Effective CO2 Capture on a Large Scale

A pilot project by Siemens and E.ON has shown that emissions of the greenhouse gas carbon dioxide from power plants can be effectively captured on a large scale. At the Staudinger coal-fired power plant near Hanau, Germany, more than 90 percent of the carbon dioxide (CO2) in the facility’s flue gas was separated. Another result of the large-scale project, which has been running since 2009, is that the flue gas scrubbing process doesn’t reduce the plant’s efficiency to the extent that had been expected. Based on this finding, the Siemens process is also suitable for use in larger demonstration facilities.

Separation of CO2 from power plant exhaust gases is one of the ways in which plants that run on fossil fuels can help protect the climate. The CO2 is removed from the flue gas by means of Siemens’ post-combustion process. The carbon dioxide is captured with a special scrubbing agent consisting of an amino acid salt solution. These acids occur in nature and aren’t harmful to the environment. The aqueous amino acid salt solution is almost completely non-volatile, so it generates practically no solvent emissions. Unlike previous processes, the new method doesn’t require extensive cleaning of the flue gas after the carbon dioxide is captured. What’s more, the scrubbing agent removes other pollutants in the flue gas besides CO2 and can be repeatedly reused.

In addition to being very environmentally friendly, the process — which is called PostCap — is also energy efficient. Thanks to improvements to the process made by the experts at Siemens Energy, the power plant’s efficiency is only reduced by about six percentage points. That’s far less than was expected: Previous estimates had indicated a loss of about ten percentage points.