Ship-based carbon capture takes a major step forward

Classified as a hard-to-abate sector, the maritime industry has ambitious plans to reduce its emissions by 50% from its current level by 2050. At a meeting of ministers from G7 countries in Japan in April, the officials doubled-down on this commitment, vowing to reach net-zero emissions from international shipping by 2050.

It goes without saying that reaching these lofty targets will require the emergence and wide-scale deployment of new low-carbon technologies. One of which that has made major inroads recently is ship-based carbon capture (SBCC), which could offer a low-cost solution in comparison to zero-emission fuels like ammonia and hydrogen.

The other key factor supporting the case for SBCC is that it could be implemented on the shorter term since SBCC does not need the development of new types of propulsion engines, which allows for a quick introduction of the technology in shipping for both newbuilds as well as retrofitted vessels.

Conversely, while battery-powered propulsion has been analysed for inland shipping, fully electric propulsion systems for utilisation in short-sea and maritime shipping are not expected to be feasible in the coming decades. Likewise, ammonia will also have a long runway towards being implemented if it is proven to be feasible. 

Given SBCC’s ability to make an immediate impact in decarbonizing the marine sector, the announcement in mid-August by TotalEnergies that it has installed an SBCC prototype on an LNG-powered LNG carrier, marks an important leap forward for the sector.

As part of the EverLoNG project led by Dutch research and development organisation TNO, the project will attempt to capture 10 tonnes of CO2 on board TotalEnergies’ vessel during a 3,000-hour test campaign. The trial will provide key data on environmental emissions as well as the impact of motion on carbon capture rates, capture solvent behaviour and degradation.

The carbon capture unit built in the Netherlands by Carbotreat will store the captured CO2 as a liquid onboard the pressurised vessel and then will be off-loaded and transported to either an industrial site or else stored in the subsurface permanently.

Following completion of the campaign, the SBCC equipment will be installed onboard a second vessel, Heerema’s LNG-powered Sleipnir crane ship. It will carry out a trial of 500 hours of CO2 capture operations to allow data analysis of the SBCC system performance on the two vessels.

Hopes are high for the project, with its developers targeting a 70% reduction in CO2 emissions from ships. In addition to demonstrating the carbon abatement credentials of SBCC technology, the project also aims to gain key insights that will help to drive down the expenses associated with CO2 capture and storage. The developers have set a target to reduce costs to below €100 ($108)/tonne by the end of 2025 with plans to drive down costs to below €50 ($54)/t in the near future. 

Given the relatively unchartered territory of the project, ground truths will be uncovered on a number of other elements concerning the captured CO2 including its off-loading, transportation, and storage. In turn, it is expected the project will provide key insights on the impact of SBCC on ships’ infrastructure and safety.

For LNG-powered ships, SBCC offers a seamless fit because gas-fuelled engines produce relatively clean exhaust gases, which in turn reduces the complexity of the CO2 capture system. Additionally, since the captured CO2 must be cooled in order to store it as a liquid, LNG stored onboard at super-chilled temperatures can be used for this liquefaction process. Consequently, this reduces both the energy required and cost of the capture system. 

Equally exciting though is that beyond onboard integration of SBCC, the technology could act as a launch pad for creating a nearly closed CO2 cycle for shipping, including the production of synthetic e-fuels such as synthetic methane from hydrogen and the captured CO2. 

Liquefied synthetic methane can be utilised directly in the LNG installations of LNG-powered ships since LNG typically consists of up to 95% of methane. Thus, by capturing the CO2 from using this e-fuel and then super-chilling it to liquid CO2 before returning it as a feedstock to the producer of the synthetic methane, the CO2 cycle is closed with the e-fuel serving as a hydrogen carrier. Therefore LNG-powered vessels have the potential to adapt to a green hydrogen economy in the future, further enabling the energy transition. 

As a hard to abate sector, the maritime industry has long faced an uphill battle in its journey to net-zero. But with emerging technologies such as SBCC moving ahead quickly an increasing number of pathways towards a low-carbon future are forming.