World geothermal power production status: Energy, environmental and economic study of high enthalpy technologies

The current world status of geothermal electricity production, including installed capacities, number of units and energy produced by exploitation technology, is presented in this paper. Four geothermal model plants based on different modes of high enthalpy technologies are analyzed from energy, environmental and economic points of view for specific reservoir characteristics. Once process parameters are optimized for the best plant operation, a cost and financial analysis is performed within a given economic frame. This analysis shows that Dry Steam power plants are the most efficient. Flash steam power plants increase their exergy efficiency with increasing reservoir temperature. Double Flash technology raises the energy produced with respect to Single Flash between 17 and 25%, and economic parameters become better. An additional third flash process increases power production by 10%, but economic parameters are not improved unless a reservoir of very high temperatures is considered. The energy and economic study conclude that the choice of the best flash technology depends on the resource characteristics, the financial frame and the technology costs.