Besides measures to increase the efficiency of lignite-fired power plants and, hence, to lower CO2 emissions in the long run, we are also working on processes in which the CO2 does not reach the atmosphere in the first place, but is captured before it does. One option here is so-called CO2 scrubbing.
In the chemical industry, CO2 scrubbing is a tried-and-tested method that has been producing carbon dioxide for years now, eg for the beverage or fertilizer industry. In the energy sector, however, the process is a novelty. CO2 scrubbing gets to work at the end of the power-plant process, ie downstream of the FGD system usual today.
Since 2009, we have been trialling, within the scope of a cooperation scheme with BASF and Linde, a new technology in a pilot plant at the Coal Innovation Centre for capturing carbon dioxide (CO2) from flue gases. The pilot can capture up to 300 kg CO2 per hour, which corresponds, given the amount of flue gas, to a capture degree of 90%.
A practical test shows that, compared with the processes usual today, the energy consumption of the innovative technology using novel chemical solvents for capturing the CO2 is some 20% lower. In addition, the new solvents are marked by much higher stability toward oxygen, so that solvent consumption is perceptibly reduced.
RWE, BASF and Linde are now working on solutions for demo and major power plants. On the basis of this technology, over 90% of the carbon dioxide could then be removed from a power station's combustion flue gases and, in a next step, stored underground or used for material conversion.