System Study on Hydrothermal Gasification Combined With a Hybrid Solid Oxide Fuel Cell Gas Turbine

The application of wet biomass in energy conversion systems is challenging, since in most conventional systems the biomass has to be dried. Drying can be very energy intensive especially when the biomass has a moisture content above 50 wt.% on a wet basis. The combination of hydrothermal biomass gasification and a solid oxide fuel cell (SOFC) gas turbine (GT) hybrid system could be an efficient way to convert very wet biomass into electricity. Therefore, thermodynamic evaluation of combined systems with hydrothermal gasification units and SOFC–GT hybrid units has been performed. Three hydrothermal gasification cases have been evaluated; one producing mainly methane, a second one producing a mixture of hydrogen and methane and the last one producing mainly hydrogen. These three gasification systems have been coupled to the same SOFC–GT hybrid system. All the integrated systems have electrical exergy efficiencies around 50%, therefore, the combination of supercritical water gasification and SOFC–GT hybrid systems seems promising. The overall system performance depends for a large part on the liquid gas separation. Further research is required for finding out the optimal separation conditions.