The development and comparison of CO2 BOG re-liquefaction processes for LNG fueled CO2 carriers

CO2 carriers are considered as a solution for CO2 transport as a part of Carbon Capture and Storage. CO2 carriers' design is similar to that of commercial liquefied gas carriers and core technology of liquefied gas carriers is to handle boil-off gas during voyages. This paper introduced newly developed CO2 boil-off gas re-liquefaction processes making use of cold LNG fuel and investigated economic feasibility of newly developed processes by comparison with a conventional boil-off gas re-liquefaction process. New processes enabled considerable main equipment costs saving and additional fuel cost saving for re-liquefying boil-off gas. Simulation study results showed total amount of boil-off gas in a LNG fueled CO2 carrier could be re-liquefied by LNG fuel consumed during the voyage and comparative cost assessment results demonstrated those newly developed processes could be applied into a LNG fueled CO2 carrier with insignificant additional cost. The finding of this paper confirms those newly introduced processes are technically and commercially feasible at present and will contribute to growing the potential market of LNG as a marine fuel as well as commercializing CCS technology by providing more cost-effective solution for CO2 shipping.