Alexandria, VA Students from 27 schools attend a "Conferenc

Alexandria, VA Students from 27 schools attend a "Conference on Sustainability" at St. Stephen's and St. Agnes Upper School. They attended a class called Biodiesel 101 to learn to make fuel, visited a bio bus, powered by waste vegetable oil, biodiesel and solar panels, visited a school garden. Here student Mariana Furey asks a question as other students gather around the bio bus. Second from left is Alan Palm of Marion, MA, co founder and director of strategy for the bio tour - bus touring on mostly used cooking oil. At left is the bus's mechanic of San Francisco Keith Poole. Bio bus is started with diesel to get it warmed up but then is fueled by used cooking oil. (Photo by Susan Biddle/The The Washington Post via Getty Images)