Butanol biofuel can be made from cellulosic agricultural waste products such as corn stalks and cobs, wheat stems, wood chips, and waste paper that don't compete with food products, and don't displace land used for cultivation of food products. Approximately 1.3 billion tons of such cellulosic materials, which could be used to produce butanol, are thrown out each year in the US. bio-butanol can be used as a direct substitute for unleaded gasoline in US cars, and carbon dioxide and smog emissions are dramatically lower than those produced by burning gasoline or gasoline blended with ethanol. Ethanol as a biofuel is less desirable because its energy content is 25% less than unleaded gasoline, and it is corrosive to engines because it absorbs water. Butanol is a gasoline substitute.



