Once a coal-fueled power plant, NRG Energy Center Dover is now considered one of the cleanest power plants in the nation.

A year ago, NRG began converting the facility to run off natural gas, instead of coal. A $500,000 grant from the state kick-started the conversion, which NRG unveiled Friday.

NRG spokesman David Gaier said it was an economic decision for the plant, but one that carried with it "huge environmental benefits." The $25 million project would have cost more, but Gaier said the power plant was able to use some of its own existing equipment.

"We swapped out the coal boiler and we substituted what's called a heat recovery steam generator in the middle ... which runs on natural gas, and then we added the existing steam turbine, so we created what's called a combined cycle package," Gaier explained. 

"This facility is a big win for our state, so we really want to thank [NRG] for reducing air emissions and contributing to our goal of a clean energy economy," Delaware Gov. Jack Markell said.

The conversion lines up with the state's energy goals of reducing air emissions and providing clean power from existing sources—efforts that Markell says are already paying off.

"A recent report showed that Delaware, over the last four years, has reduced our emissions more than any other state in the country and I don't think you can overstate the importance of that."

"We do not have to choose between having a cleaner, stronger environment and having a robust, growing economy. It is possible to have both," Sen. Tom Carper, D-Del, said.

Department of Natural Resources and Environmental Control Secretary Collin O'Mara said he believes Delaware could serve as a national model not only to other states, but also to the pols in D.C., of what happens when government works. 

"I just want all of you to feel really proud leaving today—the folks at NRG, the folks in the state, the folks at different levels of government—because this is unique, but it's something that shows that government isn't broken and government actually can achieve great things working with industry," O'Mara said.

The conversion is expected to reduce 99 percent of sulfur dioxide and nitrogen oxides, two air pollutants that can cause serious respiratory issues, and more than 65 percent of particulate matter. In addition, because NRG Dover is no longer coal-fueled, all of the emissions associated with coal combustion have been eliminated.

NRG still operates a coal-fueled power plant in Dagsboro, the only one left in the state. Once considered one of the dirtiest coal-fired plants in the country, NRG invested $360 million in 2009 to cleaning it up, and it now ranks among the cleanest.