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HomeMy WebLinkAboutGeothermal Energy in the Aleutians- An Untapped Resource 1981Introduction Energy is a critical concern to the residents of Aku- tan, Alaska. Existing energy supplies do not meet the present needs of the community and fall far short of projected future industrial requirements. The key to meeting these needs is to develop a reliable, inexpensive energy system. Geothermal resources could supply all of Akutan’s projected energy requirements, providing energy self- sufficiency and a base for growth in this community. Akutan Akutan Island is located approximately 770 miles southwest of Anchorage in the Fox Island group of the Aleutian chain. The island is mountainous and rugged, with shorelines dominated by steep cliffs and rocky headlands. Located on the east coast, Akutan Village sits at the base of a steep ridge bordering the north shore of Akutan Harbor. The village was established in 1878 as a fur trading port and is the only remaining Aleut village with a traditional chief and village council. Under provisions of the Alaska Native Claims Set- tlement Act, the Akutan Village corporation was formed in 1971. Historically, the village economy has varied con- siderably. A Norwegian shore-based whaling sta- tion was established in 1907 and operated until World War II. Employment was scarce before the development of the commercial fishing and fish processing fleets. Now, fishing dominates the economy. Up to 14 processors anchor in the har- bor each season, and the village is contemplating building a dock and cold storage at the head of the bay. Akutan Harbor is one of the few good pro- tected ports in the Aleutians and is expected to grow as the bottom fishing industry expands and outer continental shelf oil and gas leases are de- veloped. The identified 100 to 300 kilowatts of hydrogenera- tion capability near Akutan will meet only a small percentage of this demand at a relatively high price. The rapidly escalating price of diesel makes continued reliance on fossil fuel unattractive. Therefore, exploration of geothermal energy de- velopment on Akutan is both timely and pertinent. The current population of the village is estimated at 70, down from 101 in 1970, reflecting a severe housing shortage and uncertain employment. However, with the growth of the fishing industry, the population has been predicted to expand to 3000. This means the development of a new village and a radical change in life style for Akutan resi- dents. This growth signifies a major expansion in energy demand. A 36” water wheel with a 20 kilowatt generator was installed above the village in 1924 and currently supplies D.C. power at an annual cost of $12 per residence. The system works well, but is hampered by low stream flows. Diesel fuel is used for heating and to power several individual generators. Present electrical demand in Akutan is 110 kilowatts. Projected development and popula- tion growth would result in a future demand of 9000 kilowatts — over 80 times the current de- mand. CONVENTIONAL POWER PRODUCTION 350° and UP ALUMINA PROCESSING ORYING FARM PRODUCTS EXTRACTION OF SALTS REFRIGERATION (mod.temp CONCRETE BLOCK CURING CRAB PROCESSING ORYING FISH SPACE HEATING REFRIGERATION (low temp, GREENHOUSES BALNEOLOGICAL BATHS SOIL _WARMING FERMENTATION, DE-ICING FISH FARMING TYPICAL TEMPERATURES FOR GEOTHERMAL RESOURCE APPLICATIONS PRODUCTION WELLS Geothermal — The Potential Geothermal energy is derived from the earth’s in- terior heat. In areas where this heat extends close to the surface, there is potential for economical energy recovery. Geothermal resources are par- ticularly abundant in the Pacific “ring of fire,” a region of high volcanic and seismic activity result- ing from shifting of the earth’s plates. The Aleutian Islands are part of this “ring of fire.” There are three primary types of geothermal re- sources: hydrothermal, hot dry rock, and geopres- sured zones. Nearly all of the currently developed geothermal resources are hydrothermal systems, where naturally occurring ground water is heated at depth. These systems can be either vapor- dominated (steam) or