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HomeMy WebLinkAboutHoonah Waste Heat Status & Trip Reports and Field Notes 1988 ao eorpena REST HOONAH WASTE HEAT SYSTEM FEASIBILITY ANALYSIS TABLE OF CONTENTS: EXECUTIVE SUMMARY... .. cece cc cee cece cee e eee e cece eee n eee eeeeeeeeeeneeeee 1.0 Introduction and Background........ cece cece eee r cece eee e cence eeeeeere 1.1 CONCTUSTONS... cece cece eee e ee eee eee e eee e eect ee eeeeee seve cscs ccscuscce 1.2 FACILITY DESCRIPTION... . ccc ce ccc ce ce cee cee te ee eee ee tee eee e eee eee eeeeees 2.0 General... cece eee eee cece e ee cee eee cent e eee e ee eeeeeeseeeeeees pessetel Power PLAaNnt.. cc ccc cccc cece ccc cece cece eee eee e ress eee eeeeeseeeeeeeeee -2.2 Main school building........ cc cece ccc cece cece cece eee ee eeeees errr r 2.3 POON 5. sc ccc ssw esses esew sees sotsscesces es decssstssccwsceasesessvcees 2.4 AUtO SHOP... cece ccc ce cece cece ee ee cere eee eee eee eee ence cesses seeeeee 2.5 Daycare Center... cece c cece ccc cc cee ce cece cece eee eee e eee seeeeeeees 2.6 Five HAL]. ccc ccc cece cece cece ec cee cece cece eee eee eeeeeeeeeeee sees asic scl el CHEV: HAV. os oo cc ccc c sess cc hcncs cee seneses es scececssccesecscstese 2.8 Sewage Treatment Plant........ ccc cece cee w cece cree ee eeees o oecesiee 066 cies 2.9 Harbor Master's Building... .... cc cece cece cece cece cece eee eeeeccees 2.10 Police BUTIGINg....... cece cece cece eee cece eee e ence et eeeseeeeeeeees 2.11 NOW JOT ccc cccccwsvcvcccencssccenetsssesceesesscesccccceesices weevess 2.12 CIty SHOP... cece cc cce cece cece cece eee reece cece cece eee ee cere eee eeeene 2.13 Water Treatment Plant... ....... cece cece cece ee eee eee ee eee eecsacecep acs 2.14 Youth Center... ccc cece cece cece ccc cece reece eee cence reese eee eeeeeee 235. Alaska Native Brotherhood Hall........ cece eee cece cece neces Seis aw 60 a6 2.16 Health Care Center. .... cc ccc ccc cece cece cece cece cece secre eee see eees 2.17 WASTE HEAT SYSTEM CONCEPTS. 0... . cece cece cece cece cece cece cece eee eeeeees 3.0 GENEral. cece cece ccc cece ee ee ee eee eee eee ee ee eee eee e eee ee eee eeeees 3.1 Concept A 2 Concept B 3 COMCEDE Cis noes cc nn sec w cers senso bacon ss eben ensss oben wesenesesassscsss 3.4 COST ESTIMATES... 0... cece ce cece ce cee cece eee ence eee eee eee e eee eee eeeees 4.0 General. cece cece eee e eee eee eee e eee cere eee tere eee ee eee eeeeeeee 4.1 Concept A «2 CONCEPT Bac. os soo ce iis 5 ais oo ones oe oe ww eco ss ses wusec set sveswscssas 4.3 CONCEDE. Coos age coc sce see ces ss cw ener ese cee se cesses stesesecens 4.4 1651/816(1) Concept A..... ssecssseceaseesssess pa es eecsececaccccsace tess eesesees 2252 Concept Bi... ccc cce ccc cece ccc ccc ccesces weseeseeascssdceescsssce wee Ded CONCEPt Clerc ccc cc cece cece cece cence eee e erence eens nese eases eeeeeeee 5.4 CONCLUSIONS .... ccc cc cece cece cece eee e eee ceese cece eee eessescseces ses A 6.0 General DISCUSSIONS... .. ccc cee ee reece ec ec cecsecees Se seeceeseessesscesscuss 6.1 Conclusions........ wars see seeeesesasecesscsusneesseeveesscessessascvecs 6.2 1.0 EXECUTIVE SUMMARY 1.1 Introduction and Background In the fall of 1987 the City of Hoonah requested that the Alaska Power Authority investigate the feasibility of utilizing waste heat from the Tlingit Haida Electric Authority (THREA) power plant for heating City owned buildings including the local schools. Power Authority staff made a visit to Hoonah where the facilities were audited for compatibility with waste heat recovery systems. During the site visit contacts were made with City of Hoonah staff and THREA staff were contacted in order to obtain a clear picture of power loads, fuel consumptions, and community development plans. Based on the information gathered, three concepts for waste heat recovery systems were developed. For each concept a preliminary cost estimate and the pay back time were calculated with a Lotus 1-2-3 program using relevant climatic and statistical data. This program simulates the operation of a waste heat recapture system over the life span of the project. This study does not include detailed engineering data such as soils conditions, local availability of skilled labor and local experience in undertaking construction projects. Thus, the cost estimates should be used with great caution. The economic analysis of system performance over the life span of the project is fairly accurate, provided that prudent maintenance is performed on the system. 