American University was ranked number 9 in the Sierra Club's annual evaluation of U.S. colleges and universities for their level of environmental sustainability. These include energy usage, financial investments, food consumption, transportation, waste, and many other factors. Aiming to be carbon neutral by 2020, AU is off to a strong start, with 30 buildings on track for LEED Silver certification, a 27-kilowatt solar array, D.C.'s biggest solar hot-water system, and a contraption called the Vegawatt, which turns old cooking oil into electricity. The university's plan is to divert 100% of its waste, and it's already two-thirds of the way there, thanks to a new campus-wide composting program, tray-less dining (which reduced food waste by a third), quarterly e-waste drives, and such enthusiastic student participation that AU won last year's national RecycleMania competition. Students also get excited about the annual Campus Beautification Day (shown above), a springtime tradition that brings the AU community together to make the campus greener. American U. achieved a score of 759 out of a possible 1000. Nearby University of Maryland College Park was ranked number 13 and George Washington University was ranked at 23. A total of 162 institutions were ranked, while the rest of the nation's schools didn't make the list.