| Abstract |
The program on R&D projects for geothermal development technologies was launched to secure geothermal energy as one of oil-alternative energies by NEDO in 1980 just after the second oil crisis. Under the program, various kinds of technologies such as exploration, drilling, well test and utilization of geothermal water were studied. In the field of drilling and production technologies, heat-resistant durable bits in addition to effective drilling mud and cement slurry in high temperature circumstances were developed. PTSD detectors and fluids sampling devices were improved to adapt those instruments under high temperature circumstances at least below 400 oC. MWD (Measurement While Drilling) system was developed aiming at improving drilling efficiency and monitoring accuracy of well bottom information in real time. Basic studies on Hot Dry Rock power generation system (HDR) have been conducted for 18 years in the Hijiori experimental geothermal field, in the northern part of Japan. In the field test, as the final stage of the R&D on HDR, a 100 kW binary generation was successfully accomplished for 58 days with circulating water into the borehole during power generating. A Down Hole Pump (DHP), which was expected as a key technology for promoting a large-scale binary power plant in Japan in severe conditions with high temperature and high pressure, was experimentally developed as one of the R&D projects. The projects have been conducted basically according to anticipated needs of geothermal resource developers in Japan, and the results were applied to each stage of resource development aiming at contributing to increase generation capacity in future. However, all R&D projects will be terminated at the end of this fiscal year (March 2003) due to change in policy based on its result evaluations taking fruitions of other new energy R&D projects into account. From the viewpoint of global environmental issues and long-term energy security, R&D projects on geothermal energy are expected to be resumed in the very near future. |