorie is the heat needed to raise one gram of water one degree Centigrade. 1 calorie = .0002520 Btu. Glossary Page 2 Carnot -- See "Cycles". Co-generation - Total Energy -- These terms are in common use and have various meanings depending upon the ideas of the writer or speaker. The basic meaning is that both heat and power are generated and used simultaneously. Sometimes the generated power is interconnected with the local power utility, sometimes not. A power plant also producing heating steam or a heating plant Producing power are examples. Industry, university campuses, and office buildings have made use of these concepts for over 100 years. The price of fuel determines if it is cheaper to hitch a turbo generator to a heating boiler, hitch a heating boiler to a gas turbine, extract heating steam from a turbo-generator, or use separate systems each specializing in a single use. In all situa- tions there is a fuel price where co-generator or total energy concepts are profitable. Fuel prices so far have generally not allowed co-generation to be economical, but there are cases where definite savings can be realized. Cycle -- The thermal cycle is the sequence of events that takes place in converting energy in fuel to mechanical or electrical energy. For instance, the engine in your auto is an "Otto cycle" named after its inventor. There is an intake stroke, compression stroke, ignition, power stroke and exhaust stroke which is followed by the next intake stroke. The Diesel cycle is of course used in diesel engines; the Rankine cycle is the steam engine or turbine cycle; the Brayton cycle is the gas turbine cycle; the Carnot cycle is the "ideal" heat engine cycle which unfortunately has as yet be made into a practical engine. It is, however, the cycle all other cycles try to equal in theoretical efficiency. Glossary Page 3 Diesel -- See "Cycles". Economic Proximity -- is the area within which it is possible to trans- port a commodity for a larger return than the cost of transporting the commodity. For example, in analyzing the feasibility of dis- trict heating the economic proximity is a circle whose center is the heat source and radius is the maximum distance the heat can be | transported without incurring an economic loss. Outside this circle it is cheaper to obtain heat from a different source. Frost Tubes -- See "Heat Pipes". Fuel cell -- It is common knowledge that electric current passed through water breaks it into oxygen and hydrogen without the "burning" type of heat change. It should thus be possible to combine hydro- gen and oxygen and get electricity directly without a "burning" condition.' The fuel cell is this idea in actuality. It combines hydrogen and oxygen in the presence of a catylist to produce electricity and hot water. Grade -- This term used relating to heat means "usefulness of the heat". There is heat energy in the water in the gutter, but this heat cannot be used to cook vegetables, heat homes, bake bread, generate electricity, etc. However, the heat energy in the flame of a gas burner can be easily and productively used. The ex- haust and radiator heat in your auto is "low grade heat" because Heat Heat Glossary Page 4 it cannot be utilized in operating your car. Basically grade creases in direct proportion to temperature. in- Pipes -- These utilize the heat of vaporization of a liquid to gas and the difference in density of gas and liquid to affect a contin- uous transfer of heat from one end of the pipe to the other. the bottom end of the pipe is hot enough, the liquid boils to which rises. If the top end of the pipe is cold enough, the \f a gas gas condenses, releasing its heat of vaporization and the liquid drops back to the bottom. In general, this works only if the hot end is lower than the cold end. Some use capillary action to allow the hot end to be on top. The efficiency is low, size is large, and cost is high. Piles made of heat pipes allow permafrost to remain frozen as when the top end is hotter than the bottom the circu- lation stops. In winter, the thermal pile pulls heat out of the ground; in summer it prevents the summer heat from penetrating into the ground. Wheel -- This is a "wheel" much like a three foot diameter bunch of soda straws all laying parallel. Hot gas goes through half of them while cold gas passes through the other half. The "wheel" slowly rotates so that the "straws" move from the hot flow to the cold flow. In reality the "straws" are made of stainless steel, ceramic, etc. and thus are heated and cooled by the gases. These heat wheels are quite old in design but are efficient. They have mechanical design problems and of course allow the gases to mix to some extent. These are also called "Rotary Regenerators". pressing need for efficient regenerating for gas turbines has sparked new interest in heat wheels. The — Glossary Page 5 Magneto-hydro-dynamics -- is a newly possible system whereby elec- tricity is directly generated by a moving gas without going through a mechanical state. (All generation whether by steam, water- power, nuclear, or gas goes first into mechanical energy in a rotating shaft then is converted into electrical energy.) An elec- tric conductor moving through a magnetic field can generate an electric current. If a conductive gas is blown through a magnetic field, electricity is obtained directly. Simple to conceive, it is very difficult to accomplish with present knowledge. MHD -- See "Magneto-hydro-dynamics". Otto -- See "Cycles". Rankine -- See "Cycles". Rotary Regenerators -- See "Heat Wheels". Thermal Electric Machines -- These include all plants, power stations, engines, turbines, etc. which burn fuel (fossil or atomic) and produce power. Glossary Page 6 Thermal Piles -- See "Heat Pipes". Total Energy -- See "Co-generation". Transportability -- Transportability of heat. The workman's thermos bottle allows him to transport heat in his coffee from home to work. Were it not for the vacuum between the walls of the bottle, the heat in the coffee would be hardly transportable. Even so, if the coffee is not “too hot to drink" when put in the bottle it will have cooled to "too cold to satisfy" when needed. The transport- ability of the coffee's useful heat depends on insulation and the excess temperature it has at the start of the trip. Hot water, hot enough to heat a home, as it leaves the powerhouse, will be too cold for use by the time it arrives at the home. The water must have enough excess temperature to be usefully transportable through the excellently or poorly insulated transport system. The heat in hot water is much more transportable than heat in a hot gas of the same temperature. Each pound of water gives up 1 Btu of heat for each degree F it is cooled. Air gives about 4 Btu. Water at zero gage pressure weighs 62.4 Ibs/cubic foot. Air at the same pressure weighs about 0.075 Ibs/cu. ft. It would take 3500 times as many similar sized pipes to carry the heat in air as it does water at atmospheric pressure. A pressure of about 50,000 pounds per square inch (like that found in a large cannon when fired) would allow the heat in air to be as "transportable" as that in water. Thus the heat in hot water is more transportable than the heat in hot air. The combustion heat in a gallon of oil to be burned is more transportable than the heat in heated hot water it could produce. The poor transportability of heat is the reason much of it must be wasted "where it is made" because it can't be carried to "where it is needed’. Bibliography Page 1 SELECTED BIBLIOGRAPHY Note: This bibliography includes references from which specific infor- mation was obtained