Funneling carbon: The ship exhaust carbon capture race

The IEA has said carbon capture utilisation and storage needs to grow if shore based industries are to meet their responsibilities in curtailing greenhouse gases. The technology is not new but is set to expand in use. One area is in shipping where the industry is also under pressure to curb CO2 emissions. Work has now started in Norway and Japan to see if the technology can be marinised in time to be a viable solution in the industry’s race to 2030 and beyond.
Craig Eason looks at the latest developments

Work to create the technology to scrub sulphur oxide emissions from a ship’s exhaust began over 20 years ago when engineers took what is a well-established shore-based industrial process and adapted it to marine use.

Exhaust gas cleaning systems are now established technologies in shipping – there’s a handful of companies selling solutions that enable ships to use (cheaper) fuels with high sulphur content but have emissions that meet the global limits expected from low sulphur, but more expensive, fuels.

The same idea is now being applied to carbon dioxide removal. Industrial carbon capture (and then using the CO2 or sequestering it) is being seen as a key climate change mitigation tool around the world.

Capture the CO2 emissions and send them either through pipelines or a shipping network to a place of permanent storage rather than let them go into the air and add to the problem. But like Sox scrubbing, carbon capture is not new. Some of the oldest carbon capture plants are now well over 20 years old.

So there are now embryonic plans to take the technology, shrink it, and add CO2 cooling and storage and sell the idea as a shipboard process that will help the industry meet some of its decarbonisation challenges.

Three companies have begun the race and are separately test feasibility. Two companies are in Norway, Wärtsilä and Teco 2030, and one in Japan, Mitusbishi Heavy Industries. None of these are anywhere near commercial role out of a shipboard system yet.

Teco 2030 recently announced the completion of a feasibility study, while Wärtsilä plans land-based trials soon, and Mitsubishi has plans for a limited shipboard test later this year with its partners.

The case for using carbon capture on a ship

A lot of the current focus on transforming shipping is on the development of new fuels, either ones with zero emissions, such as ammonia or hydrogen, or ones that stillemit CO2 but are created by using captured CO2, so are labelled carbon-neutral, such as e-methanol and biofuels.

Carbon capture comes into the argument as a way to still use fossil fuels, but offer a technology solution to significantly cut CO2 emissions below limiting levels for ships. While there are many technology and feasibility questions around onboard CCS, there are a lot of political questions too, such as carbon pricing, carbon capture being an accepted equivalent technology.

So while it remains to be seen if onboard CO2 capture will be a suitable technology for shipping, experts like Sigurd Jenssen at Wärtsilä and Kazuki Saiki at Mitsubishi believe that the technology could, if it proves technically feasible, be applicable to both existing vessels and newbuilds and be a significant contribution to overcome the challenges the industry faces.

Jenssen, who runs Wärtsilä’s exhaust gas cleaning business in Norway, sees a significant potential for vessels which are running off LNG to meet their 2030 emission  targets if they do not already do so.

 But the challenges these technology companies face in the long journey to commercialisation are not small. Any onboard carbon capture system requires components that capturing, cooling and then store the CO2, none of which are processes with small solutions.Then there wil be the need for a CO2 storage tank and the required port infrastructure to offload and deal with it.

Wärtsilä’s Sigurd Jenssen says that the technology Wärtsilä is looking at using is similar in scope to a SOx scrubber, in that a liquid is sprayed through the engine exhaust to capture the relevant gas and then the liquid is then cleaned of the gas molecules which are then stored and disposed of. For CO2 capture the process requires a chemical known as an amine, or rather specific types of amine (monoethanolamines) which have the properties to absorb CO2 from an exhaust stream. After being passed through the exhaust the amine will need to be cooled to help separate the CO2 molecules and then reformed so it can be re-used. Which adds to the complexity of the CO2 processing system.

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