Livestock animals in the U.S. produce more than one billion tons of manure annually. ... farm waste emits two potent greenhouse gases: methane, which has 21 times the global warming potential of carbon dioxide, and nitrous oxide, which has 310 times the warming potential of carbon dioxide over a 100-year timespan. Since a 2008 University of Texas-Austin study showed that converting farm animal droppings into renewable power could generate enough power to meet up to 3% of North America’s consumption, interest in cow power has been piling up....(A recent) study found that a dairy farm with an average milking herd size of 1,212 cows amassed 69 metric tons of manure that were fed to an anaerobic digester daily, producing 5,295 kWh. The digester produced revenues from electricity of about $958 per day (at $0.181/kWh) as well as fuel savings from capturing combustion heat for hot water and space heating. But one critically limiting factor the study found was that farms with 600 to 1,500 milking cows needed a huge average initial investment of about $2 million to plan the project, obtain permits, and build the digester—making grants and subsidies from the government indispensable...Read on at: http://www.powermag.com/issues/departments/global_monitor/4182.html