as noted in the footnotes and also sources studied to gain background in the general area of Waste Heat Capture. These were selected from a literature search which produced over 1,500 recent works on the broad subject. Aamot, H.W.C. Planning Considerations For District Heating and the Alaska State Capitol at Willow. Mark Fryer & Associates, 1709 S. Bragaw, Anchorage, AK 99504. October 1977. Aamot, H.W.C. Management of Power Plant Waste Heat In Cold Regions. U.S. Army Cold Regions Research & Engineering, Hanover, NH. U.S. Department of Commerce, National Technical Information Service. No. AD-A003-217. December 1974. Alaska Department of Commerce & Economic Development, Division of Energy & Power Development, 338 Denali Street, Anchorage, AK 99501. Minimizing Consumption of Exhaustible Ener Resources Through Community Planning and Design. October, TT Anchorage Daily Times. "Cook Inlet Tidal Power". September 19, 1974. Anchorage Daily Times, Business & Financial Section. "Less Fuel Engine Has Longer Piston Stroke". Balukjian, H., and Gatzoulis, J. Improved Specific Fuel Consumption of Open Cycle Gas Turbines By Utilization of Waste Heat. The Amer- ican Society of Mechanical Engineers, United Engineering Center, 345 E. 47th Street, New York, NY 10017. 1975. Basiulis, A, and Johnson, J.H. "High Temperature Heat Pipes for Energy Conservation". Thermal Product Department, Hughes Aircraft Company, Electron Dynamics Division, 3100 W. Lomita Blvd., Torrance, CA 90509. IECEC Record. 1975. Beall, S.E., and Samuels, G. "How to Make a Profit On Waste Heat". Nuclear Technology. Vol. 12. September 1971. Bibliography Page 2 Berg, Charles A. Energy Conservation Through Effective Utilization, National Bureau of Standards, Institute for Applied Technology Report. NBSIR 73-102. February 1973. Boersma, L. Beneficial Use Of Waste Heat For Agricultural Applications. The American Society of Agricultural Engineers, Chicago, IL. 1975. Boersma, L., and Rykbost, K.A. "Soil Warming With Power Plant Waste Heat In Greenhouses". HortScience. 10;28-30. 1975. Bolan, P. and Handley, L.M. First Generation Fuel Cell Characteristics. Power Systems Division, United Technology Corporation. Business Week. "A Chicken Coop Maker's Energy Contribution". December 19, 1977. Caterpillar. Data provided at Waste Heat Utilization Seminar presented by NC Machinery Company in Anchorage, Alaska, 1978. Christianson, A.G., Berry, J.W., and Miller, H.H., Jr. "A Demon- stration of Waste Heat Use In Agriculture". Research Sanitary Engineer. Environmental Protection Agency, Corvallis, OR. Colt Industries, Fairbanks-Morse Power Systems Division, Beloit, WI 53511. Total Energy Systems. Cook, Earl. "The Flow of Energy In an Industrial Society". Scientific American. Vol. 224, No. 3. September 1971. CRC Handbook of Chemistry and Physics. CRC Press, Cleveland, Ohio. 1974. Cronin, T.S. "New Wood-Fired Generating Unit". Public Power. January/February 1978. Cummins Engine Company, Inc., Columbus, IN 47207. Application Engineering Bulletin #11.01. February 1977. Curl, Robert S. Practical Applications Of Heat Recovery Systems. The Society of Manufacturing Engineers, 20501 Ford Road, Dearbourne, Ml. 48128. Bibliography Page 3 Divine, T.E., and Demmitt, T.F. Agro-Industrial Utilization of Reject Heat & Water. Food & Agricultural Section, Battelle Memorial Institute, Pacific Northwest Laboratories, Battelle Blvd., Richmond, WA 99352. December 1974. Electric Light & Power. "Utilities Pursue Trash Burning Despite Political Barriers". February 1978. Electric Light & Power, Vol. 55. "Utilities Planned Diesel Bottoming Cycle Tests". November 1977. Encyclopedia Brittanica. General Editor Warren E. Preece. Encyclo- pedia Brittanica, Inc., William Benton, Publisher, Chicago, Ill. Energy Transformation Corp., Swinehart & Rick Roads, Foyertown, PA 19512. Thermo Magnetic Generator. Faletto, Andy. The Anchorage Times. "At Fort Richardson the State Is In the Fish Farm Business". May 21, 1978. Fiat Auto Group. Totem Total Energy Module. September 1977. Fickett, Arnold. "Fuel Cells: Versatile Power Generators". EPRI Journal. April 1976. Fields, E.F. “Adding An Economizer To the Boiler Exhaust System". Plant Engineering. March 30, 1978. Flower, A.R. "World Oil Production". Scientific American. Vol. 238, No. 3. March 1978. Fraas, A.P. Topping and Bottoming Cycles Binaries. Ninth World Energy Conference, Detroit. Vol. 5. 1974. Franks, J.M., and Rattray, L.G. "Plant Designed To Use Waste Btu's". Plant Engineering. January 1965. Friedlander, G.D. "Energy Conservation by Redesign". IEEE Spectrum. November 1973. Bibliography Page 4 General Electric Corporation. Publication #25-6516-02, Publication #22-3047-3, Publication # 25-6240-75. The General Electric Company Plant Park, Louisville, KY 40225. June, 1977. Gibson, T. "Waste Heat Boiler Possibilities". The Plant Engineer. March 1975. Gillies, J. “Heat Storage & Waste Heat Recovery". The Plant Engineer. Vol. 14, No. 11. November 1970. Godfriaux, B.L., Valkenburg, H.J., Van Riper, A., and Guerra, C.R. Power Plant Heated Water Use In Aquaculture. Public Service Electric & Gas Co., Newark, NJ. Gorzelnik, E.F. "Heat Pumps Have Still Another Study". Electrical World. November 15, 1977. Granet, Irving. Thermodynamics and Heat Power. Reston Publishing Company, inc., Reston, Virginia. 1974. Grindrod, J. "A Combined Central Heating and Incinerator Plant". Heating and Ventilating Engineering. September 1962. Gunn, D.C. "Waste Heat Recovery In Boilers". Energy World. February 1976. Handley, L.M., Grevstad, P.E. and McVay, D.R. Improvement In Phosphoric Acid Fuel Cell Power Plant Technology. United Technologies Corporation, Power Systems Division, South Windsor, CT 06074. Hatle, Z., and Lampar, M. "Exploitation of Waste Heat". |AEA-SM 187/47. Hausz, W., and Meyer, C.F. "Energy Conservation: Is the Heat Storage Well the Key?" Public Utilities Fortnightly. April 24, 1975. Heating & Ventilating Engineering. "Refuse Incineration For District Heating". October 1973. Herman, L.R. "The Roesel Generator". IEEE. Paper A 76 035-6. Bibliography Page 5 Herman, Stewart W. Inform, Inc.: Energy Futures. Ballinger Pub- lishing Co. 1977. Holm, J., and Swearingen, J.S. "Turbo-expanders Offer Processors Way to Conserve Energy". The Oil & Gas Journal. January 23, 1978. Horsley, M.E. "Principles of Waste Heat Recovery". The Plant Engineer. February 1976. Johnson, Roy W., Consulting Engineer. Harnessing Cook Inlet's Tidal Activity. Presented at Project Independence Hearings, Federal Energy Administration, Anchorage, Alaska. September 9, 1974. Jones, R.A. Caterpillar On Total Energy. Publication 345. Diesel Engineers and Users Association, 10 London St., London. Kamat, D.M., and Drucker, E.£. "The Potential of Residential Total Energy Systems". Mechanical and Aerospace Engineering. Syracuse University, Syracuse, NY 13210. 1977. Kaplan, G. "Constraining the Energy Gobbler". IEEE Spectrum. December 1977. Karkheck, J., Beardsworth, E., and Powell, J.R. "Technical and Economic Aspects of Potential U.S. District Heating Systems". |ECECTEC Journal #11. Karkheck, J., Powell, J., and Beardsworth, E. "Prospects for District Heating In the United States". Science. Volume 195. March 11, 1977. Kellock, B.C. '"Pepbow Total Energy System". Machinery and Produc- tion Engineering. March 24, 1976. Kent's Mechanical Engineers Handbook. John Wiley & Sons, New York. 1939. Kerr, N.M. "Farming Marine Flat Fish Using Waste Heat From Seawater Cooling". Energy World. October 1976. Klass, Philip J. "New Technique Offers Regulated Power". Aviation Week and Space Technology. February 26, 1973. Bibliography Page 6 Klooster, H.J. "Practical Rankine Cycles for Process Plants". 