The Global Centre for Maritime Decarbonisation (GCMD) released a Life Cycle Assessment (LCA) for Project CAPTURED. Completed in June 2025, this initiative achieved the world’s first ship-to-ship offloading of captured liquefied CO2 (LCO2) for downstream use. The report details the project’s total greenhouse gas (GHG) emissions.
Verified by DNV, the LCA assesses the project’s total GHG impact and savings. It follows the CO2 lifecycle from onboard capture through multiple transfer points. This includes ship-to-ship and ship-to-truck logistics, followed by overland transport. The chain ends with the successful utilization of the CO2 at an industrial facility.
There, the CO2 was used as a feedstock to recycle steel slag into post-carbonated slag (PCS) and produce precipitated calcium carbonate (PCC) through carbon mineralization. In this process, the captured CO2 is chemically converted into stable carbonates, fixing carbon long term.
OCCS as a mid-term decarbonization pathway—and why LCA matters
Onboard carbon capture and storage (OCCS) is increasingly recognized as a promising mid-term pathway to reduce emissions from vessels that continue to rely on conventional fuels. By capturing CO2 from exhaust gases, OCCS can significantly reduce onboard fuel-combustion (“tank-to-wake”) emissions. However, its true contribution to decarbonization must be evaluated across the entire carbon value chain, including its final utilization and/ or permanent storage.
An LCA quantifies these full-chain GHG impacts transparently and systematically, evaluating that emissions savings achieved onboard are not offset by upstream or downstream burdens.
Professor Lynn Loo, CEO of GCMD, said, “Project CAPTURED shows that onboard carbon capture, when thoughtfully integrated with utilization pathways, can deliver real emissions reductions today while we continue to scale up low- and zero-carbon fuels. If our frameworks continue to ignore avoided emissions and displaced carbon, we risk disincentivizing investments in solutions that can meaningfully bend the emissions curve.”
Scenarios evaluated
The study presents a detailed LCA of the carbon value chain demonstrated in Project CAPTURED. Building on this baseline, the study also examined two hypothetical scenarios, one in which the inefficiencies associated with the first-time pilot are addressed and another in which captured CO2 is permanently sequestered in an offshore reservoir.
In the utilization scenarios, producing PCC with captured CO2 displaces conventional carbon-intensive production methods, while the use of PCS replaces standard sintering materials in steelmaking, resulting in a reduction of emissions that would have otherwise been released (“avoided emissions”).
GHG emissions savings demonstrated
Project CAPTURED, with OCCS operating at a 10.7% capture rate, demonstrated 7.9% GHG emissions savings across the entire carbon value chain. This corresponds to 0.84 tonnes of CO2 savings realised per tonne of CO2 captured and offloaded from the vessel. These savings were achieved despite several operational constraints, including the absence of a waste heat recovery system onboard that increased the fuel penalty, long-distance overland truck transport, as well as CO2 venting during offloading and handling.
When these inefficiencies are addressed, GHG emissions savings increase markedly to 17.8%, equivalent to approximately two tonnes of CO2 avoided per tonne of CO2 captured and offloaded from the vessel.
CO₂ utilisation can avoid more GHG emissions than permanent storage
The study finds that the specific CO₂ mineralization pathway in this pilot outperforms permanent storage.
At comparable capture rates of 40%, mineralizing CO₂ yields 34% GHG emissions savings, compared with 21% if CO2 were sequestered in an offshore reservoir. When the value chain is optimized, this gap widens further, with the total GHG emissions savings rising to 68-71% depending on whether the PCS produced is used in steel sintering or in concrete production.
This comparison reveals that CO₂ utilization by carbon mineralization can deliver greater overall climate benefits than permanent storage when captured CO2 is durably fixed over extended periods, defined under the EU ETS as 100 years or more, and as in the case of PCC that is used in construction.
Current GHG accounting frameworks understate the benefits of CO2 utilization.
At present, the IMO’s GHG accounting frameworks—including its Data Collection System, Carbon Intensity Indicator, and LCA guidelines—do not recognize or account for avoided emissions from when highly emissive conventional products are displaced by captured CO2-derived counterparts.
As a result, the environmental benefits of CO₂ utilization pathways risk being systematically underestimated in formal reporting, despite their potential to avoid more emissions across the wider value chain.
