A team of University of Oregon physicists has published a paper recommending the treatment of flue gases from coal-fired power plants by cooling it sufficiently for pollutants to be deposited as "ices".

The researchers believe that this cryogenic system would capture at least 98% of sulfur dioxide, virtually 100% of mercury and 90% of carbon dioxide.The CO2 would be captured as a solid (dry ice) which would be warmed and compressed for piping to a storage facility.

They estimate that the process would add about 25% to the cost of coal-fired electricity but would reduce the overall costs to society by 38% through the reduction of associated health-care and climate-change costs.

The required cooling machinery would be large – potentially the size of a football stadium – but the cost for construction or retrofitting it would not be much more than present systems that include scrubbers, which would no longer be necessary.

The idea raises the question of whether the process could remove CO2 from the atmosphere as well as from flue gases.

Along those lines, another group of scientists has proposed building large refrigeration plants in Antartica to cool air sufficiently to cause CO2 to be deposited as "snow". This solid CO2 (dry ice) would be collected and stored in insulated landfills (or should that be "icefills").

They calculate that 446 refrigeration plants, each with a 100 metre cubed deposition chamber could remove a billion tonnes of CO2 from the atmosphere annually. These plants could be powered by a total 16 x 1.2 gigawatt wind farms.