German utility E.ON is to test a new post-combustion capture process that can be used to remove up to 90% of the carbon dioxide from power plant flue gases, at its Karlshamn power plant in Sweden, in conjunction with French power generation specialist Alstom.

The companies have agreed to develop the technology, currently being worked on by Alstom, at Karlshamn to a stage where it can be used in the actual environment of a power plant. The pilot plant at Karlshamn is to start trial operation in early 2008.

The method to be used in Sweden is based on new technology that involves using ammonia to capture CO2. The key advantage is that this cleaning process uses less energy than other CO2 removal processes, so its impact on the overall efficiency of the power plant is relatively low, E.ON said.

E.ON said that it sees CO2 capture from power plants as one of the key technologies in tackling the global climate change problem. In its quest for the best technology, E.ON is investigating a number of processes, which include pre-combustion capture, post-combustion capture and oxyfuel technology.

Pre-combustion capture involves the use of a gasification process to convert the coal into a fuel gas which is stripped of its CO2 before combustion in a combined-cycle power plant to produce electricity. This process is being investigated by E.ON Energie together with E.ON US and other industry partners as part of the FutureGen project in the US, and by E.ON UK at its Killingholme plant.

Meanwhile, in post-combustion capture, the CO2 is removed from the flue gas stream by solvent washing. E.ON said that it considers post-combustion capture to be a key technology and is therefore lobbying for the development of innovative washing processes in several national and international projects.

Finally, oxyfuel technology uses pure oxygen instead of air for the combustion of coal or natural gas, so the flue gases produced consist mainly of CO2 and water, which makes CO2 removal relatively easy. E.ON is actively involved in this field as part of joint ventures in Germany. In addition, E.ON UK operates its own pilot plant at Ratcliff.

According to E.ON, experts expect the first almost CO2-free commercial power plants to come online in 15 to 20 years.