The Intergovernmental Panel on Climate Change (IPCC) global warming scenario of 1.5 degrees Celsius by 2100 assumes an annual CO2 reduction of 6 billion tonnes from carbon capture and storage by 2050. This CO2 must be transported from capture to storage or use. . For comparison, today's annual transportation of coal is about 7.5 billion tons.

CO2 can exist in gaseous, liquid, solid or supercritical fluid form depending on temperature and pressure. There are different CO2 capture technologies. Chemical absorption, membrane separation and electrochemical capture systems deliver the captured CO2 in high purity gas form. Cryogenic capture technologies deliver captured CO2 in solid form like dry ice. CO2 storage in deep onshore or offshore geological reservoirs occurs with CO2 in the supercritical liquid phase. The Icelandic company CARBFIX has developed storage in shallow offshore or offshore wells in the young basaltic rock covering most of Iceland. With this technology, CO2 is dissolved in water, which is pumped into wells under moderate pressure. CO2 transport is most economical in dedicated CO2 pipelines when volumes are large and distances are not too long. In some cases, this also applies if the transport includes an ocean section. For smaller volumes or the transport of long ocean sections, it is more economical to transport CO2 in liquid or solid form. (Henrik Madsen)