News•July 31, 2014

Using CO2 Emissions to Pump Oil May Help the Climate

Carbon capture and storage is often talked about as a way to keep major polluters’ carbon dioxide emissions out of the atmosphere by tucking them away safely underground forever.

But carbon capture and storage, or CCS, could be used more often in a rather counterintuitive way: To produce crude oil, which releases its own CO2 emissions when it’s burned, helping drive climate change.

An oil field in California's Central Valley.
Credit:Richard Masoner/flickr

Here’s the twist: Experts say producing more oil using CO2 captured from coal-fired power plants may actually reduce the total amount of CO2 released into the atmosphere from burning coal and crude oil.

Called “carbon dioxide enhanced oil recovery,” the process works like this: CO2 emissions are captured from coal-fired power plants, then transported to old oil fields where production peaked long ago. By injecting the captured CO2 into existing oil wells that have been producing diminishing amounts of crude oil, hard-to-get crude oil will react with the CO2 and swell deep underground. The oil becomes thinner, allowing it to flow more freely into an old oil well and reviving production in an old oil field.

As counterintuitive as it may seem, that may be good news for the climate because total emissions from burning both the coal and the crude oil may be reduced, some experts say.

Injecting CO2 from a coal-fired power plant into an oil well sequesters the plant’s emissions underground, partially offsetting the CO2 emitted from burning the oil, said Patrick Falwell, a fellow with C2ES, or the Center for Climate and Energy Solutions, formerly the Pew Center on Global Climate Change.

“The hope is that the CO2 you’ve injected will exceed or equal the CO2 that results from the combustion of the oil,” Falwell said. “In terms of the greater market for oil, if the oil produced by EOR (enhanced oil recovery) actually displaces oil from another source that didn’t involve injecting man-made CO2 underground, you’re doing better from a market perspective.”RELATEDCarbon Storage Studies Grapple With Politics, Geology
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Falwell said scientists are confident that the CO2 stored underground in oil wells will remain there permanently and is unlikely to eventually leak into the atmosphere, a claim backed by several studies. One of those, a 2008 University of Texas study, shows that over 37 years of CO2 injection, leakage was rare.

Today, enhanced oil recovery with CO2 injection accounts for about 300,000 barrels of oil production per day, or about 5 percent of total U.S. crude oil production, mainly in fields in Texas, he said.

As crude oil prices rise, more and more crude oil in the U.S. will be produced using CO2 injection, a U.S. Energy Information Administration report released Wednesday shows. Depending on how much crude oil prices increase, between 8 and 12 percent of all crude oil produced in the U.S. in 2040 could be extracting using captured CO2.

A study by Stephen Melzer, a consultant for the National Enhanced Oil Recovery Initiative, says that injecting CO2 for crude oil production can help reduce emissions by turning industrial and power plant CO2 emissions into a valuable commodity, helping to accelerate storage of climate change-driving emissions.

Today, many oil and gas operations use CO2 from natural underground sources produced specifically for oil fields, resulting in no climate benefit. But that’s changing as captured CO2 emissions become a commodity, said Mark Northam, director of the School of Energy Resources at the University of Wyoming.

“As CO2 emissions regulations grow, more CO2 will become available,” he said. “EOR is currently the only revenue-generating use for a growing CO2 supply. There are hundreds of mature oil fields around the U.S. that are suitable for EOR, so the logic says project numbers will grow.”

An oil and gas field near homes in Colorado.
Credit: Bobby Magill

Some studies paint a more skeptical picture of the role of CO2 emissions injection into oil fields as a way to mitigate climate change.

James Dooley, a carbon capture and storage expert and engineer at the Pacific Northwest National Laboratory’s Joint Global Change Research Institute, published a 2010 study showing that oil field CO2 emissions injection may do little more for the climate than spark interest in new CCS technology.

Of the 129 CO2 injection projects in oil fields worldwide in 2010, only one of them was a certified carbon capture and storage project. That, and other weak interest in the technology in oil fields shows that oil field CO2 emissions injection “is not a mandatory step on the path to CCS deployment,” Dooley wrote in the study.

Dooley could not be reached for comment.

Groups interested in the prospect that oil production using captured CO2 emissions could have a climate benefit are working with Congress to create a tax incentive for it.

C2ES, a co-convener of the National Enhanced Oil Recovery Initiative, is working with Congress to pass a bill that would include CO2 injection for crude oil production as part of an existing carbon sequestration tax credit.

Members of the initiative include representatives of environmental groups such as the Natural Resources Defense Council, agricultural producers including Archer Daniels Midland, and state government agencies in New Mexico and Michigan, among other organizations.