Not a joke. From Wired:
It elicits giggles and grimaces when it emanates from cows’ rear ends, but methane represents a serious threat — it’s a greenhouse gas 20 times more potent than carbon dioxide.
Taking the “dross into gold” dictum to a whole new level, Velocys of Plain City, Ohio, is capturing the environmental pollutant and turning it into liquid fuel for heating or transportation.
Read How cow farts become fuel . The next big source waiting to be discovered–politician’s mouths.