Thermoeconomic Comparison Between ORC and Binary-flashing Cycle for Geothermal Energy

Abstract

Geothermal energy has many advantages over other renewable energy, including weather-proof, great stability, high capacity factor, base-load abilities and less ecological effect. Nonetheless, geothermal energy presents its own particular challenges. The high initial investment and long payback time make the geothermal power generation lag behind wind and solar energy. The binary flashing cycle (BFC) system is supposed to be a promising technology for the recovery geothermal energy due to the full use of geofluid. The economic performance of the system still need to be evaluated. In this paper, the thermoeconomic comparison between ORC and BFC for geothermal energy has been investigated. R245fa is selected as the working fluid. With the thermal efficiency, exergy efficiency, net power output per unit geothermal brine mass flow rate, heat exchanger area and heat recovery efficiency as evaluation indexes, the flowsheet modeling and optimization in MATLAB simulation software were conducted. The simulation results reveal that the BFC system sacrifices efficiency, and acquires larger net power output. What is more, the preliminary discussion of the economic feasibility of BFC system applied in FengShun geothermal field is presented. It is indicated that the BFC system has obvious economic benefits, especially in non-flowing geothermal well.