Hot Dry Rock Geothermal Energy Development Program Annual Report Fiscal Year 1988 PDF Download

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The complete list of HDR objectives is provided in Reference 10, and is tabulated below in Tables 1 and 2 for the reader's convenience. The primary, level 1, objective for HDR is ''to improve the technology to the point where electricity could be produced commercially from a substantial number of known HDR resource sites in a cost range of 5 to 8 cents/kWh by 1997''. A critically important milestone in attaining this cost target is the level II objective: ''Evaluate the performance of the Fenton Hill Phase II reservoir''. To appreciate the significance of this objective, a brief background is helpful. During the past 14 years the US DOE has invested $123 million to develop the technology required to make Hot Dry Rock geothermal energy commercially useful. The Governments of Japan and the Federal Republic of Germany have contributed an additional $32 million to the US program. The initial objectives of the program were met by the successful development and long-term operation of a heat-extraction loop in hydraulically-fractured hot dry rock. This Phase I reservoir produced pressurized hot water at temperatures and flow rates suitable for many commercial uses such as space heating and food processing. It operated for more than a year with no major problems or detectable environmental effect. With this accomplished and the technical feasibility of HDR energy systems demonstrated, the program undertook the more difficult task of developing a larger, deeper, hotter reservoir, called ''Phase II'', capable of supporting pilot-plant-scale operation of a commercial electricity-generating power plant. As described earlier in ''History of Research'', such a system was created and operated successfully in a preliminary 30-day flow test. However, to justify capital investment in HDR geothermal technology, industry now requires assurance that the reservoir can be operated for a long time without major problems or a significant decrease in the rate and quality of energy production. Industrial advisors to the HDR Program have concluded that, while a longer testing period would certainly be desirable, a successful and well-documented flow test of this high-temperature, Phase II reservoir lasting at least one year should convince industry that HDR geothermal energy merits their investment in its commercial development. This test is called the Long Term Flow Test (LTFT), and its completion will be a major milestone in attaining the Level 1 objective. However, before the LTFT could be initiated, well EE-2 had to be repaired, as also briefly described in the ''History of Research''. During this repair operation, superb progress was made toward satisfying the next most critically important Level II objective: Improve the Performance of HDR Drilling and Completion Technology. During the repair of EE-2, Los Alamos sidetracked by drilling out of the damaged well at 2.96 km (9700 ft), and then completed drilling a new-wellbore (EE-2A) to a total depth of 3.78 km (12,360 ft). As a consequence of this drilling experience, Los Alamos believes that if the original wells were redrilled today their combined cost would be only $8 million rather than the $18.8 million actually spent (a 60% cost saving). Further details, particularly of the completion of the well, can be found in the major section, ACCOMPLISHMENTS, but it can be seen that the second, Level II objective is already nearing attainment.