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HomeMy WebLinkAboutThorn Bay Waste Heat 1992The City of Thorne Bay has requested assistance from the Alaska Power Authority in evaluating power supply alternatives for Thorne Hay. Also, the Power Authority has been requested to assess the value of waste heat delivered to the Lousiana Pacific lumber campany’s heavy equipment shap. The paper adresses some of the issues concerning the existing generation and distribution facilities. ‘ The City of Thorne Bay has recently installed two Cummins diesel generator sets, @ach rated at 43a kw cantinous output. These units are slightly oversized for the current load. Ih appears that high tine losses and/or unmetered loads increases the cost of power in Thorne Bay and it seems prudent to install sufficient instrumentation to assess the severity of this problem. Waste heat ais currently delivered to &@ non-paying customer at same expense to the City af Thorne Bay. In 1984 two new 45@ kw Cummins generator sets were installed in the power plant and these units are now used to provide most of the power for the system. The units are equipped with separate remote radiators (Youngs vertical core type) with thermostatically controlled fans. The controls allow for one speed only. Shell and tube heat exchangers are utilized to transfer heat to a waste heat storage tank, fram which hot water is piped to a nearby heavy equipment shop. Floor coils keep the floor heated in this shop. To allow for the transfer of heat two pumps are in continous service in the power plant. The power plant dees neat have a station meter installed nor is there any way that the fuel cansumption per engine can be determined. Total pewer production is estimated using the existing meters at the cansumer ends in conjunctian with estimates for power consumption for street Lightings fireboxes etc. Accarding ta records, the power plant only produces 9-18 kilowatthours per gallon of fuel burned. Sccarding ta the engine manufacturer, this type generator should yield approximately 12 kilewatthours per gallon of fuel burned, @ven at the relatively light loads encountered. There seems to be a discrepancy between the production figures derived fram consumer metering cambined with calculations for street Lighting and fireboaxes, and the figures read off the station panel. The panel readings are cansistently higher. If sizeable line losses and/or unmetered loads exist, this would explain why the panel guages show loads that are significantly higher than they should be according to production figures. This would alse explain the relatively high fuel consumption experienced with the new generators. Power ig generated at 48% volts and transferred ta the City Substation at 2308 volts. Here it is again reduced to 48% volts before it ais distributed around the city. Fole mounted transformes reduce the voltage to 248/128 velts. Street lights and fire boxes are not metered and it is net knewn whether any additional unmetered loads exist. The distribution system is generally in need of some repair and upgrade in order to meet codes. The waste heat recapture system is a 3-looap type system with a mixing/storage tank used for expansion campensation and system stabilization. The disadvantage of this kind of system is the relatively low temperature of the heat delivered and the relatively high power consumption and maintenance cast. In Thorne Bay the relatively low temperature is not a problem as the heat is used in a floor heating system where a moderate temperature is preferred. The high power consumption and the relatively expensive maintenance is however still a problem. Vi. Waste Heat Economics The combined power consumption of the waste heat pumps alone is about 3 kw. Without the waste heat recapture system installed the average power consumption for the remote radiators would likely be approximately 2 kw. If it is assumed that the use of waste heath reduces the radiator power consumption by 47%, the average power consumption for the radiators becomes 8.467 kw. Thus the total consumption for cooling and waste heat recapture purposes becames 3.47kw. This is to be compared ta the approximately 2 kw that would be consumed if no waste heat recapture system was instalied. The additional power consumption on ano annual baiss for waste heat recapture is then 14,629 kwh. Assuming an avoided cost of 8.206 %/kwh the actual cost ta the ubdlity for praviding this amount of power is # 2,926 per year. Additional casts incurred by the utility for providing waste heat ares Installation of heat exchangers, pumps, controls, piping etc. Floagr space for waste heat recovery equipment. Maintenance of pumps, controls and heat exchangers. Reduced costs can be expected fram: Reduced maintenance on fan motors due to reduced running time. It is rather difficult to determine the benefits fram waste heat as experienced by the waste heat user. if cheap (free) heat was not available toa the user, ait