Improvements bring carbon capture method nearer
Scientists are getting closer to using smokestacks to capture large quantities of carbon dioxide. If the method can be used at coal-fired plants generating electricity, it would be a major advance in reducing greenhouse gases, a major cause of global warming.
Professor James Davis told the National Meeting of the American Chemical Society (ACS) the method mirrors techniques the oil industry has used for the last 80 years to extracting carbon dioxide from natural gas.
Professor Davis, who led the study, says, "With little fanfare or publicity and a decade of hard work, we have made many improvements in this important new technology for carbon capture.
"In 2002, we became the first research group to disclose discovery of the technology, and we have now positioned it as a viable means for carbon dioxide capture. Our research indicates that its capacity for carbon dioxide capture is greater than current technology, and the process is shaping up to be both more affordable and durable as well."
Although natural gas is known as being one of the cleanest fuels, it is often tainted with CO2 and other unwanted materials, especially if its comes from 'sour' formations, said Dr Davis, from the University of South Alabama.
The carbon dioxide is normally eliminated by using aqueous monoethanolamine (MEA) liquid. But a few issues make it more difficult to use MEA to capture CO2 on a large scale in the power stations. The carbon dioxide would need to be captured or 'scrubbed' from the smokestacks before it got into the atmosphere and contained under the ground in storage areas. It would huge quantities of MEA at a high cost.
Professor Davis and colleagues have suggested a new method using an ionic liquid based on nitrogen that could avoid these issues. The liquid is easy to recycle, but not to evaporate.
Professor Davis says the method also has a big advantage above alternative ways of iconic liquid carbon capture, he told the ACS members in San Diego.
Water, which is produced by combustion, so is contained in exhaust gases, cuts down the efficiency of various nitrogen ionic liquids, but Dr Davis says it is more prone to interact with CO2 rather than water.
Professor Davis has created a system in his laboratory that could be applied on a larger scale to factories and power plants.
Exhaust gas is bubbled though the nitrogen liquid, which is taken out and the liquid replaced. Taking out the CO2 creates a fresh supply of the ionic liquid. The removed carbon dioxide could then be buried.
Looking to the future, Professor Davis sees no reason why the scaled-down technology could eventually be used in cars or homes.
Professor Davis' comments came as part of a convention looking at advances in research surrounding ionic liquids, which are formed solely from atoms that have some electrons taken away.
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