1.2 Conclusions It is expected that the City would realize substantial savings in fuel and some savings in maintenance expenses from this project. Also, it is expected that the power plant would realize some savings from reduced station service loads. Maintenance savings have not been quantified and 1651/816(2) 2.0 2.1 ase 2.3 consequently have no effect on the calculated pay-back time. Annual operations and maintenance costs have been estimated at 2% of the capital cost of the project. No technical obstacles should prevent the installa- tion of a waste heat recapture system utilizing waste heat from the THREA power plant in a number of buildings. Provided that operational proce- dures are not changed drastically in the THREA power plant, installation of a waste heat recapture system appears technically feasible. However, due to the relatively low price of fuel, and due to the rela- tively high number of building connections required and/or the length of the necessary distribution system, the economical feasibility appears unsatisfactory at this time. The three concepts show pay-back times of approximately 17, 20, and 14 years, when an annual fuel price escalation of 2% is used in conjunction with a real interest rate of 4% and a fuel cost of .8 $/gallon. FACILITY DESCRIPTION General This facility description is limited to facilities and items that can be considered relevant in connection with waste heat recovery in Hoonah. Power Plant. The power plant is a well built and well maintained facility incorporat- ing two ea. 600kw Caterpillar 398 generating sets and one ea. 800kw caterpillar 3512 generating set. Sufficient space is available inside the Power Plant for the waste heat recapture equipment. Existing remote vertical core radiators would be incorporated into the waste heat recov- ery system to provide automatic back up cooling capacity in case the waste heat recovery system is unable to utilize all the heat generated. The Main School Building The large main building incorporates two boiler rooms where three boilers supply all the heating and hot water needs for the building. The heating system in one boiler room is a fairly simple hot water based system which easily could be modified to operate with waste heat. The heating system in the other boiler room is a steam based heating system, which would have to be converted to a water based system in order to be able to accommodate waste heat. While this is a fairly simple task, it still may include the installation of additional radiation surface in classrooms and hallways in order to supply sufficient heat during the coldest periods. Entrance for the district heating pipe entrance would be through the wall facing the road directly into the boiler rooms. Total fuel consumption for the main school building is approximately 24,000 gallons per year. 1651/816(3) 2.4 2.5 2.6 2.7 2.8 2.9 © The Pool The pool is a separate building located adjacent to the main building. The heating system is a very basic hot water system where two boilers provide all the heating and hot water needs for the building. Connection to a waste heat recapture system could be done with few or no modifica- tions to the existing system. Building penetration would be through the wall facing Carteeni Highway. Total fuel consumption for the pool is approximately 24,000 gallons per year. The Auto Shop While the heating system in the Auto Shop is compatible with waste heat recapture, the most convenient way of supplying waste heat to this building will be through separate unit heaters connected directly to the waste heat system. The Daycare Center The heating system in the Daycare Center is a simple forced air heating system, which can be connected to a waste heat system by a coil inserted in the return air duct. With this arrangement the existing furnace will provide automatic supplemental heat in case insufficient heat is avail- able from the waste heat system. The Fire Hall While the heating system in the Fire Hall is compatible with waste heat recapture, the most convenient was of supplying waste heat to this building will be through separate unit heaters connected directly to the waste heat system. The City Hall The heating system in City Hall is a simple forced air heating system, which can be connected to a waste heat system by a coil inserted in the return air duct. With this arrangement the existing furnace will provide automatic supplemental heat in case insufficient heat is available from the waste heat system. The Sewage Treatment Plant The existing unit heater in the Sewage Treatment Plant will be left in place and a separate unit heater will be connected directly to the waste heat system. 1651/816(4) 2.10 2.11 2.11 2.12 2. 2.14 2. 