1ECEC Record. 1975. Kritchley, G.N. "Summing up: Waste Heat Recovery Conference". The Journal of the Institute of Fuel. August 1961. Lassig, H. "Handling Installations In Heating Stations". Handling and Conveying Automation. 1962. Lawrence, L.R. “The ERDA Fuel Cell Program". Divison of Conser- vation, Research, and Technology, Office of Conservation, Energy Research and Development Administration, Washington, DC 20545. IEEE. Paper A 77 688-5. Levine, S.K. A Method For Increasing the Efficiency of the Electric Generating Process. The Wind Harness Company, 713 Washington St., New York, NY. Lindsley, E.F. "New Alternator Delivers 60-Cycle Power At Any Speed". Popular Science. July 1973. Lueckel, William J., and Casserly, James R. Fuel Cells For Utility Service. Power Systems Division, United Technologies Corporation. April, 1976. Marine Diesel Engine Headquarters, Inc., 2834 Northwest Market Street, Seattle, WA 98107. Power Jenny II. Marshall, O.W., Morash, R.T., and Barber, R.J., Independent Energy Systems For Better Efficiency. Roesel Laboratories, Route 2, Box 281-M, Bradenton, FL. Maslen, P.L. DeLaval Enterprise Engine Division. Letter dated 20 September, 1977 to C.R. Hilpert. Subject: DeLaval Engines S/N 77083 and 77084, Kodiak, AK. , Mauro, R.L. "ls Co-Generation Feasible In the United States?" Public Power. January - February 1978. McKetta, J.J. Why The U.S. Will Not Attain Energy Self-Sufficiency. The University of Texas - Austin. 1977. Bibliography Page 7 Mechanical Technology, Inc. Energy From Waste Through Rankine Bottoming Cycles. Latham, New York. 1977. Meyer, C.F. "Status Report On Heat Storage Wells". Water Resources Bulletin. American Water Resources Association. Volume 12, No. 2. April 1976. Moon, J. "Gas Engines Power Selective Energy Systems". Worldwide Edition of Diesel & Gas Turbine Progress. October 1973. Nelson, S.H. Utilization of Low Temperature Heat From Steam-Electric Power Plants: Techniques, Economics and Institutional Issues. The University of Wisconsin - Madison. 1975. O'Conner, J.J. "Is Industry Serious About Co-Generation?" Power. March 1978. Olszewski, M., and Diaz, L.F. "Feasibility of Using Power Plant Reject Heat for Urban Food and Methane Production". JECEC #11. Ott, R.E. “Generator Waste Cooling Water". Electrical World. October 26, 1959. . ae Pacific Power Systems and Combustion Turbine Power Company, Fair- banks, AK, Lower Power Costs For Alaska Via Coal Fired Combustion Turbines. December 15, 1976. Parchim, N.F. “Low Grade Heat Utilization By an Organic Bottoming Cycle". Proceedings: The Institute of Environmental Sciences. Patel, P.S., and Doyle, Edward F. Compounding the Truck Diesel Engine With an Organic Rankine Cycle System. Society of Automotive Engineers, Detroit, Mich. 1976. Peddie, R.A. "Combined Heat & Power -- A Utility's View". Energy Digest. August 1977. Popular Science. "Heat Pumps, Cheapest Cooling & Heating For Your Home". September 1976. Power Engineering. '"Co-Generation, A Concept That Holds Great Advantages". March 1978. Bibliography Page 8 Power. "Evaluating Heat Recovery Boilers". September 1975. Public Utilities Fortnightly. "Waste Heat May Warm Greenhouses". March 16, 1978. Raymond, James A. "Using Waste Heat for Salmon Culture In Interior Alaska". The Northern Engineer. Vol. 9, No. 1. Reay, David A. "The Heat Pipe Heat Exchanger, A Technique for Waste Heat Recovery". The Heating & Ventilating Engineer. January 1977. Reed, R.D. "Recover Energy From Furnace Stacks". Hydrocarbon Processing. January 1976. Ricken, Josef, and Schwarz, Peter. "Heat Recovery In Supermarkets". Linde Reports On Science & Technology. 25/1977. Riley Beaird, Inc. Bulletin 302-746. Maxim Silencer Division, P.O. Box 1115, Shreveport, LA 71103. Rubenstein, E. "While Politicians Struggle With Communications & Energy Policy, GE Engineers the Perfect Tomato". |EEE Spectrum. January 1978. Ruch, Michael A. “Heat Pipe Thermal Recovery Units". 1975. IECEC Record. Rutherford, J.G. “Heat Outdoor Air For Nickel Mine By Recovery Heat Exchange System". Heating Piping & Air Conditioning. May 1959. 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ORNL-4797. July 1972. Young Radiator Company, Racine, WI 53404. Catalogue 2572. Zanyk, P., The Sarnia Division, Dow Chemical Co. of Canada. "Power Plant Provides 86% Efficiency". The Oil & Gas Journal. May. 27, 1974. Zeller, Emil, Manager, Physical Facilities, Woodward Governor Co., 5001 N. Second St., Rockford, IL 61101. Letter to C.R. Hilpert, dated April 17, 1978. Zimmerman, R.A., President and Chief Operating Officer, Hershey Foods, Hershey Foods Corp., Hershey PA 17033. Letter to C.R. Hilpert, dated April 7, 1978. Appendix A Page 1 APPENDIX A DISTRICT HEATING FEASIBILTY ANALYSIS Breakeven Evaluation Breakeven analysis is frequently used to determine the demand level required in order for a product to fully recover the fixed and variable costs of its manufacture!. This analysis can also be used in evaluating alternative investments. In the instant analysis, the annual cost per customer of heating with fuel oil can be compared to the cost of a district heating system util- izing waste heat. The procedure is to determine the annual fixed cost and variable cost per foot of the proposed district heating system. The breakeven system length is determined by equating the annual cost of heating with fuel oil and the annual cost of the district heating system. This is summarized in the following equations: Fuel Oil Cost per Customer - F226 = R where, Fs = annual fuel cost per customer G = annual fuel consumed per customer in gallons R = annual cost of fuel per gallon District Heating System Cost = DS TEC. eve “Lt Weston, J. Fred and Brigham, Eugene F.; Managerial Finance, 4th ed., The Dryden Press, Hinsdale, Illinois, 1972, pp. 46-57. Appendix A Page 2 where, De = cost of district heating system TFC, = Total fixed cost of district heating system VC = cost per foot of district heating system L = length of district heating system At Breakeven Point - De = Eo * Cor Fo °C = TFC, r=Fe°S + VC + L and, EG Nc Nc where, C = number of customers Assumptions There are several assumptions made in the analysis. Heat loss calcu- lations were based on a 20,000 cubic foot building assuming standard insulation. The average customer was assumed to use five gallons of fuel oil per day based on typical residential usage patterns in Anch- orage. AVEC's current delivered cost of $.72 per gallon was used for the price of fuel. The graphs were designed to generally show the feasibility of a district heating system. A feasibility analysis should be done for a location using that location's costs and usage patterns if the analysis shows district heating feasible. General Observations The waste heat available on an average basis is dictated by the gener- ator's size and the load factor of electric demand. Because most rural Alaska locations have relatively low load factors, the use of waste heat Appendix A Page 3 is generally restricted to heating city water and proximate institutional buildings. The Alaska Commercial Company and Kotzebue presently use waste heat for heating stores and schools, respectively. Naknek pres- ently utilizes waste heat to heat the city water supply. Appendix A Page 4 BREAKEVEN EVALUATION HP-97 Program Documentation Description of Program Application This program calculates the constant and coefficient of a breakeven equation. Required inputs are the fixed cost of district heating, the variable cost of district heating, and the annual fuel cost per customer to be saved. .The program computes the coordinate of the