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HomeMy WebLinkAboutSt. Paul Electric Utility Infrastructure Report 1985ENE > Alaska Power Authority ne LIBRARY COPY Alaska Power Authority St. Paul Electric Utility Infrastructure Report | | | | June 1985 | | | | | ST. PAUL ELECTRIC UTILITY INFRASTRUCTURE REPORT June 1985 PROJECT TEAM: Bob Loeffler, Project Leader Project Economist Peter Hansen Rural Systems Engineer Afzal Khan Director, Systems Operation Brent N. Petrie Edwin L. Morris, Associate Power Systems Planning Executive Director, Planning Robert D. Heath Executive Director © 1985 ALASKA POWER AUTHORITY ENE C08 Chapter Chapter Chapter mAMOOWY <a 6 606 Electric Utility Infrastructure Report Table of Contents Page LEUSEMO Tp VAD IOS crererelercrarelevetorsrevelclelels/sictoratelere!eteretelels ii EASE TOG FiGureSire o crsierereieiaiere/olclelererotsloleieistsieletelcicl iii I. Introduction and Summary.......ccccccscecce 1 Backroads ic lrteoecictelercisieis cielerereieietelferereiereleleiiere 1 Summary Of CONCIUSTONS 36 61.05 ce cc cicieie sicleielercie.« 3 II. Powerhouse and Generation Improvements.... 6 Generation Improvements........ccccccccceccece 6 StaGton) Load PropileMms .. <c1s/e cr icle a vioierciercicjeleloreielele 10 TUT.) Distribution) Systeme cc. ccjcicccicicie + ciesisiolesie TS IV. Waste Heat Recapture System..............- 14 SYSCOM"DESCRIDEI ON. «1210.5 cle oreo cieie'sieicioieleicloreiereieloo 15 EX tSEanGi PPORIOMS «(01-15 a/c lorelele's claralsieiclelsiafels sleleisters 15 RecommendattOnSici./s.c.c.c:0's/ciereicls cielele sislelels sicistele/lel ole 17 Vv. Anatusts of Avoided: Cost...3 oc... ect e ccc 19 Fuel Efficiency and Generation Records........ 19 Accounting and Financial Information; Present AVOUGCU COS Gos leleieratecisieleleieio siololeleleloislolevaretelelelelelere 20 Future Avoided Cost.......cccccccccccccccccccs 27 VI. The Load Forecast.......cescccccccsccccces 31 Restdential) Loses cscs cine ccs eects cioslelsielclela'« a1 Commercial/Industrial Loads......c.sccsccsccee 34 Transmission Line Loads.........ccccccevcccece 36 Line Losses and Unmetered Loads............... 37, The Complete Load Forecast........cccccccccece 40 Load |Charactertstics. occ ccc ce ccc wees 43 8950/379/2 Page i List of Tables Table No. Page 1. Powerplant Station Load at Time of Visit...... 10 2. Fuel Efficiency and Generation Records........ 20 3. Expense Record: July 1984-January 1985........ 22 4. Avoided Cost Analysis: July 1984-January 1985. 25 Sas AVO1GOO 2 COS Ga PNOSECEION oroic101c 1010 cicisiole oie cvelorsiejeiore 28 6. Residential Electricity Use, 1983 & 1984...... 31 7. Residential Load Projection.......cccccccscece 34 8. Commercial/Industrial Loads, 1983 & 1984...... 34 9. Planned Commercial/Industrial Development..... 35 10. Commercial/Industrial Load Projection......... 35 11. Powerplant, Waste Heat Loads, and Line Losses: a. Unmetered loads and line losses......... +0 39 b. Total unmetered loads and line losses..... 39 12. Projected Annual Electric Consumption......... 40 13. Projected Annual Electric Generation.......... 41 14. Summary of Coast Guard Load Characteristics... 45 15. Load Duration Tables: a. b. Cc. 8950/379/3 Cumulative Frequency of Electric Demand.. 48 Frequency of Electric Demand............. 49 Cumulative Frequency of Electric Demand-Percent of Peak Load............- 50 Page ii List of Figures Figure No. Page 1. One Line Diagram, Existing St. Paul Powerplant. 7 2. Existing St. Paul Distribution Panel........... 8 3. Distribution of Avoided Cost............eeeeeee 26 4. Avoided Cost Projection... 00. cccccccccccccccs 30 5. Residential Electricity Consumption............ Se 6. Residential Consumption Change............eeeee 32 7. Coast Guard Station Energy Use.............06- oy Bm Load “ROn@CESG.c1a10 «(clei eieieieieie «io afore lelelevererelele!oforeler rere 42 9. Coast Guard Station Seasonal Loads............. 44 10.7 suyp tical Dally Poad (Prot lO. ccc ciclecicicin cic sie! 610 45 Tl. oad Duration) Curves. «21. sciccc cies oleic oolis esc 40 8950/379/4 Page iii Chapter I. Introduction and Summary A. Background This report provides the technical and economic analysis needed for St. Paul to plan the short- and long-term improvements for the City's Municipal Electric Utility. The analysis was conducted by the Alaska Power Authority at the request of the City of St. Paul. It provides a review of the existing technical problems facing the utility in the efficient operation of its generation, distribution, and waste heat recapture systems. In addition, this report pro- vides an analysis of avoided cost relative to the addition of an alternative energy source (wind) and a short-term load forecast useful for planning system expansion. Specific objectives of the report are: 1. to understand the improvements needed in the electric utility with and without the addition of a sizeable wind installation. 2. to identify any special conditions, problems, or construction needs created by the connection of a wind farm, 3. to determine St. Paul's current and forecast avoided cost of diesel-generated electricity relative to a wind farm connection, and 4. to forecast St. Paul's expected short-term electric loads. 8950/379/5 Page 1 To complete the analysis for this report, the Power Authority sent three staff members -- an economist, a mechanical engineer, and an electrical engineer -- to St. Paul to gather the required background data. This report includes their analysis plus the office research of other Power Authority staff. The analysis is provided in five chapters. Chapter II provides a brief technical review of St. Paul's powerhouse and generation system. It makes recommendations concerning improvements needed to decrease the cost of or maintain the existing system. Chapter III supplies a similar brief analysis for the distribution system. Chapter IV provides analysis of the existing waste heat recapture system. Chapter V uses St. Paul's accounting data to provide an analysis of avoided cost -- the cost that the utility can avoid spending through the introduction of an alternative energy source such as wind. Finally, Chapter VI provides a load forecast for the utility assuming that the utility maintains the existing service area and that a transmission line is built to the federal facilities near the airport. The City of St. Paul keeps excellent records, and there is a remarkable amount of data available for the electric utility. Most of the economic data is based on seven months of accounting records, July 1984 through January 1985. Although records are available prior to July 1984, the data collected before that time is not accurate due to confusion between federal and local expen- ditures. The load forecast is based on two years of records detailing the annual consumption of each consumer. In addition, discussions with City officials indicated the likelihood of near-term additions to the City load, and the Coast Guard generously provided detailed records of the consumption of the federal facilities near the 8950/379/6 Page 2 z= airport. a year of characteri Finally, the City provided monthly generation totals and strip-chart load data for analysis of St. Paul's load stics. B. Summary of Conclusions A brief summary of the conclusions are outlined below. The detail and analysis for the conclusions is contained in the remainder of this repor 8950/379/7 tC. The staff of St. Paul's Municipal Utility should be com- mended for keeping the old, outdated, difficult to main- tain equipment operating. It is a difficult task that they perform very well. It appears that a transmission line along the road to the airport connecting the airport, FAA station, Coast Guard Station, Weather Service, and the Exxon Camp would bring economic benefits to the utility's ratepayers. The line would be eligible for financing by the State's Rural Electrification Revolving Loan Fund (RERLF). Assuming RERLF financing, the electricity price to the consumers along that line would probably pay for debt service, fuel and maintenance, and would help cover operating costs for the utility. The line would most likely lower the average electricity price in St. Paul. St. Paul's diesel generators are old, worn out, inef- ficient, and in need of immediate