01 December 2011
That approach is called carbon sequestration, and a million-ton demonstration of CO2 storage has entered a critical phase — the injection of CO2 from a biofuels plant into a sandstone formation more than 2,100 meters below the surface of Decatur, Illinois.
“Establishing long-term, environmentally safe and secure underground CO2 storage is a critical component in achieving successful commercial deployment of carbon capture, utilization and storage technology,” said Chuck McConnell, chief operating officer for the Office of Fossil Energy at the U.S. Department of Energy (DOE).
This injection test is managed by the Midwest Geological Sequestration Consortium (MGSC). McConnell said in a November press release that it will help “confirm the great potential and viability of permanent geologic storage as an important option in climate change mitigation strategies.”
The Illinois State Geological Survey (ISGS), part of the Prairie Research Institute at the University of Illinois at Urbana-Champaign, is leading the project, which has been in development since 2003. The group’s study indicates that the deep, sub-surface reservoir they’ve selected — known as Mt. Simon Sandstone — “has the necessary geological characteristics to be an excellent injection target for safe and effective storage of CO2,” according to Robert J. Finley, the leader of the ISGS sequestration team. The scientists estimate that the storage capacity of Mt. Simon Sandstone is as much as 150 billion metric tons.
The CO2 is being captured from a processing complex where the Archer Daniels Midland Company is fermenting corn to make ethanol. The captured CO2 is compressed into a dense liquid and injected into the underground formation. ISGS has confirmed that this formation is the thickest and most widespread saline reservoir in the Illinois Basin, a geological feature underlying two-thirds of the state of Illinois. When the CO2 is injected into the formation, it is stored permanently in pore spaces within the rock. The Mt. Simon Sandstone lies beneath the Eau Claire shale formation that serves as an impermeable cap of rock, a layer of protection preventing CO2 release into the atmosphere.
The infrastructure for this sequestration project has been under development since 2007. MGSC has conducted a seismic survey of the area and constructed a pipeline and a facility where the CO2 is compressed. Three wells have been drilled, including an injection well and a well to be used to monitor the ongoing injection and its effects on the surrounding rock formations.
This project is one of several demonstrations being conducted by regional carbon sequestration partnerships sponsored by DOE. Seven regional partner organizations around the country are working to identify the best approaches for capturing and permanently storing greenhouse gases.
Another group involving nine states from Indiana to the mid-Atlantic coast reported in November the discovery of underground storage capacity that could permanently store hundreds of years of CO2 emissions generated by the region. This group — the Midwest Regional Carbon Sequestration Partnership — has identified deep saline rock formations that could store almost 250 billion metric tons of CO2.
These sequestration efforts move forward at an important moment in the international discussion of climate change. Representatives from almost 200 nations, parties to the U.N. Framework Convention on Climate Change, are in Durban, South Africa, November 28–December 9 working to reach international agreement on how to reduce emissions of greenhouse gases in an effort to slow the process of global warming.