A: We don't have a good example, but that doesn't mean we can't keep looking.
One of the best places to look for evidence of a leak is a place where carbon dioxide has been injected for a long time. At the SACROC oil field in west Texas, carbon dioxide has been injected underground for more than 30 years for enhanced oil recovery (EOR). The Gulf Coast Carbon Center performed a comprehensive study of the area and found no evidence of any leaks (or impacts to the freshwater).
Another way to learn about what a leak might look like is to engineer one. Controlled releases are monitored tests of the environmental signals made by carbon dioxide when it is leaked to the environment. Controlled releases are underway around the world.
The Zero Emmissions Research and Technology center (ZERT) at Montana State University and the CO2 Field Lab in Svelvik, Norway are studying the best ways to monitor potential carbon dioxide leaks using controlled releases. The Gulf Coast Carbon Center is also in the process of performing controlled simulations of CO2 leaks in Texas and Mississippi. Such engineered releases allow scientists to better understand the chemical and physical changes in the environment that could signal a leak.
While there have been no noteworthy examples of leaks from underground, there are examples of CO2 leaks from wells, pipes and other underground equipment. This is most often caused by corrosion. When CO2 mixes with water it forms a mild acid (carbonic acid) that can corrode metal. Some older wells were not equipped with corrosion-resistant casing and components, so reentering these wells trequires additional diligence by crew members and, in some cases installation of preventative equipment.
Dr. Susan Hovorka of the Gulf Coast Carbon Center approved this FAQ.
Please click on the link to the left for more information about GCCC's study of the SACROC oil field, a site of industrial injection of CO2 since the 1970's.
The Zero Emissions Research and Technology project in Montana is engineering controlled releases of CO2. To link to the ZERT website, click left.
Researchers in Norway are injecting small volumes of carbon dioxide underground to studying its migration pattern and to develop methods for monitoring a potential leak. For more information, click the icon to the left.
For more information on the risks associated with CO2 leaking from wells, please click on the link to the left.
You may have heard of a reported CO2 leak at a farm in Saskatchewan in 2011. A group of international scientists took a hard look at the geology and biology near the farm. Their extensive field and lab found no evidence that carbon dioxide was leaking from geologic reservoirs. For a documentary on the research, click the link to the left.
We can also learn about what a carbon dioxide leak at an industrial site would look like by studying naturally occuring leaks of CO2, or natural analogs. For more information about natural analogs, please see our related FAQ.