Geothermal Energy Use in Hydrogen Production

Abstract

We propose the use of geothermal energy for hydrogen production and liquefaction, and investigate six possible models for accomplishing such a task. The models are studied thermodynamically in order to assess their performance for maximizing hydrogen production rate while minimizing the used geothermal energy. The effect of geothermal water temperature on various thermodynamic performance of the models is investigated. The models include using geothermal work output as the work input for an electrolysis process (Model 1); using part of geothermal heat to produce work for electrolysis process and part of geothermal heat in an electrolysis process to preheat the electrolysis water (Model 2); using geothermal heat in an absorption refrigeration process to precool the gas before the gas is liquefied in a liquefaction cycle (Model 3); using part of the geothermal heat for absorption refrigeration to precool the hydrogen gas and part of the geothermal heat to produce work with a binary geothermal cycle and use it in a liquefaction cycle (Model 4); using geothermal work output as the electricity input for a liquefaction cycle (Model 5); and using part of geothermal work for electrolysis and the remaining part for liquefaction (Model 6).