Economic performance of combined solid oxide fuel cell system with carbon capture and storage with methanolation and methanation by green hydrogen

In addition to the promotion of pumped storage and electricity storage batteries, the minimum use of inexpensive thermal power generation for the regulation of power in Japan and other countries is being considered as a supply-demand stabilization device with the expected widespread introduction of renewable energy by 2050. Therefore, this study analyzed the economics related to the introduction of solid oxide fuel cell combined cycle using liquefied natural gas as a regulating power. The commercialization of recovered CO2 has been investigated for reducing the overall system operating costs. This study investigated a combined solid oxide fuel cell CO2 utilization system that employed green hydrogen methanolation and methanation to facilitate the use of the CO2 captured by the system. CO2 was separated from the exhaust gas of the system, captured, stored, and used through methanation and methanolation. Consequently, the synthesized methane was used for solid oxide fuel cell power generation, and the synthesized methanol was sold. The discounted cash flow method was employed to evaluate the economic performance of the proposed system. At a unit price of 0.7–0.9 USD/kWh for electricity sold, rated outputs of 1250 and 390 MW for solid oxide fuel cell combined cycle and photovoltaics, respectively, carbon capture and storage equipment cost of 800 USD/kWh, and discount rate of 0.3 %, the simple integrated payback period was obtained as 9 years whereas the dynamic payback period was 11–30 years. Consequently, the economic feasibility of the proposed system was demonstrated.