hot water dominated, de- pending on temperature and pressure. The essential ingredients for a hydrothermal sys- tem are a heat source, a sufficient supply of ground water, and a mechanism for transporting the heated ground water to near the surface (por- ous rock or natural fractures). The other two types of geothermal resources are hot dry rock, which requires injecting water as a heat transfer medium, and geopressured zones, where water is trapped with natural gas under thousands of feet of sedi- ments. The use of a geothermal resource depends on the nature of the resource (temperature, quality, quan- tity) and the energy demand around it. Conven- tional electricity generation usually requires re- source temperatures of about 350°F, although re- search facilities use temperatures as low as 290°F. Lower temperature resources can be utilized di- rectly in such applications as space heating, aquaculture and process heating. TURBINE-GENERATOR COOLING TOWER if CIRCULATING WATER PUMP BLOWDOWN PUMP. GEOTHERMAL FLUID INJECTION —_ workin Fivio WELLS coo ino water BINARY GEOTHERMAL POWER SYSTEM Geothermal Resources on Akutan Akutan Volcano has a long history of activity, with more than 23 eruptions since 1700, the most recent being in 1978. This activity indicates the presence of a shallow heat source on the island, a heat source forming the basis of the geothermal re- sources. Three hot springs ranging in temperature from 100°F to 150°F have been identified at the head of Hot Springs Bay, five miles from the village. Preliminary evaluations estimate a subsurface temperature of 330°F. Also, villagers report a hot spring near the site of the old whaling station in Akutan Harbor. Potential applications of these resources include power production, process heat, space heating, and aquaculture. The economics of these applica- tions will depend on the resource temperature and availability. Continued exploration and exploratory drilling will help define the extent to which these resources can be used. The State Geologic and Geophysical Surveys have initiated preliminary geologic reconnaissance of the resource. Major tax incentives for geothermal developments, including intangible drilling costs, depletion allowances and investment tax credits, have been enacted in recent federal energy legislation. In ad- dition, the State of Alaska is actively involved in supporting power developments. In 1981, the State put $500 million into energy projects on a grant basis. The State provides power development loans at low interest rates. With the expanding energy market on Akutan and the opportunity for creative financing, geothermal energy dewelop- ment would be a relatively low-risk venture If the geothermal resource development does prove feasible, Akutan will be assured of a stable, economically attractive and environmentally safe energy future. AKU 007 Alaska Power Authority LIBRARY COPY Geothermal Energy in the ALEUTIANS An Untapped Resource For more information about Akutan’s geothermal resources, contact: AKUTAN ISLAND Don Markle or Duane Bessette Alaska Department of Commerce & Economic Development Division of Energy & Power Development 338 Denali MORRISON Anchorage, AK 99501 KNUDSEN State of Alaska (907) 276-0508 Department of Commerce & Economic Development Division of Energy & Power Development Photos by Sue Spencer Funded by the U.S. Dept. of Energy 1981 UNA Alaska Energy Authority 042 LIBRARY COPY Final Report Geothermal Drilling Studies near Unalaska, Alaska Seen Submitted to State of Alaska Divisioin of Energy and Power Development November 20, 1980 Dames & Moore a ee Final Report Geothermal Drilling Studies near Unalaska, Alaska nites, Submitted to State of Alaska Divisioin of Energy and Power Development November 20, 1980 Dames & Moore 800 Cordova Street, Suite 101, Anchorage, Alaska 99701 ae Mca DAMES & MOORE no CONSULTANTS IN THE ENVIRONMENTAL AND APPLIED EARTH SCIENCES Ol, BOO CORDOVA + ANCHORAGE, ALASKA S950! + TELEPHONE (907) 279-0673 DAMEMORE TELEX: (O90) 25227 November 20, 1980 Mr. Don Markle, Energy Specialist Division of Energy and Power Development 338 Denali Street, 7th Floor Anchorage, AK 99501 Dear Don, We are pleased to submit our report of the drilling activities in the Summer Bay area near the village of Unalaska. As you are aware, two artesian sources of warm water were found during these activities, supporting your and State geologist John Redder's confi- dence in the geothermal potential for this area. We hope the results of this investigation and the quality of the report fulfill your requirements. Please contact me if you have any questions or comments. Sincerely, DAMES & MOORE re Douglas F. Jones Project Manager DF 3/cmb Enclosures TABLE OF CONTENTS Introduction... 