replacement. Some of the existing generators should be kept as emergency back-up, but St. Paul needs new, efficient, easy to main- tain generators large enough to supply the baseload for the utility. Page 3 8950/379/8 The City powerhouse has an exceptionally high station load due to the quantity and size of equipment used in the powerhouse. The high station load is responsible for much of the substantial difference between the utility's generation and consumption. The City needs to replace some of the powerhouse support equipment in order to decrease the station load and the operating costs of the utility. It should also begin metering the powerhouse and any other unmetered loads. The utility needs to establish a long-term schedule for gradually upgrading the 480-volt portions of the dis- tribution system to standard distribution voltage of 2400-volts. The waste-heat system is functioning poorly and is providing significantly less heat than was intended. Some redesign of the system inside both the powerhouse and the recipient buildings is probably necessary. In ad- dition, the City needs to negotiate a price for the waste heat it distributes. System operation is expensive; it requires electricity and labor, both of which the City is currently providing free. With some-redesign and a negotiated sale price, payback from the sale of waste-heat should more than cover operating costs and therefore lower the electricity price in St. Paul. The 1984 avoided cost for non-firm energy (i.e., wind en- ergy unsupported by firm capacity) is between 14 and 14.7¢/KWH. As improvements are made to the city utility (more efficient generators, decreased station load), the non-firm avoided cost will drop to just less than 12¢/KWH in 1987 but then will rise with inflation and expected increases in the price of oi] to over 15¢/KWH by 1990. Page 4 The 1985 generation requirement for the utility is expected to be approximately 3,500 MWH of which 2,700 MWH is for consumption and the rest to supply the line losses and unmetered loads. The line losses and unmetered loads are expected to decrease with system improvements. The overall generation requirements are expected to increase slightly to 3,600 MWH in 1988 assuming the transmission line to the federal facilities near the airport is not constructed. If the line is constructed, generation is expected to reach 5,100 MWH in 1988 and could be as high as 5,800 MWH. 8950/379/9 Page 5 Chapter II. Powerhouse and Generation Improvements The diesel generators powering St. Paul's utility are old, worn out, inefficient, and in need of immediate replacement. They are only kept in operation by the considerable skill of St. Paul's powerplant staff. This section briefly describes the powerhouse and the diesels and provides recommendations for improvements. A. Generation Improvements Located in the port area of St. Paul, the powerhouse consists of two buildings. Powerhouse No. 1 contains six diesel generator units: three-350 KW Cleveland diesels and three-175 KW Detroit diesel units. Powerhouse No. 2 contains two-350 KW aging Worthington diesel units. The Cleveland and Worthington units are extremely old; they are 40-year old machines reputed to come from the powerplant of World War II submarines. The three-Detroit diesels are fairly new. All units generate 480 volt, 3-phase, 60 Hz power. The control switchboard is new. Powerhouse No. 1 is kept very clean. All units have interior remote mounted radiators. Figures 1 and 2 show sketches of the electrical system for the two powerhouses. The large Cleveland and Worthington units serve as St. Paul's baseload units. The Detroits are used for peaking and occasion- ally, in parallel, serve the low load hours on weekends and even- ings. From St. Paul's fuel use and generation records, the combined system gets between 10.0 and 10.6 KWH/gallon fuel effi- ciency but only 1720 KWH/gallon for lube oi1. (See Chapter IV. A. Fuel Efficiency and Generation Records.) Although the powerplant includes fully automatic switchgear, it requires six employees to operate, including 24-hour surveillance. According to the powerplant staff, the reason for six employees is that the 8950/379/10 Page 6 “MARCH 1985 3-13-85 ABo VOLT, 3D, “GOH, 3000 A Bus. Figure 1. ST. PAUL POWER PLANT EXISTING 23-aS 3325 VBNWd NOLATIALsi_C © Jago’ ZH 29 “Pe ‘ROBY “a BEY Ad so ' zee ge ‘noe | WA Bt ©) “dag '2H09 ‘Pe ‘nog / VAN biz “"ydg0' Hes ‘Pe “noe “way biz @ |©OO@ QOO |©O68 |©O@ [OOG |©O8 ) g |oo © @ |©O \ @ |OO —1© ad oo" 2H OS De ‘AOBH ‘VAY biz ) ®© © w POWERHOUSE NO. | 1) 8 [QO ) ©@ |OO it 44 g°0 ‘2H 09 “ge "pose ‘WAN Ber da F"9' ZH oS ‘Pe ‘ROS? VWI BEX @) dd BO'ZH OF De “ROS ‘OA Sev QN6N/3279/11 Pa ) © POWERHOUSE No.2 ONE Liaske DiAGRA Ex ISTIniGg BISTRIBUTION PANEL 440A FEZ GaN WEST CITY, CAMP SHOP, LS\ NMFS OFFICE, TeacHER QTRS, WOUSES 1-24, MACHIVE sHeP, GovT House H 400A EAST CITY eer TTT TRANSF. Ze0kvA, Ls3 480-2400v Hovs&s 134-149 NEw #osPiTAu 400A FE 3 ee ScHeol, HOSPITAL, uss STORE, ORTHORAR CHURCH, HOTEL, Cute , dDOAMITS ay SPARE oN sPARE “ais . SPARE UA ZS SPARE ee iii: POWER PLANT eens TRANSF. POWER PLANT es . SUB PANEL 8950/379/12 400A WAU BY PRODUCT TRAASE. Lsz2z SookvA, 480-2400V 400A “aes FE4 LS4 SEAL Ski PROCESSING PLANT, PT WAREHOUSE, ELEPHANT MuT, EQ@uiP. BLDC) PLANT SHoP, ELECT. SHOP, STAFF QTR'S, PoRmTroRy, CHURCH | 400 A LIN FE | Ls6 SOUTH cITY Wouses 25-24, 122-131 oa : SPeRE f . SPARE & y SPARE ee SPARE SPACE SPACE DISTRIBUTION PANEL EXISTING Page 8 generators frequently break, and the old generators are such low quality that the switchgear is unable to effect fully automatic starts, stops and load shedding without an operator in attendance. In the opinion of Power Authority staff, the Cleveland and Worthington generators are old, worn out, and inefficient. They could be kept as emergency back-up, but St. Paul desperately needs new, efficient, easy to maintain base-load generators. The current generators are only operable because of the continued, skillfull care by the powerplant staff. The generators are frequently out of service and this frequency can only increase in the future. The fuel. efficiency of the current generators, roughly 10 KWH/gallon, is probably the best that can be achieved. New generators now on the market can achieve over 14 KWH/gallon (though the average would probably be slightly less). The extremely high lube oi] consump- tion is indicative of the generators' poor condition. New equipment would have a much lower oi] consumption. The issue is not whether to replace the generators, the issue is when. If St. Paul does not act to quickly purchase new base-load equipment, the old equipment could soon break beyond repair. St. Paul should purchase new equipment while the old equipment is still operating. The alternative is to face emergency, expensive purchase and possibly some lengthly period of brown-outs when one or more generators experience catastrophic failure. The two-350 KW Worthington units in Powerhouse No. 2 should be retired, and the powerhouse should be modified for installation of one or more new, large capacity units capable of providing baseload for the town. The Detroits can, if necessary, be used for peaking, and the Clevelands are adequate for emergency back-up. The primary generation, however, should come from new units. 