Can scrub CO2 from power station flue gases
Atle Kjærvik
NTH/SINTEF have developed a scrubbing process that can remove more than 90% of the greenhouse gas carbon dioxide (CO2) from the flue gases of coal, oil or gas-fired power stations.
Senior Research Scientist Olav Juliussen at NTH/SINTEFs experimental plant for removing CO2 from exhaust.
The process has been developed in an experimental plant at NTH in collaboration with Statoil.
"The aim of the oil company is to identify a cost-effective technology that will enable us to continue to use oil and gas in a world that is focusing on the greenhouse effect," says Olav Kårstad, a scientist in Statoil's research department in Trondheim. Kårstad himself, SINTEF senior scientist Olav Juliussen, Professor Olav Erga of NTH and Dr.ing. Håvard Lidal of Statoil in Stavanger make up the core group of scientists behind the project.
"Washes out" CO2
Although developing the method at NTH/SINTEF has taken four years, Erga and Juliussen say that it has not been particularly difficult to find a method of removing CO2 from flue gases."The carbon dioxide is recovered in a wet scrubbing process with the aid of amines, which are compounds produced from ammonia. The CO2 is then separated from the liquid, leaving us with pure CO2 in gas or liquid form" says Juliussen, who goes on to point out that the problem of dumping the enormous quantities of carbon dioxide recovered has only partly been overcome.
Simple but expensive
However, to build a full-scale scrubber for a power station would be expensive. Olva Bolland, senior lecturer in the Dept. of Thermal Energy at NTH has previously estimated the cost of a similar scrubber for a 700 MW power station to be about one billion NOK. The additional cost of a kilowatt hour of electricity would be 0,10 - 0,13 NOK, including the cost of a technology for recycling carbon dioxide in the gas turbines. This would have the effect of producing a higher content of CO2 in the flue gases, making it easier to separate it out."This plant would also absorb some 10 - 15% of the energy produced by the power station, so our research has focused on making the process less energy-intensive, identifying the right amines and preventing emissions of environmentally harmful substances," says Kårstad. He also tells us that Statoil plans to produce animal feed proteins from natural gas. This process requires carbon dioxide to be removed from the gas, and the experience gained in the course of the NTH/SINTEF project can come in useful here, he believes.
International research area
The consequences of a possible greenhouse effect are still uncertain, but in the worst case they could be enormous. For this reason, removing CO2 from the flue gases of power stations and engine exhausts is a hot research topic.The project researchers will be participating in a major conference on "Carbon Dioxide Removal" in Kyoto in Japan at the end of October this year.
"In this way we will be able to make a contribution to better international collaboration on long-term problems," says Professor Erga.