Energy, exergy, and economic analysis of an innovative hydrogen liquefaction cycle integrated into an absorption refrigeration system and geothermal energy

Liquid hydrogen is a solution to store and transport electricity which is produced by renewable energy sources like geothermal energy. In this paper, an organic Rankine cycle (ORC) and proton membrane electrolyzer (PEM), water-ammonia absorption refrigeration cycle, and a hydrogen liquefaction cycle are simulated and analyzed to store the geothermal energy as liquid hydrogen. The power produced by the ORC is used to produce hydrogen gas in PEM, additionally, cold energy from the absorption refrigeration cycle is used to precool the hydrogen gas to -26.9 degrees C. The novelty of this study is based on using cold energy from an absorption refrigeration system in the pre-cooling part of the hydrogen liquefaction cycle to convert geothermal energy to liquid hydrogen, this method leads to a reduction in power consumption. Specific energy consumption (SEC), figure of merit (FOM), and coefficient of performance (COP) of the final case in this study are 8.81 kWh kg-1, 0.83, and 0.49 respectively. The proposed cycle is compared with similar cycles available in the literature. The specific liquefaction cost (SLC) is 1.84 $ kg-1. The minimum selling price is estimated to be 2.11 $ kgLH2- 1 with the payback time of three years.