Life cycle cost assessment of a geothermal power assisted hydrogen energy system

In this paper, an integrated geothermal energy powered hydrogen production and liquefaction storage system is developed that has the ability to produce geothermal power of 7856 kW and hydrogen liquefaction rate of 0.05 kg/s. To simulate the integrated hydrogen energy system during thermodynamic conditions with life cycle cost analysis, the EES and Aspen Plus software is used. In the integrated system, hydrogen production and liquefaction by a geothermal source are accomplished. The geothermal power plant supplies the electrical power for both the electrolysis unit and the liquefaction cycle. The geothermal work is used for electrolysis to produce hydrogen gas and the remaining power is used for the liquefaction of hydrogen gas in the nitrogen precooled Claude cycle. In the electrolysis process, the work required for the generation of the unit hydrogen was calculated as 43.57 kW h/kg H-2 if the work was recalculated when preheating was included. The actual work consumption to hydrogen liquefaction was found to be 8.98 kW h/kg LH2. The unit costs of hydrogen and system payback period were calculated as 2.154 $/kg LH2 and 6.17 years. When life cycle cost analysis is applied to the system, the net present value (NPV) and levelized annual cost (LAC) were calculated as 78,390,000 and 9,207,000 $/yr, respectively.