The economics of capture is critical to cost effective CCS implementation. Efficiency of CO2 capture is being challenged to be increased since this step of responsible for 60-80% of the overall economic costs. Cost reduction in the capture part of the process is key.
CO2 capture technologies:
- Pre-combustion systems
- Post-combustion systems
- Oxy-fuel or Oxy-combustion processes (still being commercialised)
The power plant fuel source is decarbonised before combustion. Plant designs are being improved to convert gas produced from gasification to hydrogen and CO2 so that the CO2 is removed before the combustion of the hydrogen-rich gas in turbines. CO2 would have a higher concentration on the pre-combustion gas stream (>20% in the H2 + CO2 stream compared to 5-15% in a post-combustion flue gas stream).
The fuel source is combusted and the flue gas stream is captured for processing to remove CO2; Pre-combustion CO2/H2 separation is easier than post-combustion CO2/N2 separation due to the difference in molecular weights and molecular kinetic diameters.