One of the challenges that faces CCS is how to transport significant volumes of compressed CO2 from point sources to sites established for large-scale storage, especially offshore. Pipelines are one solution, but their viability depends on the volume to be transported and if the CO2 comes from a variety of dispersed sources.The other option is to use dedicated sea tankers that can deliver CO2 from one or more ports, either directly to an offshore storage site, or an intermediate shore-based facility connected via pipeline to the storage site.
IEAGHG commissioned a study with Element Energy, in collaboration with SINTEF Industry, Brevik Engineering and IOM Law. The objective of the study was to investigate and compare the technical and economic options of CO2 transported by sea tankers and pipelines. Ship transport offers flexibility but weather conditions can constrain the operational windows and therefore the amount of CO2 that can be delivered and stored.Two scenarios reviewed CO2 shipped to an intermediate shore based facility before transmission via pipeline to an offshore storage site. An alternative option investigated direct delivery of CO2 to an offshore storage site but without any holding time. Another option looked at direct delivery by a tanker to an offshore storage site with a temporary storage facility.This scenario would allow greater operational flexibility as it would enable CO2 to be stored without reliance on a docked tanker.
The study also looked at the cost of pipeline transport depending on the quantity of CO2 supplied and the distance compared with CO2 delivered by sea tanker. This study shows that the pipeline option is cheaper but only over shorter distances. A range of ship sizes, in terms of capacity, were reviewed to try and identify if economies of scale could be achieved. It also explored current international regulations that govern international CO2 transport.
Of the four scenarios modelled, and based on a shipping distance of 1,000 km, there is little cost advantage from increasing the ship size above 10,000 tCO2. Conversely, there is also little penalty in cost by using larger ships. However, the optimum ship size will be highly dependent on the flow rate. Ideally, size and capacity could be customised for each specific logistics chain.