INPEX and Osaka Gas Co., Ltd. are jointly conducting technology development aimed at the practical implementation of a CO2-methanation system for carbon-neutralizing city gas, based on a project subsidized by the New Energy and Industrial Technology Development Organization (NEDO).
In fiscal 2023, INPEX and Osaka Gas signed an EPC (Engineering, Procurement, Construction) contract with Chiyoda Corporation and Daigas Gas & Power Solution Co., Ltd., and began construction of the world's largest-class test facility with a capacity of 400 Nm3-CO2/h (equivalent to the city gas consumption of approximately 10,000 households, or 400 Nm3/h of methane, the main component of city gas).
Trial operations started in October 2025, construction and trial operations of the test facility were completed in February 2026, demonstration operations commenced, and injection of the produced synthetic methane (e-methane) into a natural gas pipeline was successfully implemented.
The test facility consists of raw material supply, methanation and utility equipment, using CO₂ separated and recovered at the Koshijihara Plant of the Nagaoka Field Office (Nagaoka City, Niigata Prefecture) as feedstock to produce synthetic methane. During trial operations, the technical development target of producing synthetic methane with a methane concentration of 96% was achieved, and a portion of the produced synthetic methane is injected into INPEX JAPAN's natural gas pipeline via the Koshijihara Plant for delivery to end users.