13 15 The Harbor Master's Building At this time it does not appear to be feasible to connect to the Harbor Master's Building. The Police Building While the heating system in the Police Building is compatible with waste heat recapture, the most convenient was of supplying waste heat to this building may be through separate cabinet unit heaters connected directly to the waste heat system. The New Jail While the heating system in the New Jail is compatible with waste heat recapture, the most convenient was of supplying waste heat to this building may be through separate cabinet unit heaters connected directly to the waste heat system. Alternatively, a small heat exchanger will connect the existing heating system to the waste heat system. The City Shop. The City Shop will be supplied with waste heat through separate unit heaters connected directly to the waste heat system. The Water Treatment Plant. This building will be connected to the waste heat system through a small heat exchanger which preheats the boiler return water prior to it enter- ing the boiler. The existing boiler will supply supplemental heat if this should be needed. The Youth Club The Youth Club will be supplied with waste heat through separate unit heaters connected directly to the waste heat system. The Alaska Native Brotherhood Hall The Alaska Native Brotherhood Hall will be supplied with waste heat through separate unit heaters connected directly to the waste heat system. 1651/816(5) 2.16 The Health Care Center 3.0 3.1 3.2 While the heating system in the Clinic is compatible with waste heat recapture, the most convenient was of supplying waste heat to this building may be through separate cabinet unit heaters connected directly to the waste heat system. WASTE HEAT SYSTEM CONCEPTS General Waste heat system concepts that have been investigated in this study are described here. This study does not attempt to investigate all possible waste heat system concepts for use in Hoonah, but concentrates on alter- natives found reasonable as a result of the Power Authority's extensive experience with waste heat recapture systems. Based on the field date collected, it seems clear to Power Authority staff that several details are pre-determined. Thus the differences between the concepts are limited to pipe routings, the number of build- ings connected and to some extent the method of connection. All concepts studied would involve a system using a common cooling manifold in the power plant connected to existing remote, thermostatically controlled radiators. Heat would be extracted from this jacket water cooling system using a large flat plate type heat exchanger. Heat would be delivered to the user buildings through a constant output temperature, variable flow water based system, which feeds into an underground distribution network. The network would consist of pre-insulated pipe using a steel carrier pipe, high density urethane foam insulation and high density polyethylene jacket pipe. In buildings with hydronic type heating sys- tems, a large flat plate heat exchanger would transfer heat to the boiler return line in the existing heating system. A simple control valve would maintain a pre-set temperature in the existing heating system by limiting the flow in the waste heat recovery system. With this concept the boiler would function as an automatic back up heat source in case insufficient heat is available from the power plant. It is not recommended that heat is metered as "“Btu-meters" have proven to be expensive and quite unreliable in rural applications. As all connect- ed facilities are City owned or City supported metering will not be necessary. Concept A This concept provides heat for all the above mentioned buildings except the Fire Hall and the New Jail through district heating lines extending from the THREA power plant along White Alice Site Road and Carteeni Highway to City Hall. The main pipe run will most likely be 4" diameter with 2" service lines to the two school boiler rooms and the Pool. The 1651/816(6) 3.3 3.4 4.0 4.1 pipe from the school to City Hall will also be of 2" diameter and 1" service lines will be installed to City Hall, the Daycare Center, the Auto Shop, the Sewage Treatment Plant, the Clinic, the Police Building and possibly to the Youth Club and the Native Brotherhood Hall. Concept B This concept will be identical to concept A with the only difference being the addition of a 2" line supplying the Fire Hall and the New Jail. This line could also be extended to provide heat to the new Elderly Housing facility located north of Hemlock Street; however this possibili- ty has not been addressed in the economic analysis. An alternate would include a 4" main line from the power plant along White Alice Site Road, Douglas Drive, Hemlock Street, Raven Drive and Carteeni Highway to the school with a 2" main line extending to City Hall. While this routing may