Techno-economic and environmental assessment of Onboard Carbon Capture for maritime net-zero compliance
Seyedvahid Vakili, Panos Manias, Stephen R. Turnock, D.A.H. Teagle
Abstract
The shipping sector faces mounting pressure to align with the International Maritime Organization's (IMO) revised greenhouse gas (GHG) strategy targeting net-zero emissions by 2050. Although zero- and near-zero (ZnZ) emission fuels may offer long-term solutions, their large-scale deployment is constrained by cost, infrastructure, efficacy and safety concerns. Onboard Carbon Capture and Storage (OCCS) systems may provide a transitional approach, and this study assesses the techno-economic and environmental feasibility of across four container vessel types powered by Marine Diesel Oil (MDO), liquefied natural gas (LNG), and methanol. Two OCC technologies—chemical absorption using monoethanolamine (MEA) and cryogenic separation—are evaluated in terms of energy demand, space requirements, lifecycle GHG emissions, and economic performance under the IMO's Net-Zero Framework. Results show that MEA-based systems offer the highest GHG reduction potential (up to 41.5 % for MDO) but at the cost of increased fuel consumption (15–30 %) and cargo capacity penalties (∼10 %). Cryogenic systems enhance safety but are more energy-intensive due to reliance on auxiliary power. OCC-equipped vessels can meet IMO GHG intensity targets through 2035, particularly when combined with biofuels, and provide up to a 2.2-fold cost advantage over purchasing Remedial Units (RUs). Although not a permanent solution, OCC offers a practical bridge toward maritime decarbonisation. Deployment requires policy support, port and geostorage infrastructure, and further innovation in capture technologies and waste heat integration. • OCC reduces WtW GHG emissions by up to 41 % for MDO, 37 % for LNG, and 28 % for methanol. • LNG–MEA gives highest efficiency; methanol–cryogenic suits short-sea; MDO–MEA is a cost-effective transition option. • Chemical absorption offers better abatement, but with increased heat and space demands. • Cryogenic OCC has lower energy efficiency but greater safety and simpler integration. • OCC leads to 15–30 % fuel penalties and up to 10 % cargo loss for studied container ships.