4E assessment of a geothermal-driven combined power and cooling system coupled with a liquefied natural gas cold energy recovery unit

This study introduces an innovative interconnected structure for simultaneous cooling and power generation, incorporating hydrogen production through a double-flash geothermal cycle. The system integrates DFG cycle as upper subsystem with lower subsystems including a proton exchange membrane electrolyzer, liquefied natural gas cold recovery, Kalina power cycle, and an ammonia Rankine cycle. A thorough thermo-economic assessment was performed with Aspen HYSYS program. Findings demonstrate that the system is capable of generating 15,260 kW of cooling power, 30,640 kW of electrical power, and producing hydrogen at an output of 20.16 kg/h. The system's total energy efficiency is assessed at 28.91 %, while the exergy efficiency is evaluated at 76.39 %. The overall operational cost rate is projected at 607 $/h, with an exergy cost of 5.3 $/GJ. Additionally, implementation of this system results in an annual reduction of 189,898 kg of CO2 emissions and savings of 59,497 L of oil/year. Exergy analysis reveals that the LNG evaporator accounts for 68.1 % of the total irreversibility of 65,272 kW, suggesting that optimizing the heat exchanger effectiveness could significantly enhance system performance. This innovative design not only improves energy recovery but also contributes to sustainable hydrogen production, making it a viable alternative to fossil fuel-based systems.