With cows being responsible for up to 25 percent of the methane gas released in the US each year, a group of scientists at Argentina's National Institute of Agricultural Technology is now attaching backpacks to cows to collect the animals'...farts. Here's the way it works: Tubes connected to the cows' digestive tracks are collected and then stored in the backpack. Scientists say that the farts collected each day could produce enough energy to run a car or refrigerator for an entire 24 hours.