In the hot pursuit of alternative energy sources, researchers at the University of Nevada, Reno, stumbled upon coffee grounds as a possible new basis for biodiesel. After leaving a cup of coffee on the counter top overnight, lead researcher Mano Misra noticed the oil slick that had separated and floated to the top of the coffee. He decided to ex amine the process necessary for turning used coffee grounds -- currently just a standard waste product that many non-composters just throw away -- into a viable source of biodiesel. They collected 50 lbs. of used grounds, determined that the mass contained between 10 - 15% oil by weight, went through the process of extracting the oil and then converted it into biodiesel using standard chemistry techniques. The result? Well?it worked, but they estimate that all the used coffee grounds in the world would make up less than 1% of the annual diesel consumption of the US. So while it's an interesting approach (that apparently smells fabulous!), it's not totally conceivable right now that our used up coffee will save our planet. We did love one reader suggestion, however, which was to build a coffee maker that was powered by the previous brew's coffee grounds -- now that's something we can buy into.