Capture Technologies & Cost

There threeThere are three basic types of CO2 capture:

  1. Pre-combustion,

  2. Post-combustion and

  3. Oxy-fuel with post-combustion

Pre-Combustion

  1. Pre-combustion capture processes convert fuel into a gaseous mixture of hydrogen and CO2. The hydrogen is separated and can be burnt without producing any CO2.

  2. The CO2 captured is of high purity (80%-90%) can then be compressed for transport and storage.

  3. The fuel conversion steps required for pre-combustion are more complex than the processes involved in post-combustion, making the technology more difficult to apply to existing power plants.

  4. Pre-combustion capture is used in industrial processes (natural gas processing) are low cost and most common (48%)

  5. Application in power generation is via Integrated Gas Combined Cycle (IGCC) plant for syngas. There are only six IGCC plant in the world to date. Absence of regulations and carbon cost finds fear uses

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Post-Combustion

  1. Post-combustion processes separate CO2 from combustion exhaust gases.

  2. Purity or concentration of CO2  is low (13% - 15%). Exhaust gases consist of NOx & SOX  

  3. CO2 can be captured using a liquid solvent (chemical absorption) or other separation methods.

  4. In an absorption-based approach, once absorbed by the solvent, the CO2 is released by heating to form a high purity CO2 stream.

  5. This technology is widely used to capture CO2 for use in the food and beverage industry.

Post Combustion.jpg

Courtesy: Global CCS Institute

Oxyfuel-Combustion

  1. Oxyfuel combustion processes use oxygen rather than air for combustion of fuel.

  2. This produces exhaust gas that is mainly water vapour and CO2 that can be easily separated to produce a high purity CO2 stream.

  3. The high purity CO2 is transport ready.

Oxyfuel capture.jpg

Courtesy: Global CCS Institute

Cost of Capture Technologies

  1. Pre-combustion methods are most prevalent and cost may range from $55 -$67 /tCO2

  2. Oxyfuel - combustion methods cost may range from $52 -$78 /tCO2

  3. Post-combustion methods are most cost intensive, cost may range from $80 -$107 /tCO2

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