Most fast food restaurants use huge amounts of vegetable oil. While some of these restaurants sell their used oil to people who make their own bio diesel, in actuality it is only a small amount. However, there could be a solution that not only disposes of the used oil; it will also provide around a quarter of the power needed to keep the restaurant going.
VegaWatt is a machine that turns used cooking oil into clean energy and eliminates the need to dispose of the used cooking oil. The machine is about the size of the fridge and uses a filter system; there are no chemicals or fossil fuels used in the process making it a cheap and clean source of energy.