At a dairy farm in Vermont, the cows are doing what they do best: standing still, chewing their cud, and producing poo. They're also making electricity that is powering this nearby T-shirt factory. The company pays a premium to the electric company for green energy, or what the owner calls cow power.

"A lot of people don't really know what cow power is when you first mention it to them. They think of cows on treadmills or things like that. They don't realize you can take the cow manure and make methane gas and run an eight cylinder generator to make electricity." stated Jay Cummings, co-owner and operator of Green Mountain Dairy.

In Vermont, six dairies now feed power generated from manure into the grid. It's a process that starts when the farmer feeds the manure to bacteria that digest it and release methane gas. The gas is burned inside an engine that turns a generator. Cow power is an attractive alternative energy source because the process pumps out electricity without burning fossil fuels harmful to the environment.

The environmental benefits are not just about energy use. Livestock waste makes up almost 20% of greenhouse gas emissions worldwide according to the United Nations, and methane is significantly more harmful to the environment than carbon dioxide.

Bill Rowell owner of JC Images explained, "You take the methane out of the manure waste stream and that's not being released into the atmosphere, so you've reduced the carbon footprint for agriculture. You've also supplied a couple of million kilowatts of electricity with no carbon footprint."

And the money's not so bad either. Rowell says he took in $200,000 this year from cow power.

But the process is still out of reach for many small farmers. Most dairies in Vermont have about 80 - 100 cows, and it typically takes about 800 to make the project viable, that means industrial farms would be good candidates.

However farmers in Vermont are working to adapt the process so that it's possible with just 300 of the animals.