The Bottleneck Beyond Carbon Capture

Capturing CO2 is no longer the biggest challenge for CCS. Transport, storage and financing are, says Abby Samson, who spoke to Sam Baker about her work with Mitsubishi Heavy Industries

ONE OF the earliest patents filed for amine-based carbon capture technology was granted in 1933 when aqueous alkanolamines were first used to sweeten natural gas. Nearly a century on, power stations, cement works and fertiliser plants continue to emit billions of tonnes of unabated CO2 each year.

So, what’s holding the technology back? “

In all honesty, the technology is robust and it’s there,” says Abby Samson, a member of IChemE’s Clean Energy Special Interest Group. She spent more than a decade in academia, including with the University of Sheffield’s carbon capture and storage research group, and is now a senior manager in Mitsubishi Heavy Industries’ carbon capture division across Europe, the Middle East and Africa. “The biggest challenges we’re seeing now have to do with the pipeline or the transport or whatever happens to the CO2 afterwards.”

Like many advanced post-combustion carbon capture technologies – where CO2 is absorbed directly from flue gas at source – MHI’s system uses a proprietary amine solvent which it has been developing since the 1990s. Samson says it has a very low degradation rate, and “much better thermodynamic properties” than others.

MHI installed its first carbon capture unit in 1999 at a fertiliser plant in Malaysia. Its technology is now used commercially at 18 plants worldwide and has been selected for the Padeswood cement works in north Wales, where the carbon capture system is expected to become fully operational in 2029.

A mature technology

Historically, adapting carbon capture systems to different flue gases has been a major challenge. Emissions from a gas-fired cement works are relatively consistent, while those from waste incineration can vary significantly and contain more impurities.

Samson believes these barriers have largely been overcome. Advances in flue gas pre-treatment, clean-up and demisting mean amine-based systems can now be applied across most industrial sources.

“The actual technology is the same,” she says. “If you zoom out it’s a standard amine process,” only differing by the pre-treatment of the flue gas, either with an acid wash or water wash.

With large-scale systems already proven, attention is also shifting to smaller emitters. Facilities such as waste-to-energy plants often face tighter space and planning constraints than large power stations.

“We’re seeing a trend towards smaller emitters now also needing to decarbonise,” she says. To address this, MHI has developed a “modularised approach” to their units, in addition to their conventional offering which she describes as looking like a “giant dinosaur”.

“We don’t really have an issue with the capturing,” says Samson. “It’s the rest of the infrastructure that makes the project viable or not.”

Problems beyond capture

A key challenge is how to handle CO2 once it has been captured, particularly for sites located far from transport networks.

“A large number of emitters don’t have a pipeline or anything to do with the CO2 afterwards, so they’re looking at utilisation,” Samson says. The problem with utilisation, she argues, is that the market for CO2 is currently limited and unlikely to absorb the volumes required.

Finding viable storage for the CO2 is another hurdle, one which Samson says can prevent even a “great idea” attracting investment.

Creating clusters of carbon capture projects, where emitters share CO2 transport and storage infrastructure, is one way forward. Samson is particularly enthusiastic about the UK government’s expanding cluster programme. “This time it looks really quite different,” she says, noting the growing focus on transport and storage. “It has spread the risk a lot more fairly I think.”

Financing the transition

Ultimately, the challenge is less about technology than about system integration and investment. “

We are able to scale up. We are able to scale down. We are able to deal with different flue gases and different conditions and different environments,” Samson says. “The biggest issues that we have are on the derisking and the financing of these projects.

“If we can get the carbon capture projects to self-finance and be less reliant on government subsidies, that’s really important for CCS.”