HomeMy WebLinkAboutKotzebue Geothermal Project Final Rep 1981
KOTZEBUE
GEOTHERMAL
PROJECT
Finai Report
Summary of Project Tasks and Findings
PROPERTY OF:
Alaska Power Authority
334 W. 5th Ave. Anchorage, Alaska 99507
February 1981
Prepared For
The State of Alaska
Division of Energy & Power Development
338 Denali .
Anchorage, Alaska 99501
Energy Systems, Inc.
P.O. Box 6065
Anchorage, Alaska 99502
ALASKA POWER AUTHORITY
ESI - Alaska DEPD
BRU 08-71-7-500
CONTENTS
Page
Summary of Work on Project TaSkS ...ccceccccccccccccccccee L
Findings and Recommendations......ccccccccccccccccccccccee 5
Appendices (Under Separate Cover)
Appendix A: Geological Data, Kotzebue-Selawik Basin - Appendix B: Kotzebue Geothermal Project--Analysis of Currently Available Information and Re- port of Advisory Group Meeting Appendix C: Geologic Analysis of Geothermal Energy at Kotzebue Appendix D: Proposal to Assess the Feasibility of
District Heat at Kotzebue, submitted
to US Department of Housing and Urban Development
FINAL REPORT--KOTZEBUE PROJECT
Introduction
This report summarizes work done by Energy Systems Inc. on the Kotzebue Geothermal Project for the State of Alaska Department of Commerce and Economic Development, Division of Energy and Power Development. The work reported covered the period July 1, 1980 to Feb 1, 1981. The work was done in fulfillment of two contracts, BRU Kotzebue Geothermal, 08-71-7-500 and ATN 81-525, CC 08-1582. The first section of this report lists the tasks contracted for item by item and summarizes the work done. Reference is made to four items that were completed as part of the contract tasks: geological and geophysical data for the Kotzebue Selawik Basin, "Kotzebue Geothermal Project:Currently Available Information and Report of the Advisory Group Meeting", "Geologic Analysis of Geothermal Energy at Kotzebue", and a Proposal to the Department of Housing and Urban Development on behalf of the City of Kotzebue to study the district heat prospects at Kotzebue, These four items are bound separately and are referred to as appendices A,B,C and D respectively. Reference should be made to them for a more detailed description of the results of the tasks performed, and described below.
Task 1
An energy needs analysis for the City of Kotzebue including electrical power and fuel demands to the year 2000. This task will take existing projections from a recent needs analysis by the Alaska Power Authority and put it in a form for presenta- tion at the geothermal meeting in Task 3. Potential local use geothermal applications will be projected under the assumption that if the geothermal resources were developed geothermal energy availability would stimulate commercial development to some degree.
Three independent estimates of energy use at Kotzebue were located, analyzed, and compared. No significant commercial uses of geothermal energy were identified, either in the literature or in discussion. The most beneficial application was determined to be space heat. The possibility of space heat was further examined by conceptually designing a district heat system, with a geothermal heat source, and estimating the cost of heat obtained from it. The estimated cost of the geothermal heat was too high, but the district heat portion of the system looked moderately promising. A summary of this work can be found on pp. 34 to 42 of Appendix B.
Task 2
Research currently available geological and geophysical information for the Kotzebue-Selawik Basin. This infor- mation shall be put in a form for oral, visual and written presentations on the geological possibility of developing geothermal resources.
Mr. Arlen Ehm, consulting geologist, was hired to carry out this task. The raw information is included in Appendix A, and a summary of it with some analysis is given on pp. 24-28 of Appendix B. A bibiliography is on pp. 45-46. A more detailed, and up-to-date, analysis of this data is given in Appendix C. Appendix A was supplied to the Department of Commerce and Economic Development, Division of Energy and Power Development, in only one copy because of its voluminous nature.
