Does Underground CO2 Storage Have Risks?

Written By Teacher: Teresa Pettitt-Kenney

Hi there! My name is Teresa and I just finished my Bachelor's degree in Environmental Science and am excited to pursue environmental education in the future! I am extremely passionate about climate change, equitable climate action, and how education can work to address these issues. 

When it comes to talking about climate change in our classroom, students have some creative ideas for solutions. It can be great to discuss climate science solutions with your kids and let them brainstorm their own ideas too! Older students can even participate in the En-ROADS Climate Solution Lab and research which solution they like best. Underground CO2 storage isn’t always the most popular climate solution, but students may want to investigate it further. The article below investigates the positives and negatives of CO2 storage as a solution to warming, so you can share it with a curious student, or use the content to help guide you in your teaching.

Written By: MIT Environmental Solutions Initiative

The MIT Climate Change Engagement Program, a part of MIT Climate HQ, provides the public with nonpartisan, easy-to-understand, and scientifically-grounded information on climate change and its solutions.

Because the main cause of climate change is too much carbon dioxide (CO2) in the atmosphere, one idea to fight it is to capture CO2 and store it underground. There are a few operations in the world that already do this, by capturing CO2 through a chemical process, condensing the gas into liquid form, and then injecting it deep underground. This process is known as “geologic sequestration,” because the CO2 is stored (“sequestered”) in rock.

While geologic sequestration of CO2 is not yet common, it is similar to a more common process in the oil and gas industry: wastewater injection. Fracking, or “hydraulic fracturing,” is used to collect oil or natural gas contained in rocks underground. To frack, drillers inject a mixture of water, sand and chemicals into a rock layer and break it apart, but some of the water-sand-chemical mixture flows back up the well. This wastewater is separated from the oil and is often injected back underground at a different site.

Under certain conditions, injecting this wastewater underground can cause earthquakes. Oklahoma, for example, experienced a surge in earthquakes in the 2010s due to a large amount of wastewater being injected underground. Once injected into an underground well, the fluid raises the pressure in the surrounding rocks and aquifers, reducing the friction on fractures in the rocks. If these wells are near a fault line, the pressure within the fault can also increase, moving around the rocks and causing an earthquake—just like the added pressure of air on an air hockey table can move around the puck.