Techno-economic analysis of oxy-fuel power plant for coal and biomass combined with a power-to-gas plant

Abstract

Power-to-gas (PtG) is a promising technology for the production of hydrogen via electrochemical reactions in water electrolyzers to manage intermittent power generation from renewable energy sources, such as wind and solar energy. Water electrolyzers generate hydrogen and highly purified oxygen as by-products. In this study, process analysis was performed on oxy-fuel combustion in a coal and biomass power plant and a PtG plant, which uses highly purified oxygen obtained from a water electrolyzer. The power-generation efficiency of an oxy-fuel power plant supplied with oxygen through an air separation unit and that of an oxy-fuel power plant supplied with oxygen in a polymer electrolyte membrane (PEM) water electrolysis process were also compared. Furthermore, we analyzed a combined system comprising an oxy-fuel power plant and PtG plant and found the resulting net power generation and power-generation efficiency to be higher than those of the individual oxy-fuel power plant that was supplied with oxygen through an air separation unit. This process efficiency was further improved when applying biomass to fuel the oxy-fuel combustion boiler rather than coal, and in cases where the steam-water is in a supercritical condition. Comparing with other methods, power generation using biomass is environment-friendly and sustainable. Finally, an economic analysis of hydrogen production showed that the levelized hydrogen cost was deduced to approximately $3.67/kg-H2, which is similar to the 2030 target value for hydrogen economy revitalization roadmap of the Korean government of 4000 KRW/kg-H2.