Biomass co-fired combined cycle with hydrogen production via proton exchange membrane electrolysis and waste heat recovery: Thermodynamic assessment

Abstract

The application of renewable energy sources such as biomass for power generation is becoming increasingly important, as is hydrogen production for use as a fuel or for other purposes. A novel combined cycle based on a gas turbine is proposed for a fixed power output of 10 MW using biomass as a co-fuel with natural gas, and integrated with hydrogen production via a proton-exchange membrane (PEM) electrolyzer. This combined cycle consists of two bottoming cycles: organic Rankine and steam Rankine. These allocate the generated power to the electrolyzer for hydrogen production. Energy and exergy analyses of the proposed cycle are performed to better understand it and its behavior. The produced hydrogen can be either sold in the marketplace for a variety of uses or injected into the combustion chamber. These two possibilities are considered two layouts of the system, for purposes of comparison. Hydrogen injection reduces natural gas consumption by around 33% and lowers CO2 emissions by around 11%, in addition to other environmental benefits, while hydrogen injection lowers the system exergy destruction and loss rates by around 2% and 19%, respectively. System energy and exergy efficiencies of around 58% and 52% respectively are determined for the hydrogen production layout and of 51% and 45% respectively are determined for the hydrogen injection layout.