breakeven distance vs. heat load for a given number of customers. Mathematical Relationships (fuel_cost saved/customer)(# customers) its = : Breakeven units Variable cost - total fixed cost/variable cost A = total fixed cost/variable cost B= fuel cost saved/customer variable cost Input a) Load Program, Side 1, Run Mode, Manual b) Key: fixed cost /Enter/ variable cost /A/ annual cost to be saved /B/ Output A Appendix A Page 5 To evaluate the breakeven distance: c) Key: average consumption/cust /Sto 6/ # customers /c/ Output # customers breakeven consumption (BTU x 108) breakeven units (feet) BREAKEVEN EVALUATION PROGRAM STEP 001 002 003 004 005 006 007 008 009 010 011 012 013 014 015 016 017 018 019 020 021 022 023 024 025 026 027 028 029 030 031 032 033 034 035 036 037 038 HP-97 Program KEY *LBLA STO1 Ry STo2 FIX DSP3 R/S *LBLB STO3 Ry STO4 Ry STOS R/S *EBLG RCL3 RCL4 XY STO7 RCL5 STO6 GSBD T/S *LBLD RCL7 RCL1 RCL2 RCL6 PRTX RTN R/S KEY CODE 2111 35 01 -31 35 02 -11 -63 03 51 21 12 35 03 -31 35 04 -31 35 05 51 21 13 36 03 -35 36 04 -35 -41 35 07 36 05 -55 -24 35 06 23 14 "51 21 14 36 07 36 01 -45 36 02 -35 36 06 -35 -14 24 51 Appendix A Page 6 Appendix A Page 7 BREAKEVEN EQUATIONS Interest Fuel Cost Customer Constant Pipe Type Size Rate Per Gal. Coefficient (F/V) Asbestos 4" 7% 40 598.36 541.8 50 747.95 541.8 60 897.54 541.8 70 1,047.13 541.8 80 1,188.52 541.8 6 7% 40 525.18 846.76 50 656.47 846.76 60 * 787.77 846.76 70 919.06 846.76 80 1,043.17 846.76 8" 7% 40 421.97 871.10 50 527.46 871.10 60 632.95 871.10 70 738.44 871.10 80 838.15 871.10 Appendix A Page 8 Breakeven Equations, continued... Interest Fuel Cost Customer Constant Pipe Type Size Rate Per Gal. Coefficient (F/V) Uninsulated 4" 7% 40 336.41 304.61 Ductile Iron 50 420.51 304.61 60 504.61 304.61 70 588.71 304.61 80 668.20 304.61 6" 7% 40 266.42 429.56 50 333.03 429.56 60 399.64 429.56 70 466.24 429.56 80 529.20 429.56 8" 7% 40 181.14 373.95 50 226.43 373395 60 271,71 373.95 70 317.00 373.95 80 359.80 373.95 Appendix A Page 9 Breakeven Equations, continued... Interest Fuel Cost Customer Constant Pipe Type Size Rate Per Gal. Coefficient (F/V) Insulated 4" 7% 40 180.69 163.61 Ductile Iron 50 225.87 163.61 60 271.04 163.61 70 316.21 163.61 80 358.91 163.61 6" 7% 40 144.55 233.07 50 180.69 233,07 60 216.83 233.07 70 252.97 233.07 80 287.13 233.07 8" 1s 40 104.73 216.21 50 130.92 216.21 60 157.10 216-21 70 183.29 216.21 80 208 . 03 216.21 Appendix B Page 1 APPENDIX B AVAILABLE WASTE HEAT FROM EXHAUST GAS HP-97 Program Documentation Description of Program Application This program calculates the recoverable Btu's from exhaust gas. The exhaust gas temperature, the minimum usable temperature, the exhaust gas flowrate, the exhaust gas density, and the exhaust gas specific heat are required for program execution. The program converts the observed exhaust flowrate to standard temperature and pressure prior to computing the recoverable Btu's. Mathematical Relationships Qe= hey heuct - T min) (Cp) (Density) (Flowratec+p) Lb es ; Flowratec+p ( Min? = Flowrate BneeRUea (CFM) (Cp) 520 Texhaust + 50 Input a) Load Program, Side 1, Run Mode, Manual b) Key: Specific Heat /Enter/ T min 7A/ 460 7Enter/ 520 7Enter/ Cp B 7, ll Enter/ Fiwavst je observed Smad Appendix B Page 2 Output Btu/Min. Note 1) When only the flowrate varies in successive problems, the Btu/Min may be calculated by: Key: Desnanct /Enter/ Flowratey coryeq LC/ After the initial calculation. 2) If the exhaust flowrate in Ib/min at STP is known, then: Key: Teshsuck /Sto 6/ Flowratec +p /Sto 7/ /D/ for the initial problem after pressing /B/. For additional problems when only the flowrate varies: Key: Flowratec+p /Sto 7/ /D/ Appendix B Page 3 AVAILABLE WASTE HEAT FROM EXHAUST GAS PROGRAM HP-97 Program STEP KEY KEY CODE 001 *LBLA el 11 002 STOt 35 01 003 Ry =3i 004 S702 35 02 005 FIX =) 006 DSP3 -63 03 007 R/S 51 008 *LBLB 24 12 009 STO3 35 03 010 Rv -31 011 STO4 35 04 012 Ry -31 013 STOS 35 05 014 R/S 51 015 *LBLC 21 13 016 RCL3 36 03 017 x E35 018 RCL4 36 04 019 4X =35 020 X*Y -41 021 STO7 35 07 022 RCLS 36 05 023 + 70D 024 ie -24 025 STO6 35 06 026 GSBD 23 14 027 T/S 51 028 *EBLD 21 14 029 RCL7 36 07 030 RCL1 36 01 031 7 -45 032 RCL2 36 02 033 x -35 034 RCL6 36 06 035 x =35 036 PRTX -14 037 RTN 24 038 R/S a Appendix C Page 1 APPENDIX C The big DeLaval engines at Kodiak at full load, can each produce from their cylinder jacket cooling alone 9,247,300 Btu/hour.! This is equiv- alent to heating about 330 large homes on the coldest days.2 This heat is contained in water flowing at 1500 gallons per minute at 175°F. Prudent engine operation would not allow this engine water to be used in the area piping and home radiators as a broken heating water main would shut down the power station or damage the engines. Thus a heat exchanger is necessary. Out of the heat exchanger we could receive 165° water at 1500 gallons per minute. This 1500 GPM water requires two pipes each 12 inches inside diameter to carry the heat to and from the engine.? It is of interest to note that this same heating energy would be carried to the 330 homes by three wires each about 4 inch in diameter in a usual electric distribu- tion system. The wires need no insulation in air; the pipes need 3 inches of insulation even in air. An appreciation of this heating water distribution system can be achieved when one realizes that each of these 330 homes would need a flow of 6500 gallons of water a day to heat it.4 The same home might normally use 500 gallons® per day of tap water (5 people at 100 gallons per day Maslen, P.L., DeLaval; Letter to C.R. Hilpert, Subject: DeLaval Engines #77083 and #77084, Kodiak, Alaska, dated September 20, 1977. Calculation No. Cl at end of this Section. Calculation No. C2 at end of this Section. Calculation No. C3 at end of this Section. Urquhart, L.C.; Civil Engineering Handbook, McGraw-Hill Book Com- pany, Inc., New York, 1950. Appendix C Page 2 each). The heating water distribution system carries over 12 times the flow of the city water and sewer system and in addition the heating water distribution system needs to be insulated against heat loss. In comparison, an isolated home heating system circulates the same few gallons of hotter water continuously. The pumping power to get the heating water to the 330 homes is about 4 horsepower per home.® This represents an increase of about 27% in the homes! electric bills for the heating months. 7 To utilize this 165° water in the home about twice® as much radiator Capacity would be needed as for a home furnace producing 200°F water. The lopsided proportions of a waste heat capture system for district heating from cylinder jacket water are thus seen. An insulated piping system 12 times the flow of the present water and sewer system is needed plus an equivalent 27% increase in domestic electric bills, plus about twice as many radiators in each home, plus about double the cooling system at the power house. Additionally, the whole system should be filled with an expensive mixture of glycol and water if used in an arctic environment. After some years such a water system (pres- ent Anchorage water system experience) could be leaking 3 - 4%.9 This represents a daily glycol replacement cost of about $60,000.00, which, of course, is unrealistic. It could be leaking so much glycol out c Calculation No. C4 at end of this Section. a Calculation No. C5 at end of this Section. : Young Radiator Company; Catalogue 2572, Racine, Wisconsin 53404. 9 Calculation C6 at end of this Section. Appendix C Page 3 that it would be cheaper to burn glycol to heat the homes.?