Wyoming CarbonSAFE scientists conduct soil gas analysis near Dry Fork Station, Dry Fork Mine

two people standing with a test site, with Dry Fork Station in the background
Charles Nye, a geochemistry research scientist at the University of Wyoming's Center of Economic Geology Research (CEGR), and Ben Flickinger of Earth Platform Systems, installed eight soil gas sensors at Dry Fork Station and Western Fuels’ Dry Fork Mine on Mar. 5. 

Scientists assigned to the Wyoming CarbonSAFE project, implemented by the U.S. Department of Energy near the Dry Fork Station, a coal-based power plant near Gillette, Wyoming, are conducting soil gas analysis.

The project, in its third phase, is investigating the feasibility of underground carbon dioxide emissions storage from coal-based electric generation facilities.

Charles Nye, a geochemistry research scientist at the University of Wyoming's Center of Economic Geology Research (CEGR), and Ben Flickinger of Earth Platform Systems, installed eight soil gas sensors at Dry Fork Station and Western Fuels’ Dry Fork Mine on Mar. 5. The soil gas sensors are placed near abandoned oil and gas wells to collect baseline soil gas concentration information.

“We have found the natural geology near Dry Fork Station is generally favorable for carbon storage and disposal,” Nye said. “This leaves human-made penetrations like these deep abandoned wells as one of the few remaining risks to carbon dioxide storage.”

Nye said the information collected on soil gas levels will help researchers determine the level of risk posed by these abandoned wells. “This risk is probably low because most wells in the area were built fairly recently, around 1980, but even a low risk should nevertheless be proven,” he said. “Two sensor stations will be installed off-site as a null-case. We have been discussing these sites with various public and government institutions to make sure everyone is informed.”

Nye said the depth of the sensors is important in making sure the air above ground level doesn’t interfere with results. “Preliminary data from shake-down testing (a.k.a. experimental testing) of these sensors in Laramie, Wyoming, shows air three feet below ground is substantially different from ambient atmospheric air. Although still a mix of surface and subsurface air, these data indicate what is going on 10 feet or more below ground,” he said. “Deeper installations reduce the effects of surface air, and represent deep soil gas better. One way we can tell the collected data is representative is by seeing muted daily cycles in deeper sensors.”

“The sensors collect natural gases from around three feet underground, and each only takes about 15 minutes to install,” Nye said. Power is supplied by a solar panel and a battery backup, and data is encrypted and sent to the University of Wyoming via a radio antennae.

The soil gas sensors are scheduled to remain in place for two years, with an extension to a third year if funding permits. If carbon dioxide is eventually stored in this area, Nye said, the existing network of sensor stations would be expanded to become part of a long-term monitoring plan. If operations in the area need to be relocated, the sensors are designed to make that easy.

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