Tapping the Latent Power in What's Left Around the Barnyard
Claudia H. Deutsch, NY Times
In a sense, it is the ultimate renewable source of fuel. Weather anomalies can kill off corn crops, calm the winds, obscure the sun — but through rain or shine, gusts or stillness, cows and hogs and turkeys spew forth a steady stream of manure, one of nature's richest sources of methane, a principal component of natural gas.
And now, farmers and entrepreneurs are recognizing that this immutable fact can yield a steady stream of revenue and profit, too. Slowly, but steadily, they are replacing the malodorous lagoons used to treat the waste with machines that can wrest energy from excrement.
According to AgStar, a federal program that promotes the conversion of manure to energy, there are more than 100 anaerobic digesters — devices that create an oxygen-free atmosphere in which bacteria digest manure and release gas — operating in the United States today, with another 80 on the drawing boards.
"These are the only kinds of waste management systems that can actually put money in farmers' pockets," said Kurt Roos, program manager of AgStar.
There are a number of reasons for the new spotlight on what is called brown energy. Oil and gas prices have soared, even as environmentalists have sounded alarms about climate change. In the last two years, various state and federal agencies have subsidized purchases of digesters, since they capture methane — a potent greenhouse gas — before it escapes into the atmosphere. Many utilities operate in states that require them to include environmentally aware energy sources in their portfolios. They will often accept manure gas, since many farms have installed equipment to clean it.
(4 July 2006)
It would be nice if the articles on renewable energy went a little deeper in their analysis. For example, what are the limitations of methane generation? Aren't the copious amounts of manure produced by intenstive livestock operations an artifact of cheap energy? To make intelligent decisions, we need a more complete picture. -BA
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