8950/379/13 Page 9 B. Station Load Problems The powerhouse in St. Paul has an extraordinarily high station load, approximately 400,000 KWH/year. This amount totals over 10% of the City's expected 1985 generation. The "extra" generation required to meet unnecessary station load requirements costs the city in extra fuel and maintenance on the diesels. The powerhouse load requirements are listed in Table 1. Table 1 Station Load At Time Of Visit Fuel transfer pump 1.5 hp Fuel transfer pump 1.5 hp Cooling fan, Cleveland generators 20.0 hp Cooling fan, Worthington generator 15.0 hp Cooling system booster pump 7.5 hp Cooling system booster pump 2.0 hp Exhaust gas boiler circulation pump 1.5 hp District heating booster pump 1.5 hp 0 District heating circulation pum 10.0 hp Total rated capacity of motors in operation: 60.5 hp Electricity consumption is roughly proportional to the loading of the motors. Assuming that these motors have been sized in such a way that they are loaded to 75% of capacity and assuming that a l-hp motor consumes approximately 1 KW: Total motor load = 75% x 60.5 hp x 1 KW/hp = 45.4 KW Lighting, estimated 1.5 KW Battery charging 0.2 KW Excitation, assuming 500 KW load at .2% of load 1.0 KW Total Station Load: q8.1 kW 8950/379/14 Page 10 A station load averaging 50 KW consumes approximately 400,000 KWH per year. Producing this electricity requires fuel, maintenance, and is a cost for the rate-payers. This station load seems very high when compared to other power plants of comparable size. A number of improvements could be made in order to decrease the station load to acceptable levels. These are listed below: Fuel transfer pumps. Most modern diesel power plants are not equipped with electric fuel transfer pumps. Instead, engine driven fuel pumps circulate excess fuel to return fuel lines connected to the day tank. Cooling fans. With appropriately sized horizontal core radiators placed outside the powerplant, the cooling fans' consumption should exceed 5 KW only under absolute summer peak load situations. Currently an estimated 25 KW are consumed by cooling fans. With variable speed drives or two-speed motors, the consumption would be reduced below 5 KW, especially if the waste heat recapturs system were functioning as intended. Cooling system booster pumps. If the waste heat recapture system in the power plant were designed correctly, no cooling system booster pumps would be needed. ATI cooling system circulation would be handled by the engine driven cooling pumps. Exhaust gas boiler circulation pump. If the waste heat recapture system were designed correctly, engine coolant would be circulated directly through the exhaust gas boiler. No booster pump would be needed, because the boiler has very limited flow resistance. 8950/379/15 Page 11 5. District heating booster pump. If the district heating system were designed as recommended in Chapter III, the loop in which the booster pump is used would not exist, and no pump would be needed. 6. District heating circulation pump. A 10 hp circulation pump is currently used. In a well designed district heating system, only extreme peak loads would require more than 2 hp for circulation. Conclusion. The total station load can be reduced from more than 50 KW to less than 10 KW if proper techniques are used in cooling and waste heat recapture systems. For purposes of the load forecast (Chapter VI), it is assumed that the current 400,000 KWH annual station load can be reduced to 200,000 KWH per year by 1987 by implementing the improvements recommended above. 8950/379/16 Page 12 Chapter III. Distribution System The existing primary electrical distribution system is mostly 480-volt, 3-phase, 60 Hz, with some newer 2400-volt, 3-phase, 60 Hz lines originating in powerhouse No. 1 and servicing the east part of the city (houses and a new medical facility). A second step-up transformer, 500 KVA, 480-2400-volt, 3-phase, 60 Hz, also located in powerhouse No. 1 is used to serve the “By-Product Area." 480-volt, 3-phase feeders serves West City, South City, the seal skin processing plant, the school, hospital, store, hotel, clinic, and dormitory. The secondary distribution system is 120/240-volt, single phase. The entire distribution system is underground. The 480-volt portions of the distribution system are very old and in need of replacement. The 480-volt lines are causing numerous problems to the city. Eventually all of the 480-volt system should be replaced by 2400-volt distribution lines. It is not imperative that the upgrade occur immediately, but St. Paul should implement a plan to systemically upgrade the system over the next five to seven years. If upgrade is delayed until the system experiences a catastrophic failure, the City will be faced with a more expensive, emergency replacement and perhaps a prolonged black-out for parts of the City. 8950/379/17 Page 13 Chapter IV. Waste Heat Recapture System The powerplant in St. Paul is equipped with a system to capture the waste heat from the generators and distribute it to the Store, Ho- tel Annex, Office Building, and School. Unfortunately, the system is not functioning satisfactorily; its actual heat delivery is far less than its potential. The system's poor performance is due to both operation and design errors. With limited expense, the exist- ing system could be upgraded to use much more of the available waste heat. In addition, local skills are adequate for the construction, operation, and maintenance of an_ efficient, well-designed, waste heat system. An optimal waste heat system installed on the existing St. Paul powerplant would be capable of retrieving 5,200 BTU of useable heat for every KWH of electricity produced. This means that at a 350 KW load, for example, the system could displace approximately 1.8 million BTUs of heat per hour or 18 gallons of fuel oil per hour. In addition, an efficient waste heat system decreases the electrical consumption required in the powerplant. - Maintenance work on such a system should be limited to a few hours of in- spection work per week. During the visit to St. Paul, it was not possible to determine actual fuel savings from the existing system. It was clear, howev- er, that the system was not functioning at its optimal level. During the time of the visit, the weather was relatively warm (30°F. with very light winds) but none of the buildings connected to the system were being supplied all of their heating needs. The amount of waste heat available to the system was approximately 1.9 million BTU/hour. This amount was several times the amount of heat needed in the buildings. Yet the buildings' boilers were operating and, at the same time, the diesel engine radiators were emitting 8950/379/18 Page 14 large amounts of heat to the atmosphere. It was very clear that the waste heat recapture system was not functioning as intended. Besides not producing the intended benefits, the system also adds to the already exceptionally high station load at the powerplant through the use of a number of large circulation pumps. A. System Description After the hot coolant leaves the engines, it is fed through primary shell and tube type heat exchangers where a portion of the heat is transferred to a water/glycol mixture in a secondary heating loop. After leaving the heat exchangers, the coolant in the primary loop is returned to the diesels directly or, if additional cooling is needed, through radiators. As explained above, the secondary loop receives heat from the en- gine coolant. In addition, the mixture is fed through exhaust gas boilers where it receives heat from the engines' hot exhaust gasses before those gasses vent to the atmosphere. Finally, the mixture flows through a large secondary flat plate heat exchanger where heat is transferred to a tertiary heating loop of water/glycol. In addition, the secondary loop includes a "mixing/storage" tank. The tertiary loop circulates between the powerplant and the various user buildings. In the user buildings, tertiary flat plate exchangers transfer the heat to the fluid circulating in these buildings' heating systems. B. Existing Problems The temperature delivered by the existing waste system is too low to be effectively used to heat buildings around St. Paul. There 8950/379/19 Page 15 are three reasons for this condition. First, the system uses three cooling loops (not including the loop internal to the heating system of the user buildings). Each loop with its required heat. exchanger lowers the useable temperature the system can deliver. Especially when shell and tube type heat exchangers are used (as they are in St. Paul), the final temperature delivered to the user is too low to be easily useable. Second, the "mixing/storage" tank jin the secondary loop lowers the temperature delivered by the system. Mixing/storage tanks are an obsolete design feature not used in more modern systems. Finally, the fan motors on the radiators are not thermostatically controlled. They run regardless of need. These constantly running radiator fans lower the amount of heat delivered to the system, lower the final system temperature, lower the coolant temperature returning to the diesels ‘below the optimum level, and use unnecessary electricity. The waste heat system delivers fluid from the powerplant to the us- er buildings at only 125” F. There is no guarantee that backfeed- ing does not occur. (Backfeeding is the process in which a user building does not receive heat from the waste heat system but ac- tually delivers heat to the system. It occurs when the waste heat fluid is colder than the user building's fluid it is trying to heat.) The tertiary loop is a constant flow system since no flow regulat- ing devices are used in the user buildings. This design makes it necessary to size the circulating pumps for the peak load that the system only rarely experiences. The end result is excess electric- ity consumption to run the pumps and lower temperatures delivered from the system. The problems noted above are all design problems. There are also problems with the way the system is operated. At the time of the visit to St. Paul, only one exhaust gas boiler was in operation. 