Task 3
Organize and host an interdisciplinary meeting of geothermal experts to develop a work plan for the development of the Kotzebue project and the expenditure of the State appropriation. This meeting will be held at or around the Geothermal Resource Council Annual Meeting in mid-September 1980 unless otherwise agreed upon.
A list of geothermal experts and people involved in the Kotzebue geothermal project was compiled by Energy Systems Inc. with the help of the Division of Energy and Power Development. The people contacted included representatives of the City of Kotzebue, the NANA Corporation, the University of Alaska Geophysical Institute, the State Division of Geological and Geophysical Surveys, the Alaska State Legislature, the Alaska Power Authority, Universities with relevant geothermal programs, National Laboratories with Geothermal Programs, and the US Geological Survey. These people were contacted by phone and it was determined that a meeting on September 12, 1980, immediately following the meeting of the Geothermal Resources Council would be feasible. In many cases people on the list could not attend, and it was necessary to find alternates. In the end a suitable advisory group was assembled, with Dr. William Ogle of Energy Systems Inc. as chairman, It also proved advantageous to hold a preliminary meeting in Anchorage to allow more local experts to attend. Arrangements were made for the meeting in Salt Lake City. Informatio that had been uncovered in Tasks 1 and 2 and at the meeting in Anchorage was mailed to the advisory group for their review Prior to the meeting. It was also organized into viewgraphs suitable for presentation to the group. The members of the advisory group generously donated their time at no cost to the State of Alaska. Their advice and aid was quite helpful. The final composition of the advisory group is on p.10 of Appendix B. Notes of this meeting are on pp.11-33 . Of Appendix B.
The basic conclusion from the meeting was that the geothermal prospec did not look as promising as first thought, but also that the possiblility - of direct use or use through heat pumps could not be ruled out. The district heat portion of the project looked moderately promising. Specific recommendations were to get additional (proprietary) geological data from NANA and Chevron, and to apply to the Department of Housing are Urban Development for funds to look at district heat in greater etail.
Task 4
A written final report detailing the task findings, the preliminary ideas broached at the meeting in Task 3 and possible cost and impacts of the different elements of the work plan will be required. The state geothermal development plan Kotzebue section is the preliminary plan to be critiqued at this meeting.
Appendix B is the written report. Pages 4-8 summarize the ideas presented at the meeting. Page 9 gives some conclusions and recommendations for future work. On pp. 28 and 29 is a critique, by Mr. John Reeder, of the Kotzebue section of the State's geothermal implementation plan. Pages 11-44 contain a lot of information relevant to developing a plan for further geothermal work at Kotzebue, including drilling costs and estimates of the cost of a district heat system. After the advisory group meeting, and acting on conclusions and recommendations coming from that meeting, the Division of Energy and Power Development extended its contract with Energy Systems Inc. to perform tasks 5 to 10, outlined below.
Task 5
Request from Northwest Alaska Native Association information pertinent to determining depths at Kotzebue equivalent to depths observed in the Nimiuk Point and Cape Espenberg wells, and to the salinity, specific gravity, and dissolved solids in the water from these wells.
Arlen Ehm wrote a letter to the NANA corporation requesting the required information and detailing the need for that information, NANA forwarded the request to the Chevron Resources Company, which generously allowed Mr. Ehm to view the requested material in San Francisco. The formation water chemistry information is shown in Fig.17 of Appendix C and the equivalent depths to basement at Kotzebue is Fig.19 of Appendix C. This information is crucial to determining the feasibility of geothermal energy at Kotzebue.
Task 6
Obtain further information on what data and information could be obtained by electrical geophysical methods at Kotzebue. Design same and cost out.
