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Carbon Capture and Storage (CCS)

Keeping Industrial CO₂ Out of the Atmosphere

Human (anthropogenic) activity, including the use of fossil fuel, releases greenhouse gases like CO₂ to the atmosphere.
Learn more.

Carbon capture and storage (CCS) is a method of capturing CO₂ before it is released to the atmosphere and then placing the CO₂ into long-term storage. Geologic sequestration of CO₂ is a major option for long-term CO₂ storage. CCS is best suited for use in large stationary facilities, like thermoelectric power plants or factories.

Most large facilities like power plants consume coal because it is a plentiful and economical fuel. In a large facility like a power plant, thousands of tons of coal are burned each day. The heat from burning the coal heats water in huge boilers until the water becomes steam. This steam is used to power large machines called generators. As the generators turn, they make electricity.

The coal is usually burned in air because it is the simplest and most economical system to use. Air consists of about one-fourth oxygen (O₂) and about three-fourths nitrogen (N₂). The air also has very small amounts of some other gases (argon and CO₂). The oxygen in the air combines with the carbon in the fossil fuel, but the nitrogen does not take part in combustion. As each ton of coal gives up its energy, it also gives off bits of material that can’t burn (bits of mineral matter called ash), carbon dioxide (the result of combustion—the reaction that happens when oxygen combines with carbon), nitrogen, and small amounts of sulfur combined with oxygen, which is known as sulfur dioxide.

Over the past 30 years, power plants have added equipment to reduce fly ash, nitrogen, and sulfur emissions. But managing CO₂ emissions is much more challenging because CO₂ is a very small part of the exhaust gas. Learn more. As a result, scientists are developing new technologies to capture CO₂ and new processes that will make CO₂ capture easier.

Today, the CO₂ can be captured at three points in the power production process: before combustion, during combustion, or after combustion. The majority of capture technologies focus on separating the CO₂ from the exhaust gas stream after combustion

After the CO₂ is captured, it must be compressed either for storage prior to truck transport or to be put directly into a pipeline to the sequestration site. CO₂ must be compressed to about 1200 to 1500 psi for transport in a pipeline. Compression is energy-intensive, so improved methods of compression are also being developed.