3.3 Transportation

3.3.1 Pipeline

For the transportation over short distances or for large amounts of CO2, pipeline is the preferred alternative. The CO2 is compressed to a pressure above 74 atmospheres in order to make it easier to handle. At this pressure CO2 diverts from the gas phase to a so-called supercritical phase, which means that it behaves like something between a gas and a liquid. The density at this pressure is greater than 700 kg/m3, which is close to the density of ordinary water.38 The compression is done with off-the-shelf technology and requires 100-150 kWh/tonne CO2 of energy.

There are currently more than 5 000 km of pipelines in the U.S. for the transport of CO2 for the oil industry’s Enhanced Oil Recovery (EOR) purposes,39 with a total capacity of around 50 million tonnes annually. The largest of these pipelines is the Cortez pipeline, which crosses three states and transports 20 million tonnes of CO2 per year through a pipeline with an internal diameter of 76 cm.40 The experience in the area of pipeline transport is therefore extensive and contains few uncertainties.

3.3.2 Ship

For transport over long distances and over water, transport by ship is an alternative. Today, there are ships carrying CO2 for industrial use, with a capacity of 1 250 − 1 500 tonnes. To render the CO2 manageable, it is cooled down to below -25 ° C and pressurized to 14-17 atmospheres. This makes the CO2 liquid and transportable in large tanks. Currently there exists multi-purpose ships which carry ethylene, but which could transport 10-12 000 tonnes of CO2 per shipload. In order to carry large volumes, such as several million tonnes per year, vessels with a capacity of 20 000 tonnes or more are proposed, but such ships do not exist today.

Picture 11 Ship for transport of liquid CO2. Photo: Yara International

3.3.3 Train and Truck

Neither trains nor trucks are suitable for transportation of large amounts of CO2. However, trucks are often used when smaller quantities of CO2 are needed for example in industrial processes, or in pilot projects for carbon capture and storage.

38 Elforsk 04:27, 2004

39 Parfomak och Folger, 2007

40 Elforsk 04:27, 2004