Techno-economic Evaluation of Solvent-Based Carbon Capture Systems for Methanol-Fueled Ships

Abstract

This article evaluates onboard carbon capture (OCC) for methanol-fueled ships as a pathway toward maritime emission neutrality. Two vessel segments are analyzed, a feeder container ship and an ultra large container vessel (ULCV), and two solvent systems, a 30 wt % monoethanolamine (MEA) solution and a blend of 20 wt % MEA with 10 wt % methyldiethanolamine (MDEA). The capture units are integrated with a precooled Linde–Hampson liquefaction cycle and liquid carbon dioxide (CO2) storage at 1.6 MPa. A techno-economic assessment is carried out using four key performance indicators (KPIs), avoided CO2 rate, energy consumption per unit mass of CO2, cost of CO2 avoided, and cargo penalties in terms of dead weight (DWT) reduction. Results show that OCC can avoid more than two-thirds of the CO2 emissions when steam from a waste heat recovery unit (WHRU) is used. Avoided fractions of between 67% and 70% are obtained. Larger vessels benefit slightly less in relative terms because of lower recoverable waste heat per unit of captured CO2. Reboiler energy consumption (REC) remains close to 4 GJ per ton of captured CO2 for all cases, while compression and liquefaction dominate the specific electric consumption (SEC). The cost of CO2 avoided ranges from 216 to 230 USD per tCO2, roughly 2.5 to 3 times the current European Union (EU) emissions trading system (ETS) carbon price of 89.32 USD per tCO2. Cargo penalties are moderate, about 6% of the DWT for the feeder and 3% for the ULCV.