° Elimin- ating the glycol would eliminate this possible unreasonable cost but would require a quick drain “air scavenged" system to prevent pipe freezing if flow stopped to any section. The system leakage of 3% would actually subtract about 30% of the homes heated.1! Distribution system leakage could drop 100 homes from the "heated for free" list. The engine oil coolers and intercoolers also transfer large amounts of heat to cooling water. The same engines' oil cooler could supply enough additional heat (2,215,846 Btu/hour) for 80 more homes subject to the limitations of the jacket water as above. The intercooler rejects 4,436,800 Btu/hour and could in theory heat 160 additional homes. Unfortunately this cooling water is at only 145°F which makes it nearly useless except as preheat for the jacket water system. The exhaust gas is perhaps the most available heat source as the gas is somewhere over 800°F. The gas can be used in two ways. ais As the "fire" for a heating boiler delivering either hot water or steam. 2. As the "fire" for a power boiler in some Rankine cycle power generation equipment. (The "Rankine" cycle is the name for the common steam electric plant. ) In general exhaust gasses from any combustion are not cooled much below 350° - 400° by simple boilers. Each pound of petroleum burned produces over a pound of water (in the form of superheated steam) and some corrosive products. It is best to keep this water and these corrosive products vaporized and diluted to insignificance rather than condensed as corrosive concentrates in the boiler to rapidly destroy the © 109 11 Calculation No. C7 at end of this Section. Appendix C Page 4 boiler itself. Thus the heat from exhaust practically recoverable is much less than that present. A practical commercial exhaust boiler on Kodiak's DeLavals could produce 6700 pounds of steam}? per hour at 100 psig pressure or 7,799,671 Btu/hour.1% This represents about 46% of the heat available in the exhaust gas.14 If used in a usual district steam heat system this could heat 280 homes. The higher temperature of this steam allows this system to take on reasonable proportions and be similar to "Municipal Steam Heat", "Central Steam Heat" of nearly 100 years ago or the modernly termed "District Heating Systems". Many institutional, and industrial communities are thus heated today by locally generated steam or hot water heat. University campuses and government complexes are common examples, as are steel mills and other multi-building plants. These all have common features. The steam source is centrally located to the district heated and the district is concentrated. The high pressure insulated piping cause this heat distribution to cost at least 150% more than the water and sewer system for the same number of homes. Diesel engine exhaust heat has been so well processed by the engine itself that there is little recoverable power in it. The Kodiak DeLaval diesels' exhaust heat might produce 250 kW from a steam Rankine!> cycle system which is about 5% of the engine's present output. Util- izing the most modern "Organic Rankine Cycle" (O.R.C.) system the engine might gain 10 to 15% total kW output.?® A 250 kW steam plant would cost about $900.00 per kW. O.R.C. systems are as yet federally financed research projects, for which no real price is available, but it is certain that the higher technology of the system will make its com- 12 Spence, J.E., Cessco, P.O. Box 6415, Anchorage; Letter to C.R. Hilpert dated March 8, 1978. 13 Calculation No. C8 at end of this Section. 14 Calculation No. C9 at end of this Section. 15 Calculation No. C10 at end of this Section. 16 Sundstrand Energy Systems, Rockford, Illinois 61101. Harold M. Sweet, G.E. Heat Pump (206) 575-2771. Appendix C Page 5 mercial cost higher than for a simple steam system. The name "Organic Rankine Cycle" comes from the use of the organic fluid toluene instead of water as the working fluid. Some O.R.C. makers quote $1,200 - $1,500 per kW. Exhaust heat power systems suffer another problem. The 250 kW steam Rankine cycle system driven by one of Kodiak's DeLavals would be able to perform as stated above only when the engine was operating at 100% power. Diesel exhaust temperature falls rapidly as the engine is un- toaded. Thus when the diesel is at 50% power the steam turbine is not at 50% power but near zero. The end result is that a sophisticated added system making possible a 5% increase in overall efficiency prob- ably realizes considerably less. Functionally it can easily oscillate between a cost and a saving for such an operation. In general, diesel exhaust heat is of limited use for power generation. It can deliver process steam and heating steam or water. The above example can be scaled up or down for a view of other size engine installations. However, when the engine plant becomes small enough to alleviate the requirement for a full time human operator these steam Rankine cycle systems are not realistic. Steam power generation systems are not as foolproof as packaged skid mounted engines and cannot be made so. Thus a full time interested knowledgeable operator will be required to wring an extra 5% maximum from an engine which itself needs only once a day or once a week attention. O.R.C. system makers believe simple automation is possible, but such machinery is not a commercial practicality today (1978). Considerable research and development are being conducted, and it is reasonable to expect con- tinuing improvements in capabilities as the price of fuel continues to climb. The small bush sized diesel power plants have about the same cooling water and exhaust heat proportions as the example considered above. The manufacturers have this information ready for application in easy to use form. The specifications for proper heat exchangers and exhaust Appendix C Page 6 heat recovery boilers are already established as are recommended cir- cuits and possible fuel savings. Typical is this information on Cater- pillar engine generator plants from Dehn Engineering Sales Company, P.O. Box 66040, Seattle, WA 98166. This material shows a possible saving in fuel oil for heating of $15,400.00/year at 40¢/gallon minus the $9,746.00 equipment cost. The fixed costs are such that if a heat need exists which is equal to the recoverable waste heat, a heat recovery system can be economically justified. The variable costs of system design which change a system from gain to loss are mainly those of economic proximity, as explained in Section IV. The following information from Dehn Engineering Sales Company can be considered typical, but by no means comprehensive. BOILER FUEL SAVINGS WiTH HEAT RECOVERY SYSTEM | ENGINE WITHOUT EXHAUST | WITH EXMAUST HEAT ee | MBH | = etamA 1.65 . ue ino : 33047 90 || 258 2.3 i | 32067 | 135 | 384 3.5 ee cee hs { S408TA | 210 | 648 5.8 { i { i} 3408TA | 275 oo 8.0 BA12TA 460 la L478 13.2 ae Sage nao D353TA Sot | 20 8.4 i D379ITA 429 1,446 13.0 7? D398TA | 600 |, 1,830 16.9 2,980 | i { D399TA F GSO 2550 22.6 Beh Ont ese. poe moe Nias Ss sade ey MBH = Thousands of BTU per Hour ASSUMPTIONS: 19,500 aTu/LB 6% Efe ency J 23) 15,600 BTUAS af 12 LASGAL 4 AS Sans "191,000 BIU/GAL & DEYN ENGINEZRING SALES COMPANY P. ©. Box 66049, Saatile, WV 226 243~2523 HEAT RECOVERY SYSTE:A DATA FOR CATERPILLAR DIESEL 60 HZ PRIME POWER WITHOUT FAN ENGINE KW ELECTRICITY KW HEATED WATER CYLINDER JACKETS EXHAUST HEAT EXCH. KW HEATED AIR &, RADIATED HEAT | GENERATOR TOTAL KILOWATTS GALLONS PER HOUR TOTAL KW-HR/GAL 3304NA 3304T 58 54 15 163 32 3306T 3406TA 3408TA 3412TA D353 ~—S«379 90 135 210 275 460 300 420 76 112 190 261 432 272 422 62 91 148 179 261 167 278 7 32 34 4g 72 48 72 9 13 14 19 32 22 