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IMO and onboard carbon capture, storage and sequestration (long read)



quipped with onboard CO2 capture and storage (CCS) systems
Photo: Evergreen’s Neopanamax container vessel Ever Top, equipped with onboard CO2 capture and storage (CCS) systems.


As the maritime industry works towards decarbonisation, International Maritime Organisation (IMO) is driving the advancement of regulatory frameworks and supporting the adoption of innovative technologies, such as onboard carbon capture and storage (OCCS) and CO2 sequestration.


These initiatives, led by the Intersessional Working Group on Greenhouse Gases (ISWG-GHG) and other IMO bodies, have been described as crritical elements in addressing the shipping sector’s environmental footprint and ensuring IMO’s climate goals for 2050 are met.

Discussions within various IMO committees are shaping the future of CO2 management, highlighting both the technological possibilities and the regulatory challenges that must be addressed.


One of the central themes emerging from IMO’s recent work is the development of regulatory measures for OCCS.


Norway has been at the forefront of these discussions, providing detailed insights into pilot projects and case studies that demonstrate the potential of onboard carbon capture systems.

In a submission to IMO, Norway outlined the ongoing full-scale pilot project on 2019-built, 21,289-m3 Clipper Eris, an LPG tanker equipped with a carbon capture plant. This system, utilising scrubbers and a wet electrostatic precipitator, is designed to capture up to 70% of the CO2 emissions from the ship’s exhaust gases.


According to the submission, “The goal is to demonstrate CO2 can be captured from heavy fuel oil and stored aboard in deck tanks, and to gain experience on operational aspects of the process, energy consumption and maintenance needs of the system” (ISWG-GHG 16/4/1).

The success of this project could pave the way for broader adoption of OCCS systems, especially in hard-to-abate segments of the shipping industry.


While OCCS technologies hold great promise, they also face challenges. High capital expenditure and operational expenditure present economic barriers, as noted in several submissions to IMO.


In Norway’s case study on a 15,000-TEU container ship fitted with an OCCS system, the costs were compared against alternative compliance strategies, such as transitioning to LNG or ammonia fuels.


“The low-cost CCS scenario performs well compared with other fuel strategies... if carbon capture technologies can reach low fuel penalties and a CCS industry is developed with offloading infrastructure” (ISWG-GHG 16/4/1).


This underscores the need for a well-developed regulatory framework to support OCCS deployment, to reduce uncertainties and provide shipping companies with the confidence to invest in this technology.


Another major focus of IMO’s work on CO2 management is the sequestration of CO2 in sub-seabed geological formations.


Italy’s submission to IMO provided detailed information on its first experimental project for CO2 geological storage, which involves injecting CO2 into a depleted gas field in the Northern Adriatic Sea. The project aims to store 50,000 tonnes of CO2 over two years, marking a critical step in Italy’s efforts to develop its regulatory framework for sub-seabed sequestration.


“The technical assessment dealt with various aspects, related to the static geological model, the tsunami risk, monitoring soil deformations and related risks,” according to the submission, which highlights the multi-disciplinary nature of such projects (London Protocol Scientific Group 47-INF.4).


The Italian submission also touches on the need for clear regulatory guidance to manage impurities in CO2 streams, which can complicate the sequestration process. Impurities like water or sulphur dioxide in captured CO2 can lead to corrosive reactions, posing challenges for long-term storage, an issue echoed in other submissions.


In a related submission, the Correspondence Group on Experiences with the CO2 Streams Assessment Guidelines stressed the importance of monitoring incidental associated substances from the source, capture, or injection process, and trace substances added to assist in monitoring and verifying CO2 migration. These factors must be carefully monitored to avoid adverse environmental impacts (London Convention 45-INF.5, Correspondence Group submission).


In addition to sequestration, the potential role of CO2 as a feedstock for synthetic fuels has gained attention.


China’s proposal to IMO explores the possibility of crediting CO2 emissions that are captured and reused in the production of synthetic fuels. The paper argues that “emissions credits from industrial captured CO2... could play a role in reducing the overall greenhouse gas footprint of shipping” (ISWG-GHG 17/3/2).


This approach aligns with the broader decarbonisation strategy by promoting carbon-neutral fuels, which could become a significant component of the maritime sector’s future energy mix.

IMO’s work on revising the International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code) also plays a crucial role in ensuring the safe transport of liquefied CO2. Current proposals focus on improving safety measures to account for the unique hazards posed by CO2.


As noted by the Society of International Gas Tanker and Terminal Operators (SIGTTO), “CO2 is not assumed to be corrosive, but in the presence of impurities such as water and sulphur dioxide, it can form acid, which can cause corrosion” (Sub-Committee on Carriage of Cargoes and Containers 9/4/3, SIGTTO submission).


The proposed revisions to the IGC Code include enhanced monitoring systems for CO2 cargoes, particularly focusing on thermodynamic properties, pressure control, and impurity management to mitigate risks of solidification or structural damage during transport.


IMO has also gathered feedback from its contracting parties on their experiences with CO2 sequestration projects, which will help shape future regulatory updates. A questionnaire circulated among member states revealed a range of responses, with some countries, like Norway and Japan, having well-developed frameworks for CO2 storage, while others are still in the early stages of developing regulations.


The responses indicate that monitoring and financial liability remain key concerns for countries looking to implement CO2 sequestration projects.


“Monitoring CO2 injection sites for potential leaks remains a priority... reliable and low-cost methods such as spot-seismic technology have been used in pilot projects” (LC 45-INF.5).


These insights will be crucial as the IMO continues to refine its CO2 Sequestration Guidelines and establish best practices for long-term monitoring and risk management.






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