Capture Basics

CO₂ can be captured from large emission sources that burn fossil fuels such as coal, natural gas and oil. These sources include:

• Coal-fired power plants
• Oil and gas operations (including the oil sands)
• Other industrial activities such as chemical, fertilizer and cement manufacturing

There are several ways to capture CO₂:

• directly separating CO₂ from regular flue gas after the combustion process at the emission source – this is called post-combustion capture, and
• by modifying the fossil fuel combustion technology to make the CO_­2 easier to capture. There are two ways to do this: through processes called pre-combustion capture (gasification) and oxyfuel combustion.

Post-combustion capture is the most common and widely used process. CO₂ is separated from other gases in the flue stack using a solvent. The most common solvent is chilled ammonia; however, other selective amines are also used. This process is well developed and has existed for several decades.

With pre-combustion capture, carbon and hydrogen in the fossil fuel energy source are separated prior to combustion. The fuel source becomes chemically transformed into two gas streams consisting of hydrogen and CO₂ that can be easily captured_. This is often called pre-combustion capture.

Oxyfuel combustion involves the burning of a fossil fuel energy source in the presence of pure oxygen. This removes contaminants, including nitrogen, creating an exhaust stream of pure CO₂ that is easier to capture.