What To Do With Captured CO2

Updated 14 March 2022

Early in February, Mitsubishi Heavy Industries announced that they will build the world's first ship for transporting carbon dioxide solely from carbon-capture facilities. The demonstration ship, which will be able to haul 1,450 cubic meters of liquefied CO₂, is scheduled to be operational by late 2023.

The Japanese shipbuilding giant joins a list of ambitious projects that plan to ship CO₂ from the power plants and factories where it's emitted to sites where the gas can be used or permanently stored. By providing a cost-effective option to transport the greenhouse gas, CO₂ shipping could provide an impetus for large-scale deployment of carbon-capture utilization and storage (CCUS).

Carbon capture is picking up steam around the world as heavy industries and power plants try to meet emissions-reductions targets. Twenty-seven commercial CCUS projects are operational as of 2021, with another 108 in the pipeline. And while technologies for capturing CO₂ or utilizing it to make chemicals and fuels get a lot of attention, transport of the greenhouse gas is critical but often overlooked.

Pipelines are good for moving CO₂ over short distances, but they get increasingly expensive with increasing distance. Ships, on the other hand, could safely transport varying amounts of CO₂ over long ranges for a relatively low cost, says Toby Lockwood, a carbon-capture technology and markets expert at the Clean Air Task Force, in London.Shipping is especially appealing for certain places in the European Union, the United Kingdom, and Japan that have a keen interest in carbon capture but don't have the right geological formations for storage, he says. Shipping is good for small volumes and for coastal sites, and it's flexible and scalable."

Mitsubishi might be the first to float its ship, but the Norwegian project Northern Lights, slated to be operational by 2024, will be the biggest and first cross-border CO₂ transport and storage network. Equinor, Shell, and TotalEnergies launched the project in 2021, and it has 1.7 billion in funding from the Norwegian government.

China's Dalian Shipbuilding will build two 7,500-cubic-meter-capacity carriers for Northern Lights to ship captured CO₂ to be stored permanently deep in a geological reservoir under the seabed in the North Sea. By 2024, Northern Lights aims to transport and store about 0.8 million tonnes of CO₂ from a cement factory and a waste-to-energy facility in Norway, with plans to expand capacity to 5 million tonnes.

When the Northern Lights project begins operations in mid-2024, ships will take captured carbon dioxide from onshore sites to a terminal in western Norway for intermediate storage, before being piped to a reservoir under the seabed for permanent storage.Northern Lights

The project is spurring commercial interest and is now linked with nine potential carbon-capture facilities across Europe. With a recently announced partnership with carbon-capture company Aker Carbon Capture, it should offer companies across Europe an all-in-one value package to capture and store their emissions. The Norwegian project is the only one that has money on the table, but people are expecting it to kick-start a bigger thing," Lockwood says.

Indeed, several other shipping companies have recently announced interest in building carriers for captured-carbon transport. Japan's NYK and the Knutsen group of Norway in January established a joint venture to develop a CO₂ marine transportation and storage business. Shipping giant Mitsui O.S.K. Lines has invested in Norway's Larvik Shipping as part of its plans to study CO₂ transport for CCUS. Several shipping companies that transport liquefied natural gas (LNG), including Belgium's Exmar, Denmark's BW Epic Kosan, and Norway's Hoegh, are all planning their own large-scale CO₂ transport operations.

Shipping CO₂ seems in general to be more of a European and Asian phenomenon, says Lockwood. But a new company called Ecolog, connected to the LNG shipper Gaslog, is now interested in large-scale shipping of CO₂ between Europe and the United States as well as other places like the Middle East, he says, which is not something I've heard proposed before."

Shipping is good for small volumes and for coastal sites, and it's flexible and scalable."

All these ships will carry liquefied CO₂ in large pressurized cargo tanks. Liquefied CO₂ is already shipped around the world for the food and beverage industry. But shipping the gas at the scales required for CCUS brings technical challenges. There are different conditions in which it can be kept, and lots of debate about the best way to keep it," Lockwood says.

The Northern Lights ships, for instance, will carry CO₂ at medium-pressure conditions of 1.5 megapascal pressure at -26 C. But that won't work as ships get bigger, he says. The massive steel tanks needed to carry more than 10,000 m³ of CO₂ at that pressure become expensive and carbon intensive to haul. At some point we are going to need bigger ships and lower pressure conditions of 0.7 MPa and -15 C."

Larger carriers should also help reduce CO₂ shipping costs over time. Right now, companies have signed agreements to pay 30 to 50 for transporting a tonne of CO₂, according to Northern Lights. But capture and transport costs are still a barrier for many companies. Government subsidies would help, of course. But more companies with large, dedicated CO₂ carriers competing for business could also boost a steadily growing CCUS ecosystem.