8950/379/20 Page 16 The other was being by-passed and the heat was not being utilized. In the school and hotel, the valves were also not being operated as intended. By-pass valves around the heat exchangers' secondary sides were left open and there was only very limited flow through the heat exchangers. In order to utilize the heat, these valves must be kept closed. However, as mentioned earlier, the powerplant fluid is delivered at 125°F, a temperature insufficient for heating purposes. Until this changes, it does not make any difference whether the user building installation is operated correctly. C. Recommendations It is clear that the waste heat system will not function well as currently designed and installed. Valuable heating resources are being wasted and the operating costs of the-system are much higher than is necessary (both in maintenance and in the electricity required to run the system). In order to get the system to func- tion as intended, a partial redesign is recommended. 1. Remove the primary shell and tube type heat exchangers and connect most diesels to one common cooling manifold. One set of diesels (e.g., one Cleveland and one GMC) should be on another separate manifold for emergency back-up. 2. Connect the common cooling manifold to one large flat plate type heat exchanger (the existing one can be en- larged and reused), and to three or more remote radiators (existing radiators can be reused). Remove the "mix- ing/storage" tank. It is an archaic design normally found in low temperature systems only. This and the pre- vious recommendation have the effect of eliminating the secondary loop. 8950/379/21 Page 17 3. Install thermostatic controls on the radiator fan motors. This addition will decrease the amount of electricity used by the fans and will decrease unnecessary cooling not directed to the waste heat system. 4. Install smaller pumps and AMOT-type thermostatic controls on the district heating lines in the powerplant to secure adequate supply temperature (i.e., to raise the tempera- ture delivered to the user buildings). 5. Install Danfoss-type thermostatic controls on the dis- trict heating return lines in all user buildings to se- cure adequate temperature drop. 6. Expand the system to deliver heat to other buildings as the excess waste heat becomes available. (A lot of equipment was delivered to St. Paul but was never in- stalled. ) These changes should give substantial benefits to St. Paul. An ef- fective, efficient waste heat recapture system will eliminate the need for many buildings in the community to burn oi] on all but the coldest days. The system should deliver substantial benefits -- much greater than today's system delivers -- whether or not the proposed wind system is installed. Without the wind installation, the waste heat benefits are, of course, potentially greater, but even with a substantial wind installation, the benefits should be significantly greater than that being produced by the current sys- tem. 8950/379/22 Page 18 Chapter V. Analysis of Avoided Cost Avoided cost is the cost that St. Paul can expect to save if wind- generated energy replaces some of the present diesel generation. The avoided cost represents the benefits of a wind farm to St. Paul. But not all costs are avoided costs. For example, if a wind farm existed, St. Paul would need to burn less diesel fuel and would save the cost of the fuel's purchase. Thus, the cost of die- sel fuel is a part of St. Paul's avoided cost. The cost of reading consumers' electric meters, however, is not an avoided cost. The utility will have to pay someone to read the meters whether or not a wind farm exists. This chapter analyzes the avoided cost for St. Paul's electric utility with respect to a sizeable addition of wind energy. It calculates the cost structure for the present utility and the ex- pected cost structure after planned improvements are made. It then forecasts these costs through the year 2000. A. Fuel Efficiency and Generation Records A record of seven months of fuel use and generation records are displayed in Table 2. The records show that St. Paul averaged ap- proximately 10.6 KWH/gallon from July 1, 1984 through January 31, 1985. That generation efficiency is low relative to the new diesel equipment now being sold but is higher than was expected from the old, inefficient equipment operated by St. Paul. In addition, the August generation data, 435,264 KWH, seems to be exceptionally high; it is 30 percent higher than the next highest month, and it is not supported by analysis of St. Paul's recording demand meter. The fuel efficiency calculated on the basis of that generation is also exceptionally high, 13.8 KWH/gallon, and that figure is probably higher than the equipment in St. Paul can realistically 8950/379/23 Page 19 Table 2, Fuel Efficiency and Generation Records EFFICIENCY Fuel Lube Generation Fuel Lube Month (Gal) (Gal) (KWH) (KWH/gal) (KWH/gal) July 34,696 332,741 9.6 August 31,440 435 ,264 13.8 September 30,186 195 273,600 9.1 1,403 October 25,218 146 272,640 10.8 1,874 November 26,172 199 274,560 10.5 1,380 December 27,034 115 274,560 10.2 2,387 January 27 ,829 297 281,280 10.1 947 February 30,548 297 Total: 202,575 1,249 2, 144,645 10.6 1,718 Average achieve. If there is an error in the data and August's generation is, in fact, lower than the amount recorded, average fuel efficien- cy would be closer to 10.0 KWH/gallon. B. Accounting and Financial Information; Present Avoided Cost St. Paul's electric rates are designed to cover costs incurred in five different accounts: 4100 Administrative Department 4200 Public Service Department 4600 Public Works Department 4860 General Maintenance Department 4710 Power Plant Fund Costs from the first four accounts, the various departments, are assigned to the utility on a fixed percentage of the Department's expenses. For example, 15% of the Administrative Department's expenses are charged to the utility (to cover the cost of the City Manager and other overhead functions). The only avoidable costs in these accounts are the salaries of the City's Public Works Director 8950/379/24 Page 20 and Electrician who spend part of their valuable time to help fix the system whenever it breaks. The costs are not a significant part of the utility's total costs and are not included in the analysis below. The largest cost area is the Power Plant Fund; it includes the fuel, operating supplies, maintenance, and labor for operating the power plant. Only the Power Plant Fund includes significant ex- penses that can be saved with the addition of wind power. This section explains the accounting information for the Power Plan Fund in some detail and provides a general explanation of the remaining four account categories. The detailed cost categories in the Power Plant Fund and its expense record from July 1984 through January 1985 are shown in Table 3. Labor Cost Labor charges include the wages, taxes, and benefits for the six-person power plant staff. A six-person staff is unusually large for a utility serving St. Paul's population and generation needs. According to the Public Works and Power Plant Directors, the six-person staff is needed because the old worn-out equipment frequently breaks down. All six people are needed to keep the plant and the distribution lines in working order. After viewing the plant, Power Authority staff had no doubt that this was true. If planned improvements are made and the old diesels are replaced with more reliable equipment, the City should expect that the tasks can be adequately handled by a four-person staff. If wind-generated electricity replaced diesel electricity for a portion of the city's load, some but not all of the labor costs can be avoided. If each generator ran fewer hours and ran with lower loads, they would break down less frequently and scheduled mainte- nance could be completed less often. It is unlikely, however, that the system could be operated with less than four people. 