Reducing CO₂ emissions from thermal power generation and other processes is an important climate change countermeasure. There is also a need to develop technologies that effectively utilize CO₂ as a resource. Reuse of CO₂ as fuels, chemical feedstock and other valuable materials is considered a useful way of efficient CO₂ usage. Methane, the main component of natural gas (or town gas), holds great potential as an energy carrier^*1, and because existing infrastructure for natural gas can be employed directly, it offers significant benefits.

According to this background, there are high expectations at the moment for practical application of methanation, which is the process of utilizing CO₂ as a material in the production of methane. Methanation is a technology for synthesizing methane through a chemical reaction in a reactor containing a catalyst with CO₂ from thermal power plants and other sources, which has been separated and captured, and hydrogen produced through electrolysis of water or other methods. Because CO₂ emitted during combustion of methane can be offset against separated and captured CO₂, if renewable energy can be used in the future to produce hydrogen through electrolysis of water, then the process might be able to dramatically reduce CO₂ emissions.

NEDO is implementing a project^*2 to develop technologies for effective utilization of CO₂. Working with INPEX Corporation and Hitachi Zosen Corporation, the organizations have now completed construction of a test facility for synthesizing methane from CO₂ and hydrogen at the Koshijihara Plant of INPEX's Nagaoka Field Office in Nagaoka City, Niigata Prefecture. After commissioning, they will conduct a series of tests and continuous operation by the end of fiscal 2019.

At this test facility, the organizations will produce methane through synthesis of the CO₂ generated at the Koshijihara Plant during the natural gas production process, together with hydrogen produced through electrolysis of water.

Through later full-scale operation, they aim to evaluate and examine technical issues, including how to optimize the methane synthesis process by varying a range of parameters including reaction temperature, reaction pressure and reaction loads, and to develop methanation technology, which is one of carbon recycling^*3 technologies.

For methane synthesis, the test facility uses a Hitachi Zosen plate reactor that achieves highly efficient heat recovery (figure 3). As the world's first trial using actual CO₂ in a plate reactor, this initiative is focused on use of larger facilities in the future. This test facility has a methane synthesis capacity of 8 Nm³ per hour.

After commissioning, a series of tests and continuous operation will be conducted by the end of fiscal 2019. Technical issues will be examined and evaluated, and further improvements in capacity of the methane synthesis facility will be considered.