provide for shorter over all pipe runs, the length of main line may be somewhat longer and consequently the cost savings may be marginal. Concept C This concept will provide heat to the Pool, the school and the clinic. A 3" main line will follow White Alice Road and the Carteeni Highway from the power plant to the school. A small 1" branch line will connect the clinic to the system. The installation in the power plant will be as described earlier. COST ESTIMATES General The cost estimates presented in this report are based on the following assumptions: a. System design follows Alaska Power Authority standards. b. Construction is performed by City of Hoonah crews on a "force account" basis with the Alaska Power Authority providing basic engineering, some supervision and inspection, and start-up assis- tance. Note that all cost estimates are based on preliminary designs only and consequently the cost estimates should be used with some caution. It is assumed that all lines will be buried in existing roads and that these roads will be re-established as gravel roads only. Labor rates of approximately $15/hour have been used for cost estimating purposes. 1651/816(7) 4.2 4.3 Concept A Cost estimate: Power plant work District heating pipe High School installation Pool installation School installation 10 building connections ea. $5,500 Net construction Job Indirects, 30% Construction cost Overhead, 10% Net project cost Contingency, 15% Total cost estimate Concept B Cost estimate: Power plant work District heating pipe High School installation Pool installation School installation 12 building connections ea. $5,500 Net construction Job Indirects, 30% Construction cost Overhead, 10% Net project cost Contingency, 15% Total cost estimate 1651/816(8) $ 25,500 204 ,299 52,500 12,500 8,000 55 ,000 357,799 107 ,340 465,139 46,514 511,653 76,748 588 ,400 25,500 218,442 52,500 12,500 8,000 66 ,000 382 ,942 114,883 497 ,825 49,782 547 ,607 82,141 629,748 4.4 5.0 Concept C Cost estimate: Power plant work $ 25,500 District heating pipe 127,405 High School installation 52,500 Pool installation 12,500 School installation 8,000 Clinic installation 5,500 Net construction $ 231,405 Job Indirects, 30% 69 ,422 Construction cost $ 300,827 Overhead, 10% 30,083 Net project cost $ 330,909 Contingency, 15% 49 636 Total cost estimate $ 380,546 ECONOMIC ANALYSIS 5.1 General The economic analysis for the waste heat recapture system concepts addressed in this report was performed using the LOTUS 1-2-3 software and the following methodology: Based on actual power production figures provided by THREA together with specific data for the generators in use, the available waste heat was calculated for each hour during the year. Based on heating degree variations for Hoonah together with fuel consump- tion data and operational characteristics provided by the City of Hoonah the actual heat demand was calculated for each hour of the vear. Comparing the available heat and the demand showed how much waste heat was actually utilized. At this point the estimated heat loss for the district heating lines was also taken into account. The waste heat utilized was added up hour by hour for the entire year. With a set of assumptions for load growth over the next 20 years, the same operation was done for each of the next 20 years and the annual fuel savings were derived. Based on current fuel cost and estimated fuel cost escalation together with the cost estimates presented in this report, a cash flow analysis and a pay back time were calculated for each of the concepts. Generally speaking, the pay back time indicates the period of 1651/816(9) 5.2 5.3 5.4 time during which the project will have to operate as intended in order to pay off the initial investment. In this study, a discount rate of 4 percent has been used. The discount rate is approximately equal to the difference between the interest rate and the inflation rate. The annual operations and maintenance cost for each concept has been estimated at 2% of the construction cost for general operation and maintenance. (This item will be discussed in greater detail is subsequent sections.) Concept A With the assumptions made, Concept A shows a pay back time of 17 years. 78% of all heating needs for the buildings can be met during the first year of operation and it is anticipated that this waste heat recapture concept would have annual operation and maintenance expenses of $11,768. Operation and maintenance expenses for the boiler systems could be expected to decrease significantly due to the systems being idle. Pay back times are based on the assumption that basic engineering and construction management is provided by the Alaska Power Authority and that all construction efforts are undertaken by the City of Hoonah on a “force account" basis. Concept B With the assumptions made, Concept B shows a pay back time of 20 years. 