A demonstration plant in Japan will capture and liquefy carbon dioxide from boiler exhaust gas and supply it to the local CO2 market, according to Japanese newsletter the Gas Review.
The facility is a joint venture between Niterra and Hitachi Plant Services and will start up at Niterra’s Komaki plant in October next year. The plant will capture around three tonnes of CO2 per day before it is liquefied and delivered through existing supply chains to regional customers at a purity of 99.95%, making it suitable for food and beverage use.
The capture system increases the CO2 concentration in boiler exhaust from the typical 10% to more than 30% by enriching the combustion air with oxygen. Niterra is using a once-through boiler co-developed with Nippon Thermoener that operates with oxygen-enriched combustion.
This higher CO2 concentration enables a more efficient capture step using vacuum pressure swing adsorption. The VPSA unit uses zeolite to selectively adsorb CO2 and achieves a minimum of 90% CO2 purity and 90% recovery.
Hiroki Kawase, Section-Chief of CCU Technology at Niterra, said, “By increasing the CO2 concentration in the exhaust stream, the capture step becomes much more efficient and allows us to use compact VPSA equipment that can operate at industrial scale.”
The design is modular. A single 64 m³/h VPSA unit fits into a standard 20-foot container containing the adsorption towers, vacuum pumps, and blowers. The full commercial concept involves three units, giving a total capacity of about 10 tonnes per day. The demonstration unit at Komaki will operate at half scale.
Captured CO2 will be processed in a compact liquefaction and refining system supplied by Hitachi Plant Services, which has adapted its large-scale technology into a smaller natural-refrigerant design that recovers waste heat to improve efficiency.
CO2 from the capture unit is dehumidified, compressed, cooled in a natural-coolant chiller, then rectified to a purity of 99.95%.
The liquefied CO2 is stored in standard cryogenic tanks and transported by tanker truck. The demonstration equipment will include five tonnes of liquid CO2 storage, while the commercial model will occupy the space of two 20-foot containers.
The project follows an earlier initiative in Gamagori City that supplied captured boiler CO2 to mandarin orange growers, although this was limited by the need to transport gas-phase CO2. Liquefaction is seen as essential for meaningful CCU volumes.
During next year’s demonstration, Niterra plans to sell the resulting liquid CO2 through local gas companies in order to validate the commercial model.
Niterra and Hitachi have already begun discussions with liquid CO2 manufacturers regarding tanker collection. According to Niterra’s modelling, a 10 tonne per day system could deliver about 2,000 tonnes per year of liquid CO2.
If sold at ¥30 ($0.19) per kg, annual revenue could be roughly ¥60m ($383m), although installation, operating and maintenance costs will determine the final economics.