GCMD LCA shows Onboard Carbon Capture and Storage can provide major savings

In Singapore, a comprehensive life cycle assessment (LCA) conducted by the Global Centre for Maritime Decarbonisation (GCMD) quantifies Onboard Carbon Capture and Storage (OCCS)’s potential to provide GHG emissions savings. The study, named COLOSSUS (Carbon capture, offloading, onshore storage, utilisation and permanent storage), provides an in-depth analysis of GHG emissions and costs associated with OCCS across the entire carbon value chain, accounting for emissions from fuel production, transport and use, to CO2 capture onboard the vessel and its final disposition.

The study used a WtW GHG emissions of 93.3 gCO2eq/MJ for Heavy Fuel Oil (HFO) as a baseline for comparison against other scenarios. This study explored five OCCS technologies, with six marine fuel options, and three post-capture scenarios. Among OCCS technologies, the study examined different post-capture scenarios with conventional monoethanolamine (MEA)-based OCCS, with it being the most mature of the OCCS technologies in the industry. Based on the practical limitations of storing large quantities of liquid CO2 onboard vessels, the study further assumed a 40% gross carbon capture for all scenarios explored, consistent with industry recommendations.

Notably, the deployment of conventional MEA-based OCCS can result in a WtW GHG emissions savings of 29% for an HFO-fuelled ship.

Replacing HFO with biofuels presents a promising strategy for maximising GHG emissions savings. The WtW emissions savings for a vessel deploying MEA-based OCCS range from 69% to 121% when using bio-LNG and biodiesel from used cooking oil, respectively.

Among the post-capture scenarios evaluated, fixing the captured CO2 in concrete is most effective. This approach can increase GHG emissions savings from 29% to 60% across the carbon value chain by partially displacing the need for carbon-intensive cement in applications ashore.

Post-capture transport and permanent storage of CO2 add minimal emissions, approximately 1% to the WtW emissions of a vessel deploying MEA-based OCCS when the captured CO2 is transported 1,000 km.

Captured CO2 can also be used to produce e-methanol with renewable electricity, allowing the vessel that consumes this e-methanol to claim a 17% GHG emissions savings.

The cost of avoided carbon for OCCS with permanent storage is between USD 269-405/tCO2 for a 40% gross capture on an MR tanker, considering a full-scale, Nth-of-a-kind installation of an OCCS system with full heat recovery.