Anaerobic Digestion
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Technology name
Anaerobic Digestion
Date introduced in the market
The use of anaerobic digestion for industrial purposes pre-dates the 20th century. Modern on-farm applications of anaerobic digestion have existed for at least two decades (primarily in Europe ).
Maturity of the technology
Anaerobic digestion can be considered a mature technology, with several decades of commercial development, primarily in Europe . The application of on-farm anaerobic digester technology in Canada , has unfortunately not reflected this maturity as yet. There is a need for more success stories to be reported.
Type of energy produced
Anaerobic digestion produces biogas, which consists of approximately 65% methane. Biogas can undergo combustion to generate electricity and heat, or it can be further purified into a functional equivalent of natural gas.
Typical example/application
Anaerobic digestion is primarily suitable in an agricultural context for the treatment of livestock manure. It is most appropriate for operations requiring such a process as a component of a manure management strategy. An anaerobic digester venture can involve a single farm, a co-operative of closely located farms, or a centralized facility that collects local agricultural waste and off-farm feedstocks.
Payback and/or benefits
An anaerobic digester offers three potential revenue streams:
1. The sale of heat and electricity from the combustion of biogas;
2. The sale of the spent digestate (processed feedstock) as a nutrient-rich fertilizer/soil amendment;
3. Fees for accepting off-farm “wastes” that are used as feedstocks for the digester (where digester design and regulations permit).
In the future, it may be possible to generate revenue from the sale of carbon credits, although Canada currently has no regulatory infrastructure to this end.
On balance, however, the economic viability of anaerobic digesters in Canada must currently be considered uncertain at best.
Several environmental and operational benefits associated with anaerobic digestion could make it an attractive technology for a livestock operation. These include the use of this technology as an effective manure treatment method that produces a stable, sanitized, consistent and nutrient-rich material that can be used as is for soil amendment purposes, or separated into liquid and solid fractions for application to the land. Anaerobic digestion reduces the odour of processed manure by approximately 80%, effectively kills virtually all weed seeds, and can be an effective step in meeting the new regulatory requirements for the treatment of manure that are coming into force in jurisdictions across Canada.
Anaerobic digestion also generates environmental benefits. These include an attractive energy balance (energy produced by comparison with the energy used to ensure the digestion process), the displacement of fossil fuels, a significant reduction in the pathogen load of processed feedstocks, and a zero-net increase in carbon dioxide released into the atmosphere through the combustion of biogas.
Modified: 03-31-2008
