In a key step toward maritime decarbonization, the IMO’s Marine Environment Protection Committee (MEPC) has adopted new guidelines to support the measurement and management of methane (CH₄) and nitrous oxide (N₂O) emissions, as well as the use of Onboard Carbon Capture and Storage (OCCS) systems. These efforts reflect growing recognition of non-CO₂ greenhouse gases in shipping and the potential of OCCS as a complementary tool in the global push toward net-zero emissions.
New Emissions Guidelines Adopted
The Committee adopted new testbed and onboard measurement guidelines for methane and nitrous oxide emissions from marine diesel engines. These guidelines aim to standardize how CH₄ and N₂O emissions are monitored, providing a foundation for future regulations. The increased attention on these potent greenhouse gases is essential, as methane and nitrous oxide have significantly higher global warming potentials compared to CO₂.
Re-established Correspondence Group
To further build on these guidelines, MEPC re-established the Correspondence Group on Measurement and Verification of Non-CO₂ GHG Emissions and Onboard Carbon Capture. The group has been tasked with:
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Developing a comprehensive framework to measure and verify methane and N₂O emission factors and fuel slippage from marine diesel fuels.
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Designing a regulatory structure for the use of onboard carbon capture systems, using a pre-approved work plan.
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Submitting a detailed report to MEPC 84.
This continued focus ensures that emission reduction strategies evolve alongside emerging technologies and reflect the complexities of real-world operations.
The Promise of Onboard Carbon Capture
According to Akshat Arora, Senior Risk Assessor at the UK P&I Club, OCCS technologies hold strong potential in the maritime sector’s decarbonization journey. These systems aim to capture carbon emissions before they are released into the atmosphere, storing them safely onboard for later disposal or utilization.
However, Arora notes that several key factors will determine the successful deployment of OCCS:
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Technical compatibility with shipboard environments, including space and integration with other systems.
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Economic viability, influenced by fuel availability, alternative options, and carbon pricing.
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Regulatory clarity, as comprehensive frameworks are required to govern the use, storage, and eventual offloading of captured CO₂.
Looking Ahead
With these new guidelines and task forces in place, the maritime industry is poised to explore innovative solutions that go beyond fuel-switching. Carbon capture and improved emissions measurement systems represent the next wave of green maritime innovation, aligning with the IMO’s goals to significantly reduce GHG emissions by 2050.
The developments at MEPC underscore the industry’s commitment to proactive, science-driven policy as it navigates the energy transition
