New study pinpoints opportunities and challenges of OCCS to decarbonize shipping

The onboard carbon capture and storage (OCCS) technology has the potential to help maritime transport significantly reduce its greenhouse gas emissions; however, many challenges still need to be addressed, a new study has shown.

The project Realising Maritime Carbon Capture to Demonstrate the Ability to Lower Emissions (REMARCCABLE) was carried out by the Oil and Gas Climate Initiative (OGCI), the Global Centre for Maritime Decarbonisation (GCMD) and Stena Bulk together with a consortium of maritime industry players. These include classification societies American Bureau of Shipping (ABS) and Lloyd’s Register (LR), as well as the companies Alfa Laval, Deltamarin, Seatrium, and TNO.

The engineering project examined the design and cost implications of retrofitting a carbon capture system on the medium-range (MR) tanker Stena Impero. The research showed that this technology could reduce the vessel’s carbon dioxide (CO2) emissions by up to 20% annually, with a fuel consumption increase of just under 10%, according to the project partners.

The estimated cost for building and installing the complete system on the Stena Impero is approximately $13.6 million, resulting in an abatement cost of $769 per ton of avoided CO2 for the prototype. However, the consortium anticipates that further research and development will lower these costs, enhancing the viability of onboard carbon capture and storage for the shipping industry.

The study also explored the integration of OCCS in new vessels, suggesting that advancements in capture rates and fuel penalties could be achieved through the use of more efficient engines, heat pumps, and alternative solvents.

“OCCS has gained traction in recent years as a feasible approach to meet the 2023 IMO revised GHG emissions reduction targets. However, its adoption faces numerous hurdles, including the need to balance the tension between maximising CO₂ capture rates while maintaining commercially acceptable CapEx and OpEx. This study provides quantitative insights on managing the trade-offs between the actual cost of operating OCCS and its emissions reductions potential,” Professor Lynn Loo, CEO of GCMD, said.

“For OCCS systems to be practical, the industry needs to manage captured CO₂ effectively. To this end, GCMD has previously completed a study to define the operational envelope for offloading onboard captured CO₂, contributing to the whole-of-system approach to emissions reduction via carbon capture,” Loo added.

• ClassNK: Practical operation of onboard CCS is significant for maritime decarbonization goals
• DNV: Commercial uptake of OCC relies on industry collaboration
• Low port readiness is main hurdle to wider adoption of onboard CCS, study finds
• DNV: Onboard CC and nuclear propulsion can compete with other decarbonization solutions

Since the project began, OCCS has progressed from a technology that very few in the industry discussed to a serious option being considered within the regulatory framework of the European Union (EU) and the International Maritime Organization (IMO). As per the regulatory framework, the industry awaits guidance from IMO’s Correspondence Group tasked with developing a framework for OCCS in MEPC 83.  

A few days ago, the international organization reported that progress has been made toward finalizing the net-zero framework, set for approval at the ‘critical’ MEPC 83 meeting in April 2025. The group has been instructed to consider all possible options to address the challenges and gaps of the net-zero goal, and then develop draft amendments to existing instruments, or develop new instruments.

On the operational front, challenges include recurring additional costs due to fuel penalties, amine solvent replenishment, manpower, maintenance and offloading services, the partners highlighted.

Offloading captured CO2 is still in its early stages, facing challenges due to the absence of national and port policies for tracking captured CO2 and its final disposal. Additionally, there is insufficient infrastructure at ports to facilitate offloading and storage.

To address these issues, collaboration among stakeholders across the value chain is essential for developing the necessary offloading infrastructure and onshore storage solutions. Furthermore, logistical and policy support for the permanent sequestration or utilization of the offloaded CO2 will be crucial to promote the adoption of onboard carbon capture and storage solutions.

“This may be expensive for first movers, but the consortium believes that further research and development will drive down costs, making OCCS an increasingly viable solution for the shipping industry,” Erik Hånell, President and CEO of Stena Bulk, said

“The results will be instrumental for not only us, but for the whole sector, to evaluate the operational and commercial opportunities, as well as the challenges when capturing CO₂ at sea,” he concluded.