Questions Beset Bush CO2 Underground Storage Plans

DENVER, Colorado, February 17, 2003 (ENS) - Storing carbon dioxide inside coal seams or reservoirs far below the Earth's surface, rather than releasing the gas into the atmosphere, is a tempting prospect. It could reduce the overall emissions of the greenhouse gas most scientists believe is responsible for global warming, without forcing a change in the amount of emissions produced.

This is a concept the Bush administration strongly supports. It has provided some $3 million for research on how to put carbon dioxide into coal seams and fields of briny water deep beneath the Earth and proposed millions more in funding to foster public private ventures.

But scientists at the ongoing American Association for the Advancement of Science (AAAS) annual meeting, questioned whether the current policy fully acknowledges the costs and technical limitations of current sequestration technologies or the size of meaningful sequestration efforts.

Coal seam in Tertiary rocks of the Powder River basin, northern Wyoming. (Photo courtesy of the National Science Geology Dept., University of Akron)

The Intergovernmental Panel on Climate Change has estimated that worldwide carbon dioxide emissions could more than triple over the next 100 years, from 7.4 billion tons of carbon per year in 1997 to approximately 20 billion tons per year by 2100.

Deep saline reservoirs underlie all or part of 35 states, and these are a focus of the government's research, according to Energy Secretary Spencer Abraham.

"Theoretically, they could hold all of the carbon dioxide emitted by the nation's coal burning power plants for the next 100 years," the energy secretary said last November, when he announced the administration's plan to fund public private ventures to explore carbon storage.

Energy Secretary Spencer Abraham sees underground carbon storage as a leading technology in the fight against global warming. (Photo courtesy of the U.S. Department of Energy

The task is not the same as what has been done by the oil industry, which has injected methane into mature oil fields to produce additional, or enhanced, oil.

One potential consequence of injecting carbon into reservoirs is that it could force millions of gallons of salty water to the Earth's surface, substantially greater amounts than the briny water produced during recovery of natural gas, according to Curt White, the leading carbon sequestration scientist at the National Energy Technology Laboratory, Pittsburgh, Pennsylvania.

"This is not a trivial problem," he said, adding that high concentrations of salt and other dissolves solids can be toxic.

"Development of technologies to properly dispose of huge amounts of produced water is a problem area that needs further research," White said.

White is researching the physical and chemical phenomena that occur when carbon dioxide is injected into coal seams and how much carbon can be stored safely within the seams.

It may be the cost, rather than the technological hurdles, that proves the biggest barrier to large scale carbon sequestration efforts.

"Unless the economic incentives are in place, the technology is not going to go anywhere," said Howard Herzog, principal research engineer at Massachusetts Institute of Technology Laboratory for Energy and the Environment.

Herzog argues that because the cost of emitting carbon compounds is free, there are no incentives to capture and store the carbon dioxide. If costs can be directly attributed to carbon dioxide emissions, he said, sequestration efforts will begin to make economic sense.

MIT professor Howard Herzog says without costs for emitting carbon compounds, storage efforts will not succeed. (Photo courtesy of MIT )

The Bush administration has been strongly opposed to imposing fees on carbon dioxide emissions.

White and his colleagues are analyzing surveys conducted by the U.S. Bureau of Mines to determine which U.S. coal seams might contain the most methane.

Lackner argues these efforts are shortsighted and that the administration should think larger, not smaller. At the AAAS meeting, he shared designs for new power plants that would capture the gas before it leaves the facility.

This design could be complemented with "synthetic trees," Lackner explained, that could take carbon from the air, mix it with magnesium silicate, and store it in the "rocks" that would result from the chemical interaction between the elements.

Klaus Lackner, a geophysics professor at Columbia University, believes the government's carbon underground storage plans are too small. (Photo courtesy of Columbia University)

Environmentalists generally support the study of carbon sequestration, but worry that it could stall mandated emissions cuts. They have raised concerns about possible leaks and the subsequent health and environmental risks.

Despite concerns with progress to date, White said the concept of storing carbon in coal seams and underground aquifers still holds potential.

"We now have a much better understanding of what we think is going to happen," White said. "I think that with the proper research and the right resources, the problem areas can be overcome."