| Abstract |
Ethiopia started a long term geothermal exploration undertaking in 1969. The study has revealed the existence of both low and high enthalpy geothermal resources in the Ethiopian Rift Valley and in the Afar depression, which are both part of the Great East African Rift System. Over the years, a good inventory of the possible resource areas has been built up and a number of the more important sites have been explored. Of these areas, about sixteen geothermal prospect areas are judged to have potential for high temperature steam suited to electricity generation. A much larger number are capable of being developed for non-electricity generation applications in agriculture, agro-industry etc. Exploration work peaked during the early to mid-1980s when exploration drilling was carried out at the Aluto-Langano geothermal field. Eight deep (maximum depth of about 2500m) exploratory wells were drilled, of which four are potentially productive. During the early 1990s, exploration drilling was also carried out at Tendaho. Three deep (about 2100m) and three shallow (about 450m) wells were drilled at the Tendaho geothermal field, and proved the existence of high temperature and pressure fluid . Resource utilization at the Aluto-Langano was delayed until 1998 due to financial constraints. During the year 1998, a new era of resource utilization started by installing the 7.2 MWe net capacity pilot plant at Aluto-Langano. However, the pilot plant has faced operational difficulties that are essentially due to the lack of the appropriate field and plant management skills. With the rectification of these problems, the plant should run more reliably and provide experience that would be useful in the exploitation of the country's extensive resources, to augment power supply from hydro-resources and diversify the energy supply structure. In the Tendaho geothermal field, a production test and feasibility study is currently in progress. The feasibility study indicates that four productive wells (out of six) of this geothermal field could supply enough steam to operate a pilot power plant of about 5 MWe, and the potential of the deep reservoir is estimated about 20 MWe. The GSE did detailed geological, geochemical and geophysical studies in the Corbetti (Lakes District) during the year 1985-86 (Kebede, 1986) and Tulu Moye- Gedemsa and Abaya (Southern Afar) geothermal prospective areas during the years between 1998 and 2000 (Ayele et al., 2002). This integrated geoscientific study included drilling of five shallow temperature gradient wells (150-200m) in the Tulu-Moye geothermal prospect area, and has delineated areas for further deep exploration wells. At present, the Survey is carrying out detailed geoscientific studies (geology, geochemistry and geophysics) in the Southern Afar areas (Dofan, Fantale and Meteka). These exploration works of geothermal resources in the Ethiopian Rift are with emphasis on proven sources and systematic detail surveys on target areas delineated during the first reconnaissance investigation (UNDP, 1973). |