The GCMD study traced Project CAPTURED CO2 flows and found higher savings when pilot inefficiencies were removed, with utilisation outperforming storage
The Global Centre for Maritime Decarbonisation (GCMD) has published part two of a lifecycle assessment (LCA) quantifying greenhouse gas (GHG) emissions and savings across the Project CAPTURED carbon value chain, covering onboard capture and liquefaction through to offloading logistics and downstream use.
GCMD described Project CAPTURED as the world’s first ship-to-ship offloading of onboard captured and liquefied CO2 with downstream utilisation, completed in June 2025.
The LCA, verified by DNV, traced the captured CO2 from an oceangoing container vessel through ship-to-ship and ship-to-truck transfers, overland transport, and utilisation at an industrial facility.
"Current IMO GHG accounting frameworks... do not recognise avoided emissions"
GCMD said the CO2 was used as a feedstock to recycle steel slag into post-carbonated slag (PCS) and to produce precipitated calcium carbonate through carbon mineralisation, in which captured CO2 was chemically converted into stable carbonates intended to fix carbon long term.
The work was a way to assess onboard carbon capture and storage (OCCS) beyond tank-to-wake reductions, noting that full-chain impacts depended on downstream utilisation or permanent storage outcomes.
In the baseline pilot case, GCMD said OCCS operated at an 11% capture rate and delivered 8% GHG emissions savings across the full carbon value chain, equivalent to 0.84 tonnes of CO2 savings per tonne of CO2 captured and offloaded.
It attributed the lower baseline outcome to operational constraints that included the absence of a waste heat recovery system on board, long-distance overland truck transport, and CO2 venting during offloading and handling.
GCMD said that addressing these first-time pilot inefficiencies lifted full-chain savings to 18%, equivalent to approximately 2 tonnes of CO2 avoided per tonne of CO2 captured and offloaded.
GCMD also compared utilisation with permanent sequestration, stating that at comparable capture rates of 40%, the mineralisation pathway yielded 34% GHG emissions savings versus 21% if the CO2 were sequestered in an offshore reservoir.
It said optimisation widened the gap further, with total savings rising to 68–71% depending on end-use for the PCS produced, and linked the utilisation case to durable fixation over extended periods, citing the EU ETS definition of 100 years or more for permanent storage.
GCMD chief executive Professor Lynn Loo said, “Project CAPTURED shows that onboard carbon capture, when thoughtfully integrated with utilisation pathways, can deliver real emissions reductions today”.
GCMD argued that current IMO GHG accounting frameworks – including the Data Collection System, Carbon Intensity Indicator, and LCA guidelines – did not recognise avoided emissions from displacement of conventional products, which it said risked undervaluing utilisation pathways in formal reporting.
At Riviera’s Tanker 2030 Conference in Singapore in November 2030, Professor Lynn Loo received the Tanker Industry Leader Award 2025.
The award was accepted on her behalf by GCMD chief projects officer Wee Meng Tan.
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