Anaerobic Digestion Use Rises in the United States

Thanks to two pieces of recent legislation, 13 additional methane systems are now under construction in the US, and renewable-energy advocates are predicting that scores more are sure to follow. The Straus project is the first of 14 methane projects to receive matching funds from the California Energy Commission, one result of incentives following the rolling blackouts that plagued the state during the summer of 2001.

With net metering, small producers like Straus can reduce or erase their energy bills but cannot be paid for pumping excess energy into the grid. Net metering has been available to owners of home solar systems for several years, but it can also be used for digester power delivered into the grid.


For Anaerobic Digestion (biogas digestion) to really take off economically it is essential that the liquid and solid products - compost and liquid digestate fertilsier - can be marketed and sold. There has been recent success in this area as well.

Garick has recently trademarked Moo Moss - made from the fibrous solids (digestate) processed in the Tillamook Bay Port's digester and then pressed from the liquid fraction after anaerobic digestion, stabile enough to be used directly in nursery potting mixes. This trademarked product has proven itself as an ideal alternative or amendment to peat moss in nursery media.

The story goes back to 2003, when the Port of Tillamook Bay, Oregon constructed a centralized methane digester to biologically process the manure from 4000 of the county's 30,000 dairy cows. The project was 14 years in development as MEAD (Methane Energy and Agricultural Development). The facility, owned and managed by the Port, utilizes simple, proven cost-effective digester, solids separation and biogas-to-electricity technology also now currently being employed at over a dozen sites nationally.

By summer, the methane digester will handle the fresh manure generated by Fiscalini's Californian 1,500 Holstein, Jersey and Brown Swiss herd. In addition, whey from their cheese making facility plus any feed waste is to be pumped into the digester tanks and composted at 100 degrees. The digester itself is kept warm by radiant heating using simple plastic tubing.

The methane will power a generator located near the cheese plant producing sufficient electricity to power the dairy barn (which holds 54 cows at one time) plus the 88,000 sq ft cheese plant. The heat from the system will also help pre-warm the water for the plant's heat exchangers.

The Dennis Haubenschild dairy farm near Princeton, Minnesota reports that it has added another "one of the first" distinguished honors to its list of accomplishments, after previous honors included the first methane digester to be built in Minnesota and that is said to be the first digester in the world to run a hydrogen fuel cell off of biogas.

When the Haubenschilds began trading carbon credits from methane captured by their anaerobic digester in November, they were only one of two farms in the nation to do so. Now there are a reported dozen plus farms trading carbon credits from captured methane. The credits provide an additional source of revenue for the farm and address a growing, serious concern: global warming.

Perham, Minnesota. Reports that dairy farm wastes could someday heat homes and dry clothes for residents of a northern Minnesota town as well.

Tobkin has designed a city-rural cooperation scheme where, besides dairy manure, a digester would convert waste from one of the city's biggest employers, Barrel O' Fun, into energy. Primera Foods, another Perham business, has also expressed interest. Waste diverted to the digester would ease burdens on the city's wastewater handling system, Tobkin says, allowing industry to expand. Perham could sustain more jobs without increasing its wastewater treatment capacity.