Glossary:Carbon capture and storage

Carbon capture and storage (CCS) refers to a collection of technologies that can combat climate change by reducing carbon dioxide (CO2) emissions. The idea behind CCS is to capture the CO2 generated by burning fossil fuels before it is released to the atmosphere. The question is then: What to do with the captured CO2? Most current CCS strategies call for the injection of CO2 deep underground.

This forms a “closed loop”, where the carbon is extracted from the Earth as fossil fuels and then is returned to the Earth as CO2.

Today, CCS projects are storing almost 45 million tons of CO2 every year, which is about the amount of CO2 emissions created by 10 million passenger cars. Capture generally takes place at large stationary sources of CO2, like power plants or industrial plants that make cement, steel, and chemicals. Most current carbon capture projects use a liquid to chemically remove the CO2 before it goes out the smokestack, but several new types of capture processes are under development.

The captured CO2 gas is then compressed so it becomes liquid-like and transported to a storage site, generally through a pipeline. Ship transport is more expensive than using pipelines, but it is being considered in both Europe and Japan. Once at the storage site, the CO2 is pumped more than 2,500 feet down wells into geological formations like used-up oil and gas reservoirs, as well as formations that contain unusable, salty water.