Energy efficiency assessment of hybrid solar-geothermal power plant

Abstract

An assessment of the energy efficiency of a hybrid solar-geothermal power plant is performed taking into account the geothermal resource of one of the productive well (TD4) and the direct normal irradiance at Tendaho geothermal site in Ethiopia. A thermodynamic model of a single-flash geothermal plant integrated with a parabolic trough concentrated solar power system is developed to estimate the energy production in a hybrid solar-geothermal power plant. In the hybrid power plant, the parabolic trough concentrated solar power system is employed to superheat the geothermal steam in order to gain more energy before it expands in the turbine. Thermodynamic analysis, based on the principles of mass and energy conservation, was performed to assess the efficiency of the hybrid power plant at the given conditions of Tendaho geothermal site. A figure of merit analysis was also employed to evaluate whether a hybrid power plant could produce more power than two stand-alone power plants namely the solar and geothermal power plants that constitute the hybrid power plant. Results showed that the hybrid power plant technically outperformed the two stand-alone power plants. By integrating the two energy resources, the hybrid power plant proved to generate 7158 kW of electricity which is larger than the sum of the two stand-alone power plants (geothermal and solar).