28 264 383 596 780 1,257 809 1,220 8 12 17 22 35 23 35 33 32 35 35 36 35 35 D398 600 551 322 96 39 1,608 47 34 NOTES: 1. Cylinder jacket heat value includes lubricating oil heat load, aftercooler, water shielded manifolds and turbocharger oil cooling where appropriate. DEHN ENGINEERING SALES COMPANY D399 850 735 469 133 2,230 65 34 os = =. j HEAT RECOVERY SYSTEM DATA CATERPILLAR GIESEL 60 HZ PRIME PCWER WITHOUT FAN 50% GLYCOL - §0% WATER ENGINE COCLANT WITHGUT EXHAUST HEAT RECOVERY i ENGINE 3304NA, 3304T + «=»: 3306T 3406%s & 34087A 3422TA 0353 0379 0398 0399 kW $5 50 5 219: 275 460 300 420 600 850 BTU/HR 183,000 252,000 384,000 648,002 ' 891,000 1,476,0C0 930,000 1,440,000 1,880,000 2,510,000 GAL/WR BOILER FUEL 16 26 3.5 5.3 8.6 13.3 8.4 13.0 16.9 22.6 FEAT EXCHANGER FOR CLOSED LOOP _{ACCYRCULATING) CIRCUIT AS USED WITH SPACE MEATING MODEL F503 F-S04 = F-604 F~696 F-608 HF-G03 F-608 HF-€10 HiF-810 F-1010 GPM SHELL 50% GLYCOL 20 35 59 75 100 160 100 1€0 210 300 BTU/AR PER DEG. ETD - 4,830, 6.399, 10,600, 14,900, 20,000, 37,000, 23,600, 32,000, 42,700, $3,000, TIN F. 157° 3540 158° pie 154° 150° 1560 1509 151° 146° T OUT PF. 178 nz? 176 Wi 173 179 71 170 171 167 tl - ENGINE OUT of, 195° 195° 195° 195° 195° 195° 195° 195° 195° 195° t2 + ENGINE IN ORs 187° 134° 1€2° 121° 184 179° 183° 183° 162° 181° HEAT EXCHANGER FOR ONCE THROUGH (NON-RECIRCULAT ING) CIRCUIT TATE. MODEL (R = .002 F-302 -F-303.— F802 F-5u5 F -603 F-€06 F603 HF-804 HF-805 HF-805 GPit SHELL - WATER 3 5 g 12 18 25 20 30 35 50 T IN (MAXIMUM) er. 46° 490 430 585 Ban 489 555 476 446 eae T OUT F. 172° 150 142 165 155) 170 151 146 155 157 BTU/HR PER DEG. ETD 1,320 1,830 2,700 5,085 6,750 10,780 7,150 10,400 13,300 19,000 P SHELL Pst 23 & 7 28.5 5.4 2.8 6.6 1.4 2.9 1.0 P TUBES PSI 3.6 3.6 1 33 3.4 7.5 2.4 ud 1.9 6.4 tl ENGINE OUT OF 165° 195° 185° 195° 195° 195° 165° 185° 186° 135° t2 ENGINE IN OF. ize 174° 172° vie 174° 169° 173° 173° 172° 171° REMOTE RADIATOR Mac 2600, 260 260, 669, 860, 260, 660, 860, 1260, 156, AMGIENT T. ( P) 100 100) 95 55 105°(1.5) 100°(0.9) 103°(1.5) -94°(1.8) 168°(2.1) __98°(2.9) OPTIONAL RADTATOR HNC ICH-360 ICH-3¢0 260, 469, 6€9 106D 1089 1260, mareny f, (.P) 95°(1.2) 83 23°(1.5) 91°(2.1) 85 THERMOSTATIC VALVE WA DA 26 283 38 33 38 43 43 4B P PSI 1.2 1.2 1.5 1.2 3 4.3 3 1.8 2.5 3.9 NOTES: 1. 19,500 BTU/LB 0% EFF. 7.12 LB/GAL. 2. MAXIMUM TEMPERATURE AT "GPM SHELL" FLOW RATE DEHN ENGINEERING SALES CO. 3/16/78 ENGINE KILOWATTS ENGINE HEAT BTU/HR EXHAUST HEAT Gal. fuel per nour FT Model BTU/HR RECOVERED HEAT STU/AR BTU/AR per KW elec Kid heat per KW elec Gel/Hr of boiler fuel HEAT EXCHANGER GPM shell Tin T out Oeita P, shell Delta P, tubes BRU/HR per Deg ETD RADLATOR 1005 & 5¢0" (AP) 60° & 100' (a?) THERMOSTATIC VALVE Delta P, PSI ENGINE ROOM HEAT Q, RADIATED Q, GENERATOR Total STU/MIN HEAT RECOVERY SYSTEM DATA FOR CATFRPILLAR DIESEL 60 HZ PRIME POWER WIT20UT FAN -- WITH EXHAUST HEAT RECOVERY 3304NA 3306T 3306T 3406TA 3408TA 3412TA 0353 0379 55 90 135 210 275 460 300 420 183,000 258,000 384,000 648,090 891,000 1,476,000 930,000 1,440,000 5 8 12 v7 22 35 23 35 40-3 70-4 110-5 275-6 273-8 420-10 275-8 410-10 112,000 . 210,000 310,000 505,000 610,000 890 ,000 570,000 950,000 295,020 468 090 694,000 1,153,600 1,506,060 2,366,000 1,500,000 2,390,000 5.369 5.299 5,140 5,490 5,450 5,140 5,600 5,690 1,57 1.82 1.51 1.61 3.00 1.51 1.465 1.667 2.66 4.21 6.25 10.4 13.5 21.3 13.5 21.5 F-504 F604 F-6065 HF-308 HF-810 HF-619 HF-810 HF-610 30, 70 10 MG 220, 150 210 156° 152° 142° 1479 1328 1480 1352 176° 100° 12? Yi 154) 167' 101° 2 nS 4.0 2. 3.9 2,4 3.6 4.5 4.6 3.0 1.7 2.0 1.0 2.9 6,660 12,680 18,200 27,360 32,500 25,150 34,600 2690.7) 460(0.5) 665(0.5) $30(0.2) 1662(C.?) 1260(0.8) 1069(0.4) 156V(1.1 269(9.7) 300(0.7) 459(3.7) 665(1.4) @60(0.7) 1¢60{0.9) 860(G.5) 1209(1.2) 1.54 1.54 15h 26 3B 30 38 4B 1 1 1 1 3 4 1.9 1.4 £6 1,550 1,550 1,935 2,640 4,105 2,710 4,075 325 519 720 a0 1,050 2,600 1,250 1,600 3,650 5,905 3,960 5,675 1,210 2,060 2,570 2,725 0398 60¢ 1,880,300 47 410-10 1,10 ,090 2,980,000 4,960 1.455 27 F190 30 1470 365 6.6 1.9 48,500 2064(1. 1s64(1. 48 2 5,450 2,210 7,660 6) 7) 0399 850 2,510,000 65 635-12 1,600,000 4,110,000 4,835 1.417 37 Fe1010 425 ° 135 156° 12.5 2.8 58,£00 256v(1. 2064(2. 58 1.5 7,559 2,450 10,000 6) 6) — mmf HEAT REGECTION DATA TOTAL a RECOVERABLE BTU NON-RECOVERABLE BTU a t Prine J.W. Total Engine Total Piss Ki-WO Input Work Rej Exhaust Ree. Exhaust Rad. N/R Model___No. _ Fan ZO. TOTAL BTU INPUT : 50690 41800 30570 122060 20380 7550 27930 D379 a eS Pe a ee 30.25 ~B81.5 e006 =OdGSC : : 34120 «31200 «= 22504 += 8 7924 15630 5450 21080 = — ee TE a 30.65 80.66 14.34 5.00 19.34 pease 26100 «—«5820 «67072 «=—S«10347 «= 4075«= 14422 0379 354420 61494 32s 32.03 10.04 . 8.30 te 0 «6 17060 15500 ©1475 = 44035, 7495 ©2707 ~—S«10112 — 173 300 54147 Beh — 28763 21.18 81. 32 13.68 5.00 18.68 3 2 3 23067 20910 «=««agel@«=gean7§=— 8808 280k S162 er ee ee .i9 429.63 4899.42 9854F 8 8= 2.56 «4.001856 18780 13820 9944 «3954 6434-2362 8796 1 2 ty Fd ols sa =e ee = ei eee 3.64 28.59 0.57 81.80 1.31 4.89 18.20 i ne ee ee ae oe 33.40 © 25.25 Zi.7i 2-83.38 lief 5.00 6.64 9434 6400 6085 20989 3301 1850 5151 3 ee pa = oe = ag 629135 26120 32.48 24.50 33.30 80.20 me 6 Ce 5727 4300 4188 14215 2255 1550 3805 — 805 2. ae 7 eC“ CCG we 890 Ze 3304 815 a NA a ie QO oOo be ol | Ww} ny} I @ A EXAMPLE A. C. ENGINE MODEL 3406 PCTA WITH DRY EXH, MANIFOLD 3406 PCTA WITH DRY EXH, MANIFOLD 3406 PCTA WITH WATER COOLED EXH, MANIFOLD kw 210 210 210 SYSTEM HEAT. EXCHANGER AMOT VALVE REMOTE RADIATOR HEAT REC, SIL, HEAT EXCH, AMOT VALVE REMOTE RADIATOR BOOSTER PUMP HEAT EXCH, AMOT VALVE REMOTE RADIATOR OPERATION - FUEL AT $ .40 PER GALLON 100% UTILIZATION EXAMPLE A = $9,280.00 EXAMPLE B = $15,400.00 EXAMPLE C = $11,648.00 *DIFFERENCE IN COST OF ENGINE ARRANGEMENTS DRY VS, WATERCOOLED MANIFOLD & TURBOCHARGER AND DIFFERENT RADIATOR 60% UTILIZATION $5,568.00 $9,240.00 $6,989.00 PRIMARY LOOP H.R. EQUIP. COST FOB FACT, $ 3,016.00 $ 9,746.00 $ 3,016.00 +S 2,585.00* $ 5,601.00 - HEAT SAVINGS $ IN TERMS OF BOILER FULL FOR 4000 HRS/YR REC. HEAT VALWE 648,000 BTU/HR EQUIV. FURNACE FUEL = 5.8 GHP 1,077,000 : 66.2% INCR AS RELATED TO " EQUIV, FURNACE FUEL = 9.69 GPH 809,000 BTU/HR + 24.8% AS RELATED TO "A EQUIV. FURNACE FUEL = 7.28 GPIl Sheet 1 of 3 CALCULATIONS: Diesel Engine Waste Heat Utilization cl c2 c3 c4 77 18 19 20 9,247,300 Btu/hour!? @ 100% load Assume large home needs 5 gallons oil/day @ 5,608,000 btu per 42 gallon barrel!® 9,247,300 btu/hr + (5,608,000 btu/bbl + 42 gal/bbl) X 24 + 5 = 332 homes Assume 4 ft/sec velocity!9 1500 gal/min? X 231 cu.in./gal. + 1728 cu.in./cu.ft. + 60 + 4 ft/sec +mX J X12 X 2 = 12.38 inches diameter 1500 gpm!” + 332 homes X 60 X 24 = 6497 gal/day 1500 gpm in 12" pipe = .878 ft head/100 ft?° Assume 2 miles pipe, pump 50% eff. distribution loss equal to pipe loss. 2x5280 ft./mile x 62.4 1lbs./cu.ft.H20 1500 gpm X .878 ft.hd/100 ft. X 100 144 1 = ne a 1714 gmp psi/HP — 140 HP 140 HP + 332 homes = .42 HP per home (from C1) Madsen, P.L., DeLaval; Letter to C.R. Hilpert, Subject: Engines #77083 & 77084 at Kodiak, Alaska, dated September 10, 1977. U.S. Dept. of Commerce or Bureau of the Census; Statistical Abstract. UrQuhart, see footnote °. Shaw, G.V. and Loomis, A.W.; Cameron Hydraulics Data, Ingersol-Rand Company, Cameron Pump Div., Woodcliff Lake, N.J., 1970. AEDP/k-1 cs cé C7 21 Sheet 2 of 3 U.S. Average kWh per year per capita?! 10,316. 86231 -42 HP X 746 watts/HP + 1000 X 24 + (10316.86231 + 365) X 100% = 26.79901265% (from C5, C4) Mr. William C. Armstrong, Municipality of Anchorage Water Utility in a telephone conversation March 10, 1978, says all new ductile iron system would level off at 3-4% leakage after some years. Others state "negligible leakage" a realization. 