Benefits of Methane Digesters

Animated presentation of digester benefits.

Farms that install methane digesters benefit in multiple ways. One fascinating aspect of developing a digester is that every farm is unique, and the benefits are limited only by the imagination. For example:

  • in Europe, Canada and the American state of Vermont farmers can earn more than 20 cents per kW for their electricity. A multi-year power purchase agreement (PPA) from a utility ensures the farm a dependable revenue stream while milk prices fluctuate over time.
  • methane digesters with combined heat and power generators can be utilized the heat in buildings, including homes near the digester. Some farmers use this for other commercial purposes such as heating a greenhouse. See above – engine room at Pennsylvania farm in winter heated by its CHP generator. 
  • larger farms near pipelines can produce RNG (renewable natural gas) which currently provides sky high profits for farmers and developers. 

Slurry food waste delivery in New England increases energy output and often pays tipping fees to farms with methane digesters.

  • farms near population centers can co-digest food processing and other organic waste with their manure. This increases the digester’s energy output while haulers who deliver waste typically pay significant tipping fees per ton. If the farm adds a “de-packager”, fees can be much higher. Several American states have laws mandating organic waste be taken to environmentally friendly systems like methane digesters.
  • a major annual expense (e.g. $45,000 for a 500 cow farm) is bedding. A methane digester produces as much as twice the amount required by that farm. Quality, low pathogen, largely odor free bedding increases cow comfort – and cow comfort means more milk. Digester bedding also helps protect the herd from costly mastitis infections. Here is video from an experienced nutrient manger.
  • excess phosphorus can lead to serious environmental problems in water bodies such as Lake Champlain in Vermont and New York state (USA). With a digester, manure management becomes more flexible. Phosphorous is somewhat concentrated in the solids separation process. Excess bedding solids from biodigesters can be sold as compost or peat moss replacement and this market is expanding.
  • the liquid resulting from the digesting plus separation process has less phosphorus and total solids than separated raw manure and is also more plant available. 
  • when combined with modern field spreading techniques, like drag lining and injection, digesters can offer major water quality benefit. It is outlined here in our “Watershed Digester” concept.

Separated liquid manure from a digester facilitates drag line irrigation in Pennsylvania.

  • some farms even press digested solids in a mold to create flower pots. Material that was formerly manure, now a profitable product.

Reviewing this list you can see the many benefits of a methane digester. Creative farmers and developers regularly discover new ones.

Discussing possible revenue streams with Vermont farmer developing methane digester.