CO₂ capture from ships: An in-depth multi-criteria screening of CO₂ capture technologies

Shipping is the backbone of global freight. Due to its currently strong reliance on fossil fuels, it accounts for 3 % of global greenhouse gas emissions, highlighting both the need and challenge of achieving the required rapid decarbonization. Over the past decade, onboard carbon capture and storage (OCCS) has gained interest as a potential mitigation strategy while alternative fuels continue to develop. This study screens different capture technologies, including absorption, membrane-assisted liquefaction, adsorption-assisted liquefaction, and calcium-looping, using a combination carrier as a case vessel under retrofit and newbuilding scenarios. Overall, the results indicate that retrofit installations can reduce onboard CO₂ emissions by at least 45 %, even when using the existing ship power system, thereby complying with FuelEU Maritime requirements until 2040. Once heat, power, and space are assumed sufficient (newbuilding scenario), 90 % reduction or higher becomes feasible, enabling compliance with FuelEU Maritime targets until 2045 and, for some processes, until 2050. Although the additional fuel usage is not negligible in both scenarios, the net emission reduction remains substantial, confirming OCCS as a viable ship decarbonization option. Among the evaluated options, membrane-assisted liquefaction shows the most favorable energy and space performance, while absorption and CaL-based concepts remain relevant under heat-available and energy-limited conditions, respectively. The results also show that OCCS performance is highly case-specific and depends on ship type, available heat and power, fuel costs, regulatory targets, and downstream CO₂ handling. These findings show that OCCS can deliver substantial, case-dependent CO₂ reductions, while techno-economic and full-chain assessments are needed to confirm commercial deployment potential. © 2026 The Authors. Published by Elsevier Ltd on behalf of Institution of Chemical Engineers (IChemE). This is an open access article under the CC BY license. http://creativecommons.org/licenses/by/4.0/