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Robert Finley

Editor’s note: One of the largest carbon sequestration projects in the U.S., the Illinois Basin – Decatur Project (IBDP) has reached its goal of capturing 1 million metric tons of carbon dioxide and injecting it deep underground in the Mount Simon Sandstone formation beneath Decatur, Illinois. The project is designed to demonstrate the feasibility of carbon capture and storage. IBDP director Robert Finley talked about the million-ton milestone with News Bureau physical sciences editor Liz Ahlberg. Finley is director of the Advanced Energy Technology Institute at the Illinois State Geological Survey, part of the Prairie Research Institute at the University of Illinois.  

What is carbon sequestration? How does it work?

Geological storage of carbon dioxide (CO2) is one method of isolating CO2 from the earth’s atmosphere. Reducing the amount of CO2 released into the atmosphere may slow the global warming trends that have been observed in the last decade or more. Geological storage can play a significant role in preventing continued buildup of CO2 in the atmosphere.

At the IBDP, 1 million tons of CO2 were captured from the ethanol production facility at Archer Daniels Midland Company. After the CO2 is captured, it is dehydrated and compressed from atmospheric pressure to 1,400 psi for injection into a well, which is 7,000 feet deep. The CO2 enters the rock formation through a set of perforations in the well that isolate the injection zone from the rest of the environment. The CO2 is stored in the pore spaces of the sandstone and sealed in place by a cap layer of impermeable shale.

Why the Decatur site?

For more than 100 years, the Illinois State Geological Survey has collected background information on the subsurface rocks of the Illinois Basin, and it has been investigating the carbon storage potential of the Mount Simon Sandstone in particular for more than 10 years. The uppermost Mount Simon Sandstone has performed well as a natural gas storage reservoir in Illinois, and we expected the same storage performance for CO2 in the deep Mount Simon Sandstone at Decatur, Illinois, and other locations throughout Illinois, Indiana and Kentucky.

Our industrial partner, Archer Daniels Midland, is located in Decatur above the Mount Simon Sandstone. They provide the source of CO2 from their ethanol production facility and storage takes place on location, more than a mile beneath the surface.

What does it mean that 1 million tons was injected?

One million tons is scalable in its behavior to the 3 million tons that would be emitted annually from a typical medium-sized, coal-fired power plant. That is why it is important that this project achieved its objective of 1 million tons injected. The fact that this objective was achieved safely and effectively suggests that CO2 storage technology can be one of several tools for mitigating climate change.

Did you observe any effects on the local environment from having so much CO2 injected?

Extensive monitoring takes place during and after injection to be sure the stored CO2 stays in place. Monitoring techniques include using geophysical technology to confirm the position of the CO2 underground and wells to monitor groundwater and soils.

No out-of-bounds health, safety or environmental risks were observed from this properly designed and managed storage site. Appropriate risk mitigation and management plans were an integral part of the overall project planning. Extensive monitoring took place before, during and now after the injection to be sure the CO2 stays in place. The first line of monitoring begins deep below the ground, so we know if any leakage occurs long before any CO2 might reach the surface.

How does the IBDP compare to other sequestration efforts around the world?

Geological sequestration of CO2 by injection into the Earth’s surface is a promising technology being studied around the world.  There are currently projects underway in Algeria, Australia, Canada and Norway, and under development in China, South Africa, South Korea and other locations.  The Illinois Basin – Decatur Project is one of the first projects of similar scope in the United States to complete the goal of a 1-million-ton injection of CO2 for geological sequestration. 

Editor’s note: To reach Robert Finley, call 217-244-8389; email