Transport is that stage of carbon capture and storage that links sources and storage sites.
CO2 is transported in three states: gas, liquid and solid. Commercial-scale transport uses tanks, pipelines and ships for gaseous and liquid carbon dioxide. Gas transported at close to atmospheric pressure occupies such a large volume that very large facilities are needed. Gas occupies less volume if it is compressed, and compressed gas is transported by pipeline. Volume can be further reduced by liquefaction, solidification or hydration.
Liquefaction is an established technology for gas transport by ship for LPG (liquefied petroleum gas) and LNG (liquefied natural gas). Liquefied natural gas and petroleum gases such as propane and butane are routinely transported by marine tankers; this trade already takes place on a very large scale. Carbon dioxide is transported in the same way, but on a small scale because of limited demand. The properties of liquefied carbon dioxide are not greatly different from those of liquefied petroleum gases, and the technology can be scaled up to large carbon dioxide carriers
This existing technology and experience can be transferred to liquid CO2 transport. Solidification needs much more energy compared with other options, and is inferior from a cost and energy viewpoint. Each of the commercially viable technologies is currently used to transport carbon dioxide.
In the context of long-distance movement of large quantities of carbon dioxide, pipeline transport is part of current practice. Liquefied gas can also be carried by rail and road tankers, but it is unlikely that they will be considered attractive options for large-scale carbon dioxide capture and storage projects. Future power plant owners may find carbon dioxide transport component one of the leading issues in their decision-making.
Transport in dedicated pipelines is the most promising method for delivering captured CO2 to storage facilities, though other methods, such as barges or ships for ocean storage, have been suggested. The oil and gas industry has years of experience with CO2 pipelines, transporting CO2 hundreds of kilometers for use in EOR operations.
Large-scale CO2 transport would undoubtedly require the development of additional infrastructure, though there may be limited opportunities to use existing oil and gas pipelines when the fields they serve are retired and converted to storage sites.
Transport costs often depend on a fortuitous matching of CO2 sources and storage locations, generating considerable variations in cost. The combined costs of transport and storage are typically estimated to range from about $20/tC to $55/tC.
Operation and maintenance costs are small in comparison, and the average cost of transporting CO2 falls dramatically with scale.
Transport costs are also reduced significantly when CO2 has been pressurized to its liquid form, though most storage options require pressurized injection of CO2 anyway. Transport costs are estimated to be about $5/tC to $10/tC per 100 km.