8950/379/25 Page 21 Table 3 Expense Record: July 1984 - January 1985 duly Aug Sept Oct Nov Dec Jan Direct Wages tian pe nes ee pea pice teas Benefits/Taxes 927 1,350 1,383 1,488 1,667 1,743 1,889 TOTAL LABOR $1,3er «= STABT. «$16,978 «$17,663 «| $B,477« $19,285 S17, Operate Supplies -0- 6,315 -0- 811 -0- 1,886 -0- Small Parts/Equip -0- 941 -0- 7,636 -0- -0- -0- Equip Maintenance -0- -0- -0- -0- -0- 0 -0- Consultants -0- -0- 612 3,869 15,548 -0- 27,684 Travel/Per diem -0- -0- -0- -0- -0- -0- -0- Freight/Postage -0- 46 -0- 1,998 309 62 724 Insurance -0- -0- -0- -0- -0- -0- 2,416 FUEL 0i1 (gal) 34,696 31,440 30,186 25,218 26,172 27 ,034 27,829 . Fuel Price $ 1.03 $ 1.03 $ 1.03 $ 1.03 $ 1.03 $ 1.08 $ 1.03 Fuel Cost 35,737 32,383 31,092 25,975 26 ,957 27,845 28,664 Oil Hand. % 5% 5% 5% 5% 5% 5% 5% O71 Handling 1,787 1,619 1,555 1,299 1,348 1,392 1,433 Interest _1,966 1,781 1,710 1,429 1,483 1,531 1,577 TOTAL EXPENDITURES $57,850 $54,536 $51,943 $60,679 $64,122 $52,002 $80,483 Generation (KWH) 332,741 435,264 273,600 272,640 274,560 274,560 281,280 8950/379/26 Page 22 Total (July-Jan) $120,196 Partially avoidable 9,012 Avoided cost varies with generation 8,577 Avoided cost varies with generation -0- Account category unused (no avoided cost} 47,713 Not avoidable -0- = Not avoidable 3,139 Avoided cost varies with generation 2,416 Not avoidable 202,575 += Avoided cost varies with generation 208,652 Avoided cost varies with generation 10,433 Avoided cost varies with generation 11,476 Avoided cost varies with generation $421,614 2,144,645 (July through January) The system cannot avoid more than one-third of its labor costs with the addition of wind energy. The exact avoided cost cannot be ascertained exactly; however, Power Authority staff estimates that one-third of the labor costs should be considered avoided cost for purposes of wind generation. If new generators were added to the system, the labor component of avoided cost would decrease significantly. It is only because of the age of the present equipment that every additional kilowatt hour causes more frequent break-downs. If the loads and on-line time can be cut down, the City can save on the parts and labor nec- essary to fix the system. If a new, reliable generator were used, each additional kilowatt-hour would require much less maintenance, and both the labor required and the avoided cost would be corre- spondingly lower. Operating Supplies. The Operating Supplies category includes rags, lube oil, etc. Use of these supplies is directly proportional to the power being generated. Thus, the avoided cost is proportional to the amount of energy produced by the wind system. Small Parts and Equipment. Small Parts and Equipment are similar to Operating Supplies. It includes the miscellaneous parts needed for operation. It should be avoidable in proportion to the energy produced by another source. Equipment Maintenance & Consultants. The Equipment Maintenance Category was not used by the power plant staff during the seven months of records and is not included in avoided costs. "Consul- tants" includes the contract engineers who help with the system, the City's regional planners who prepare grant applications, etc. These costs are not likely to change with the addition of wind generation. 8950/379/27 Page 23 Freight and Postage. According to the City's accountant, Freight and Postage is mostly used to pay for sending parts out to be re- paired. Its small cost is considered to be avoidable in proportion to the amount of generation replaced by other sources. Insurance. Insurance is currently not charged to the utility. (It should be.) However, insurance costs are not proportional to gen- eration, and insurance is not an avoided cost. Fuel Costs. Fuel and the incidental associated costs (handling, interest, etc.) are the largest component of avoided cost. The fuel saved is roughly proportional to the amount of energy produced from non-diesel sources. St. Paul also assesses a 5% fuel handling charge to cover the cost of fuel transfer. In addition, there is an interest cost associated with holding stocks of fuel between the yearly fuel purchases. The cost savings is equal to the interest paid on the cost of each gallon of fuel not used. The interest rate is assumed to be 11 percent, and the average time between pur- chase and fuel use is approximately a half year. St. Paul expenses are converted to avoided cost per KWH in Table 4. The table shows that the avoided cost for the period between July 1984 and January 1985 is roughly between $0.14 and $0.147 per KWH. In addition, it shows that the great proportion of the total avoided cost comes from the fuel savings, 11.4¢ of 14¢. The make-up of the avoided cost is in Figure 3. Operation and Maintenance costs are only 5 percent of the total, less than 1¢/KWH. This amount appears low, and the utility may be using in- ventory left over from the federal government. If so, the O&M costs are not fully reflected in the seven months of data avail- able, and the avoided cost estimate understates the true amount. Figure 3 also shows that fuel and related costs make up over 3/4 of the total avoided cost. 8950/379/28 Page 24 Table 4 Avoided Cost Analysis: July 1984 - January 1985 (S/W) Jduly-Jan July-Dec July-Jan (excl Aug) Weighted Weighted Weighted July Aug Sept Oct Nov Dec dan Average Average Average TOTAL LABOR $0.022 $0.011 $0.025 $0.026 $0.027 $0.028 $0.026 $0.022 $0.022 $0.025 Operat Suppl 0.000 0.015 0.000 0.003 0.000 0.007 0.000 0.005 0.004 0.002 Small Parts/Equi 0.000 0.002 0.000 0.028 0.000 0.000 0.000 0.005 0.004 0.004 Freight/Postage 0.000 0.000 0.000 0.007 0.001 -000 0.003 0.001 0.001 0.002 FUEL Fuel Cost 0.107 0.074 0.114 0.095 0.098 0.101 0.102 0.097 0.097 0.103 0i1 Handling 0.005 0.004 0.006 0.005 0.005 0.005 0.005 0.005 0.005 0.005 Interest 0.006 0.004 0.096 0.005 0.005 0.006 0.006 0.005 0.005 0.006 TOTAL: Generation $0.141 $0.110 $0.150 $0.170 $0.137 $0.147 $0.141 $0.139 $0.140 $0.147 Generation (KWH) 332,741 435,264 273,600 272,640 274,560 274,560 281,280 1,863,365 2,144,645 1,709,381 8950/379/29 Page 25 Distribution of Avoided Cost St. Paul Municipal Utility, 1985 Labor (17.3%) O & M (5.3%) Other Fuel Costs (7.4% Fuel Purchase (70.0%) Figure 3 The avoided costs of Table 4 are calculated as costs per kilo- watt-hour generated. Most costs per KWH are quoted in costs per KWH consumed. It is a subtle but important distinction. The con- sumer sees a price of, say, $0.32 per KWH. The KWH referred to is that consumed. Indeed, most avoided cost analyses do not make a distinction between generation and consumption. St. Paul's station loads, unmetered loads, and line losses are large enough, however, that there is an important difference between consumption and generation. There is a 29% difference between costs/KWH generated and costs/KWH consumed. If the utility buys wind generated electricity, it is replacing its own generation. To be consistent, then, the avoided costs must be in terms of generation. The avoided costs per KWH consumed is much higher, $0.18 per KWH, but it is a misleading figure. Table 4 calculates a mean avoided cost in two ways, with and without the month of August. Because August's generation is suspi- ciously large (and because that generation is disputed by the RQ6N/3279/2N Pane 26 utility's recording demand meter), the avoided cost calculation is made without August's record included. C. Future Avoided Cost St. Paul's avoided cost is expected to change. St. Paul plans to replace its old diesel generators. This change will cause almost all components of the avoided cost to decrease. The newer diesels