2 2 3 2 6 6. 6 «6 6 6 6 es we 4 1 Results --.. 3... 6-0-3 0 0» 8 0 we we ew ee ee ee Conclusion... .2:5- 2-3) 4-6 6 6 se 0 ee ee ee ee es Appendix LIST OF PLATES Follows Page i. Regional Location Map of Geothermal Drilling Site Near Summer Bay ........l1 2. Site Location for S.Bis$l* . 2. . . s 2 ee oe 2 3. Bite Locetion For 6.8108 . « 2 6 ee ew wet BJ INTRODUCTION Dames & Moore supervised a drilling program adjacent to Summer Bay on Unalaska Island to determine the existence of a warm water aquifer system (see Plate 1). This study as pro- posed consisted of drilling two holes to a depth of 100 feet, casing the holes with plastic (PVC) pipe, filling the pipe with 30 wt. or heavier oil, and then capping these holes. Thermistors were to be installed at a later date to determine the extent of any warm water aquifer system encountered. The two drill site locations were determined by a State geologist familiar with the area (Dr. John Redder). The first drill site was on a narrow beach adjacent to Summer Bay: where heavily iron-stained sediments existed. The second drill site was to be located adjacent to an existing hot spring area approximately 400 yards from the edge of Summer Bay. RESULTS The first boring was drilled on the edge of Summer Bay in an area of heavily iron-stained surficial sediments. A stan- dard wash boring technique was used that permitted a con- tinuous log of materials as they were encountered down the test hole. These logs are contained in an appendix at the end of this report. Test hole number 1 (designated S.B.#1) passed through medium to coarse black sands and some larger cobbles down to a depth of 34 feet. A very small amount of cold water flowed out of the casing at this depth. A sharp contrast in sedimen- tary characteristics was noted at this depth as well; sedi- ments changed from a medium to coarse black sand to a very fine chalky clay containing several small shell fragments. A gradual increase of black sandy material was noted in sedi- ments below 37 feet. At approximately 43 feet, a significant ze 9 Needle Roc! 11tSM NS a ‘a. pth yagi 122 . 13 R2 FIR &sec BELL DUTCH 7, HARBO (righted) , efa2es SON 2 Be a Se Fk DRILLING ~ eS AREA CUnalaska Lake oo —™ : REGIONAL LOCATION MAP OF GEOTHERMAL DRILLING SITE NEAR SUMMER BAY Nautical Miles 7 1 Yards 2000 PLATE 1 volume of warm water flowed from the test hole. This was unexpected and complicated the drilling procedure. The hole was cased to a depth of 45 feet, and artesian flow from the test hole ceased. Drilling continued and bedrock was encoun- tered at a depth of 54 feet. Water flowed from the hole around the outside of the casing and also forced some sandy material between the casing and the drill stem, causing the casing to rotate with the drill stem. In taking corrective measures to alleviate these problems, and in changing bits to drill through the bedrock, 20 feet of drill stem and 5 feet of casing were irretrievably lost down the hole. The well became "bridged-off" and water ceased to flow from the well. The drilling rig was relocated about 10 feet from the original site. The drill log of material encountered in this new hole, designated S.B.#1', was nearly identical to S.B.#1l. Large volumes of warm water again were encountered at 43 feet. S.B.#1' was drilled to bedrock and allowed to flow overnight. A State geologist (Dr. John Redder) was present as S.B.#1' was drilled. The top photograph on Plate 2 shows the heavily iron- stained sediments near the edge of Summer Bay where S.B.