Petra Nova removes CO2 and makes oil extraction easier

Angela Kang

Everything’s bigger in Texas: Oil companies and environmentalists alike welcome Petra Nova, the largest carbon dioxide capture system in the world, to the state. 

The system, a partnership between UT’s Bureau of Economic Geology, NRG Energy and Hilcorp Energy, was declared operational last December. Petra Nova removes carbon dioxide, which is a greenhouse gas that contributes to climate change, from a coal-powered power plant and pipes it 80 miles away to an oil field near Houston. The system then pumps the carbon dioxide approximately one mile underground, through a process called sequestration. Once underground, the carbon dioxide makes it easier for oil companies to extract oil.

“The project is expected to last for about 15 years and produce an additional 60 million barrels of oil that could not otherwise be produced, all while using carbon dioxide that would have otherwise been released,” said Justin Furnace, Hilcorp Energy’s Director of External Affairs.

Furnace said while carbon dioxide-based enhanced oil recovery projects are nothing new, Petra Nova is recycling carbon dioxide from a new source. 

“What makes this project unique is that it uses anthropogenic (or human-created) carbon dioxide captured from a coal-fired power plant rather than underground sources of carbon dioxide,” Furnace said.

Petra Nova pressurizes this captured carbon dioxide and carries it 80 miles away, where it is returned to the ground. When the pressurized gas is transported underground, it changes the pressure and temperature of the surrounding geological environment, making it easier to extract oil. 

“(The injected carbon dioxide) doesn’t change the oil chemically, but it does change…the viscosity of the oil to make it more slippery, which allows oil companies easier access to the oil,” said NRG Energy spokesperson David Knox.

Knox said some of the carbon dioxide stays in the earth, while some is returned to the surface with the extracted oil. The carbon dioxide that makes it to the surface is once again recaptured, repressurized and reinjected into the oil field. 

Knox said because 25 percent of the carbon dioxide stays within the earth, Petra Nova helps reduce carbon emissions that would otherwise escape into the atmosphere. 

UT’s Bureau of Economic Geology will be monitoring the underground carbon dioxide levels to ensure that the expected 25 percent remains underground.

“We have established the carbon capture system as a business, but part of that business is sequestering that carbon dioxide and having the world’s premier geological monitoring team as part of this allows us to have scientific backing and credibility,” Knox said.

Knox said the lack of current regulation requiring carbon-capture and the high cost of the process means there is little incentive for businesses to begin the process. Knox said Petra Nova, while expensive, is a model for how carbon-capture systems can be profitable in the long run. 

“Petra Nova pays for itself,” he said. “Petra Nova turns (carbon capture) around and makes it a business model so that businesses are incentivized to do it.”

Since December, Petra Nova has captured and returned underground 300,000 tons of carbon dioxide, setting a precedent for future capture systems.

“You look at the amount of carbon going into the atmosphere, and coal is a large contributor,” Knox said. “We’re doing a lot to reduce carbon dioxide with solar and wind, but there’s still going to be coal for many decades, and we need to address coal emissions in the existing infrastructure.”