Property owners might someday earn extra money from leasing the space between rocks under their land to store carbon dioxide and other substances.

Storing greenhouse gases underground rather than releasing them into the atmosphere could help reduce global warming.

A bill introduced in the state Senate by Clint D. Harden, R-Clovis, would give land owners control over the subsurface "pore space." Under the bill, if the surface land was sold, the rights to the pore space would go with it, unless specifically excluded.

The owners of mineral rights would still have the right to mine oil and gas from pore spaces.

Wyoming was the first state to pass a pore-space bill. California and Montana are considering similar measures.

Pore spaces could also be used to store compressed air, which can be used to turn wind turbine blades to generate power when the wind doesn't blow.

Harden's original bill caused some consternation at the Office of the State Engineer and the Oil Conservation Division. Both are working on a substitute bill addressing their concerns.

The OSE said the bill contains no requirement that pore spaces used for storage be vacant and warned that it could have "wide ranging implications potentially affecting every landowner and owner of groundwater rights in the State."

Because "most porous strata are currently filled with groundwater," the state engineer said that using the space for capturing carbon dioxide could "displace groundwater or cause carbon dioxide to dissolve into groundwater, which could have an effect on existing water rights and/or groundwater quality."

Mark Fesmire, director of the Oil Conservation Division, said he thinks the pore space bill is "a great idea."

But he said his division wanted to address some technical issues with the bill, such as potential legal conflicts on state trust lands. He said that the State Land Office owns the title to all the minerals and anything else below the surface of those lands.

According to Fesmire, the proposed law would codify what is common law in New Mexico — that the mineral rights owner does not automatically own the pore rights.

"There are some oil company attorneys that disagree with me on that," he acknowledged.

Harden said it was a Mosquero, N.M., rancher and horse trainer, Jack Chatfield, who worked with him on the bill.

Chatfield did not immediately return a call for comment.

Harden said he feels confident some version of the pore-space bill will pass this session, though it has not yet had a committee hearing. "We want to get as much input as possible before it goes to committee so we have broad-based support," Harden said.

Contact Staci Matlock at 470-9843 or smatlock@sfnewmexican.com.