1500 gpm = 90000 gallons per hour X .03 = 2700 gallons per hour loss X 231 + 1728 X 62.4 = 22522.5 lbs per hour loss Assume supply water 40°F raised to 160°F AT = 120°F 22522.5 X 120°F = 2702700 btu/hour lost Total heat left for homes 9,247,300 btu/hour - 2702700 btu/hour = 6544600 btu/hour or enough to heat 6544600 + 9,247,300 X 332.4279030 = 235 homes Statistical Abstract, (see footnote !8). AEDP/k-2 64 c8 c9 C10 22 Sheet 3 of 3 (6700 # X 1187.2 h,) - (6700 # X 23.07 hy) 7,799,671.0 X 10® btu/hr. 7,799,671 + 16,973,500 X 100% = 45.95204878% # steam per kWh = 3412 + (n, {hy - h,])#? Assume n, = 59% h, = 1187 btu/Ib. h, = 970 btu/1b. # steam per kWh = 3412 + (.59 [1187-970]) = 26.65 #/kWh 6700 #/hr + 26.65 = 251 kW n, = engine efficiency at generator terminals. ia ey ' = enthalpy saturated steam @ 100 psi. hg = enthalpy @ 4 psi isentropic expansion from 100 psi. Kent's Mechanical Engineer's Handbook Power, John Wiley & Sons, Inc., New York. AEDP/k-3 Fin / CATERPILLAR F TYPE Shell and Tube Heat Exchanger Recommendations QUOTATION NO.: ag STANDBY 60Hz GENERATOR SETS Q-7397 DATE:__APRIL 28, 1978 — F/HF HEAT GPM RAW WATER REQUIRED ENGINE | iy BTU/MIN. 200) EXCHANGER @ @ S MODEL 70F 85F 100F 3304NA 60 3545 52 | F-502-AR-2P 8 10 13 3304T 105 4950 52 | F-502-AR-2P 19 26 he 3306T 355 7250 64 | F-503-ER-2P 19 25 36 3306TA 175 8650 64 | F-504-AR-2P 18 2k 34 3406T 210 7800 | 108 | F-602-AR-4P 18 23 35 34.06TA 260 | 13500 | 108 | F-603-AR-2P 27 34 48 3408DI-T 285 12250 75 HF-802-AR-4P 20 25 32 3408PC-TA 310 16700 175 | HF-802-AR-4P ho 55 86 ¥3412DI- ne } 370 16200 205 | HF-802-AR-4P 35 47 70 *3412DI-T(d)| 420 | 18500 | 205 | HF-804—TR-lP 22 26 33 3412PC-TA 520 21100 | 205 HF-803-TR-2P 41 52 T2 D343TA 285 | 13800 183 | HF-802-AR-4P 25 32 43 D346TA 410 | 20700 | 290 | F-1005-2R-4P 20 23 27 D348TA 620 | 28400 305 F-1005-2R-4P 30 34 41 D349TA 750 30400 330 | F-1005-2R-4P 32 38 45 D353TA 33> 17400 | 180 HF-803-AR-4.P 25 30 39 D379TA 450 26100 280 | F-1005-2R-4P 27 31 37 D398TA 675 36100 350 | F-1005-2R-4P 41 48 60 D399TA 930 | 45500 410 | F-1005-2R-4P 58 71 91 | *(s) = Single Turbocharger *(d) = Dual ce arger Notes: 1 11 jacket water |press e drops are legs than 5 Ls 2. pL copling water presgure drops are less than 5 psi. Se leat rejections are baged on standard manifolds. 4, aoe water is she side, aie is on tube side, | | | | | | | | | | | | | | | —k... NOTES: @ Ratings based on 210°F max. jacket water temperature. @ GPM refers to cooling water as proportion of engine jacket water flow. @ °F refers to inlet cooling water temperature. @ Total fouling factor O02 —hhr-ft?-°F /Btu. ; YOUNG RADIATOR COMPANY y 2825 Four Mile Road @ Racine, Wisconsin 53404 @° Plants at: Racine. WI. Mattoon. IL and Centerville 1A ma) APPENDIX D February 27, 1978 wea Jeng F Shell and Tube Heat Exchanger Prices PRICES | SHIPPING BRASS END BONNET OPTION & i WEIGHT i iti = Standard wee ib oe Price Addition | F-301-*Y-*P $125 $151 17 | F-500 27 F-302-*Y-*P 176 226 25 F-600 35 F-303-*Y-*P 212 289 30 Il F-1000 457 F-502-*Y-*P 314 429 40 For Substitution: Ot Brass Bonnets in lieu of Standard Cast Iron, add 50 F-503-*Y-*P 376 550 50 above prices to appropriate Type F price. Brass End Bonnets are designated F-504-*Y-*P 425 657 | 60 | by a B suffixto the model name F-602-*Y-*P 428 583 55) eo | |) |B -604-*Y-* 924 F-606-*Y-*P 769 1231 130 fay pean F-608-*Y-*P 919 1538 170 6 : F-301-*R*P 106 125 7 Number of Anodes: —- aaa two to five F-302-*R-*P 15 197 F-303-*R*P | 183 241 | 30 Sonnet Kit F-502-*R-*P 284 350 40 F-503-*R-*P 348 444 50 F-504-*R-*P 386 514 | 60 F-602-*R-*P 356 447 55 F-603-*R-*P 444 580 70 F-604-*R-*P 513 694 90 F-606-*R-*P 643 914 130 F-608-*R-*P 742 1105 170 Bonnet Kit: Inciudes one bonnet & gasket. When ordering specify neat exchanger model, bonnet material and end (return or inlet-out!et). Gasket Kit: Includes equal quantity of both inlet-outlet and return gaskets. F-800 SERIES NOT Number shown is total quantity in kit. When ordering, specify heat excnanger AILABLE model number. ocher TYPE HF - Model Number: Includes baffle spacing code in first asterisk position and SEE FORM 2805 number of passes in the second asterisk position. CNT suffix is added for 90-10 CuNi option B suffix is added for Brass End Bonnet option. Set Up: Charge of $150 list per production order applies for non-stock F-300, F-1005-*R-*P 2462 2926 670 500 and 600. Set up charge for F-1000 is $300 list. Consult stock list or local F-1006-*R-*P | 2593 3090 720 representative. F-1008-*R-*P 2894 3440 820 Conversion Of: Stock units to other pass arrangements is available at $30 F-1010-*R-*P 3199 3805 920 list per unit. Se moe oe 2626 pa Prices: Subject to change without notice, and a $35/order minimum charge. -1006-*C- 2778 Prices Apply: To one, two & f ts with standard battle spacings. F-1008-*C-*P | 2572 3014 Standard tubes are seamless inibited Admuralty Brass 90-10 CuNs refers to F-1010-*C-*P 2861 3504 tubes and tube sheets of 90-10 CuNi (designated by letters CNT after model and recommended for salt water). All units are furnished with zinc anodes. Terms: Net 30 on approved credit exclusive of sales and use taxes, F.0.B Racine, Wisconsin or Mattoon, Illinois. User Multiplier 37 oe Quantity Discounts: Apply to a single moaei shipped and billed at one time. YOUNG RADIATOR CORIPANY 2825 Four Mile Road @ Racine, Wisconsin 53404 © . Plants at: Racine, WI, Mattoon, IL and Centerville, IA © ¥ Form No. 2696 2-27-78 DISCOUNT SCHEDULE ee [Fo [Was | 162 | Peas | 5058 | TOO TOR | 00 94 92 .90 87 85 82 80 78 i i i : { Iitha in tia MAXIM HEAT RECOVERY SILENCERS MFT Estimating Price List 3/1/78 Caterpillar Maxim Price Price Model Kilowatts Model Std. Unit Insulation 10-2 $ 1,184 $ 719 3304NA 55 40-3 1,972 843 3304T 90 70-4 2,605 894 3306T 135 110-5 33955 946 160-6 3,802 1,482 3406TA 210 275-8 4,736 1,644 3408TA 275 275-8 4,736 1,644 D353 300 275-8 4,736 1,644 3412TA 460 410-10 6,450 1,882 D379 420 410-10 6,450 1,882 D398 600 410-10 6,450 1,882 D399 850 635-12 9,514 2,680 1070-14 13,222 3,690 1375-16 16,630 4,150 1700-18 21,520 5,194 2115-20 26,327 6,003 2580-22 30,549 6,436 3050-24 37,655 8,318 3620-26 44,735 9,570 4100-28 52,829 12,738 4500-30 57 5702 14,906 ASME Sect. VIII & 75 psig RILEY-BEAIRD, INC. P50. Box 31115 Shreveport, Louisiana 71130 APPENDIX E HEAT RECOVERED ~ BruyHR x 1000 HEAT RECOVERED = BTU'YHR x 10° B ° & MFT stat EXHAUST MFT 1000 EXHAUST 10-2 FLOW = Ibs/hr 70-4 1200 hoo FLOW ~ Iba/hr | MAXIM | HEAT RECOVERY EQUIPMENT| MFT RATING CHARTS HEAT RECOVERY AND PRESSURE DROP g EXHAUST TEMPERATURE °F MFT 40-3 8 16 a g g 3 EXHAUST TEMPERATURE~ °F 8 too tetas +t tt 600 500 600 oo 800 90 2000 EXHAUST FLOW- Ibs/hr MFT 110-5 HEAT RECOVERED - BTU'YHR X 10° Fg 8 308 EXHAUST TEMPERATURE- °F 3 600 1000 hoo 1800 2200 2600 3000 EXHAUST FLOW - Ibs/hr 318-746 HEAT RECOVERED = BTU'YHR X 10° MFT RATING CHARTS HEAT RECOVERY AND PRESSURE DROP MFT 160-6 MFT 275-8 EXHAUST TEMPERATURE- °F HEAT RECOVERED - BTU'YHR Xx 107 x» 35 Mo aS » EXHAUST FLOW- Ibs/hr X 100 EXHAUST FLOW - Ibs/hr X 100 MFT 635-12 MFT 410-10 =H ry ce we & ® 8 w So HEAT RECOVERED~ BTU'YHR X 10° EXHAUST TEMPERATURE~ °F HEAT RECOVERED - BTU'/HR X 10° & Fr HRS 319-746 6 7 8 9 10 s 6 8 10 a EXHAUST FLOW- Ibs/hr X 107 EXHAUST FLOW- Ibs/hr X 107 We reserve the right to change specifications appearing in this bulletin without incurring any obligation for equipment previously or subsequently sold. 35 8 EXHAUST TEMPERATURE- °F g EXHAUST TEMPERATURE- °F HEAT RECOVERED ~ BTU'/HR X 10° HEAT RECOVERED ~ BTU'/HR X 10° oS ..