The Demeter renewable natural gas (RNG) anaerobic digestion project in Madison, Wisconsin, converts 90,000 gallons per day of dairy waste from three area farms into 50,000 MMBtu of RNG each year – enough fuel to travel from San Francisco to New York and back over 200 times in a compressed natural gas vehicle. The digester upgrades were completed in June 2020.

“As a participating farm, we are excited to have Brightmark as a partner in anaerobic digestion of the manure from our cows. This agreement will help local farms continue to be environmentally friendly to our community and help us to stay in compliance with environmental regulations. We have always taken pride in being excellent stewards of land conservation and ensuring our land is a safe environment for our neighbors.”
– Chuck Ripp of Ripp’s Dairy Valley LLC

Project Benefits

GHG Reductions
The facility will offset 16,000 metric tons of greenhouse gas emissions each year.

Waste to New Products
Renewable products generated by the project include biofertilizer, digested dairy fiber for use as cow bedding or as a peat moss substitute, and reclaimed irrigation water.

Resource Recovery
The process of recovering and processing manure from the farms will prevent excess nitrogen and phosphorus from escaping into local air and water, reducing phosphorus runoff alone by 60%.

Project Locations

  • Ripp’s Dairy Valley – Dane, WI
  • Endres Daity – Dane, WI
  • White Gold Dairy – Waunakee, WI


Clean Fuel Partners, which is a subsidiary of Brightmark Energy, provides operations and maintenance support for the digester. The project was also developed in close coordination with Dane County, Wisconsin. The renewable natural gas collected from the anaerobic digester is transported to the county’s landfill-gas-processing facility, where it is injected directly into an interstate pipeline.

Transform Your Waste.

Let's team up and turn your farm waste into renewable natural gas.