Development and multi-objective optimization of geothermal-based organic Rankine cycle integrated with thermoelectric generator and proton exchange membrane electrolyzer for power and hydrogen production

The aim of this study is to enhance the performance of a geothermal-based organic Rankine cycle by proposing two novel systems in which some part of the waste heat is recovered employing thermoelectric generator for power and/or hydrogen production (using proton exchange membrane electrolyzer). Accordingly, two novel systems are proposed and analyzed along with the basic organic Rankine cycle (configuration (a)). In the first proposed system, some part of the waste heat is recovered by employing thermoelectric generator (configuration (b)), while in the second one the additional power generated by thermoelectric generator is used in the proton exchange membrane electrolyzer for hydrogen production (configuration (c)). The performances of the proposed systems are investigated and compared with that of the basic cycle from energy, exergy and exergoeconomic viewpoints and are optimized using genetic algorithm via a multi-objective optimization strategy. The results indicate that, at the best solution point obtained from multi-objective optimization, the exergy efficiencies of the proposed systems (configurations (b) and (c)) are higher than that of the basic organic Rankine cycle by 21.9% and 12.7%, respectively. Furthermore, another interesting result is found which reveals that the specific product cost for the proposed configurations (b) and (c) is lower than that for the basic organic Rankine cycle, despite the higher total cost rate for the proposed configurations.