Techno-economic and environmental evaluation of onboard carbon capture and storage system through heat integration and solvent selection

Onboard carbon capture and storage (OCCS) systems have garnered attention as attractive solutions to reduce greenhouse gas (GHG) emissions from marine sector. However, the high energy demands for solvent regeneration remain a major challenge. To address this issue, this study proposes an OCCS system that utilizes compression heat recovery from a CO2 liquefaction system in combination with amino methyl propanol-piperazine (AMP-PZ) and a heat pump. The proposed system decreased additional heat demand by 45.2 % in diesel mode and 73.7 % in liquefied natural gas (LNG) mode, compared to combination with monoethanolamine (MEA) and boiler. Although LNG mode results in lower CO2 emissions owing to its lower carbon content, its well-to-wake (WtW) GHG intensity is higher than that of the diesel mode owing to methane slip (2.1 gCH4/kWh) from LNG combustion in the main engine. Consequently, the proposed system in diesel mode achieved the lowest WtW GHG intensity of 37.51 gCO2eq/MJ. The reductions in additional heat demand and CO2 emissions led to lower CO2 avoidance cost (CAC) with reductions of up to 43.3 % in diesel mode and 36.6 % in LNG mode. When the FuelEU Maritime penalty is considered, all OCCS systems generate surplus credits until 2044, with the proposed system in diesel mode achieving the highest surplus. Although the system improves environmental and economic performance through heat integration, it will not meet GHG limits beyond 2045. These results indicate that further measures, such as ship pooling and capturing CO2 from auxiliary engines, will be required to ensure compliance in the future.