is likely that the building would be upgraded in order to reduce infiltration and heat loss through conduction. Tf mot, the heating casts would be very high. Preliminary calculations shaw that on a 48 degree day, the infiltration losses alone for the heavy equipment shop exceed the heating capacity of the power plant if it assumed that the heavy equipment shop is kept at 6% degrees. It is here. assumed that two air changes are experienced per hourt the actual number may very well be higher due to broken windaws, leaky doors, and doors left open curing movement of equipment. The tetal heat output from the power plant based on metered and calculated loads is currentiy 36,234 gallons fuel equivalent. The heat available during the 8 coldest month of the year is 22,218 galions of fuel equivalent. Actual amounts of heat is likely toa be somewhat higher as the actual loads experienced by the generators (Cand thus the heat output) is samewhat higher due ta line losses and unmetered loads. In other words, it seems to be a conservative estimate that the Heavy Equipment Shop recieves heat equivalent to 22,218 gallons of fuel per year. This assumes that no heat at all is used during the 4 summer month. It would seem reasonable for the Utility to charge the heat user at least 3¢-75% of the value of the fuel displaced. Ef. "fer instance 68% are charged, the benefits to the consumer will be 48% of the fuel savings plus expenses for installation, operation and maintenance of a heating system. The benefits to the Utility will be 68% of the fuel savings minus the expenses incurred for installation, aperation and maintenance of the waste heat recapture system. if the Utility does not charge an amount equal hea or higher than the actual costs incurred from the installation, operation and maintenance of the system, it does net make economical sense ta continue the oaperatian of the system. The following recommendations are based on rather preliminary studies and the economical feasibility of each item should be investigated to more detail before implementation. ay Upgrade electrical distribution system to meet codes and ta minimize losses. Identify all unmetered loads and install meters. a Install station meters and fuel meters for continous performance as monitoring in the power plant. 4. Install two speed motors on the radiator fans. Se Negotiate and implement waste heat sales agreement with the heat consumer. 004 VVESL OUI Avetiue, 2nd Floor Anchorage, Alaska 99501 (907) 276-0001 (907) 277-7641 To Cin oe Taneue OA P.09. Box Wg Al Vase Bay, KK FR GENTLEMEN: WE ARE SENDING YOU i Attached (© Under separate cover via__________»_ the following items: O Shop drawings OD Prints a Pla Oo ee O Specifications O Copy of letter U Change order Nee pare COPIES DESCRIPTION ZITA tina Gav re 4 acne ~ THESE ARE TRANSMITTED as checked below: O For approval O Approved as submitted O Resubmit__________ copies for approval O For your use O Approved as noted O Submit_________ copies for distribution Las requested O Returned for corrections O Return_________ corrected prints O For review and comment i) 0 FOR BIDS DUE —_________19__]] PRINTS RETURNED AFTER LOAN TO US REMARKS Chastona ye ( FU Fill a z Lot be EH Jb Pe han NSD DWE LZR = = ellaklaf- If enclosures are not as noted, kindly notify us at once. FROM: Stassel, Steven TO: Nelson, Emily DATE: 08/05/92 TIME: 12:39 PM cc: Denig-Chakroff, David Gray, Brian Stassel, Steven SUBJECT: TICKLERS PRIORITY: ATTACHMENTS: Regarding Tanana, I talked with DDC today and I will respond by phone today to Mayor Platten explaining that I will not be available to come to Tanana, But that I will be happy to speak with his people on a conference call. Regarding Thorne Bay, I will call them today and see what they can tell me. ,There is not much info in our files. + ‘Do you know if GDS has a file on Thorne Bay? REPLY FROM: Stassel, Steven FROM: Nelson, Emily TO: Stassel, Steven DATE: 08/05/92 TIME: 10:00 AM _CC: Nelson, Emily SUBJECT: TICKLERS PRIORITY: ATTACHMENTS: STEVE, WHAT IS THE STATUS OF RESPONSES TO THE FOLLOWING LETTERS? CITY OF TANANA - RE: YOUR ATTENDENCE TO THEIR AUGUST 20TH MEETING REGARDING THEIR WASTE HEAT SYSTEM CITY OF THORNE BAY - RE: WASTE HEAT UTILIZATION (THERE WERE 3 LETTERS REGARDING THORNE BAY AND THEIR WASTE HEAT UTILIZATION PROBLEMS /MISUNDERSTANDINGS BUT NONE OF THEM WERE ADDRESSED DIRECTLY TO AEA ALTHOUGH WE WERE DISCUSSED & CC'D. PROBABLY A PHONE CALL WOULD TAKE CARE OF THIS - LET ME KNOW IF THIS HAS BEEN DONE.) THANKS, EMILY (X252) FROM: Denig-Chakroff, Da | TO: Gray, Brian DATE: 07-24-92 Stassel, Steven TIME: 16:25 cc: Rogers, Richard SUBJECT: Thorne Bay Waste Heat PRIORITY: ATTACHMENTS: Bob Winestein, Superintendent of Southeast Island School District, called regarding a waste heat project at Thorne Bay. Someone at the City told Mr. Winestein that Gary Smith told them a school board member told him the school district would not be interested in buying heat from the project. He says