MADISON, Wis. -

Dane County is expanding its use of clean energy, and it could eventually save taxpayers money while also reducing pollution.

The method essentially turns trash into fuel for vehicles. Dane County is capturing methane gas from the landfill and converting it to compressed natural gas, or CNG.

The county has been experimenting with this for the last year, powering 16 county vehicles with the green gas.

Leaders announced Thursday that they'll be nearly doubling the fleet of CNG vehicles, due to a $150,000 state grant.

Dane County Executive Joe Parisi said that 30 county vehicles will run on CNG by the end of the year.

"The CNG fuel costs are the equivalent of about 20 cents per gallon. It's cleaner than gasoline. The EPA estimates that CNG reduces carbon monoxide by 90 percent, reduces ground level ozone emissions by 75 percent, and greenhouse gasses by 25 percent," Parisi said.

It will cost about $360,000 to expand this program. County officials said within a few years, the return on investment will be worth the upfront cost.

The county said with the upgraded system, it will be able to produce more compressed natural gas than what county vehicles need. It's expected that there will some revenue gained from the sale of compressed gas to private businesses.

"This increased use of CNG in our county fleet is estimated to off-set the use of about 20,000 gallons of gasoline this year, and it will save taxpayers about $40,000 annually," Parisi said.

County leaders said that because CNG burns so much cleaner than petroleum-based fuels, the county will also save money on vehicle maintenance as CNG vehicles show less engine wear.

The new filling station will be capable of producing about 200 gallons a day of bio-CNG from landfill gas and even more CNG from natural gas if needed.