Theoretical Study on Sustainability of Geothermal Power Generation

Abstract

One of the main objectives of geothermal reservoir assessment is to find an optimum electrical generating capacity which is sustainable over the entire project life (usually fifty years). However, if the average output rate is significantly in excess of the rate of natural recharge, the capacity will decline after fifty years of successful power generation. Recently Pritchett (1998) has carried out numerical simulation of the behavior of an hypothetical geothermal reservoir which has been produced for electrical power for fifty years and then abandoned. These calculations indicate that, after a long period of shut-in, the electrical generating capacity for the field will recover ; for geothermal systems which become depleted due to large-scale cooling, the resource is still renewable, but long periods of time (centuries) are likely to be required for substantial recovery. Although it is beyond the scope of the present geothermal reservoir engineering, if we seek the sustainability of geothermal power projects for much longer time scales than fifty years, it is desirable to prepare “long-term” scenarios. Several possible scenarios are discussed in this paper.