Members of the Monroe County Solid Waste Management District (MCSWMD) Citizens Advisory Committee (CAC) have recently been researching anaerobic digesters and their potential both to reduce the volume and emissions of organic materials going to landfill, but also as a source of renewable energy.
In short, anaerobic digestion is “the process where plant and animal material (biomass) is converted into useful products by micro-organisms in the absence of air. This biomass can be unwanted ‘wastes’, such as slurry or leftover food, or crops grown specifically for feeding the digester.” The outputs from the digestion process are biogas (which can be burned as fuel) and digestate, which can be used as fertilizer and plant nutrient. (Source: NNFCC Renewable Fuels and Energy Factsheet Anaerobic Digestion Nov 11).
Traditionally, anaerobic digestion has been used mainly as a waste management technology for industrial agricultural operations. However, the technology is seeing increasing use in municipal applications, and the energy generation through biogas, originally merely a side-effect of the process, is becoming in and of itself a reason to implement the system (though efficiencies are still relatively low compared to other power generation technologies).
CAC members Steve Akers and Dave Parsons (also a member of the newly-created Monroe County Environmental Quality and Sustainability Commission), along with District Executive Director Larry Barker attended the BioCycle 11th Annual Conference on Renewable Energy from Organics Recycling in Madison, WI in October, and brought back some information about anaerobic digestion. Akers and Parsons presented some of the topics they learned about to other CAC members at the December meeting (see the MCSWMD Citizens Advisory Committee Minutes for 2011-12-01 for a nice synopsis, and their slides are available here).
I suspect we will be hearing quite a bit more about anaerobic digestion in the near future, as it would seem to plan an integral role in fulfilling a vision of Monroe County as a zero-waste community.