Thermoeconomic optimization of hydrogen production and liquefaction by geothermal power

In this study, the thermoeconomic approximation is applied to the optimization of a case study of a geothermal hydrogen production and liquefaction system. The objective of this application is to minimize its overall product unit costs (electricity, hydrogen production, and hydrogen liquefaction). The approximation is based on the cost-optimal exergetic efficiency that is obtained for a component isolated from the remaining of the system components. The objective function that expresses the optimization methodology for each subcomponent of the system is developed. In the iterative optimization methodology, the variables, relative cost differences, and exergy efficiency with the corresponding optimal values are obtained. Exergoeconomically optimal values for total product cost flow rate, total cost fuel flow rate, cost of electricity, cost of hydrogen production, and cost of hydrogen liquefaction are calculated to be 1820 $/h, 274.2 $/h, 0.01908 $/kWh, 1.967 $/kg, and 1.095 $/kg, respectively, whereas the corresponding actual base case values are 3031 $/h, 290 $/h, 34.34 $/h, 0.02076 $/kWh, 2.091 $/kg, and 1.725 $/kg, respectively.