The results of Task 5 were such that task 6 was no longer relevant. The seismic depth to basement obtained in Task 6 is far more reliable than what could be obtained by any electrical method, and the 2000 ft. depth to basement obviates the need for the informa- tion on salinity. Thus it was decided to determine the cost of drilling a 2000 ft. well at Kotzebue. Battelle Pacific Northwest Laboratories was drilling similar wells at Bethel. We asked their contractor and Battelle themselves
to estimate the cost of a 2000 ft well at Kotzebue. Both estimated that the cost would be about $350,000, including mobilization and demobilization. However, the contractor contacted would only do the job on a time and materials basis, and he has never drilled that deep with the rig he anticipated using on the job. He did not think the anticipated depth would be a problem, however, as long as a slim-hole is used.
Task 7
Integrate information obtained in tasks 5 and 6 with previously obtained gravity surveys, well logs, surface geology maps, and other pertinent information to formulate the best estimate presently obtainable of subsurface temperature, permeability, pressure, and porosity at Kotzebue.
The information requested in the above task is given in the report that is Task 8. The geological information gives a fairly complete Picture of the subsurface geology at Kotzebue relevant to determining the feasiblity of using geothermal energy there. Of course, no amount of information could ever be sufficient for answering every conceivable question. The depth to impermeable basement at Kotzebue is about 2000 ft. The probability of finding sufficiently permeable rocks below 2000 ft. is very low. The temperature at 2000 ft. depth is predicted to be low (105F to 135F). Above the basement, the rocks would have permeable zones that would produce adequate volumes of water. Of course, this water would be at a temperature below 135F. The downhole pressures would not be sufficient to bring the water to the surface. In general, the only feasible way to determine pumping requirements is to drill a well and test it. The water would have a lot of dissolved solids. Drilling costs would be low in comparison to the costs usually quoted for petroleum wells in the area because there is little point in drilling below 2000 ft, and the formations are easy to drill, both because of the sedimentary rocks and because no extraordinary downhole pressures are anticipated. A truck mounted rig could be used.
Task 8
Write a report on the geology of the Kotzebue Selawik basin as it applies to the utilization of geothermal energy, including figures that summarize the surface geology (rocks and faults), regional geology, temperature profiles from the Cape Espenberg and Nimiuk Point wells, lithologic sections, electric logs, etc.
Mr. Arlen Ehm compiled the requested information in the report titled "Geologic Analysis of Geothermal Energy at Kotzebue", which is Appendix C to this document.
Task 9
Answer H.U.D. solicitation for district heating for the village of Kotzebue. The work plan for this solicitation will be an economic scoping study considering wind, coal, wood, geothermal, and waste heat separately and in conjuction with each other for the most economical district heating system for the village.
An outline of the proposal was constructed by Energy Systems Inc. John Beebee of Energy Systems and Don Markle of the Division of Energy and Power Development traveled to Kotzebue and discussed the draft of the proposal with as many ._people who would partici- pate in it as possible. In Particular, Gene Moore, the City Manager of Kotzebue, was most helpful in setting up the District Heat Working Group, suggesting changes in the management plan of the proposal, and getting background information and letters of support. The proposal was sent to HUD on January 16, 1981. Appendix D is a partial copy of the proposal. Complete copies were sent to HUD, the City Manager of Kotzebue, and the Division of Energy and Power Development. Missing from the copy given in Appendix D is "Appendix B" of the proposal, which is essentially the same as Appendix B attached to this report.
Task 10
Work in conjunction with the City of Kotzebue and the Mauneluk Native Association to form a District Heating System Association for Kotzebue.
After some discussion, it was decided that the City Manager's Suggestion of using the City Council as the core of the District Heat Working Group called for in the HUD Proposal was most satisfactory. The composition
and duties of this group can be found in Appendix D of this report, Pp.3. Since the Department of Commerce and Economic Development contemplated participating financially in the project, representa- tives of the Alaska Power Authority and the Division of Energy and Power Development were added. This should be a useful advisory group in beneficially expending the remainder of the geothermal project appropriation.
