Energy and Exergy analysis and selection of the appropriate operating fluid for a combined power and hydrogen production system using a Geothermal fueled ORC and a PEM electrolyzer

Abstract

This research aims to introduce an efficient power cycle that simultaneously produces power and hydrogen by PEM electrolyzer. This cycle is driven by geothermal energy. Comprehensive thermodynamic modeling (energy and exergy) has been performed to compare four different operating fluids' performance on the proposed system. EES software was used for modeling. A parametric study has also been applied to investigate the effect of important parameters on the system's energy and exergy performance. As a brief novelty statement, the unique model can be mentioned in which both power and chemicals can be produced, and hydrogen output can be used as a storage system that transforms energy into an energy carrier. The results showed that R245fa operating fluid with 3.5% and %67.6 of energy and exergy efficiency had the highest performance. The operating fluids R114, R600, and R236fa are also in the next ranks of performance characteristics. As the geothermal fluid temperature increases, the production of power and hydrogen increases, but the energy and exergy efficiency decrease. Also, it can be noted that the hydrogen unit significantly increases the exergy efficiency of the plant. As an example, in the R245fa case, it increases from 36% to 67.6%.