A Geothermal-Driven Zero-Emission Poly- Generation Energy System for Power and Green Hydrogen Production: Exergetic Analysis, Impact of Operating Conditions and Optimization

Since the hydrogen production process is not yet fully efficient, this paper proposes a poly-generation system which is driven by a geothermal energy source and utilizes a combined Kalina/Organic Rankine cycle coupled with an electrolyzer unit to produce simultaneously power and green hydrogen in an efficient way. A comprehensive ther-modynamic analysis and an exergetic evaluation are carried out to assess the effect of system key parameters (geothermal temperature, high pressure, ammonia-water concen-tration ratio, and terminal thermal difference) on the performance of concurrent produc-tion of power and green hydrogen. Thereby, two configurations are investigated with/without separation of turbines. The optimal ammonia mass fraction of basic solution in KC is identified that leads to an overall optimal system performance in terms of ex-ergetic efficiency and green hydrogen production rate. In both configurations, the optimal evaluation is made possible by conducting a genetic algorithm optimization. The simula-tion results without/with separation of turbines demonstrate the potential of the suggested cycle combination and emphasize its effectiveness and efficiency. Exemplary, for the case without separation of turbines, it turns out that the combination of ammonia-water and MD2M provides the best performance with net power of 1470 kW, energy efficiency of 0.1181, exergy efficiency of 0.1258 while producing a significant green hydrogen amount of 3194.208 Kg/day.