Greasestock is an American event held yearly in Yorktown Heights, New York. It is one of the largest alternative fuel, renewable energy, and low-energy green vehicle exhibitions in the United States. Exhibitors showcase a variety of alternative energy vehicles, as well as exhibits with a sustainable lifestyle theme. Although it is illegal in New York to power a vehicle with waste vegetable oil (the Federal Clean Air Act of 1990 forbids the use of non-compliant biodiesels such as raw vegetable oil; this is illegal nationwide, not just in New York), authorities in New York have stated they have no problem with the festival and have even participated in it.