Investigation of Geothermal Energy Use in Gas Liquefaction

Abstract

In this paper, we propose the use of geothermal energy for gas liquefaction, and investigate three possible cases for accomplishing such a task: using geothermal output work as the input for a liquefaction cycle; using geothermal energy in an absorption refrigeration process to precool the gas before the gas is liquefied in a liquefaction cycle; and using geothermal energy both for the absorption refrigeration to precool the gas as well as to produce work and use it in a liquefaction cycle (i.e., cogeneration). A binary geothermal power plant is considered for power production, while the Linde-Hampson cycle is considered for liquefaction. A liquid geothermal resource at 165°C is considered and both the ideal (i.e., reversible) and non-ideal (e.g., irreversible) system operations are analyzed. A procedure for such an investigation is developed and certain performance parameters are defined. Also, the effects of geothermal water temperature and gas precooling temperature on the system performance parameters are studied. The results show that there is a significant amount of energy savings potential in the liquefaction work requirement as a result of precooling the gas in a geothermal absorption cooling system, which indicates that it makes thermodynamic sense to use geothermal energy for absorption cooling rather than to use it for power generation.