Can We Move Carbon from the Atmosphere and into Rocks?

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Jessica Robertson: Hello and welcome to USGS CoreCast, I'm Jessica Robertson. The U.S. Geological Survey recently developed a new method to assess the nation's potential for storing carbon dioxide in rocks below the earth's surface. This storage process is known as geologic carbon sequestration and will help mitigate the effects of climate change.

Today, we are joined by USGS scientist Robert Burruss to discuss this new methodology. Thank you for joining us today, Bob.

Robert Burruss: Hi, Jessica, it's a pleasure to be here.

Jessica Robertson: So first, can you tell us about the new methodology?

Robert Burruss: Certainly. This is a geologically based, statistical method that evaluates the potential to store carbon dioxide in geologic formations. The storage process is what we mean when we talk about geologic carbon sequestration. The new method focuses on the fraction of pore space in rocks that is technically accessible, the part that we believe we can use today.

Jessica Robertson: And what is the value of this new methodology to the general public?

Robert Burruss: Well Jessica, this work is important to the general public because geologic sequestration is one of a number of technologies that we need to limit carbon emissions to the atmosphere. If we truly plan to mitigate climate change we need to use every possible means of limiting emissions including renewable energy, like wind and solar, energy conservation and geologic carbon sequestration is one of those technologies.

Sequestration is certainly important, and indeed all these technologies are important, because the president has stated that as a nation we need to cut emissions by 80% by 2050. That goal is incredibly ambitious and requires us to evaluate all possible technologies including geologic carbon sequestration.

Jessica Robertson: Now Bob, can you tell us why the USGS conducted this research?

Robert Burruss: Yes, Jessica. There are number of reasons why we carried out this work. First is that we simply do not know with any degree of certainty the global storage capacity for CO₂ in geologic formations.

A second reason, and one that makes this work unique, is that we have focused on what we call the technically accessible storage resource. This is the part of the storage space we believe we can use today, with present day technology, so that we could start storing emissions as soon as possible.

A third reason is that the USGS is uniquely qualified to develop methods to assess natural resources. We have conducted national and international assessments of fossil fuels, water and minerals for many years. So, we are building on that experience and treating pore space as a resource in which we can store CO₂.

And then, the fourth reason is that Congress authorized USGS to create an assessment methodology and conduct a national assessment within the legislation of the Energy Independence and Security Act of 2007.

Jessica Robertson: Can you give us some insight on the science behind this report?

Robert Burruss: Sure. There are two basic science issues that are really important for developing this methodology. The first one is really coming to grips with the statistical methods needed to estimate resources when there are very large uncertainties in many of the parameters we need for the calculations.

The second is the challenge of understanding the flow of large volumes of fluids in the subsurface. The amount of CO₂ that must be injected to really impact climate is quite large. So we must be very careful that, (1) no CO₂ will leak back out; or (2) that any water that is displaced by injection does not cause any type of environmental contamination. So this is an area where there is considerable interagency study, with USGS working EPA and the Department of Energy to try to understand the potential of displacement of formation water.

Jessica Robertson: And Bob, is the USGS doing any other research regarding carbon sequestration?

Robert Burruss: Yes, Jessica. Our colleagues in the water and biology disciplines are working on the potential for carbon sequestration in ecosystems. Also, they're evaluating the potential that as the climate changes, some ecosystems like the Arctic tundra might actually become sources for carbon dioxide and other greenhouse gases. And that could cause feedbacks that would limit the impact of carbon sequestration to mitigate climate change.

Jessica Robertson: Now, from your perspective, what was the most interesting part of this research?

Robert Burruss: Well Jessica, understanding the potential for carbon sequestration to mitigate climate change is a really difficult problem because it's truly a global issue. And as a scientist, it's been really fascinating to see how a fundamental science issue like the flow of CO₂ and water in rocks might ultimately help U.S. policy makers deal with climate change issues.

Jessica Robertson: Thanks, Bob. And is there anything else you want to share with us regarding this report?

Robert Burruss: I think the only other thing I'd like to share, Jessica, is to acknowledge the hard work of everyone on the project team and to thank our colleagues in the State geological surveys and other Federal agencies for many helpful discussions because all of that allowed us to complete our project on time.

Jessica Robertson: Well, thank you for joining us today, Bob. And thanks to all of you for listening to this episode of CoreCast. For more information about USGS geologic carbon sequestration efforts, and to learn more about this new methodology, visit the USGS Energy Resources Program website at energy.usgs.gov.

As always, CoreCast is a product of the US Geological Survey, Department of the Interior.

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Mentioned in this Episode:

• USGS Energy Resources Program