Basic principle of any oxyfuel process is the combustion of a fuel with pure oxygen instead of air. The flue gas produced by this contains no air nitrogen, so the CO2 concentration can be as high as 75 %.
Flue gas recirculation
Of course, combustion temperatures will raise in comparison to air-blown combustion, which effect is utilized already for years in the glass and steel industry.
A new idea was to use the oxyfuel principle also in fossil fuel power stations as a simple approach to easily sequester the CO2 produced. In this case, high flame temperatures are unwanted, so the solution is to recycle larger amounts of flue gas back to the combustion zone.
CO2 processing
CO2 is highly enriched in a typical oxyfuel flue gas. It becomes obvious that actually no separation of the CO2 will be necessary, but only some cleaning from water vapour and other disturbing gases like surplus oxygen or sulphurdioxide.
Possibilities for CO2 storage
There are a number of storage options for CO2 that are currently investigated and which will not affect the climate. Aside from commercial utilisation for Enhanced Oil Recovery or Enhanced Gas Recovery (CO2 as a displacement gas to increase the production capacity), aquifer storage seems to be most promising for Europe. These formations deep below the surface of the earth are considered safe, offer sufficient capacity and the storage technology is estimated to be easy to handle.
Utilization of CO2 for Enhanced Oil Recovery Source: EnCana
CO2 storage in deep saline aquifers. Source: CO2Store
