THE world's first ship-to-ship offloading of liquefied carbon dioxide (LCO2) captured directly from a containership has been achieved at Shanghai's Yangshan Port.

The operation involved Evergreen's 2014-built 13,800 TEU Ever Top, retrofitted with an onboard carbon capture and storage (OCCS) system in 2024.

The vessel transferred the captured CO2 to the barge Dejin while docked at Shengdong Terminal - in what is being hailed as a breakthrough that could transform carbon logistics across the shipping sector, reports Singapore's Splash 247.

Developed by the Shanghai Marine Diesel Engine Research Institute, part of the China State Shipbuilding Corporation, the OCCS system captures over 80 per cent of the vessel's carbon emissions at 99.9 per cent purity.

The technology allows the gas to be liquefied and transferred at sea, bypassing the need for specialised port infrastructure and making CO2 offloading more flexible and accessible.

With a retrofit cost of about US$10 million - less than half the price of converting to methanol or ammonia propulsion - the system presents a commercially viable solution for emissions reduction, according to project stakeholders.

More notably, the captured CO2 is not merely stored or sequestered - it's being sold into industrial markets, with project estimates suggesting it could generate as much as $8 million in annual revenue per vessel.

One of the barriers to maritime carbon capture has been the difficulty of offloading captured gases at port.

The STS transfer approach is seen as a practical workaround, allowing CO2 to be offloaded mid-voyage or near ports using smaller, nimble carriers that can operate closer to end-use markets.