Benefits of Methane Digesters
Vermont farmers visiting engine room at Pennsylvania farm in winter. It is heated at no cost by the farm digester’s CHP generator set.
Animated presentation of digester benefits.
Farms that install methane digesters benefit in multiple ways.
One fascinating aspect of developing a biodigester is that every farm is unique,and
benefits are limited only by the imagination.
- Methane digesters with CHP generators produce enough electricity to offset the farm’s electricity costs with additional to sell to the grid.
- Bedding solids from dairy digesters can offset the farm’s entire bedding cost. Depending on how heavy the farm beds its cows, and the size of its cows, the digester can produce as much as twice the bedding needed. The excess can then be sold to other farms or as organic compost and peat moss replacement.
- Methane digesters with CHP generators can be utilized to heat buildings, including homes near the digester, offsetting those costs. Some farmers use this for other commercial purposes, such as heating a greenhouse.
- Excess bedding solids from dairy digesters can be sold as compost or peat moss replacement and this market is expanding.
- One farm even presses digested solids in a mold to create flower pots! Material that was formerly manure is now a profitable product.
Social and Environmental Benefits
- Farms near population centers can co-digest food waste with their manure. This greatly increases the digester’s biogas energy output, and in addition, food haulers typically pay significant tipping fees. If the farm adds a “de-packager,” tipping fees can be much higher. Several American states now have laws mandating food waste be taken to environmentally friendly systems like methane digesters.
- Larger farms near pipelines can produce RNG (renewable natural gas). This currently provides sky-high profits for farmers and developers.
- Digesters can be a solution to excess phosphorus, which can lead to serious environmental problems in water bodies such as Lake Champlain in Vermont and New York. With a digester, manure management becomes more flexible. Phosphorous is somewhat concentrated in the solids separation process.
- 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 save the farmer time and fuel costs while providing major water quality benefit. It is outlined here in our “Watershed Digester” concept.
- Homeowners sometimes threaten legal action against nearby farms due to manure odors. An anaerobic digester system reduces these by as much as 90 percent, making the farm a good neighbor. One of our Vermont farms is building a digester to help the students next door concentrate on their studies.
Reviewing this list, you can see the many benefits of a methane digester. Creative farmers and developers regularly discover new ones.