Geothermal Energy in Hawaii—Present and Future1
Drilling at geothermal well HGP-A on the Big Island of Hawaii was completed on April 27, 1976 to a depth of 6,450 ft (1,966 m). This culminated a 4-year program of planning, exploratory surveys, related research, and experimental drilling requiring over $2.5 million of federal, state, county, and private funding. Maximum downhole temperature recorded was 358°C (676°F), and initial sampling indicated that the quality of the fluid was excellent—low in chloride content, mercury, and hydrogen sulfide.
Subsequent ERDA and state funding supported a comprehensive well-testing program, which resulted in the following preliminary results:
1. The Kapoho reservoir is liquid-dominated; has a tight formation, permeability thickness of approximately 1,000 md/ft; has high temperatures and formation pressures 350°C and 2,000 psi; is a potentially large reservoir, possibly 1,000 MWe for 50 years; and contains slightly brackish relatively benign fluid, although high in dissolved silica.
2. HGP-A geothermal well drilled in the Kapoho reservoir probably has severe skin damage, since the flow rate increases with each test. It exhibits wellhead pressure of 160 psi at steam flow rate of 60,000 Ib/hr; has a potential power output of 3.5 MWe for at least 30 years; and indicates that flashing occurs in the formation. During flashing, the borehole contains steam and water at saturation. The probable producing zones are at bottomhole and 4,300 ft (1,310 m).
Approval has been obtained from DOE for major funding for a wellhead generator of around 2 MWe capacity—the limit of the existing power line in the area. State and county matching funds will be provided and negotiations are under way. The Big Island utility has agreed to purchase the power and assist with construction.
Deterrents to rapid expansion of geothermal energy on the big island are: (1) Limited guaranteed power demand; (2) the onlv confirmed aeothermal resource is in an active vulnerability on seaborne petroleum and high energy costs; (2) major potential markets in mineral refining and other energy intensive industry; (3) potential nonelectrical geothermal uses; and (4) a very positive attitude toward geothermal energy use at all levels of government in Hawaii, as well as by the general public.
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The energy and mineral resources of the vast Pacific basin and its neighboring land areas play a vital role in meeting the ever-growing needs of society worldwide. Building on the foundation of a highly successful conference held in 1978, this volume contains 51 of the 135 papers presented there. Subjects included are general and specific in nature--oil, gas, and coal resources; geothermal fields, uranium; tin; evaporites, trace elements; water resources; magma energy and fuels from magma. Geological and geophysical techniques, and also the new tool of remote sending for petroleum and minerals exploration are represented. Tectonics, structure fundamentals, subsurface hazards, international treaties and the law of the deep sea are discussed. Seventeen countries and regions are represented in these papers: Thailand, Nicaragua, the United States, Japan, Peru, Antarctica, El Salvador, Australia, Mexico, Taiwan, New Zealand, China, Chile, Indonesia, Canada, and the Pacific Ocean.