A nanostructured polymer membrane that can extract carbon dioxide from a gaseous flow and convert it to bicarbonate ions could be the key to carbon sequestration in the fight to control levels of the greenhouse gas.
Carbon sequestration is a well-studied theoretical approach to reduce carbon emissions by locking up carbon dioxide deep in the ground or on the ocean floor in various forms. Whether or not such an approach is tenable in terms of the overall energy balance is open to debate but experimental efforts at developing efficient systems to extract the gas from the emissions of electric power stations are underway. The latest effort was recently patented by researchers at The Norwegian University of Science and Technology (NTNU) in Trondheim.
May Britt Hägg
May-Britt Hägg and colleagues have developed a new type of polymer membrane that has a porous internal structure perfectly suited to catching and trapping carbon dioxide molecules and nothing else in a gas flow.
Approximately one third of all carbon dioxide emissions across the globe comes from energy production. So, selective extraction of CO2 from power station emissions ready for sequestration has significant potential to reduce CO2 emissions.
The new membrane technology is effective, say its developers, it is also inexpensive. Moreover, the design of the material means its effectiveness increases proportionally with rising concentration of carbon dioxide in the gas being filtered, because of the nature of the facilitated transport phenomenon being exploited.
The novelty is that instead of using a filter that separates carbon dioxide and other molecules directly, we use an agent that is fixed in the membrane, which converts carbon dioxide and moisture in the gas flow into bicarbonate, explains May-Britt Hägg. With this method, we can remove more CO2 and obtain a cleaner product for smaller plants. Thus, it becomes less expensive, Hägg adds. We also have membranes today that are used to separate CO2 and have been used for a couple of decades, but these membranes are used for natural gases at high pressures, and are not suited for CO2 from flue gas. If the membrane separates poorly, very large amounts of the material are needed, and that makes this separation expensive, she explains
According to Hägg, the new technology will be of greatest benefit to coal-powered power stations. Within a five-year period, the plan is to test the membrane technology in four large power plants in Europe. We believe this will result in an international breakthrough for energy-efficient CO2 membranes, she says.
Further reading
Chemical Conversion of Natural Gas to Liquid Components (GTL) at Department of Chemical Engineering
http://www.ntnu.no/gass/research/Groups/chemical.html
Suggested searches
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