that isn't necessarily true. If this project is viable, he would also like some information regarding waste heat systems involving other schools in rural Alaska. He wants something the layman can understand to present to his board. I am not familiar with this project; please brief me on it. Perhaps you could call Mr. Winestein and give him the status as well and, if appropriate, send him the waste heat information he wants. Neves —& VL Shasse] CITY OF THORNE BAY P. O. BOX 19110 THORNE BAY, ALASKA 99919 (907) 828-3380 FAX (907) 828-3374 ECEIVED yuL 2° Le July 16, 1992 piaska Energy Authority Mr. Robert Weinstein Southeast Island School District 1621 Tongass Avenue, Suite 301 P. O. Box 8340 Ketchikan, AK 99901 Re: Waste Heat Utilization Dear Bob: This is in reply to your letter of July 10, 1992. Gary D. Smith, Manager/Rural Projects, was the Alaska Energy Authority representative who related to me his understanding of the school board president’s position regarding the subject. I appreciate the district’s willingness to discuss this apparent misunderstanding with the Alaska Energy Authority. Having a potention user identified will only assist with the project. , Sincerely, remy bch BY C27 Ginny L. ee a City Administrator GUT: gt va Gary D. Smith, Alaska Energy Authority (hte SOUTHEAST ISLAND 1621 TONGASS AVENUE Chyuspnd SCHOOL RECEIVED POST OFFICE BOX 8340 DISTRICT JUL 15 1992 (907) 276-9688 OF 225-9659 ALASKA ENERGY AUTHORITY, Robert Weinstein SUPERINTENDENT July 10, 1992 Ginny Tierney, City Administrator City of Thorne Bay P.O. Box 19110 Thorne Bay, Alaska 99919 Dear Ginny: This is to respond to your letter of July 2, 1992 regarding waste heat utilization from a new municipal power plant. As you know from previous conversations, I have expressed interest in the concept to determine whether this is economically feasible for the School District. I will review the subject with the School Board at its meeting next week, and I will respond further to you at that time. On another subject that you referenced in your letter, the School Board President does not have any recollection of discussing this subject with a representative of the Alaska Energy Authority. I would appreciate it if you could send me the name of the AEA staff member involved so that I could contact him or her in an effort to clarify this. Sincerely, ¢ Ut iLanalece! Robert Weinstein Superintendent RW:eb cc: Board Members “VAlaska Energy Authority = CITY OF THORNE BAY Se ET S/5 THORNE BAY ALASKA 99919 i LU, (907) 828-3380 JUL = 6 1992— FAX (907) 828-3374 MOULD ow i8aRC July 2, 1992 S2hen Sieur Mr. Bob Weinstein Superintendent Southeast Island School District P. O. Box 8340 Ketchikan, AK 99901 Re: New ici wer Plant - Wast e Uti Dear Mr. Weinstein: The City of Thorne Bay requests you to advise whether or not Southeast Island School District has any interest in purchasing waste heat from the city as an alternative means to fossil fuel heating of the new Thorne Bay school facilities. The city desires to identify sincere potential users for the waste heat resource. As you are aware, the city is working with the Alaska Energy Authority and plans to construct a new municipal electric power plant. The plant will be designed so that waste heat created by the operation of diesel powered generators may be captured and used for heating. You have previously indicated your interest in exploring utilization of waste heat created by the city’s power plant for heating the SISD school buildings located in Thorne Bay. It is understood SISD would not purchase waste heat unless such heating method proved to be more cost effective for the district. I have been informed by the Alaska Energy Authority that the SISD school board chair is not interested in purchasing waste heat from the city period. I do not know whether the chair is speaking for the board or as ‘an individual member. The current preferred alternative site selected for the new plant is located immediately adjacent to the new Thorne Bay School. fThis site is being considered as the preferred alternative because of its close proximity to the community’s most likely user of waste heat - the school. Should SISD not be interested in purchasing waste heat from the city, the city and Alaska Energy Authority will identify other potential users and site the plant accordingly. We look forward to hearing from you in this tegard. Should you have any questions or require any further information, please do not hesitate to contact me. shnnap hang Ginny L. a a vi city Administrator GLT:gt ALASKA POWER AUTHORITY 334 West Sth Avenue, 2nd Floor Anchorage, Alaska 99501 (307) 276-0001 Telephone Conversation Record (907) 277-7641 f- yy kif - Date LLC £7. ime fOgo i am []PM Project No. o t pean j “TN 7\ B To From Z Zadar Recorded By | ne Ca Company Phone No. Address Project Name SUBJECT: / Yay KER pag Ii ftiit tA One LnQz he tne _2/ dentine Yas LP Lys Ghing— & WW Late LeU yl 37 Vix ann i hoot —_ oer LAL g d 2 ogt- t. a hl