Environmental Impact Evaluation of Geothermal Power Plant System by Means of Life Cycle Assessment

Abstract

Among the renewable energy sources, geothermal power is a promising power generation system from the power supply stability point of view. The environmental load from geothermal power system is regarded to be small since this system produces energy not due to fossil fuel combustion, and consequently emits a lower amount of carbon dioxide（CO₂）. The aim of this paper is to calculate the additional load of emitted greenhouse gases from the steam（emitted GHGs）and land use by geothermal power system occupation and to evaluate comprehensive impact caused from the system. As the results, the amount of entire GHGs from the system is estimated to the range from 34 to 113g-CO₂-eq/kWh depending on the consistency of emitted GHG. Social cost of total environmental impact considering emitted GHG, land use and waste is estimated from 0.44 to 0.74yen/kWh, and it is shown that environmental impact by emitted GHG, land use and waste is about 80 percent of total environmental impact.