#1' was drilled. The bottom photograph shows the same location during the drilling process. The following day a series of water samples and tempera- ture measurements were conducted by the State geologist. Water flowed through the 4-inch casing from S.B.#1' at a rate of 48 gallons per minute and at a temperature of 122°F. A hydrostatic head of 6 feet was determined (i.e., water rose 6 feet above ground level in the well casing when water was not allowed to overflow). The unexpected volume of artesian flow, limitations of the drilling rig, and a continuous infilling of sandy material -2- ITRON-STAINED SEDIMENTS NEAR EDGE OF SUMMER BAY WHERE S.B.#1' WAS DRILLED DRILL RIG ON LOCATION AT S.bB. #1' DAMES & MOORE Plate 2 into the well from the aquifer system seriously hampered drilling operations. The State geologist and the Dames & Moore representative agreed to terminate drilling operations at depths where bedrock was encountered. Several attempts to install plastic (PVC) pipe into the well were unsuccessful due to the large volume of water flowing from the well and the continuous infilling of sandy material into the casing from around its base. The unexpected characteristics and conditions found at this drill site, coupled with the possibility of an uncon- trolled flowing well, prompted a reconsideration of the scope of work. The State geologist and the Dames & Moore represen- tative agreed that it would be in the best interest of the drilling project to: (1) determine as much as possible. about the warm water aquifer system via water sampling and tempera- ture measurements; and (2) abandon the drill site in such a fashion as to preserve the artesian system. After sufficient water sampling and temperature measure- ments were taken, the casing was pulled without the installa- tion of the PVC pipe and 30 wt. oil. The well was successfully plugged with sediments, and the site was abandoned. The unexpected results obtained from S.B.#1' resulted in the relocation of the second drill site in an attempt to determine the lateral extent of the warm water aquifer system. This site (S.B.#2) was relocated approximately 180-200 yards away from S.B.#1' along the beach adjacent to Summer Bay. This position, which was away from a trending line that in- cluded the existing hot spring and S.B.#1', allowed for good lateral control of the warm water aquifer system. A complete log of the sedimentary material encountered in drilling S.B.#2 is contained in the appendix at the end of this report. The sediments consisted of medium to fine black DRILL RIG AT LOCATION WHERE S.B.#2 WAS DRILLED. LOCATION OF S.B.#1' IS IN FOREGROUND. WATER FLOWING FROM S.B. DAMES 6 MOORE sands with several large cobbles in the top 15 feet. Below 15 feet there were very few cobbles and an increase in fine material to a depth of 52 feet. From 52 to 57 feet, a layer of chalky silt and clay with small shell fragments was noted. Bedrock was found at 57 feet, and drilling operations were terminated at this depth. The top photograph on Plate 3 indicates the relative position of S.B.#2 (drill rig) with respect to S.B.#1 (foreground). The bottom photograph shows the surface sedi- ments at S.B.#2 as well as warm water flowing from the well. A warm water aquifer was again encountered in S.B.#2 at a depth of approximately 44 to 45 feet. Water flowed under artesian pressure at a rate of about 8 gallons per minute through the 4-inch well casing at a temperature of 111°F. The hydrostatic head was determined to be 3 feet above ground level. This water was allowed to flow a few hours before the State geologist took several water samples and temperature measurements. The well casing was pulled, the water flow ceased, and the drill site was abandoned upon the completion of the sampling procedure. No attempt was made to install Pvc pipe filled with 30 wt. oil into S.B.#2, as conditions were similar to those at S.B.#1l'. CONCLUSIONS The two test wells drilled at Summer Bay indicate that a fairly extensive warm water aquifer system exists in sandy soils beneath this region at depths between 40 and 45 feet below the surface. Water flowed under artesian pressures at 48 gallons per minute through a 4-inch well casing at 122°F from S.B.