There are two main methods for capturing CO2: absorption towers and pure oxygen combustion. In power plants carbon dioxide is released to the atmosphere through smokestacks. These smokestacks can be replaced with absorption towers. Absorption towers are big chimneys that have specific chemicals. These chemicals absorb CO2 before it is released to the atmosphere and in this way prevent pollution.
Usually there are two towers. The first tower contains the chemicals that separate carbon dioxide from the byproducts of combustion (nitrogen and water vapor). When CO2 passes through this tower it is separated from the other gases and it is directed to the second tower. The second tower segregates CO2 from the absorbing chemicals and makes it available to be stored underground. The remaining chemicals are returned to the first tower for further use.
An alternative process to this is pure oxygen combustion. Pure oxygen combustion constitutes in burning fossil fuel into an environment of pure oxygen rather than air. That makes separating and sequestrating CO2 easier because the exhaust of the combustion constitutes only of water vapor and CO2 but not nitrogen. By changing the combustion process at the very beginning carbon sequestration becomes more effective and economical. After this process, water vapor is liquefied and CO2 becomes available for storage.
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Photo by flickr.com / Senor Codo