Oxyfuel Combustion

Oxyfuel combustion separates oxygen from air using established cryogenic methods and then burns the coal or gas fuel in a mixture of that oxygen, often combined with recycled flue gas to regulate the temperature of combustion. Advantages of oxyfuel are the comparative ease with which CO2 can be separated (no solvent is required) which allows for very high capture levels, small physical size of the unit, and the possibility of retrofit to an existing plant with some alterations. Drawbacks include , inflexibility due to the use of multiple burners and air separation requirements, large energy penalty of the air separation unit, high combustion temperatures requiring expensive materials, very low SOx require on leaving burners, possible need for an extra purification stage for the CO2 and the challenges of operation at sub-atmospheric pressure to prevent leakage leading to ingress of air and reduced purity. Future gains may come from improved high temperature operation, reduction of energy costs of oxygen separation from the air and minimizing air leak.

Post-combustion Capture

In post-combustion capture, fuel is burned as usual in a (more-or-less) unmodified power plant. Currently the commercialised technology for post combustion capture is chemical absorption. It is the most advanced method due to considerable industrial experience with similar processes. CO...

Pre-combustion Capture

Pre-combustion capture, typically operated with Integrated Gasification Combined Cycles (IGCC), involves gasification and partial oxidisation of the fuel to produce CO 2 and hydrogen which are then separated, commonly using physical absorption processes. The hydrogen is then combusted in a...