A $150,000 grant will allow Dane County to expand the number of county vehicles that run on sustainable energy by the end of year and take a step toward reduces fossil fuel usage and emissions.

Dane County Executive Joe Parisi said in an email to The Badger Herald that the county’s fleet currently contains approximately 20 vehicles running on compressed natural gas out of 500 vehicles total, a figure which would increase to 30 by the end of the year.

“Sustainability in Dane County government is a priority for me,” Parisi said. “As cars in the county fleet continue to age and need to be replaced, we will replace those vehicles with ones that can run on CNG whenever possible or practical.”

The natural gas used in the vehicles comes from the county’s Rodefeld landfill, which receives an average of 175,000 tons of non-hazardous solid waste per year, Parisi said.

UW microbiology professor Thomas Jeffries said in an email to The Badger Herald that the landfill material is converted into fuel by a process known as anaerobic digestion. He said the garbage that goes into the landfill is first covered with a layer of soil. As the organic materials degrade, they are converted into methane.

The methane is collected through a pipeline and sent through an on-site biogas compressor. This equipment cleans the gas to specified purity standards and then compresses it for use in vehicles capable of running on CNG, Parisi said in the email.

Jeffries says this saves on space and is economical because the landfill can be turned over faster and new landfills do not need to be opened as often.

The CNG station has been installed at the county’s Rodefeld landfill for nearly a year. At that time, Dane County was the first county in Wisconsin to begin converting trash to gas to power its fleet.

“We hope that by leading by example, more units of government and private companies will begin to use this cheaper, cleaner burning, home-grown fuel,” Parisi said.

The county has already sold 870 gallons of CNG to two private trucking companies that haul new CNG garbage trucks to customers, he added.

The people of Dane County could also personally benefit from this increased reliance on natural gas. According to Parisi, it is estimated to save taxpayers $40,000 annually by saving on maintenance costs as the natural gas runs cleaner than gasoline and is a cheaper alternative to high gasoline prices.

Jeffries said this change is significant in several ways. Vehicles running on CNG will emit less carbon dioxide for every mile driven and help avoid greenhouse gas emissions in the atmosphere. The county can further reduces the emission of greenhouse gases by avoiding the use of fossil fuels wherever possible, he said.

According to Parisi, Dane County CNG use has replaced the equivalent use of 20,000 gallons of gasoline. The Environment Protection Agency estimates that CNG reduces carbon monoxide by as much as 90 percent, ground-level ozone emissions by 75 percent and greenhouse gas emissions by 25 percent.