Deep underground CO2 storage considered

WASHINGTON, June 26 (UPI) -- U.S. government scientists have determined deep coal seams that aren't commercially viable for coal production might be used for carbon dioxide storage.

Such permanent underground CO2 storage would avoid atmospheric release, thereby combating climate change, as well as displacing additional useful methane from the coal beds, scientists said.

Researchers at the U.S. Department of Energy's National Energy Technology Laboratory collected 2,000 coal samples from 250 unmineable coal beds across 17 states. The scientists theorize there is storage capacity for nearly 3 trillion tons of CO2 in such deep coal seams worldwide.

The research team also investigated possible side-effects of sequestering CO2 in coal mines and found some toxic metals originally trapped in the coal would be released by the process.

"Changes in water chemistry and the potential for mobilizing toxic trace elements from coal beds are potentially important factors to be considered when evaluating deep, unmineable coal seams for CO2 sequestration," they said, although they noted such effects might be harmless given the depth of such coal seams.

The research appears in two studies published in the International Journal of Environment and Pollution.