are more fuel efficient; less fuel will be used and less will be saved by the addition of other generating sources. Similarly, less labor will be needed and less will be saved as wind generation replaces diesel. There is, however, an opposing force that is expected to raise the avoided cost: inflation. One expects St. Paul's avoided cost to fall as the utility installs new diesels and then to rise with inflation and increases in the price of oil. Table 5 shows the parameters and results from a simple avoided cost model constructed on a personal computer. The three components of avoided cost are labor, operation and maintenance (0&M), and fuel costs. It was assumed that the planned improvements would be com- pleted by 1987. Thus, 1984 costs are those calculated as in the section above, and 1987 costs are based on a hypothetical, effi- cient system. Post-1987 costs are inflated from the 1987 base. Labor costs are calculated by taking the expected monthly labor costs (in 1984 dollars), the portion of those labor costs that are avoidable, and the monthly generation expected from wind. The $12,300 monthly labor bill is 2/3 of the July-January mean cost. The figure is based on the assumption that maintenance of a newer power plant will require only four of the present six people. As a guess, it is assumed that 20% of the labor bill could be avoided if alternative generation sources supplied 170,000 KWH per month. 8950/379/31 Page 27 The hypothetical labor cost for the improved system is calculated as below: Labor Cost = ($12,300/month) x (.20)/(170,000 KWH/month) That labor cost is then inflated at 5 percent (the assumed in- flation rate) to compute the cost in 1987 and future years. Table 5 St. Paul Municipal Utility, Avoided Cost Projection Actual ----------- Projected--- 1984 1987 1990 1995 Monthly Labor Cost ($) = $ 12,300 Avoidable Labor Percentage (%) = 20% Labor Cost $0.023 $0.017 $0.021 $0.027 Monthly Generation (KWH) = 170,000 0 & M Costs 0.010 0.005 0.006 0.008 Fuel & Related Costs 0.107 0.098 0.124 0.175 Operating Supplies ($/KWH) = 0.001 --- --- --- --- Parts & Equipment ($/KWH) = 0.002 Avoided Cost 0.140 0.119 0.152 0.210 Freight & Postage ($/KWH) = 0.001 Fuel Efficiency (KWH/gallon) = 13 Fuel Cost ($/gallon) = 1.03 Interest Rate (%) = 11% Fuel Handling (%) = 5% Inflation Rate (%) = 5% Operation and maintenance costs are estimated by taking half of the present, costs for Operating Supplies, Smal] Parts & Equipment, and Freight and Postage. This results in an 0&M avoided cost of only half of a cent per KWH in 1987. It is a barely significant portion of the total. It also seems suspiciously low. Fuel and related costs make up the bulk of the avoided cost. avoided fuel cost is the fuel price (in $/gallon). The For these cal- 8950/379/32 Page 28 $0.035 0.010 0.272 0.316 culations, the 1984 fuel price of $1.03/gallon is assumed to be a realistic price. An average fuel efficiency of 13 KWH/gallon is also assumed. From the experience of Power Authority staff, thir- teen KWH/gallon is a realistic fuel efficiency for a well run diesel. It is probably above the median fuel efficiencies for sim- ilarly sized diesel installation in rural Alaska, but, on the other hand, slightly higher efficiencies are also possible to achieve. A very efficient rural diesel system now in operation is Unalakleet Valley Electric Coop. That system averages just less than 14 KWH/gallon. The price of fuel is escalated at inflation plus an addition factor to represent the Power Authority's expectations for fuel price changes over the next twenty years. The fuel escalation factor assumed that the fuel price will decrease 4% from present prices by 1986, remain constant (in real terms) for two years, and then increase by 2% per year. The fuel-related costs, handling and interest, are small but no- ticeable. Handling is calculated at 5 percent of the fuel price, and interest is calculated to be the fuel price per KWH invested at 11 percent for a half year. The results of the avoided cost projection are displayed in Figure 4. It shows, as expected, that the avoided cost decreases as more efficient generation is installed in 1987, and after that date, costs increase with inflation and fuel prices. 8950/379/33 Page 29 Avoided Cost ($”“KWH) Avoided Cost Projection St. Paul Municipal Utility $0.35 | Total Avoided Cos voided Fuel Cost $0.05 4 Avoided Labor Cost Avoided O & M Cost $0.00 1984 1987 1990 1995 2000 Year Figure 4 RAEN /27Q0/24 Pane 20 Chapter VI. The Load Forecast This chapter contains a short-term electric load forecast for the City of St. Paul. Because it is the short-term developments in the City's loads that will determine the extent and type of improve- ments to be made in the utility, the forecast focuses on the next few years. It analyzes current residential and commercial/- industrial loads and estimates changes for the future. It also es- timates current and projected unmetered loads and line losses. The result is a near-term forecast of both the expected consumption and the generation requirements. A. Residential Loads. Electric use per residential customer is decreasing in St. Paul. This trend is expected to continue for the next few years. Total residential electricity use will increase with the construction of the Ellerman Heights Subdivision. 1983 and 1984 residential electricity use is shown in Table 6. The table shows that the mean annual use per customer during 1984 was approximately 12,200 KWH, down 570 KWH from 1983. Table 6. 1983 & 1984 Residential Electricity Use. Year: 1983 1984 Total Consumption (KWH/yr) 1,522,180 1,422,118 Number of Customers 119 118 Mean Consumption per Customer (KWH/yr) 12,791 12,221 Total Change in Consumption (KWH) -80,062 Mean Change in Consumption per Customer -570 The distribution in electricity use is quite large among the vari- ous consumers. Figure 5 shows that 29 customers used 8950/379/35 Page 31 Number of Consumers Number of Residential Consumers Residential Consumption Change Comparison of 1983 and 1984 Consumption me he ee ee PNoOPe AOI OWOS . m o 9 8 7 6 — 5 + 4-4 3-4 2 iJ 0 —6 -6 -4 -2 0 2 4 6 8 (Thousands) Change in Residential Consumption (KWH) Figure 5 Residential Electricity Consumption October 1983 through September 1984 0 10000 20000 Annual Consumption (KWH) approximately 10,000 KWH/yr but that many used an amount significantly more than that: 19 residences used 14,000 KWH, ten used 20,000 KWH, and three used even more. The distribution in the change between 1983 and 1984 is similarly large. Figure 6 shows the increase and decrease in consumption between the two years by the number of residences. For example, 14 residences decreased their use by approximately 500 KWH between the two periods. In fact, 64 residences recorded a decrease but 47 recorded an increase. The per household decrease in electricity consumption will probably continue for the next year or two. Community consumption is still responding to the price increase that occurred when the federal government left the island and electricity rates increased. There is typically a lag of a few years between a change in price and the time a new equilibrium consumption level is established. In addi- tion, the community is only now beginning to establish serious col- lection procedures for long-time delinquent bills. The shock of this process will also bring a decrease to some consumers (even to some consumers without delinquent bills). Finally, as 20 new houses are built and current households split up, the electricity required to run these smaller households is apt to be somewhat less than was previously required. For this load forecast, continued decrease of approximately 600 KWH per year is expected for the next two years. Average consumption is projected to be 11,600 KWH for 1985 and 11,000 KWH for 1986 and beyond. There are currently 118 residential customers. Twenty new custom- ers will be added in September of this year (the Ellerman Heights Subdivision addition). Six new units will be added by the school district (also in September). Finally, there is a fourteen unit Senior Citizen's complex also expected in September. The complex 8950/379/37 Page 33 Senior Citizen's complex also expected in September. The complex is projected to use 500 KWH/unit/month, or 84,000 KWH/yr. The residential load projection is contained below. It assumes that the new developments use three months of electricity in 1985. Table 7. Residential Load Projection Year Load Projection 1985 1,470,000 KWH 1986 and beyond 1,670,000 KWH B. Commercial/Industrial Loads Commercial/Industrial Loads have increased during the last year as shown in the Table 8. Table 8. 