Amine-based CO2 capture on-board of marine ships: A comparison between MEA and MDEA/PZ aqueous solvents

International maritime shipping contributed nearly 3 % of global CO₂eq emissions in 2018. The IMO has set an ambition to reach net zero CO₂ emissions from maritime activities by 2050 with checkpoints of 40 % reduction by 2030 and 70 % by 2040 compared to 2008 baseline levels. In addition to alternative fuels (LNG, biofuel, methanol, hydrogen, ammonia) and efficiency-based technologies, mobile carbon capture (MCC, called also ship-borne/based carbon capture SBCC) could become a plausible technology to help meet these decarbonization aspirations. In this work, we performed a simulation to compare the use of methyl-ethanolamine (MEA) and methyl-di-ethanolamine/piperazine (MDEA/PZ) aqueous mixtures for chemical temperature swing separation of CO₂ on-board a ship. We studied the main MCC system integration and design parameters and demonstrated that MDEA/PZ could represent a more efficient and cheaper path than MEA due to the heat availability limitations from the exhaust stream of the ship. Specifically, MDEA/PZ could enable 10 % savings in heat demand at the reboiler compared to MEA (3.3 vs 3.7 GJ/tCO₂). Additionally, we showed that an MDEA/PZ amine-based CO₂ capture and storage unit on-board the ship could lead to as low as 191$/ton CO₂ avoided compared to 281$/ton of CO₂ when using MEA