Model-Based Analysis of a Liquid Organic Hydrogen Carrier (LOHC) System for the Operation of a Hydrogen-Fired Gas Turbine

Abstract

One of the main challenges currently hindering the transition to energy systems based on renewable power generation is grid stability. To compensate for the volatility of wind- and solar-based power generation, storage facilities able to adapt to seasonal and short-term differences in energy production and demand are required. Liquid organic hydrogen carriers (LOHCs) represent a viable method of chemically binding elemental hydrogen, offering opportunities for large-scale and safe energy storage. In times of energy shortage, flexible and dispatchable power generation technologies such as gas turbines can be fueled by hydrogen stored in this manner. Hydrogen can be released from its liquid carrier via an endothermic dehydrogenation reaction using waste heat provided by the gas turbine. This gaseous hydrogen can be supplied to the gas turbine combustion chamber using a hydrogen compressor. In this study, a steady-state model is developed in order to analyze the heat-integrated combination of a 7.7 MW hydrogen-fired gas turbine and a perhydrodibenzyltoluene (H18-DBT)/dibenzyltoluene (H0-DBT) LOHC system. For the best-performing parameter set, the effective storage density of the LOHC oil comes to 1.5 kWh/L. This value is situated in between that of compressed hydrogen at 350 bar (1.01 kWh/L) and liquid hydrogen (2.33 kWh/L). Concurrently, the corresponding energy required for hydrogen compression reduces the overall system efficiency to 22.00% (ηGT=30.15%). The resulting optimal electricity yield, being a product of these two values, amounts to 0.33 kWhel/L.