In the not too-distant future, carbon dioxide will be stored in vast reservoirs deep under North Dakota.

It will most likely be put there by companies that inject the buoyant gas deep into oil fields to bubble out the last reluctant portion of valuable crude oil.

On Wednesday, a compact of oil- and gas-producing states, led by Gov. John Hoeven, released a framework for how those reservoirs should be managed over the infinity of time when the gas will be stored underground.

The issue is relevant in North Dakota, because coal-fired power plants and other sources emit millions of tons of CO2, a so-called greenhouse gas that contributes to global warming. It's doubly relevant because the state's oil fields are reaching an age where enhanced oil recovery is practical.

The gas is not regulated now, but it's anticipated that some CO2 management practices will eventually be mandated to help solve the global warming problem.

Injecting the gas into the geologic formations of oil fields both increases oil revenue and takes the gas out of the atmosphere. It's already being done in oil fields in Texas and Canada.

The 30-state Interstate Oil and Gas Compact Commission developed the framework to help oil and gas producing states grapple with the legal issues as the practice moves forward.

Larry Bengal, of Arkansas, chaired the commission's CO2 taskforce at the request of Hoeven, who Monday ended two terms as compact chairman.

The framework recommends that individual states, not the federal government, manage and regulate underground CO2 reservoirs.

Bengal said the framework is purposely simple, a living document that leaves room for states to develop policies based on real experience.

The taskforce recommends that states levy a per-ton fee on injected CO2 in order to create a trust fund.

Oil companies would close the injection sites, monitor and maintain liability for the gas reservoirs for 10 years and then responsibility would shift to states. The trust funds would finance state monitoring to watch where and if the gas moves and any liability problems.

Bengal said another reason states should manage the underground gas reservoirs is because eminent domain may have to be invoked to acquire the storage rights.

In some states, the underground pore spaces where the gas would be stored are part of mineral ownership and in other states they're part of the surface ownership - in both cases, though, the pore space is private property and would have to be acquired from the owner, Bengal said.

Bengal said states, not the federal government, should license the sites and "be there in the end, when someone has to take liability. There would have to be major (federal) changes for the Environmental Protection Agency to take cradle to grave responsibility."

The taskforce also recommends that CO2 be managed as a resource rather than a waste product, because it is still considered safe and not toxic.

"We don't think it should be considered a pollutant like sulfur dioxide and nitrous oxide," Bengal said. "We're hoping to make that point; that when it comes to management, that it's not a waste product."

(Reach reporter Lauren Donovan at 888-303-5511 or lauren@;westriv.com.)