% ¥ Sw YS 8B RR F BR & ae + MFT RATING CHARTS HEAT RECOVERY AND PRESSURE DROP MFT 1070-14 MFT 1375-16 HH BEES tH 9 ERE att t a Ho Hit etret ; See EH ETE Hitt He ececeasect 7 HF 1000 © 0 2 i x e © 50 : 5 800 3 = Pa e 5 od 5 g 5 i> 6&0 2 300 Tere 0 Stitt EER as 16 18 Fy ze ow 16 sate as 2 EXHAUST FLOW- Ibshr X 10 EXHAUST FLOW - Ibs/hr X 10° MFT 1700-18 7 MFT 2115-20 8 rp 2100 * = “x 1000 « ‘ x” x0 3 s 8 0 f ae = > § § mo 3 “ 3 3” 60 00 20 a 26 Bo x» R EXHAUST FLOW-Ibe/hr X 107 EXHAUST FLOW-Ibs/hr x 107 HEAT RECOVERY EQUIPMENT EXHAUST TEMPERATURE- °F fff s. 8S % EXHAUST TEMPERATURE~ °F 320-746 MFT RATING CHARTS HEAT RECOVERY AND PRESSURE DROP MFT 2580-22 HH i *e Str ss +tt & -O cn = 00 rp ~ 6 a a 2 3 : re i a 2s 5 i + i* 5 » » 2B ae uM » > EXHAUST FLOW- Ibe/hr X 10° MFT 3620-26 8 8 3 HEAT RECOVERED~ BTUYHR Xx 10° s EXHAUST TEMPERATURE- °F ss se 6 © ao EXHAUST FLOW=Ibe/hr x 107 HEAT RECOVERED- BTU'YHR x 10° no 3 s ¥ EXHAUST TEMPERATURE- °F » B ne M6 »” » 8 EXHAUST FLOW- Ibs/hr X 10? MFT 4100-28 3 8 8 s HEAT RECOVERED BTUYHR Xx 10° EXHAUST TEMPERATURE- °F Pw u re) 32 6 6 a EXHAUST FLOW-~Ibe/hr x 103 We reserve the right to change specifications appearing in this bulletin without 321-746 incurring any obligationfor equipment previously or subsequently sold. Heat Recovery Multiplier 1.2 WwW 1.0 © 160 MFT RATING CHARTS HEAT RECOVERY AND PRESSURE DROP 30 MFT4500 HEAT RECOVERED- BTU'/HR Xx 10° EXHAUST TEMPERATURE- °F EXHAUST FLOW-Ibs/hr xX 107 180 200 220 240 | 260 280 10 15 35 Pressure - PSIG | MAXIM | HEAT RECOVERY EQUIPMENT] Mean Temperature < f° 300 50 1200 1000 800 600 500 320 75 Exhaust Temperature 322-746 MFT WATER SIDE PRESSURE DROP INSTRUCTIONS SINGLE PASS FLOW TWO PASS FLOW The following curves are used for determining water side pressure drop through the MFT heat recovery silencer. (1) Flow Known: First determine whether single or two pass flow is required. (If water inlet conn. velocity is below 4 FPS use two pass flow configuration.) Each curve is designated by the MFT exhaust connection size (Ex. MFT 275-8, shown as 8”). From the horizontal scale representing water flow (gpm) read vertically to intersect with the proper line representing the desired MFT. Then read horizontally to the scale representing pressure drop. (2) Flow Unknown: (a) Determine exhaust recovery rate from the Heat Recovery Rating charts. (b) Use the inlet and outlet water temperature. The flow rate is determined from this data, as follows: Gpm = —Exhaust Heat Recovery in BTUH __— (Water outlet temp - water inlet temp) x 500 From this, return to the known flow condition to determine the water side pressure drop. All figures should be confirmed by Maxim prior to purchase of equipment selected. For application concerning other heat transfer fluids, consult Maxim. NOTE: PRESSURE DROPS IN EXCESS OF 10 PSIG NOT RECOMMENDED. We reserve the right to change specifications appearing in this bulletin without _323-746 incurring anyobligationfor equipment previously or subsequently sold. PRESSURE DROP— PSI eo N © OO wo a @ wv 10 MFT Heat Recovery Silencers Water Side Pressure Drop On Single Flow i Ti feb pete 1! 20 30 40 50 60 70 8090100 WATER FLOW—GPM | MAXIM | HEAT RECOVERY EQUIPMENT] (BEaae) 200 324-746 MFT Heat Recovery Silencers Water Side Pressure Drop On Two Pass Flow CURVE II a a I a Oo a a Ww leg 2 n wn WwW e a Tne nbn mpl! i Heb debt Tatil pe tvil ii Li I i iii 10 20 30 40 50 60 70 80 90 100 WATER FLOW — GPM We reserve the right to change specifications appearing in this bulletin without 325-746 incurring any obligation for equipment previously or subsequently sold. 10 PRESSURE DROP - PSI a ao N © O yy Ww wv 100 PAFT Heat Recovery Silencers Water Side Pressure Drop CURVE III 200 300 400 500 600 700 800 900 1000 WATER FLOW - GPM Curve A — 10; 12, & 14, Two Pass Flow Curve B — 10,12 & 14; Single Flow Curve C — 16 to 30, Two Pass Flow Curve D — 16 to 30’, Single Flow | MAXIM | HEAT RECOVERY cquirment | 2000 326-746 MFT SELECTION PROCEDURE The following data must be known for proper application of the selection charts: (1) Exhaust gas flow in pounds per hour. (2) Exhaust gas temperature in degrees Fahrenheit. (3) Allowable exhaust gas pressure drop in inches of water. (4) The average (mean) temperature of the heated liquid (tube side) in degrees Fahrenheit. For steam service, use the saturated temperature of steam at the intended use pressure (i.e. 5 psig steam, 250 °F) as mean temperature. NOTE: FOR LIQUIDS OTHER THAN WATER, CONSULT MAXIM. The following procedure determines the maximum heat recovery for a specified pressure drop. STEP #1 From the horizontal scale representing exhaust flow, read vertically to intersect with the line represent- ing the given exhaust temperature. From this point read pressure drop from the angled scale (P) and determine if the pressure drop is within the criteria. If not, go to the next larger size MFT and repeat this step. STEP #2 From this point determined in STEP #1, read horizontally to the scale representing heat recovery rate. STEP #3 Correct the recovery rate determined in STEP #2 by the use of the conversion curves for mean tem- perature, read vertically to intersect with the line representing the given exhaust gas temperature. From this point, read horizontally to the scale representing heat recovery mutliplier (HRM). Multiply HRM x heat recovery rate determined in STEP #2 to obtain actual heat recovery rate. EXAMPLE: Given - Exhaust Flow 9000 Ib./Hr. Exhaust Temperature 1000 °F Max. Allow. Pressure Drop 8 in. w. g. Water Inlet Temperature 220°F Water Outlet Temperature 240 °F. Determine - Model MFT Required Pressure Drop Heat Recovery Rate Procedure- The first chart covering flow rates of 9000 Ibs./hr. is for the MFT 410-10. Reading vertically to intersect with the 1000 °F. line indicates a pressure drop of approximatley 11 in. w. g.. As only 8 in. w. g. is allowed, the next size larger unit must be considered. On the chart for the MFT 635-12, read vertically from the 9000 Ibs./hr. value to intersect with the 1000 °F. ex- haust temperature line. The pressure drop at this point is approximatley 5.5 w. g., which is acceptable. From the point determined, read horizontally to intersect the scale for recovery rates at 14.0 x 155 or 1,400,000 BTU/Hr. The mean water temperature in our example is found to be 230 °F. From the horizontal scale of the conversion Curves for mean temperature, read vertically from 230 °F to intersect with the line for 1000 °F exhaust tempera- ture. From this point read horizontally to intersect the heat recovery multiplier scale at 0.96. | MAXIM | HEAT RECOVERY EQUIPMENT | See 317-746 Multiply 0.96 x 1,400,000 BTU/Hr for a corrected recovery rate of 1,344,000 BTU/Hr . To determine the outlet exhaust gas temperature,divide the corrected recovery rate by the exhaust flow x 0.25 and subtract from the inlet exhaust gas temperature. Example: 1,344,000 _ : mei = 5Q7° 9000%0.25 change in exhaust gas temperature = 597° F. 1000° F Inlet exhaust gas temperature -597 Change in exhaust gas temperature 403° F Outlet exhaust gas temperature Notes: (1) If the exhaust flow in Ibs/hr is not known, this may be determined by multiplying the intake air flow in cfm x 4.5. (2) If only one water temperature is given, satisfactory results may be achieved by a logical assump- tion of the mean water temperature. (3) Outlet exhaust gas temperatures below 350 ° are not recommended. All figures should be confirmed by Maxim prior to purchase of equipment selected by these charts. We reserve the right to change specifications appearing in this bulletin with- out incurring any obligation for equipment previously or subsequently sold.