73% of all heating needs for the buildings can be met during the first year of operation and it is anticipated that this waste heat recapture concept would have annual operation and maintenance expenses of $12,595. Operation and maintenance expenses for the boiler systems could be expected to decrease significantly due to the systems being idle. Pay back times are based on the assumption that basic engineering and construction management is provided by the Alaska Power Authority and that all construction efforts are undertaken by the City of Hoonah on a "force account" basis. Concept C With the assumptions made, Concept C shows a pay back time of 14 years. All heating needs for the buildings can be met during the first year of operation and it is anticipated that this waste heat recapture concept would have annual operation and maintenance expenses of $7,611. Operation and maintenance expenses for the boiler systems could be expected to decrease significantly due to the systems being idle. 1651/816(10) Pay back times are based on the assumption that basic engineering and construction management is provided by the Alaska Power Authority and that all construction efforts are undertaken by the City of Hoonah on a "force account" basis. CONCLUSIONS 6.1 6.2 General Discussion The power plant in Hoonah is very well suited for the utilization of waste heat. District heating lines would be installed in a fairly simple manner in generally accessible areas and seemingly acceptable soils. No rights of way are needed from third parties and the district heating line installa- tion in general seems very simple. The existing heating systems in the school can be modified for the utilization of waste heat. All systems seem to be capable of operating on medium grade heat, which is what is available from the power plant. Tie-ins in the existing boiler rooms would be very easy, as sufficient floor space is available and relatively simple heating systems are in place. The heating systems in the new school additions have been reviewed for compatibility with waste heat recapture systems. No major technical obstacles will prevent the utilization of waste heat in the buildings addressed in this report. Conclusion It is expected that the City would realize substantial savings in fuel and some savings in maintenance expenses from this project. Also, it is expected that the power plant would realize some savings from reduced station service loads. Maintenance savings have not been quantified and consequently have no effect on the calculated pay-back time. Annual operations and maintenance costs have been estimated at 2% of the capital cost of the project. No technical obstacles should prevent the installa- tion of a waste heat recapture system utilizing waste heat from the THREA power plant in a number of buildings. Provided that operational proce- dures are not changed drastically in the THREA power plant, installation of a waste heat recapture system appears technically feasible. However, due to the relatively low price of fuel, and due to the rela- tively high number of building connections required and/or the length of the necessary distribution system, the economical feasibility appears unsatisfactory at this time. The three concepts show pay-back times of approximately 17, 20, and 14 years, when an annual fuel price escalation 1651/816(11) of 2% is used in conjunction with a real interest rate of 4% and a fuel cost of .80$/gallon. The three concepts are similar in the respect that both cost estimates are dominated by the cost of the distribution system. While it may be possible to reduce the cost of the distribution system through efficient installation techniques, it would not be prudent to base the cost esti- mates and thereby the project on such hopes. At the start up of concepts A and B concepts, the power plant would only be capable of providing approximately 73-78% of the heating demand for all buildings connected. However, as the heating needs and the system losses are expected to be constant and as the power production is expect- ed to increase by 2% per year, all heating needs can be met before the end of the expected project life. At the start up of concept C, the power plant is capable of providing all the heating needs for the clinic and the school and pool buildings. With a pay back time of 14 years, concept C does not appear feasible. However, it should be noted that the feasibility is highly dependent on the price of fuel. If the price of fuel jumped to $1.20 per gallon and then escalated 2% per year as assumed throughout this study, the pay back time would be 8 years. In accordance with the feasibility demonstrated above, it is hereby recommended that the project be postponed until such times when the potential fuel savings will provide for a pay back time of no more than 10 years. 