A beam of light in Upper Antelope Canyon. Photo Credit: Public Domain

clean feul noun

• Fuels which have lower emissions than conventional gasoline and diesel. Refers to alternative fuels as well as to reformulated gasoline and diesel.
• Low-pollution fuels that can replace ordinary gasoline. These are alternative fuels, including gasohol (gasoline-alcohol mixtures), natural gas and LPG (liquefied petroleum gas).
• Blends or substitutes for gasoline fuels, including compressed natural gas, methanol, ethanol, and liquified petroleum gas.

Thought of as an alternative fuel and clean fuel, ethanol is a renewable energy source that is made from corn or other grains, for instance in Brazil from sugar cane.