Monday, December 3, 2007 12:09 AM CST
State geologists: Illinois sites best for CO2 storage
By NATHANIEL WEST, Staff Writer
nwest@jg-tc.com
ARCOLA — Geologist Hannes Leetaru used the analogy of drinking straws to describe the effect that drilling for oil could have on the storage of the “greenhouse gas” carbon dioxide in layers of sandstone thousands of feet underground.
“If you have a lot of penetrations, those wells (of carbon dioxide) could fail,” said Leetaru, senior geologist with the Illinois State Geological Survey. “Then you have a problem.”
Federal officials are slated to decide soon whether carbon dioxide from an environmentally friendly, coal-burning power plant prototype will be buried below either Texas or Central Illinois. And ISGS officials advocated the latter as the best site for FutureGen, claiming the proposed locations in Texas are perforated by “potential leakage pathways” because of oil exploration and retrieval efforts.
“Their risk (of CO2 leaks) is significantly higher than ours,” said Leetaru.
The FutureGen project, backed by the U.S. Department of Energy and major energy companies, calls for the construction of a coal-powered plant that would make electricity — as well as hydrogen for use in fuel cells — but store almost all of the harmful emissions through a process called “carbon sequestration.”
Sallie Greenberg, geochemist and sequestration communications coordinator for the ISGS, said it is no coincidence the process shares a name with the act of confining a trial jury beyond the reach of outside influences.
“You’re taking (carbon dioxide) out of the atmosphere and storing it where it’s not communicating with anything else,” Greenberg said. “We’re storing carbon dioxide in earth materials — storing it in sandstone and keeping it in place, capping it” with relatively impermeable rock such as shale.
If FutureGen is awarded to either Mattoon or Tuscola, Leetaru said the carbon dioxide produced by the power plant would be pumped into the “Mount Simon” layer of sandstone 6,000 to 7,000 feet below the surface and blanketed by numerous other rock strata.
“We have a number of seals that will stop any carbon dioxide movement upward,” Leetaru said of the proposed FutureGen sites in East Central Illinois.
“There’s always a slight risk (of leaks), but realistically, it’s negligible” in the Mattoon and Tuscola regions, Leetaru said.
This has been validated by “seismic reflection profiling,” in which sound waves directed into the ground reflect off the various layers of rock to reveal their traits — similar to the way radar and sonar work, according to Leetaru.
He added that a Champaign-area natural gas company has used the Mount Simon layer for storage without incident for more than three decades.
Mount Simon is so safe because there has been no substantial drilling for fossil fuels in this region, said Leetaru.
Greenberg also said the prospects for future oil or gas exploration in the Mount Simon layer are nil. “There’s no petroleum or fossil fuel resources in or beneath Mount Simon,” she said.
“In Illinois, we have no reason to drill.”
However, officials noted, this is not the case in the areas around the Texas cities of the Jewett and Odessa — the other two of four FutureGen finalists.
“Their sites have a lot of (oil) wells that have gone through,” said Leetaru.
Greenberg said the oil wells in Texas could serve as “potential leakage pathways” for the buried carbon dioxide.
“They have holes — think of soda straws — that have gone through the seal” of rock, Leetaru said.
Contact Nathaniel West at nwest@jg-tc.com or 238-6860.
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gringa wrote on Dec 5, 2007 1:00 PM: