Thermodynamic and economic analysis of a new hydrogen liquefaction configuration based on low-temperature geothermal energy

In this paper, a new system is proposed for the hydrogen liquefaction based on geothermal energy, in which, the nitrogen is first converted to liquid, and then, is used as to temperature decrease the gas hydrogen, in the hydrogen liquefaction cycle. This system includes four sub-systems; an Organic Rankine Cycle (ORC), an ammonia-water absorption chiller, and two Claude cycles for hydrogen and nitrogen liquefaction. The geothermal fluid at a temperature of 200 ℃ and a mass flow rate of 100 kg/s is considered as the energy source of the system. The proposed system is assessed from the thermodynamics and economic viewpoints. Then, the effects of the compressor outlet pressure, the geothermal fluid inlet temperature, the evaporator temperature, and the generator temperature on the exergy efficiency, the cost of the produced liquid hydrogen, and the hydrogen liquefaction ratio are investigated through a parametric study. Also, increasing the compressor outlet pressure increases the power consumption of the system. Also, at the geothermal fluid temperature of 430 K, the exergy efficiency of the system is determined as 69%. Moreover, the results of the economic analysis show that the production cost of 6.629 (kg/s) liquid hydrogen will be 1.39 $/kg (7.79 $/GJ).