Geothermal binary cycle power plant principles, operation and maintenance

Abstract

Binary cycle power plants play an important role in the world, generating electricity from low and medium temperature geothermal temperature resources. This report describes a thermodynamic model of a binary cycle power plant and its components. A basic binary cycle and a binary cycle with a recuperator for different turbine inlet pressures are modelled. How the addition of a recuperator in the cycle shifts the maximum point of turbine work output, increasing the turbine work output for a given reinjection temperature and helping when the reinjection temperature is limited by the geothermal water chemistry, is analysed. The report shows that Isopentane and n-Pentane are the working fluid options for the Berlin binary cycle power plant in El Salvador. The parasitic loads for wet and air cooling systems are influenced by the seasonal fluctuations of the ambient temperature. The maintenance of binary cycle power plants is highly influenced by different factors, such as the nature of the geothermal fluid used in the primary loop, the nature of the working fluid, the technology and location of the plant, climate and weather. The operation and maintenance in both Svartsengi and the Berlin binary cycle power plants are presented.