At a virtual meeting of the USDA’s Northeast Climate Hub Leadership we were invited to speak about smaller anaerobic digesters for dairy farms of a50-700 adult cows. Following our presentation, questions were asked about the profitability, amount of greenhouse gas mitigation and operational requirements.
We explained that some digesters are less expensive because they are slurry only and assembled/constructed above ground of stainless steel rather rather than in-ground of concrete. In addition, increasing environmental payments related to RECs, carbon credits and in some cases RINS, should compensate for the low prices paid for green electricity in most states.
Due to past experience the attendees were surprised by the fact these European made systems have minimal operational requirements. We explained that this was due to the fact that slurry only digesters are largely manure and a manure is a much less problematical feedstock than food waste. A consistent supply of manure stimulates the biogas process and buffers the system against challenges presented by other substrates.
More detail about the medium size digester system is available here:
A Smaller, Affordable, Digester | Agricultural Digesters