This type of fuel is considered to be more friendly to the environment.<ref>http://www.alternative-energy-news.info/technology/biofuels/</ref>. The main type of biofuel available in America is corn-based ethanol. This is added to gasoline as an anti-knock compound. It replaces previously used compounds like tetramethyl lead and MTBE. | This type of fuel is considered to be more friendly to the environment.<ref>http://www.alternative-energy-news.info/technology/biofuels/</ref>. The main type of biofuel available in America is corn-based ethanol. This is added to gasoline as an anti-knock compound. It replaces previously used compounds like tetramethyl lead and MTBE. |