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Carbon Capture and Storage


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Carbon Capture and Storage or Carbon Sequestration is a technology to reduce global warming

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Carbon Capture and Storage

  2. 2. WHAT IS CARBON CAPTURE AND STORAGE? • CCS is a technology that will attempt to prevent large quantities of CO2 from being released into the atmosphere from the use of fossil fuels in power generation and other industries. • It is often regarded as a means of mitigating the contribution of fossil fuel emissions to global warming.
  4. 4. CAPTURING CARBON • There are essentially three ways to capture the carbon dioxide from a power plant: • Before the fuel is burned (precombustion), • After the fuel is burned (postcombustion), or • By burning the fuel in more oxygen and storing all the gases produced as a result (oxyfuel).
  5. 5. PRECOMBUSTION In precombustion, the aim is to remove the carbon from coal fuel before it's burned. The coal is reacted with oxygen to make syngas (synthesis gas), a mixture of carbon monoxide and hydrogen gases. The hydrogen can be removed and either burned directly as fuel or compressed and stored for use in fuel-cell cars. Water is added to the carbon monoxide to make carbon dioxide (which is stored) and additional hydrogen, which is added to the hydrogen previously removed.
  6. 6. POSTCOMBUSTION • In postcombustion, we're trying to remove carbon dioxide from a power station's output after a fuel has been burned. That means waste gases have to be captured and scrubbed clean of their CO2 before they travel up smokestacks. The scrubbing is done by passing the gases through ammonia, which is then blasted clean with steam, releasing the CO2 for storage.
  7. 7. OXYFUEL • Power plants don't produce pure CO2: because there's often not enough oxygen for complete combustion they produce other pollutant gases as well. • One way to purify the exhaust is to blow extra oxygen into the furnace so the fuel burns completely producing relatively pure steam and CO2. • Once the steam is removed (by cooling and condensing it to make water), the CO2 can be stored.
  8. 8. TRANSPORTATION • After capture, the CO2 would have to be transported to suitable storage sites. • This is done by pipeline, which is generally the cheapest form of transport. • A conveyor belt system or ship could also be utilized for transport.
  10. 10. • Storing carbon dioxide under Earth's surface is called geo-sequestration and uses things like worked out oil fields, aquifers, or other rock formations deep underground. • Oil companies already pump CO2 into underground rocks to flush oil to the surface. • Storing CO2 in the oceans. • Storing CO2 by reacting it with minerals, though that requires a lot more energy.
  11. 11. MAJOR STORAGE SITES IN THE WORLD • Sleipner, Norwegian North Sea • Altmark, Germany • Weyburn, Canada • In Salah, Algeria • Miranga, Brazil • Hontomin, Spain • Hastings, Texas, USA
  12. 12. ADVANTAGES • CCS applied to a modern conventional power plant could reduce CO2 emissions to the atmosphere by 80-90 % compared to a plant without CCS. • the solvents used to capture CO2 from the flue gases will remove some nitrogen oxides and sulphur oxides.
  13. 13. DISADVANTAGES • Increase significantly the emissions of acid gas pollutants. • Capturing and compressing C02 requires much energy and would increase the fuel needs of a coal-fired plant with CCS by 25-40%. • These and other system costs are estimated to increase the cost of energy from a new power plant with CCS by 21-90 %.
  14. 14. • Water consumption, however, may be an issue for carbon capture systems which rely on solvents to remove CO2 from flue gases. • This increase in water consumption may make these systems less suited to dry regions.
  15. 15. CARBON CAPTURE: ENVIRONMENTAL IMPACTS • In ocean storage carbon dioxide reacts with water to form acid, so the oceans could become significantly more acidic . • Another difficulty is that the CO2 would also eventually return to the atmosphere. • In addition to the global climate change impact of CO2 returning to the atmosphere, leakages pose local risks to health and ecosystems.
  16. 16. • For storage sites under water, there are concerns about chronic exposure of marine ecosystems to raised CO2 levels, such as might occur near injection sites. • For CO2 storage sites on land, there are concerns that large scale leakage could harm people and wildlife in the immediate vicinity.
  17. 17. REFERENCES • Gibbins, J., Chalmers, H. (2007). Preparing for global rollout: A ‘developed country first’ demonstration programme for rapid CCS deployment. Energy Policy. doi:10.1016/j.enol.2007.10.021. • Tzimas, T., Mercier, A., Cormos, C. and Petevas, S.D. (2007). Trade-off in emissions of acid gas pollutants and of carbon dioxide in fossil fuel power plants with carbon capture. Energy Policy. 35 (8):3991-3998. • Bickle, M., Chadwick, A., Huppert, H. E., et al. (2007). Modelling carbon dioxide accumulation at Sleipner: Implications for underground carbon storage. Earth and Planetary Science. 255, 164–176. • Johansson, M., Mattisson, T., Lyngfelt, A. et al. (2008). Using continuous and pulse experiments to compare two promising nickelbased oxygen carriers for use in chemicallooping technologies. Fuel. 87 :988-1001. • Race, J.M., Seevam, P. N., Downie, M.J. (2007). Challenges for offshore transport of anthropogenic carbon dioxide. Proceedings of OMEA2007, 10-15 June, 2007, San Diego, CA,USA.