U.S. oil fields could store decades of carbon emissions

Depleted North American oil fields could hold billions more tons of carbon dioxide than previously estimated, providing a way to both curb greenhouse gas emissions and boost production of domestic fuels.

In a report released yesterday, the U.S. Department of Energy said the underground capacity of oil fields in the U.S. and Canada is 225 billion metric tons, or about 60 percent greater than estimates from two years ago. That’s the equivalent of more than a century of U.S. power-plant emissions at current levels.

“These numbers are jaw-dropping,” Kurt Waltzer, coordinator for carbon capture at the Clean Air Task Force, said in an interview. “The more we learn about enhanced-oil recovery the better it looks as a technology.”

Under enhanced-oil recovery, drilling companies pump carbon dioxide into the earth, where the gas acts as a solvent to help extract oil from older deposits. The technique helps produce 281,000 barrels of oil a day in the U.S., or 6 percent of domestic production, according to a report this year by the Center for Climate and Energy Solutions.

Most of the carbon dioxide now used in oil drilling is pulled from underground reservoirs and transported to the wells. Meanwhile, U.S. power plants emitted 2.3 billion metric tons of carbon dioxide equivalents in 2010, according to the Environmental Protection Agency.

With investments in pipelines and upgraded technologies to improve collection of carbon dioxide, oil companies could buy the gas from power plants or ethanol manufacturers instead of extracting it from underground deposits, advocates say.

“What’s constraining enhanced oil recovery now is the lack of carbon dioxide,” Waltzer said.

Once it’s pumped deep into the ground, most of the gas remains trapped, and kept from release into the atmosphere where it can cause global warming.