#1' and 8 gallons per minute through a 4-inch well casing at 111°F from S.B.#2. The warm water aquifer occurred at approximately the same depth in both holes and appeared to be contained in the same black sandy formation. The results of this study suggest that the warm water aquifer system may have direct use applications. Before this potential can be fully realized, a much more detailed drilling program, coupled with an extensive geophysical survey of the area, should be undertaken to fully assess the extent of, source of, and temperature of this aquifer system. APPENDIX LABORATORY TEST DATA BORING S.B. 1 ATTERBERG STRENGTH TEST DATA SURFACE ELEVATION: 2 FEET TESTS REPORTED ELSEWHERE LIQUID LIMIT PLASTICITY INDEX (%) WORMAL OR CONFINING DEVIATOR STRESS (PSF) MOISTURE CONTENT DRY DENSITY RESSURE (PSF) TYPE OF TEST SHEAR STRENGTH) BLOWS/FT. SYMBOLS DESCRIPTION Firs], | SITE IS LOCATED ON A NARROW BEACH ON THE EDGE OF SUMMER SP | BAY. SURFACE SEDIMENTS ARE HEAVILY IRON-STAINED. BLACK SANDS WITH SOME LARGER COBBLES AT SURFACE. MEDIUM TO COARSE, OARK TO BLACK COBBLES AS FOUND ‘ON SURFACE. SAME AS ABOVE. VERY EASY DRILLING, MOSTLY SANOS. LITTLE OR NO FINES OR LARGE ROCKS OR COBBLES. © DEPTH IN FEET P SAME AS ABOVE, EXCEPT CUTTINGS ARE ALMOST ALL BLACK WITH NO OR VERY LITTLE FINES. SAME_AS ABOVE. MOSTLY BLACK, SANDY MATERIAL. VERY LITTLE FINES AND FEW LARGE COBBLES OR ROCKY MATERIAL. VERY DARK, BLACK, COARSE SANDS. LITTLE OR NO FINES, BUT SOME LARGER COBBLES - AS BEFORE. FAIRLY EASY DRILLING. SAME AS ABOVE. NO SAMPLES | TAKEN, SAME MATERIAL. ABRUPT CHANGE TO A WHITE CHALKY MATERIAL WITH SOME SHELL FRAGMENTS . GRADUAL INCREASE OF BLACK SANDS AS CLAYEY MATERIAL DECREASES. SLIGHT PRESENCE OF CHALKY MATERIAL. SAME AS ABOVE, MIXTURE OF BLACK MEDIUM TO COARSE VOLCANIC SANDS WITH SOME FINER CHALKY - CLAYEY MATERIAL PRESENT. WATER IS COMING OUT OF HOLE IN LARGE VOLUME AND TS HOT AND STEAMING. AS WE DROVE CASING TO 45’ WE HAVE SEALED THE HOT WATER TONE OFF. CUTTING MATERIAL IS SAME AS ABOVE. ENO OF CASING. CUTTINGS HAVE BECOME VERY COARSE, GRANULAR AND LOOK LIKE CHIPS OF BASALT. ORILLER SAYS ORILLING HAS GREATLY SLOWED AND FEELS THIS IS BEDROCK. KEY LETTER Laie Barre TYPICAL DESCRIPTION POORLY-GRADED SANDS, GRAVELLY SANDS, LITTLE OR NO FINES ZY cL INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, Wh GRAVELLY CLAYS, SANDY CLAYS, SILTY CLAYS, LEAN CLAYS VS Gy, « | CLAYEY SANDS, SAND-CLAY MIXTURES POORLY-GRADED GRAVELS, GRAVEL-SAND MIXTURES, LITTLE OR NO FINES EL = [eariome ma LOG OF BORINGS PLATE LABORATORY TEST DATA BORING S.B.2 T ATTERDERG STRENGTH TEST DATA SURFACE ELEVATION: 4 FEET (PSF ELSEWHERE INDEX (x) NORMAL R CONFINING LIQUID LIMIT TESTS REPORTED STRESS (PSF] PLASTICITY TYPE OF TEST RESSURE MOISTURE CONTENT DRY DENSITY (PCF BLOWS/FT. | SYMBOLS DESCRIPTION SITE IS ABOUT 200 YARDS AWAY FROM S.8. 2. SURFACE SEDIMENTS ARE LARGE COBBLES AND GRASS. LARGE WOOD LOGS NEARBY. DRILLING IS VERY SLOW QUE TO LARGE AMOUNT OF LARGE COBBLES IN THE TOP FEW FEET OF SEDIMENT. CUTTINGS ARE SMALL ROCK CHIPS AND COARSE BLACK SANDS, WITH LITTLE FINES. SAME AS ABOVE. © DEPTH IN FEET SHEAR STRENGTH) (PSF) DEVIATOR ORILLING IS STILL SLOW, MATERIAL GOING THROUGH IS SAME AS ABOVE. DRILLING IS GOING EASIER AND FASTER NOW. MOSTLY ALL DARK BLACK SANDS WITH AN OCCASSIONAL SMALL COBBLE. CUTTINGS ARE ALL MEDIUM TO FINE BLACK SANOS, WITH ‘SOME FINES. ORILLING IS STILL GOING SMOOTHLY - NO LARGE COBBLES, MOSTLY MEDIUM TO FINE SANDS WITH INCREASING AMOUNT OF FINES. NO SAMPLES] TAKEN, SAME AS ABOVE EXCEPT CUTTINGS ARE NEARLY ALL BLACK FINE SANDS AND SILTS. SAME AS ABOVE. MOSTLY DARK SANDS WITH SOME LIGHTER FRAGMENTS AND SOME FINES. ‘SAME AS ABOVE. WARM WATER 111° AT 8 GALLONS/MINUTE FLOWING OUT OF TOP OF WELL. WATER WENT ABOUT 3° ABOVE GROUND LEVEL INTO CASING. CUTTINGS LOOK SAME AS ABOVE - BUT WITH AN INCREASE IN SILTS AND CLAYS. THE CUTTINGS COMING OUT OF THE HOLE HAVE CHANGED TO A MUCH LIGHTER CHALKY COLOR WITH SOME SHELL FRAGMENTS. ORILLING IS GETTING MUCH HARDER. JORILLER HAS REACHED BROKEN LARGE CHUNKS OF BEDROCK WITH VERY SLOW DRILLING AS BEFORE. ‘TD 57* CUTTINGS ARE SMALL ANGULAR BASALTIC CHIPS AS IN S.8, 1", BUT WITH SOME WHITER MATERIAL PRESENT. LOG OF BORINGS PLATE