Cut the crap. Stop the off-gassing of the cows. Sure, but how?
Methane is being emitted daily by cows and horses across this land, pigs too. Manure's another problem. But it could also be a solution. Right now the federal government is starting to lean toward cracking down on huge manure emitters, those factory farms where livestock are concentrated in tight space for more efficient feeding and eventual slaughter for the meat industry. Or to produce lots of eggs and milk. Here's what the Environmental Protection Administration is saying. I paraphrase: "Cut the crap."
How bad is our manure problem? Well, here's one manure leak that created a local...uh, crap-storm. This one came from a factory farm full of next month's bacon. Beyond the health and nausea quotient from manure leaks, there's the problem that methane from rotting manure and from livestock digesting their food puts more methane into the atmosphere and that methane is a greenhosue gas. The EPA does have some suggestions on livestock-rearing that could reduce methane from the natural process of mammals' digestive tracks. Beyond that the only foreseeable solution is fewer cows, sheep, pigs, llamas, humans, etc.
The sorta good news is that livestock are not the #1 methane-producers in America. They trail far behind our trash dumps (politely referred to as landfills in official docs), and behind the natural gas and petroleum industry which leaks a lot of methane around the edges. The really bad news: livestock around the globe are the #1 source of methane, ahead of industry and even rice-growing.
Can't We UseThis Crap?
Unlike cow-sourced methane, manure as a solution could be on more solid ground right now. Indeed, it's long been a dream of making money from manure, beyond selling it to weekend gardeners for their tomato patch. Here's a detailed fifteen-year old summary of the manure to methane dreams from one Midwestern ag school. They weren't too hopeful fore anything to happen quickly: "If energy and fertilizer shortages become more acute and pollution regulations concerning odor become more strict, methane generation may become a feasible process in waste management systems. Research is needed to reduce capital costs of methane generation systems and provide techniques for proper management of such systems."
Well, higher energy and fertilizer prices have moved the methane-from-manure tech a bit since then. But as recently as 2001 Purdue University was still merely hopeful.
It's Working!
Here's one example of an American utility using cow manure to generate methane and then buring that for electricity. The utility behind this program, which now includes four dairy farms, is Central Vermont Public Service. Here's their FAQ on cow manure power. It comes complete with an animated cow behaving in a manner suited to polite company. Here's a news story giving some general idea of the hopes for methane production and turning manure into something greener.
In short, manure to methane to electricity or heat is happening, in small increments. But capturing all that free methane being emitted? Cowabunga. As far as I can tell, that awaits a new generation of greentech thinking.