A novel sustainable biomass-fueled cogeneration cycle integrated with carbon dioxide capture utilizing LNG regasification and green hydrogen production via PEM electrolysis: Thermodynamic assessment

Abstract

This paper proposes a novel biomass-fueled sustainable cogeneration power cycle with hydrogen production via a PEM electrolyzer. In this system, exiting product gases from the combustion chamber undergoes a CO2 capture process utilizing LNG regasification to avoid CO2 emissions to the atmosphere. Since biomass has a lower emission rate compared to fossil fuels and is subject to easier replacement and conversion, this system is considered to have a zero CO2 emission rate. LNG is the only cooling medium in this system; no exterior fluid like water is used to cool the system, making the overall process more environmentally friendly. This present system offers a unique structure utilizing renewable technologies for future zero-emission power layouts with sustainable and clean commodities such as green energy and hydrogen. A parametric study for this system is performed and results of energy and exergy analyses are presented to depict a better view of the system's performance and its advantages. The system includes a gas Brayton cycle as the main cycle, a LNG expander, as well as one steam Rankine and three organic Rankine cycles as bottoming cycles. Generated power from the organic Rankine cycles and LNG expander is allocated to the PEM electrolyzer for green hydrogen production. Municipal waste is the sole source of fuel for this system; a downdraft gasifier is used to convert it to syngas for combustion. For a fixed net power generation rate (10 MW), of which a portion is fed to the electrolyzer, the system consumes around 0.66 kg/s of municipal waste, and captures around 1.32 kg/s of CO2 using LNG regasification. Energy and exergy efficiencies of 84% and 50% respectively as well as 47 kmol/h green hydrogen generation are achieved.