June 15, 2010

New Tech Could Help Track Carbon Dioxide

Scientists have developed a way to detect and track carbon dioxide deep underground, giving the government an important tool that may help people find a way to keep carbon dioxide and other greenhouse gases from polluting the atmosphere.

Scientists at the U.S. Department of Energy's National Energy Technology Laboratory used colorless, nontoxic liquids called perflourocarbon tracers to basically fingerprint carbon dioxide that was injected into a coal seam in northwestern New Mexico.

They were able to follow the carbon dioxide's movements by tracking the tracers.

Brian Strazisar, a physical scientist at the National Energy Technology Laboratory in Pittsburgh, said that using the tracers helps to eliminate some of the uncertainty surrounding carbon capture and sequestration.

"There is going to be some sort of requirement that we verify that the carbon dioxide is going where we expect it to and that it's not going back into the atmosphere or into geologic zones that weren't intended. The tracers help with that," Strazisar told the Associated Press (AP).

Scientists have been studying underground fissures, caverns and coal beds to find out if carbon emissions can be stored safely in these areas to reduce a buildup of greenhouse gases in the atmosphere.

The Obama administration established a task force on carbon capture and sequestration and has pledged $4 billion for research. The goal is to get carbon capture and sequestration technology used widely within a decade.

Scientists injected more than 18,000 tons of carbon dioxide along with tracers into a coal layer 3,000 feet below the surface at Pump Canyon near Aztec, New Mexico. Special units were set up a three nearby coal bed methane production wells and in shallow bore holes throughout the area to monitor for signs of the tracers and the injected CO2. The project lasted for around one year.

The technology is able to measure concentrations as small as parts-per-quadrillion and can also tell the difference between injected CO2 and that that is naturally produced.

At the New Mexico Legislature this year critics expressed concerns over the unknowns surrounding carbon capture and storage, related property rights and potential effects on water and oil and natural gas resources. Inquiries were made as to who would be liable if injected CO2 contaminated an aquifer or if it leaked its way back to the surface.

Brian McPherson, a University of Utah professor who was involved in the Pump Canyon project, said the tracer technology would be able to address some of the question better than other geophysical tools like seismic imaging.

"The tracers are a direct observation. They're less subjective and less interpretive," he told AP. "We can actually forecast how much a tracer is going to go where and then measure it and watch for it. They will help nail down the uncertainty."

Sean McCoy, manager of the Carbon Capture and Sequestration Regulatory Project at Carnegie Mellon University, who wasn't involved in the study, said the findings appear to show tracer technology will improve scientist's ability to determine what places would be best suited to store CO2 over long periods of time.

"There's great potential, and in the real world, we're definitely going to see carbon capture and sequestration happening. But I think there's going to need to be a concerted push to remove some of the obstacles that are out there right now to get this technology rolled out on a large scale," McCoy told AP.

McPherson agreed, saying carbon capture and sequestration is a "real possibility" for limiting the greenhouse gases.

"CO2 storage in the subsurface is just part of everything else that needs to be done, like increasing efficiency and developing better coal combustion technologies that produce less CO2," said McPherson, adding that it "can be done and these tests and positive results like these tracers are just more evidence that it's something that we should continue examining."


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