OMAHA, Neb. (AP) — Nebraska utilities might be forced to make expensive changes to comply with new proposed restrictions on carbon dioxide emissions because they rely heavily on coal power.

But utility and state officials said Monday the potential impact of the new rules won't be clear until after they've had a chance to study the details.

The plan calls for Nebraska to reduce its carbon emissions by 26 percent by 2030. That's less than the 30 percent reduction nationwide the Obama administration is seeking, but it's still ambitious.

"We're going through this carefully to see what the potential ramifications are for Nebraska," said Brian McManus, spokesman for the state Department of Environmental Quality.

Nebraska has long relied heavily on coal because, with Wyoming's mines not far away, it has been cheaper than most other options.

These new regulations could change that cost calculation, which is important because state law requires Nebraska's public utilities to deliver the cheapest power possible. Nebraska is the only state served entirely by publicly owned utilities.

That low-cost mandate in state law has helped limit how much utilities have been willing to invest in wind power even though experts have said Nebraska has the potential to generate a significant amount of electricity from wind.

"We don't anticipate major changes in the early years, but NPPD will have a solid strategy in place to meet the long-term requirement," said Mark Becker, spokesman for the Nebraska Public Power District.

Troy Bredenkamp with the Nebraska Rural Electric Association said the rules will likely require some expensive updates to power plants.

"These costs get passed on to our membership and the consumer," he said.

But he hopes the state will be able to comply without drastic changes because it does get a significant amount of its electricity from nuclear and hydropower.

Federal statistics show that Nebraskans got about 73 percent of their electricity from coal in 2012, but that is when one of the state's two nuclear power plants, Fort Calhoun, was offline for repairs.

In 2010, about 64 percent of Nebraska's power came from coal and 30 percent came from nuclear power plants.

Utility officials said coal power has been an important part of providing reliable electricity in the state. And a recent University of Nebraska-Lincoln report estimated that coal power and railroad transportation of coal across Nebraska supports 22,800 jobs in the state.

Omaha Public Power District spokesman Mike Jones said the diverse mix of power sources Nebraska utilities rely on should help the state meet the carbon emissions goals.