Thermo-economic analysis of a new dual expansion geothermal-LNG cold energy based on multi-generation system with green hydrogen generation

This study carries out an original thermoeconomic assessment of a hybrid energy system that mixes modified geothermal technology with LNG cold energy to produce sustainable hydrogen. The innovative configuration uses three main parts: a geothermal plant that works in a special way and uses hydraulics instead of usual expansion valves, a water-powered PEM electrolysis plant from a dual-effect desalination facility, and an LNG unit for converting cold energy. Thorough assessments prove that the system has superior technical features, saving 67.4 % of energy and 38.7 % of exergy, as well as producing electricity with 11.01 % efficiency. There is a total of 2.18 MW of exergy destruction, where the desalination part is responsible for approximately half, and the facility remains profitable at $0.021 per kWh by spending $2.02 million a year on operations. Parametric results indicate that increasing the geothermal turbine inlet pressure does not change the exergy efficiency by much and only increases water productivity, while pumping LNG at 70 bar improves all the system’s performance. With these changes, the coefficient of performance goes up to 0.29 and each of the aforementioned efficiencies rises, proving that the solution offered here is practical.