[ 1 ] International Energy Agency. Net Zero by 2050. A Roadmap for the global energy sector [Internet]. Pairs: International Energy Agency; 2021 May [cited 2021 Oct 11]. Available from https://iea.blob.core.windows.net/assets/ beceb956-0dcf-4d73-89fe-1310e3046d68/NetZeroby2050-ARoadmapforthe GlobalEnergySector_CORR.pdf. link1

[ 2 ] Binnewies M, Milke E. Thermochemical data of elements and compounds. 2nd ed. Weinheim: WILEY-VCH; 1999. link1

[ 3 ] Center for Low Carbon Society Strategy, Japan Science and Technology Agency. SOFC system (Vol.8), evaluations of energy conversion and utilization technologies for hydrogen economy. Report. Tokyo: Center for Low Carbon Society Strategy, Japan Science and Technology Agency; 2021 Jul. Report No.: LCS-FY2020-PP-02. Japanese.

[ 4 ] Yoshida K et al. Exergy kougaku. In: Exergy engineering. Tokyo: Kyoritsushuppan 1999. Japanese. link1

[ 5 ] The Chemical Society of Japan. Handbook of chemistry, basics. 3rd ed. Tokyo: Maruzen publishing; 1991. Japanese.

[ 6 ] Corgnale C, Gorensek MB, Summers WA. Review of sulfuric acid decomposition processes for sulfur-based thermochemical hydrogen production cycles. Processes 2020;8(11):1383. link1

[ 7 ] The Japan Gas Association. Natural gas resources [Intetnet]. Tokyo: The Japan Gas Association; [cited 2021 Aug 6]. Available from: https://www.gas.or. jp/tokucho/shigen/. Japanese. link1