Nagoya-based NGK Insulators is working on direct air capture of CO2 using Honeyceram, a ceramic catalyst used mainly in vehicles to clean auto emissions.
Direct air capture involves using chemical reactions to absorb carbon dioxide from the surrounding atmosphere, which can then be stored underground or used to produce fuels or industrial chemicals. These facilities can work anywhere there is air, making them a good fit for deserts or other hard-to-utilise lands.
NGK’s demonstration plant, slated to start operations in fiscal 2025, is expected to be able to soak up hundreds to thousands of tonnes of carbon dioxide per year.
The plant will use thousands of vanilla-coloured Honeyceram blocks. Fans push air through the blocks’ honeycomb structure, which is coated with a substance that reacts with carbon dioxide. The Honeyceram is then heated to release high-purity CO2 for recovery.
The honeycomb structure provides more surface area for contact between the material and the air, letting it absorb CO2 more efficiently, an NGK representative said. “It also allows for plants to be made more compact.”
NGK aims to have products related to carbon neutrality and digital initiatives make up half of its sales by 2030 and 80% by 2050.
The carbon capture technology “will be a big draw for us”, said President Shigeru Kobayashi.
Another Nagoya-based company, Toho Gas, is working on direct air capture technology that could be installed at liquefied natural gas terminals.
Working with Nagoya University and other partners, Toho Gas plans to build a prototype plant by fiscal 2024 that will absorb 1 tonne of carbon dioxide a year. Further tests are expected to begin at a scaled-up facility in fiscal 2029.
Natural gas is cooled to make LNG. When the process is reversed, heat is absorbed, producing a cooling effect. Toho Gas’s method uses this “cold energy” recovered from LNG regasification to cool a solvent containing carbon dioxide to below minus 140°C, turning the CO2 into dry ice.
The dry ice is later brought to room temperature, leaving gaseous CO2 under high pressure. This approach uses less energy than the usual process of heating the solvent, according to Toho Gas.
The company plans to use the captured gas in methanation – a reaction that converts carbon dioxide to synthetic methane, a component of natural gas piped to urban customers, by combining it with hydrogen.
“We aim to deploy this at other companies’ LNG receiving terminals and overseas,” said Soichiro Masuda, of the research and development division of Toho Gas.
While hopes are high for direct air capture, cost remains a hurdle at roughly US$300 to US$600 per tonne. Because carbon dioxide concentrations in the air are so low, direct air capture requires significantly more energy than scrubbing power plant emissions.
A total of 18 direct air capture facilities are now in operation worldwide, taking about 7,700 tonnes of carbon dioxide out of the atmosphere a year, according to the International Energy Agency. To achieve net-zero carbon emissions by 2050, 85 million tonnes need to be captured annually by 2030 and 980 million tonnes by 2050, IEA estimates show.