Integrated modelling and simulation of liquefied CO2 tank and cargo handling system with new marine transportation greenhouse gas intensity

Ship transport of liquefied carbon dioxide (LCO 2 ) is competitive for long-distance transportation in the supply chain of carbon capture and storage, but inevitably has a problem of pressurization due to boil-off gas (BOG) generation from the low-temperature LCO 2 . Conventionally, BOG can be vented, but it results in increased greenhouse gas (GHG) emissions. This study suggests two advanced cargo handling systems (CHS) of continuously and periodically operated re-liquefaction for handling the LCO 2 BOG, and compares the GHG intensity with that of the BOG venting case. A new index of marine transportation GHG intensity (MGI) was developed to accurately evaluate the well-to-wake GHG intensity of shipping and advanced CHS. An integrated model of the tank and CHS was built to evaluate their continuous interaction. The results with BOR 0 (design specification of boil-off rate) of 0.15 % show that the venting case has a lower MGI up to 13 days of short voyage, but the re-liquefaction systems are preferable for longer voyages because vented CO 2 increases faster in the venting case. Additionally, the periodically operated re-liquefaction system can be considerable for a wide range of voyage days, as it enables flexible operation to cover shorter voyages with low BOR 0 . • We suggest continuous and periodic re-liquefaction systems for LCO 2 carriers. • A marine transportation GHG intensity (MGI) is suggested as a new index for ships. • We designed an integrated model of tank and CHS considering their interactions. • The tank behaviors of BOG generation and pressure build-up were analyzed. • We showed the optimal CHS by voyage days in terms of MGI.