A consortium led by Finish VTT Technical Research Centre has developed a new technology to capture carbon dioxide emissions from coal-fired power plants' flue gases.
The method relies on so called circulating fluidised bed combustion technology – a method widely used in power plants where parts of solid fuels , like coal, are held in the air by upward-blowing jets, creating a bubbling mixture that enables more efficient burning.
In the case of the new FLEXI BURN CFB technology, this method is combined with oxyfuel combustion, using pure oxygen instead of air to feed the fire.
The flue gases released during the oxyfuel combustion have higher CO2 concentration than those of conventional air-powered combustion. That means CO2 can be efficiently removed and stored – preventing it from entering the atmosphere where it would add to the climate change.
Using the combination of the two above mentioned technologies makes it possible also for the power plant to run on cheaper fuels or even biomass, further decreasing its carbon footprint.
The team believes that by broadening the scope of acceptable fuels while remaining the efficiency level would reduce dependency on coal and result in cost savings.
The technology, that requires fitting existing power plants with carbon removal technologies, has been successfully tested on a 30MWth demonstration plant in Spain, which is the world’s largest operational plant using the circulating bed oxyfuel combustion technology. The team has also developed a commercial-scale concept for a 300MWe plant.
Deploying the technology, however, doesn’t require investment only into the technology itself but also increases the operating costs as part of the electricity generated has to be used to power the oxygen production and the CO2 capture systems.
According to the International Energy Agency (IEA), carbon dioxide capture is essential if the emission reduction targets set for greenhouse gases are to be met. The intergovernmental climate change panel IPPC said carbon dioxide emissions should be reduced by 50 to 85 per cent by 2050, if humankind wants to reduce the effects of the climate change.
To meet this target, it is deemed necessary to equip existing coal-fired power plants with carbon dioxide capture systems. However, the technology is still at trial stages.