Findings and Recommendations
The general conclusion of the geothermal advisory group meeting was that geothermal energy was not likely to be an economical source of heat for Kotzebue, but that district heat might be feasible. The specific recommendations were that further data be sought from Chevron and NANA and that HUD should be approached for funds for a more detailed study of district heat. The Division of Energy and Power Development followed these recommendations. The geological information obtained from Chevron clearly reinforced the conclusion that geothermal energy would not be feasible at Kotzebue. The conclusion is based on several interrelated facts that are described in greater detail in Appendix Cc. (1) The depth to impermeable basement at Kotzebue is only about 2000 ft. (2) The temperature at 2000 ft. will be too low (105F-135F) for direct use. (3) The formation pressures are too low to push the water to the surface
(4) Pumping will be required to get adequate volumes of water to the surface, and this pumping will be expensive. (5) The water is so saline that it must be passed through a heat exchanger and reinjected. (6) Higher temperature water cannot be economically produced from the Nimiuk point well and transported to Kotzebue, both because of the pumping cost and because of the pipeline cost. (7) Because of the high cost of diesel generated electricity at Kotzebue heat pumps would not be advantageous, either if used individually or in a central installation. (8) The hot dry rock technique of energy extraction would require drilling wells that would be too expensive to deliver energy at a cost competitive with the anticipated cost of oil. Of course, the geological parameters are predictions, based on data and assumptions that are explained in detail in Appendix C. The best method for verifying these predictions of temperature, permeability, porosity, and formation pressure is to drill a well at Kotzebue, and test it. Such a well, to a depth of 2000 ft, would probably not cost less than $350,000. The $350,000 cost is based on using a rig that has not drilled to 2000 ft, must drill a 4 in. or less diameter hole, and it assumes that there are no hole problems. To be certain of getting the results desired, it would be necessary to anticipate expenses that would be much greater than $350,000. Other than verifying the geological predictions, such a hole could be used to locate aquifers suitable for thermal energy storage, to gather subsurface water quality data, and would be of interest simply as a source of subsurface information at Kotzebue. The recommendation that district heat be examined more closely is based on a feasiblity study done in preparation for the advisory group meeting. This study, which used general costs for components of district heat systems and experience by the Public Health Service in constructing the present water and sewer system, predicted that the cost of delivering 1.16 x 10 Btu per year was $1.1 million per year, or $9.48 per million btu. (This cost includes an allowance for retrofitting house heating systems, but does not include the cost of heating the water.) This estimate was based on using low temperature geo- thermal water, which resulted in mains that were larger than necessary for higher temperature water. Also, due to the danger of subsidence around the geothermal wells it was necessary to transport the water from over a mile out of town, which added considerably to the cost. The present cost of fuel for oil heat is about $14.80 per million Btu. Since Kotzebue presents some rather difficult engineering problems for a district heat system, both in soil conditions and the need for extreme system reliability, it is felt that pursuing the district heat option will require a detailed feasibility study, as outlined in the proposal, Appendix D. The total cost of this study was estimated to be $185,500, of which the City of Kotzebue would provide $10,500, the State of Alaska would provide $120,000, and HUD would supply $55,000. The cost of the contract for a detailed study of the district heat system is $135,000. The remaining costs were for administration and to fulfill HUD goals. In fulfilling this contract, Energy Systems Inc and the Division of Energy and Power Development had considerable contact with
the City of Kotzebue. In particular, the City Council agreed to serve as an advisory group on the proposed district heat study. This group could be asked to help direct how the remaining funds in the Kotzebue geothermal appropriation should be spent. Further study of the district heat option, as outlined in appendix D, pp. 1-18, would be a useful application for the funds. The proposed district heat study, and the geothermal study reported h appendices B and C, could be considered parts of an integrated space heat study for Kotzebue. Other possible sources of heat that might be examined as part of such an integrated study are the direct use of coal in home furnaces and distributing low btu gas from coal to the city.
Anc
Alaska Powe
PROPERTy OF:
334 W. Sin Ave, horage, Alaska 99501
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