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In addition to the sun, many other renewable power sources exist, and a number of them may be particularly well-suited to rural sites. Small-scale wind power, biomass generation, micro-hydro power, and methane digesters are all potential sources of renewable power for agricultural buildings.

Anaerobic Digestion of Animal Wastes: Factors to Consider

Rising energy prices, broader regulatory requirements, and increased competition in the marketplace are causing many in American agriculture’s livestock sector to consider anaerobic digestion of animal wastes. They view the technology as a way to cut costs, address environmental concerns, and sometimes generate new revenues.

While hundreds of anaerobic-digestion projects have been installed in Europe and the U.S. cp-3c.jpgsince the 1970s, it was not until the 1990s that better designed, more successful projects started to come on line in the U.S. Today, there are an estimated 40 farm-scale projects in operation on swine, dairy, and poultry farms across the country. The key by-products of anaerobic digestion include digested solids (useful as a soil amendment) and methane, the primary component of “bio-gas,” which can be used to fuel a variety of cooking, heating, cooling, and lighting applications, as well as to generate electricity.

Capturing and using the methane also precludes its release to the atmosphere, where it is 20 times more damaging to the ozone layer than carbon dioxide. Despite the many benefits, anaerobic-digestion systems are not appropriate for all farm operations. AgStar, a cooperative effort by the U.S. Departments of Agriculture and Energy and the Environmental Protection Agency to promote bio-gas projects, estimates that anaerobic digestion could be cost-effective on about 3,000 U.S. farms. The critical issue is planning, with each system needing to be designed to accommodate a variety of factors.

Risks Associated with Bio-gas

While methane is a very promising energy resource, the non-methane components of bio-gas tend to inhibit methane production and, with the exception of the water vapor, are harmful to humans and/or the environment. For these reasons, the bio-gas produced should be properly “cleaned” using appropriate scrubbing and separation techniques. In addition, the methane itself represents a serious danger, as it is odorless, colorless, and difficult to detect.

Methane is also highly explosive if allowed to come into contact with atmospheric air at proportions of 6-15 percent methane. For these reasons, it is recommended that buildings be well ventilated; motors, wiring, and lights should be explosion-proof; flame arrestors should be used on gas lines; and alarms and gas-detection devices should be used.

attra.jpg navodnicil.pngI was wrong: free market trade policies hurt the poor…the rules of international trade are rigged against the poorest countries.

2 Comments

  1. I am very busy these days. But I hope to find time to reading the posts of your excellent blog.
    (sorry on my bad english)

  2. At http://www.Anaerobic-Digestion.com we agree 100% with your article.

    There are a lot of new Anaerobic Digestion plants in Europe, but the biggest no is in Germany and many more planned. The reason for this is that the German government gives those building AD Plants in Germany a huge help to do so by requiring the power companies to buy the power at special renewable energy (premium rates), but not only that – the power companies must undertake to continue to buy the AD producer’s power for a period (something like 10 years).

    This makes these projects (most are using bio-crops as their feedstock) bankable – that is, they can get loans to build the plants where in other countries where there is no long term commitment by government by the guaranteed sale of the power. In my view this is not only good environmentally but also because Germany is developing a lead in the technology it will enable them to sell their advanced AD technology throughout Europe and beyond. Those Germans are clever guys and this will bring their economy great profits – you bet!


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