1651/816(12) August 8, 1987. Mr. Michael J. Tavoliero City Manager City of Hoonah P.O.Box 360 Hoonah, Alaska 99829. Subject: Technical assistance request of July 14, 1987. Dear Mr. Tavoliero: The Alaska Power Authority has reviewed your request for technical assistance and intends to provide the assistance as soon as staff workload permits. In order to define the scope of our efforts more closely, I propose that you meet with some of our staff members at the earliest time convenient. Two of our engineers could attempt to make a trip to Hoonah within the next 6 weeks at which time a meeting could be held. Or, if you prefer, you are always welcome to visit with us when ever your travel plans brings you. through Anchorage. Please call Peter Hansen at 261-7221 or Jerry Larson at 261-7230 to discuss this issue further. Sincerely, Don Shira Director/Program Development & Facilities Operation. cc: Jerry Larson, APA Peter N. Hansen, APA Dir dukhuair~ , OM We: S (000 ae August 8, 1987 Mr. Michael J. Tavoliero City Manager City of Hoonah P.O. Box 360 Hoonah, AK 99829 Subject: Technical Assistance Request of July 14, 1987 Dear Mr. Tavoliero: The Alaska Power Authority has reviewed your request for technical assistance and intends to provide the assistance as soon as staff workload permits. In order to define the scope of our efforts more closely, I propose that you meet with some of our staff members at the earliest time convenient. Two of our engineers could attempt to make a trip to Hoonah within the next 6 weeks at which time a meeting could be held. Or, if your prefer, you are always welcome to visit with us whenever your travel plans bring you through Anchorage. Please call Peter Hansen at 261-7221 or Jerry Larson at 261-7230 to discuss this issue further. a Bram tA Cee Robert E. LeResche Executive Director PH: REL: it cc: Peter Hansen, Alaska Power Authority Jerry Larson, Alaska Power Authority 9869/DD24 April 15, 1988 Mr. Michael Tavoliero City Manager City of Hoonah P.O. Box 360 Hoonah, Alaska 99829 Subject: Hoonah Waste Heat Recapture System Re: Your Request for Additional Information Dear Mr. Tavoliero: Please find below additional information regarding this project and its cost estimate. The fuel savings outlined in the report are expected to be very accurate and I do not expect that you would want to go through the exercise of calculating those by hand. It is my impression that the cost estimates are your primary area of concern, and as it was outlined in the draft report, these estimates are indeed rough estimates based on preliminary designs only. I would not expect the building connection to be much cheaper than indicated. The school connection will require a conversion of a part of the school heating system from steam to hot water and this is likely to be somewhat costly. ; The piping system cost is based on the following assumptions: Trenching and backfilling: $1.80 per foot of pipe or $3.60 per foot of trench Installation, Average: 1" pipe: 6 manhours/40 foot of pipe 2" = : 12 manhours/40 foot of pipe 4" = : 20 manhours/40 foot of pipe Materials, Average: 1" pipe: $ 7.00 per foot of pipe 2" = : $11.53 per foot of pipe 4" ~ : $16.62 per foot of pipe Concept A incorporates approximately 2,900 feet of trench with 4 inch pipes, 1,120 feet of 2 inch pipe and 400 feet with 1 inch pipes. Concept B incorporates 2,900 feet of 4 inch pipe, 1,600 feet of 2 inch pipe, and 500 feet of 1 inch pipe. 2396/DD34/1 If you need additional information, please do not hesitate to contact me. Sincerely, [Uv 4} fic ox Peter N. Hansen, P.E. Project Manager PNH: tq 2396/DD34/2 February 16, 1988 Mr. Michael J. Taveliero City Manager City ef HYoonah P.O, Box 360 Hoonah, Alaska 99829 Subject: Hoonah Waste Heat System Feasibility Analysis Dear Mr. Tavoliero: Please find enclosed a preliminary feasibility analysis for a waste heat system in Hoonah, As you will see, the feasibility of such a system is not satisfactory at this time. I must admit that I was somewhat surprised by the end results; I had expected the feasibility to be better. It appears that I parang as the distances involved and overestimated the potential savings. Please review this analysis and return a copy to me. If vou have any questions concerning this subject, please do not hesitate to contact me. Sincerely, K, da D¥y Wie ’ Peter N. Hansen Rural Systems Engineer PNH: tg Enclosure as stated 1696/DD31/1