Development of Hybrid Geothermal Power Plants Combined with Other Thermal Energy Sources

Abstract

Geothermal energy is the clean and sustainable heat that lies beneath the earth’s surface, and it is considered a renewable energy resource. A geothermal power plant has negligible environmental impact (approximately 0.015kg-CO2/kWh) and can help reduce carbon dioxide emissions to the atmosphere. Although geothermal energy is potentially a very valuable domestic power source for Japan, much of the geothermal resource base in Japan cannot yet be economically used. Therefore, many industries and research institutes in Japan have researched and developed technologies to harness geothermal energy. We have started to develop highly efficient hybrid geothermal power plants combined with other thermal energy sources such as biomass, solar heat and exhaust heat from fuel cells. It is expected that the thermal efficiency of these systems can be improved by superheating the main flow of steam through the use of the other energy sources. We have looked into the feasibility of these hybrid power plants in terms of their engineering, economic performance, environmental laws and regulations. To report the latest status of this project executed by CRIEPI, in this paper, we discuss the plant performance of our hybrid geothermal power generation systems. This project was supported by the New Energy and Industrial Technology Development Organization (NEDO) program. NEDO is a semi-governmental organization in Japan set up to promote the development and introduction of new energy technologies.