|Location||Rice Lake, Wisconsin|
|Project Type||Farm Scale|
|Population Feeding Digester||1,240|
|Baseline System||Storage Lagoon|
|Digester Type||Complete Mix|
|Co-Digestion||Off-farm food waste (whey, slaughterhouse, foodwaste station, mostly grease)|
|Biogas Generation||2,908,000 ft3/day|
|Generating Capacity||850 kW|
|Receiving Utility||Dairyland Power Cooperative; Barron Electric|
Farm Bill Funded Project
At Norswiss Farms, manure is scraped and collected three times each day and pumped into an above ground complete mix steel tank digester. A limited amount of off-farm food wastes are also systematically pumped into the digester to boost biogas production. The digester has an operating temperature around 125°F and has a hydraulic retention time of approximately 20 days.
Norswiss Farms manages the digester using a unique business model. Microgy provides financing for the development, construction, and ongoing operation and maintenance of the digester. With Microgy providing the financing, Norswiss Farms did not have a large cash outlay. All the generated biogas is sold to Dairyland Power which owns and operates the on-site engine-generator set. Dairyland Power sells the generated electricity to member cooperatives and receives renewable energy credits. Norswiss Farms pays off the debt of the digester through biogas sales to Dairyland and the sale of accumulated carbon credits.
The generated biogas is scrubbed and fed into an engine-generator set with a 850 kW capacity. Dairyland Power relies on the synchronous system to provide voltage support for their distribution system. In the event of a power failure, the synchronous system shuts down. The farm has a backup boiler to provide heat to the digester if the engine is not operating.
A screw press solids separator is used to divide digester effluent into liquid and solid fractions. The liquid is pumped into a storage lagoon where it is later used to fertilize crops and all the fibrous solids are used for animal bedding.
Norswiss Farm's digester project includes the following benefits:
- Revenue from sales of biogas and carbon credits
- Cost savings on bedding (~$1,800 every 6 days)
- Electricity generation and odor reduction
There are now three farms which have seen the advantages of adopting our digester technology, and we expect many more to follow.
—Andy Livingston, President, Microgy, Inc.