Scientists at Universities of Manchester, Edinburgh and Toronto tap nature for clues to safe carbon capture and storage method
Friday, December 4, 2009 11:00:00 AM
Carbon capture and storage (CCS) has the potential to reduce harmful fossil-fuel related emissions to the Earth's atmosphere by recapturing CO2 and storing it beneath the Earth's surface. The technique holds promise for reducing global warming but key questions remain about safe long-term storage of CO2, and specifically about the means by which CO2 is trapped underground. An international team of scientists from the Universities of Manchester, Edinburgh and Toronto including Barbara Sherwood Lollar, a Professor in the Department of Geology at U of T, have uncovered a phenomenon in nature that could point the way to successful CCS. Their findings were published as the cover story in the prestigious international journal Nature1 in April 2009.
"To solve the problem of carbon capture and storage, it is important to understand the possible storage mechanisms," said Dr. Sherwood Lollar. Much of the research that is currently underway on CCS involves artificially pumping CO2 into the ground, but the Manchester-Toronto investigated the way in which CO2 was trapped in the ancient underground natural gas fields. They identified strong correlations between two different types of gas tracers - the noble gases (helium and neon) measured at Manchester, and carbon isotope variations in the CO2 gases determined at the U of T's Stable Isotope Laboratory in the Department of Geology.
"What we found was remarkable. At sites throughout the world, we found that the major way CO2 is stored is by dissolution into the underground water, rather than by mineral trapping," says Dr. Sherwood Lollar.
"Water containing dissolved CO2 is more dense than water without CO2," explained Stuart Gilfillan, lead author of the study. Dr. Gilfillan was a Ph.D. student at the University of Manchester when the work was completed and is now with the Scottish Centre for Carbon Storage at the University of Edinburgh. "The CO2-rich water sinks to the bottom of the reservoir where it is more likely to be securely stored."
"Manchester and Toronto are international leaders in different aspects of gas tracing. By combining our expertise we have been able to invent a new way of looking at old gas fields," said Chris Ballentine, a University of Manchester professor and primary director on the project. "This new approach will also be essential for monitoring and tracing where carbon dioxide goes when we inject it underground. It will be critical for future safety verification."
(This is an edited excerpt from an article found at http://www.news.utoronto.ca.)
1 S. Gilfillan et al. Solubility trapping in formation water as dominant CO2 sink in natural gas fields Nature 458: 614-618.
Available online at http://www.nature.com/nature/journal/v458/n7238/pdf/nature07852.pdf
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