1983 & 1984 Commercial/Industrial Loads. 1983 1984 Annual Electric Use (KWH/yr) 1,095,034 1,230,708 Increase, 1983-1984 (KWH/yr) 134,774 Increase, 1983-1984 (%) 12% There is little reason to expect these loads to continue to show any dramatic increase. Thus, existing commercial/industrial con- sumers are projected to continue their 1984 use levels. While there are some commercial/industrial additions currently being con- sidered, none have firm plans and are still somewhat speculative. These uncertain: load additions are listed in Table 9. 8950/379/38 Page 34 Table 9. Planned Commercial/Industrial Development Year Description Annual Energy Use On-Line 1987 Public Safety Building 14,000 KWH/yr 1987 Floating Processor tied up at City dock 300 KW Peak; Load Factor = .33; 2 1/2 months 160,000 KWH/yr 1988 School Addition 42,000 KWH/yr 1988 Multi-Family Complex 10 Units @ 700 KWH/unit/month 84,000 KWH/yr Total Planned loads - 1987 174,000 KWH/yr Total Planned loads - 1988 300,000 KWH/yr Using the explanation and the table above, the commer- cial/industrial load projection is given in Table 10. Table 10. Commercial/Industrial Load Projection Year Projected Annual Loads 1985 - 1,230,000 KWH 1986 1,230,000 KWH 1987 1,230,000 KWH (Firm) 1,400,000 KWH (Planned) 1988 1,230,000 KWH (Firm) 1,500,000 KWH (Planned) 8950/379/40 Page 35 C. Transmission Line Loads The transmission line proposals would allow the city utility to provide power to the existing facilities near the airport: Coast Guard Loran Facility Federal Aviation Administration Facility (FAA) Weather Service Airport FAA Radar Station Water Supply Pump Station Currently, these facilities are powered by diesel generators operated by the Coast Guard. The Power Authority received hourly load records from the Coast Guard for one 24-hour period every two weeks from September 1, 1984 through March 1, 1985 (13 sets of records). The load records include generation for all of the existing facilities. These loads are remarkably stable. Figures 7 shows the energy use for the period. (March energy use is extrapolated from March 1 data.) The figure shows that the energy use varies extremely little over the six month period. In addition, the load has only an insignificant variation by hour. The annual load for all facilities is projected to be 1,675,000 KWH per year. The Exxon Camp near the airport is left out of the analysis above because it represents a very speculative load. It is not clear how long the camp will operate in St. Paul. If oil is found, it could be there quite a long time. On the other hand, it could leave in the fall of 1985. In addition, the camp is seasonal; it is expected to operate only 5 1/2 months per year but to average 100 KW during that period. Peak load is expected to be 200 KW. Put another way, the monthly energy is projected to be 73,000 KWH for the summer months and to total 401,000 KWH annually. 8950/379/40 Page 36 180 170 160 = 180 E140 4 130 ‘5 120 Bg 110 na 100 ‘5 qe 80 ué 70 >” 60 4 50 8 40 - 30 20 10 0 Coast Guard Station Energy Use September 1984 through March 1985 Figure 7 D. Line Losses and Unmetered Loads St. Paul Municipal Utility experiences a significant difference be- tween the electricity generated and its. metered consumption. For the six months between July and December 1984, the difference was 29%. That figure is incredibly high. Part of the discrepancy could be due to incorrect generation totals for the month of August. But even with the August figure excluded from the calcu- lation, the difference is 22%. Two problems are responsible for the discrepancy: unmetered loads and line losses. The City carries significant unmetered loads on the system. The 8950/379/41 Page 37 most significant of these is the powerhouse itself. Chapter II includes an explanation of the powerplant load. In summary, the load currently totals approximately 400,000 KWH per year, some of which is required to run the waste heat equipment. The powerplant load could be significantly reduced by the improve- ments suggested in Chapter II. It is assumed that the system improvements are implemented during 1987 and that the load de- creases to 200,000 KWH the following year. Line losses for the distribution system appear to be approximately 11% of generation. For purposes of this forecast, they are assumed to decrease to 9% by 1993. (Line losses will decrease as "leaky" splices are replaced and as new loads are connected to higher volt- age distribution and transmission lines, especially the Ellerman Heights Subdivision and federal facilities at the end of the trans- mission line.) Tables lla and 11b show the line loss and unmetered load forecast. Table 11a shows that the unmetered and powerplant loads will total 400,000 KWH in 1985 and 1986 but that powerplant improvements will reduce that load to 200,000 KWH by 1987. In addition, line losses totalling 11% of generation in 1985 drop to 9% by 1991. Table 11b adds the unmetered and powerplant loads to the line losses. The total varies with the load forecast. 8950/379/43 Page 38 Table lla Unmetered Loads and Line Losses (MWH) UNMETERED and POWER LINE YEAR PLANT LOADS LOSSES 1985 400 11% 1986 400 11% 1987 200 10% 1988 200 10% 1989 200 10% 1990 200 10% 1991 200 9% 1992 200 9% 1993 200 9% Table 11b shows the total “unconsumed" KWH projected at four different load levels each year: without the transmission line assuming that the firm load projection is accurate or assuming all planned facilities are built, and the same two assumptions with the transmission line. For example, the total of unmetered loads and line losses will be 362 MWH in 1987 if the transmission line is not built and only the firmly known developments (Ellerman Heights Subdivision, etc) are added to the grid. If all of the planned facilities are added (including the transmission line), the “unconsumed" MWH will total 624 MWH that year. Table 11b Projected Total Unmetered Loads and Line Losses (MWH) WITHOUT TRANSMISSION LINE WITH TRANSMISSION LINE YEAR FIRM PLANNED FIRM PLANNED 1985 780 780 1986 795 795 795 843 1987 362 382 557 624 1988 353 383 543 619 1989 343 373 529 603 1990 334 363 515 587 1991 325 353 501 571 1992 316 344 487 555 1993 307 334 473 539 8950/379/43 Page 39 E. The Complete Load Forecast The two tables in this section, 12 and 13, compile the various load projections given above: residential, commercial/industrial, transmission line loads, and the unmetered loads and line losses. The tables show that 1985 consumption is expected to be approxi- mately 2,700 MWH and that to supply this electricity, the City will need to generate 3,500 MWH. Consumption is certain to increase as the Ellerman Heights Subdivision and the other funded projects are constructed; a total increase of 2,900 MWH in 1986. If planned projects are brought on line, consumption will slowly. increase throughout the next four years. The transmission line portion of the forecast shows the effect the transmission line will have on the City's total consumption. The "Planned" Section of the transmission line forecast shows the effect as the planned projects are constructed. It also assumes that the Exxon Camp is connected to the grid. If any of these developments do not occur, they can easily be subtracted from the totals. Total consumption, then, is expected to remain just less than 3,000 MWH without the transmission line and to grow to between 4,575 and 5,246 MWH if the line is built. Table 12 Projected Annual Electric Consumption (MWH) WITHOUT TRANSMISSION LINE WITH TRANSMISSION LINE YEAR FIRM PLANNED FIRM PLANNED 1985 2,700 2,700 1986 2,900 2,900 4,575 4,976 1987 2,900 3.070 4,575 5.146 1988 2,900 3,170 4.575 5,246 1989 2,900 3,170 4,575 5,246 1990 2,900 3,170 4,575 5,246 1991 2,900 3,170 4,575 5,246 1992 2,900 3,170 4,575 5,246 1993 2,900 3,170 . 