A review on geothermal Organic Rankine cycles: modeling and optimization

Abstract

Employing renewable energy sources for power generation have been developed in recent years due to their several benefits including low emission of greenhouse gases and their inexhaustible nature. Among the applicable renewable energy sources for electricity generation, geothermal energy is one of the most appropriate ones owing to its independent availability from the weather condition. Due to the acceptable performance of Organic Rankine cycles (ORCs) in generating power from low- or medium-temperature heat sources, these cycles are appropriate choices for utilization in geothermal power plants. There are several parameters that influence the rate of power production and the efficiency of geothermal-based ORCs. The impacts of influential parameters have been investigated in several studies by modeling and optimization of these cycles. This article provides a comprehensive review of the previous studies focused on modeling and optimization of the ORCs with different configurations and operating conditions, which would be useful for the researchers working in this field of science. Conclusions of the reviewed studies reveal that geothermal-based ORCs performance is significantly influenced by the applied operating fluid in the cycle, working condition in addition to configuration and architecture of the applied cycle. Moreover, studies that concentrated on the optimization of geothermal-based ORCs are also reviewed and their key conclusions are reflected as well. In the majority of the studies in this field, technical and economic objectives have been considered for optimization of the cycles. Depending on the characteristics of the case studies, the efficiency and cost of the generated power in optimized geothermal-based ORCs vary greatly. Finally, several recommendations are proposed for future studies in this field.