Geologists take next step testing subsurface containment of greenhouse gases

September 22, 2006

AUSTIN, Texas—Researchers from the Bureau of Economic Geology at The University of Texas at Austin's Jackson School of Geosciences will pump 700 metric tons of carbon dioxide (CO2) a mile below ground in east Texas next week to test a technique for storing CO2 under the Earth's surface.

The test, funded by the National Energy Technology Laboratory of the United States Department of Energy, is the second in a series conducted by the Bureau of Economic Geology to determine the long-term feasibility of carbon sequestration.

Carbon sequestration is the capture and storage of CO2 and other greenhouse gases that would otherwise be emitted to the atmosphere. The technique could play a major role in reducing the effects of greenhouse gases from power plants and other industrial sources.

For two days starting Sept. 25, researchers will inject CO2 into a well at a test site near Dayton, Texas, 40 miles northeast of Houston. Over the next year, scientists will monitor how the CO2 moves through the subsurface.

The field test is part of a series known as the Frio brine tests, named after their geological location. The current test follows an October 2004 pilot that was the first test in the U.S. to monitor the capacity of the subsurface to store injected CO2. In the pilot, scientists successfully used a computer model to predict that injected CO2 would move a short distance through pores in the rock and brine and quickly come to a stop. The pilot also demonstrated the ability of instruments to measure the movement and location of CO2.

"The pilot was a success in that the CO2 did what we thought it would do," said Sue Hovorka, a research scientist at the Bureau of Economic Geology and the project's principal investigator. "We think we have a significant result, but we want to repeat it under more rigorous conditions. We have some new tools to evaluate what's happening. And we want to optimize the experimental design."

The team for the second experiment includes researchers from the Bureau of Economic Geology, Sandia Technologies LLC, Lawrence Berkeley National Laboratory, Oak Ridge National Laboratory, the U.S. Geological Survey, Schlumberger, Praxair, and the Australian organizations CSIRO Petroleum and the Cooperative Research Centre for Greenhouse Gas Technologies.

Carbon sequestration is being explored worldwide as a method for storing CO2 emissions from industrial sources. “We know the pontential risks of transferring carbon from the ground to the atmosphere,” said Hovorka. “But what if you could make it a closed loop? Take it out of the Earth, extract the energy and put it back in the ground. In a way, that would be a green approach. You’re no longer taking it from one earth system and putting it into another.”

The oil industry already pumps CO2 into the ground to force more oil out of depleted deposits, a process called Enhanced Oil Recovery (EOR). Although EOR is a common practice which has not resulted in apparent environmental impact, geoscientists have not rigorously assessed if or how long the CO2 remains underground or whether it eventually makes its way back to the atmosphere. The Frio experiments will help answer that question, at least for some types of geology.

Carbon sequestration could become an important tool for the electrical power and other industries if reduction of CO2 becomes mandatory. New monitoring techniques being developed for the Frio brine tests could help companies verify that their stored carbon remains in place.

Carbon sequestration is also an important component of FutureGen, a $1 billion dollar federal project to create the world's first zero-emissions power plant producing electricity and hydrogen from coal while capturing and storing carbon dioxide. The Bureau of Economic Geology led the Texas bid for FutureGen. As a result of that effort, two Texas sites—Odessa and Heart of Brazos—are among the four finalists that the Department of Energy is now considering for the project.

“The bureau’s leadership in carbon sequestration has been instrumental in our work on FutureGen,” said Scott Tinker, director of the Bureau of Economic Geology and the state geologist of Texas in charge of the Texas team responsible for the Texas FutureGen proposals. “Regardless of whether or not FutureGen ends up in Texas, our research in sequestration will end up benefiting Texas and the world, advancing clean coal technologies that may become one of the most important approaches to reducing greenhouse gas emissions in the atmosphere.”

To find out more about the Frio brine tests, visit the Bureau of Economic Geology's Gulf Coast Carbon Center.

For more information about the Jackson School, contact J.B. Bird at jbird@jsg.utexas.edu, 512-232-9623.