Most of our energy requirements come from burning of fossil fuels like oil, natural gas and especially coal, which leads to high CO
2 emissions in the atmosphere. Carbon Capture is the process by which carbon dioxide is first separated from the flue gases of power-plants and other industries and then reused in other industrial processes or stored deep underground, thus preventing it from being released in the air. Carbon Capture can reduce the CO
2 emissions from these plants by almost 90%.
The International Energy Agency (IEA) has studied a number of global greenhouse-gas-reduction scenarios and concluded that CCS is "the most important single new technology for CO
2 savings" in both power generation and industry. The agency estimates that attempting to stabilize emissions without CCS could cost about 70% more—equivalent to $4.7 trillion between 2010 and 2050. CO
2 can be captured either before or after burning of the fossil fuels through various techniques such as Post-combustion Carbon Capture, Pre-combustion Carbon Capture and Oxy fuel combustion.
Post Combustion Capture This is the most technologically proven and widely tested method of carbon capture which uses chemical/physical solvent to isolate and capture CO
2 after combustion of fossil fuels. This method is most suitable for pulverized coal, supercritical and ultra super critical power plants.
Pre combustion Capture: In this method, carbon dioxide is removed from the fuel before it is burnt. The syngas is further shifted through water to produce CO
2 and H2 which is stored and used separately. This method is mostly applicable in IGCC (integrated gas combustion cycle) power plants, chemical and fertilizer industries.
Oxy Fuel Combustion: This process uses a conventional boiler where the fossil fuel is burnt in pure oxygen and re-circulated flue gases. The result is a pure stream of concentrated CO
2. Though this method can reduce carbon emission to almost nil, it's a highly energy intensive process.