4,575 5,246 Table 13 shows the generation required to supply the expected consumption. The generation requirements decrease slightly after 1987 as the line losses decrease and as the powerplant load decreases in response to system improvements. The total generation requirement in 1988 is expected to be between 3,600 and 3,900 MWH without the transmission line and between 5,500 and 6,200 MWH if the line is built. The numbers in Table 13 are displayed in a graphic form in Figure 8. The figure shows that the load will increase dramatically with the construction of the transmission line. Table 13 Projected Annual Electric Generation (MWH) WITHOUT TRANSMISSION LINE WITH TRANSMISSION LINE YEAR FIRM PLANNED FIRM PLANNED 1985 3,500 3,500 1986 3,500 3,500 5,400 5,800 1987 3,300 3,500 5,100 5,800 1988 3,300 3,600 5,100 5,900 1989 3,200 3,500 5,100 5,800 1990 3,200 3,500 5,100 5,800 1991 3,200 3,500 5,100 5,800 1992 3,200 3,500 5,100 5,800 1993 3,200 3,500 5,000 5,800 8950/379/46 Page 41 Wd {I'ZFR—”’DD.J WW o»>°>OWI Lhe MX ©§i Od 1988 Planned SO QQ YQ J 0 Ves RM 8x QQ 1987 Firm With Transmission Line YEAR KLZ3 WME. MG 7> LLL RMA Load Forecast St. Paul Municipal Utility 1985 Without Transmission Line Figure 8 Page 42 8950/379/47 F. Load Characteristics Load characteristics -- load factors, load-duration relationships, peak and average loads -- are an important parameter for sizing generators, planning future capital expansions, and estimating the potential energy use from wind or other alternative energy sources. In an effort to assess the load characteristics for St. Paul, the Power Authority transcribed a year of strip-chart demand records from St. Paul's recording demand meter: from March 1984 through February 1985. The meter records the average electrical demand every 15 minutes. The Power Authority transcribed the chart once every hour, every other day for a full year. The data was used to generate the load characteristics based on the existing load. If added to the City grid, the Coast Guard and other federal facilities would stabilize the City's load. The Coast Guard currently generates electricity for all of the federal facilities near the airport. The Power Authority received hourly load records for one 24-hour period every two weeks from September 1, 1984 through March 1, 1985. That data was combined with the City's existing load data to create hypothetical load characteristics assuming the transmission line was built and the federal facilities were a part of the City's grid. The Coast Guard and other federal loads are remarkably stable. Figure 9 shows the energy use and load characteristics for the September through March period (March energy use is extrapolated from March 1 data.) The figure shows that the energy use (peak and base loads) vary extremely little over the six month period. In fact, the load has only an insignificant variation by hour. The load factor for the entire period averaged 0.81! This stable profile makes the facilities a very desirable load for the utility. The yearly load projection and load characteristics for both the City alone, the federal facilities alone, and the two together are outlined in Table 14. 8950/379/48 Page 43 Demand (KW) Coast Guard Station Season Loads September 1984 through March 1985 Figure 9 8950/379/49 Page 44 Electrical Demand (KW) Table 14. Summary of Load Characteristic, 1985 City Federal (Existing) Facilities Average Load 400 KW 191 KW Peak Load 725 KW 215 KW Base Load 125 KW 175 KW Load Factor 0.17 0.81 Combined Load 591 KW 900KW 325 KW 0.36 Figure 10 shows a typical daily load profile for the existing City load. It shows that the City load develops from a low level in the early part of the day to the peak level just before noon and then declines into the evening until the daily cycle begins again. St. Paul Daily Load Provile June 11, 1984 800 200 ~ 100 Midnight 6:00 Noon 6:00 oT Figure 10 ee aa en nen as Ae Midnight Electrical Demand (KW) Figure 11 shows the load-duration curve for St. Paul with and without the addition of the proposed transmission line. The figure shows that the existing load (without the transmission line) varies from a base of 125 KW to a peak of 725 KW but that these extremes occur rarely. Fifty percent of the time the load is greater than 425 KW without the transmission line, and if the transmission line is built, 50% of the time the load will exceed 625 KW. Once the transmission line is built, the load will exceed 500 KW, 80% of the time. Load—Duration Curve St. Paul Municipal Utility, 1984 h Transmission Line Without Transmission Lin Percent of Hours Figure 11 R98N/379/51 Pade 46 Actually a series of three tables, table 15, shows’ the Joad-duration curve in tabular form. It provides the numbers on which Figure 11 is based. Table 15a shows the cumulative frequency -- the proportion of the time the load exceeds any given value. For example, Table 15a shows that the load will exceed 300 KW, 90% of the time assuming no transmission line, but it will exceed 300 KW 100% of the time once the line is constructed. Table 15b displays similar information. Using the same example, the table shows that without the line, the load would be between 300 and 325 KW, 8.1% of the time, but that with the line, the load will never fall in that range. Finally, Table 15c shows the same information again, but in percent of peak load. That is, the load without the transmission line would exceed 55% of the peak load 61% of the time. The advantage of Table 15c is that as the City grows, the load-duration relationship will probably be approximately the same as it is today, but the generation levels will be higher. After significant growth, Tables 15a and 15b will no longer be accurate. The peak load will be greater than 725 KW (or 900 KW with the Coast Guard). Table 15c, however, is in a more "generic" form and should remain roughly accurate for a longer time. 8950/379/52 Page 47 Table 15a. ELECTRIC DEMAND (KW) 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 8950/379/53 CUMULATIVE FREQUENCY thout ac Line 100. 100. 100. 100. 100. 100. 99. 9% 99, 99. 99 99. 97. 90. 82. 73. 68. 61. 4% 4% 54 46 Load-Duration: 0% 0% 0% 0% 0% 0% 9% 7% 7% 0% 6% 4% 4% 0% 0% 1% Line 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% Cumulative Frequency of Electric Demand (With and Without the Proposed Transmission Line) CUMULATIVE FREQUENCY jithout it Page 48 ELECTRIC DEMAND (KW) 475 500 525 550 575 600 625 650 675 700 725 750 775 800 825 850 875 900 Line 39. 28, 20. 11. Ue ooo ooo0o°o ooorw oO ae 4% 2% 4% 4% 1% 1% -5% 4% 2% 1% 0% 0% 0% -0% 0% 0% -0% Line 87. 6% Ake 65. 60. 78 52. 5% -0% 29. 19. 46 38 13. 0% 8% -6% 6% ooo Orwn 1% 2% 3% 0% 7% 5% 2% 1% 2% 1% 0% Table 15b. Load-Duration: Frequency of Electric Demand (With and Without the Proposed Transmission Line) ELECTRIC *****FREQUENCY***** ELECTRIC week * FREQUENCY ***** DEMAND Without With DEMAND Without With (KW) Line Line (KW) Line Line 0 0.0% 0.0% 475 7.0% 8.2% 25 0.0% 0.0%" 500 11.2% 8.6% 50 0.0% 0.0% 525 7.7% 7.4% 7 0.0% 0.0% 550 9.1% 5.9% 100 0.0% 0.0% 575 4.3% 5. oe 125 0.0% 0.0% 600 4.0% 7.3% 150 0.1% 0.0% 625 1.6% 6.2% 175 0.1% 0.0% 650 iis 8.5% 200 0.1% 0.0% 675 0.3% 8.5% 225 0.0% 0.0% 700 0.1% 10.3% 250 0.8% 0.0% 725 0.1% 6.2% 275 1.4% 0.0% 750 0.0% 6.0% 300 7.1% 0.0% 775 0.0% 3.2% 325 8.1% 0.1% 800 0.0% 2.2% 350 9.4% 0.1% 825 0.0% 1.0% 375 5.0% 0% 850 0.0% 0.4% 400 6.8% 0.2% 875 0.0% C.1% 425 6.7% 1.3% 900 0.0% 0.1% 450 8.1% 3.0% 8950/379/54 Page 49 Table 15c. Load-Duration: Cumulative Frequency of Electric Demand (Percent of Peak Load) Without Transmission Line With Transmission Line Percent Cumulative Percent Cumulative of Peak Frequency of Peak Frequency 0% 100.0% 0% 100.0% 3% 100.0% 3% 100.0% 7% 100.0% 6% 100.0% 10% 100.0% 8% 100.0% 14% 100.0% 11% 100.0% 17% - 100.0% 14% 100.0% 21% 99.9% 17% 100.0% 24% 99.9% 19% 100.0% 28% 99.7% 22% 100.0% 31% 99.7% 25% 100.0% 34% 99.0% 28% 100.0% 38% 97.6% 31% 100.0% 41% 90.4% ; 33% 100.0% 45% 82.4% 36% 100.0% 48% 73.0% 39% 100.0% 52% 68.0% 42% 100.0% 55% 61.1% 44% 100.0% 59% 54.4% 47% 100.0% 66% 39.4% 50% 100.0% 69% 28.2% 53% 87.1% 72% 20.4% 56% 78.6% 76% 11.4% 58% 71.2% 79% 7.1% 61% 65.3% 83% Sale 64% 60.0% 86% 1.5% 67% 52.7% 90% 0.4% 69% 46.5% 93% 0.2% 72% 38.0% 97% 0.1% 75% 29.5% 100% 0.0% 78% 19.2% 81% 13.1% 83% 7.0% 86% 3.8% 89% 1.6% 92% 0.6% 94% 0.2% 97% 0.1% 100% 0.0% 8950/379/55 Page 50