A new cascade arrangement integrated with a biomass-based gas turbine and a steam electrolysis process: Technical and economic optimization

Heretofore, various multi-generation configurations have been suggested to recuperate the waste heat from a topping gas turbine. Among the layouts in which hydrogen was produced, solid oxide steam electrolyzers (SOSEs) were overlooked for inclusion in the system design. A new cascade arrangement integrated with an SOSE is suggested and analyzed in the current research for the multi-generation of electricity, hydrogen, hot water, and potable water. For this purpose, a biomass-driven gas turbine is utilized as the topping system, and its waste heat is recovered through a steam generator, a domestic hot water heat exchanger, and a cascade system comprised of an organic Rankine cycle, a Stirling engine, and a liquefied natural gas (LNG) subsystem. The potable water and hydrogen are produced in a reverse osmosis unit and an SOSE. According to the optimization results, the unit cost of hydrogen generation is 7.77 $GJ−1, which is much lower than that of previously proposed multi-generation systems. Notably, the proposed system achieves an optimum exergy efficiency of 51.2%, surpassing the performances of existing systems in this regard. The system generates 6.62 MW of electricity, 5.53 MW of heating, 79.3 kgh−1 of hydrogen, and 28.2 kgs−1 of freshwater. The total cost related to the economic and environmental aspects of the system amounts to 577.7 $h−1.