Stephanie+Gardner

//Climate Change Technology: // **Carbon Capture**  **image: coal plants provide 40% of carbon dioxide emissions in the U.S.** (Dirty Coal Power [|Sierra Club])

**What is carbon capture?** Carbon capture is exactly what it sounds like. It is the process by which carbon dioxide is captured. There are two major approaches to carbon capture: air extraction and capture from power plants. Air extraction is when existing carbon dioxide is captured irrespective to where it was created or released. Capture from power plants is when carbon dioxide is separated from power plant emissions (such as a coal plant), at the source- the power plant.
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What is done with the carbon once it is captured?** Once the carbon is successfully captured it is pumped into “disused wells or porous rock or salt formations,” for storage. Another option that is being explored is the idea of an underground CO2 vault. The problem with this is that what happens if there is a leak in the vault? This is another reason why carbon capture is not a major practice yet, a efficient form of storage needs to be found first.
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Why aren't we widely using carbon capture?** The problem with carbon capture are that the machinery used to execute the process of carbon capture is expensive. Another issue is that carbon capture has not been tested on a large scale, but inferring from what we’ve seen so far, carbon capture could slow the process of human induced climate change.
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How does carbon capture effect our environment and climate change?** As many of us know by now, humans contribute to climate change through that green house gasses we release into the atmosphere. Those gasses are then trapped by our ozone layer and heat up our earth. A major green house gas is CO2 (carbon dioxide). We release this gas through our car emissions, factory emissions, and power plant emissions (etc.). Carbon capture would capture the CO2 we had previously released and slow the effects of our CO2 emissions on our environment. One problem that scientists foresee is that with this new technology we will not be continue to be pushed towards finding clean energy alternatives.


 * How exactly does carbon capture work?** Check out the diagrams below to see how the process of cabon capture works:

[|(www.co2captureproject.org)]

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 * Check out this video to learn more about what carbon capture is and how it works:

 .The Chemistry of Carbon Capture a closer look at some of the methods **Air Extraction Method** The concept behind air extraction is rather simplistic, but there are different forms that are mostly experimental at this point. In Gabrielle Walker and Sir David King's book __The Hot Topic__, a comprehensive look at global warming and solutions, the air extraction method is described as towers acting like anti-chimneys pulling in polluted air. To "scrub" CO2 from the air, giant towers, which can be located anywhere due to a fairly constant concentration of carbon dioxide around the world, would be used to capture carbon dioxide. **The carbon dioxide in the air would be soaked up by a solvent, enabling it to be isolated and then safely stored.** (Owen [|National Geographic]) The role of the solvent is to act as a transport for the carbon dioxide molecules. (News Archive [|Columbia Earth Institute]) The illustration below is an example of air extraction which is supposed to emulate a tree. (Turning Airborne Carbon Into Fuel [])



**Pre-Combustion Capture:** The chemical process behind this technology  for the production of coal is intended to remove CO2 from the fossil fuel before the combustion reaction that takes place in the plant. (For a better look at the diagram on the right, go to the [|National Mining Association - CCS] page.) A **syngas** is formed when the coal is gasified through the application of steam and pressure. (CCS) A syngas is a gas mixture that is produced from the gasification of a carbon. (What is Syngas [|Biofuel Information]) **The coal is gasified in order to produce** **carbon monoxide and hydrogen gases. The CO is combined with water, which produces CO2 and H2 gases**. This is important because the H2 gases could be used as a separate energy source, like fuel cells. (Coal Paradox [|National Geographic]) The CO2 is now isolated and can be stored rather than released into the atmosphere. When fossil fuels are burned, an exhaust called a **flue gas** is produced. The flue gas consists of nitrogen gas and CO2. (CCS [|National Mining Association]) To prevent CO2 escaping from the flue gas into the atmosphere, post-combustion capture implements a rinsing process that relies on solvents and water. (CO2 Capture [|Bellona]) **MEA, or monethanolamine**, is the most commonly used solvent. This amine solvent is used because of its high absorption capacity, and the importance of the solvent in post-combustion capture is to act as a transport for the CO2. The solvent is combined with the flue gas in water, and the CO2 is taken out of the flue gas by the solvent. The purpose of the water is to rinse the flue gas of any solvent residue. (Davidson [|IEA Coal Centre])
 * Post- Combustion Capture: **

After the flue gas and the solvents have been combined in the scrubber column, (see image from bellona.org) the solvents go through regeneration where the CO2 is stripped from the solvents and then released as pure carbon dioxide by applying heat to the solvents. Steam acts as a stripping gas in this process. The result is pure carbon dioxide which can be stored before it enters the atmosphere, and the solvents are reused in the absorption process. (Davidson [|IEA Clean Coal Centre])

 **<span style="color: rgb(250,143,30);">C R<span style="color: rgb(0,227,255);">E D<span style="color: rgb(255,255,0);">I T<span style="color: rgb(0,0,255);">S ** <span style="color: rgb(207,23,23);">**This Page was created by: Stephanie Gardner and Teki Omara-Otunnu Summary and Background information by Teki Omara-Otunnu Chemistry of Carbon Capture section by Stephanie Gardner** Appenzeller, Tim. "The Coal Paradox." __National Geographic__ Mar. 2006. 19 Mar. 2009 <span class="wiki_link_ext"><[]>. Braun, David. "The Quest to Capture and Store Carbon." 1 Oct. 2008. National Geographic. <[]>.
 * SOURCES **

"Carbon Capture Research." 6 Sept. 2007. <[]>.

"CCS - Carbon Capture." __National Mining Association__. 21 Mar. 2009 <span class="wiki_link_ext"><[]>.

"CO2 Capture - Bellona." __Bellona Foundation - Bellona__. 20 Mar. 2009 <span class="wiki_link_ext"><[]>.

Davidson, Robert. "Post-combustion carbon capture from coal-fired plants - solvent scrubbing." __IEA Clean Coal Centre | Home__. 20 Mar. 2009 <span class="wiki_link_ext"><[]>.

"Dirty Coal Power - Clean Air - Sierra Club." __Sierra Club Home Page: Explore, Enjoy and Protect the Planet__. 23 Mar. 2009 <[]>.

Kanter, James. "On the Long Road to Carbon Capture." 23 Sept. 2008. <[]>.

Krupp, Fred. __Earth: The Sequel: The Race to Reinvent Energy and Stop Global Warming__. 1st ed. New York: W.W. Norton & Co., 2008.

Lance, Jennifer. "Bye, Bye Coal Plants Say Environmental Groups." __Green Options - Helping You Make Good Choices__. 15 Apr. 2008. 23 Mar. 2009 <[]>.

"News Archive -." __The Earth Institute at Columbia University__. 20 Mar. 2009 <[]>.

"Turning Airborne Carbon Into Fuel." __Alternative Energy News__. 23 Mar. 2009 <http://www.alternative-energy-news.info/airborne-carbon-fuel/>.

Walker, Gabrielle, and Sir David King. __The Hot Topic__. Orlando, Fl: Houghton Mifflin Harcourt, 2008.

"What is CO2 Capture and Storage?" 2008. <[]>.

"What is Syngas - BioFuel Information." __Home - BioFuel Information__. 21 Mar. 2009 <[]>.