Guest Blogger: Christy Zheng - 16 years old - Madison, Wisconsin - Printed with permission of the Simpson Street Free Press
One man’s trash will be converted into another man’s fuel in a recently completed $29 million landfill biogas facility at the Dane County Landfill. The County works with a local contractor, BioFerm Energy Systems.
The new facility converts gas from the Dane County Landfill into compressed natural gas (CNG), which is then sold as transportation fuel at Kwik Trip gas stations.
CNG is an environmentally friendly alternative to gasoline and diesel. Cars and other vehicles running on CNG burn methane, a notorious greenhouse gas, but then release the less-harmful carbon dioxide in its place. Cutting down on gasoline and diesel use reduces greenhouse emissions and helps the environment.
CNG from the new facility will offset about three million gallons a year of gasoline that would have otherwise been used, claims County Executive Joe Parisi. That number could grow to four million in future years, which would be like taking 4,800 cars off of the road.
Methane has been used as a fuel for decades but sourcing it from landfills requires extra work. Decomposing food and other garbage stored in landfills releases large amounts of methane, but it’s diluted, mixed in with other compounds and particles. Current vehicles do not have sensors to detect the amount of diluted methane it should burn compared to concentrated methane. So, using the diluted gas from landfills might cause cars to use the wrong amount of fuel.
The facility solves this problem by purifying the methane. The gas harvested from the landfill is sent through a series of large, cylindrical tanks, each one designed to separate compounds and particles from the methane. The methane leaves the tanks much cleaner and enters a pipeline owned by ANR Pipeline Company. For quality control purposes, the pipeline has sensors to measure the condition of methane. The valve to the pipeline shuts down if sensors detect the methane falls short of appropriate standards.
Currently, the compounds and particles separated out from the methane are burned, in accordance with Environmental Protection Agency regulations. However, the county hopes to find a use for this kind of waste in the future. For instance, carbon dioxide from the cylinders could be used to make dry ice.
“Long term, our goal is to have zero emissions,'' stated John Welch, director of the county Department of Waste and Renewables.
The facility will eventually run on solar energy, once the solar panels at the Dane County Airport are installed.
County officials would like to use the ANR pipeline to make methane collection more practical for other methane suppliers too. Manure digesters, in particular, could build biogas facilities like used at the landfill and produce CNG, which they could inject into the pipeline. The landfill’s biogas facility includes an injection station for other suppliers to send their CNG to the pipeline. These suppliers would, in turn, receive economic incentives, including profits from selling CNG and renewable energy credits.
According to Parisi, the landfill biogas facility will pay for itself in just four years, making the ambitious project a long-term benefit, both environmentally and economically.