Influence of system boundary conditions on the life cycle cost and carbon emissions of CO2 transport

One of the critical stages in carbon capture and storage (CCS) is the transport of CO2 from the point of capture to the storage site. Besides pipeline transport, the present proposition of marine CO2 transport is to make use of vessels that transport chemicals of similar physical properties to CO2 such as liquefied propane gas (LPG) and liquefied natural gas. Through a life cycle analysis, this study examines the influence of system boundary con-ditions on the total cost and benefits of CO2 transport using a reference LPG tanker. While the levelized cost of transport (i.e. shipping) can be intuitively obtained at 31.65-47.05$/t when LPG and CO2 are assumed to be transported as cargos between two fixed ports, the total system-level CO2 emission is contentious when the greater "interconnected" systems including LPG and a fictitious power plant life cycle are considered. Base on the analysis of the proposed most reasonable boundary condition, a break-even carbon price is further examined and found to be ranging from 39.37 to 22.32$/t-CO2. While the boundary conditions can influence the break-even price of CO2, such variations and the associated change in boundary conditions can be used to facilitate pol-icy debate on the right carbon price for international shipping.