Comprehensive analysis and multi-objective optimization of a power and hydrogen production system based on a combination of flash-binary geothermal and PEM electrolyzer

Abstract

In this study, comprehensive energy, exergy, and economic modeling, and optimization of a flash-binary geothermal system, were carried out for power and hydrogen production. The binary system is a combination of a dual-pressure organic Rankine cycle and proton exchange membrane electrolyzer. For performance improvement of dual-pressure organic Rankine cycle, zeotropic mixtures were used as the working fluids. The multi-objective Genetic algorithm was employed to optimize the system performance. According to the obtained results, the highest rate of exergy destruction was obtained for the steam turbine with a value of 16.42 kW. For the base case simulation, the energy and exergy efficiencies of the proposed system were obtained by 16.66% and 58.03%, respectively; also, the generated power, overall exergy destruction, and hydrogen production capacity were calculated by 114.53 kW, 82.755 kW, and 0.306 kg·hr−1, respectively. For the multi-objective optimization mode, the best performance was calculated for Pentane (0.467)/Butane (0.533) with energy and exergy efficiencies and hydrogen production of 16.67%, 58.14%, and 0.37 kg·hr−1. Moreover, the optimized payback period and NPV were around 5.52 years and 402600 $, respectively.