Biofuels will be an important piece of our energy future, but they cannot come close to replacing current US or world oil consumption. The U.S. used almost 140 billion gallons of gasoline and 62.3 billion gallons of distillate fuel (diesel fuel for highway transportation; add around 3 billion gallons of diesel for agricultural use) in CY 2004. Usage was about the same in 2005.
Ethanol is being billed as the leading supplement/alternate for gasoline. The U.S. produced approximately 4 billion gallons of ethanol in 2005, which equals about 2.9% of gasoline consumption. With current technology, a bushel of corn will yield 2.8 gallons of ethanol in a dry mill. Therefore, the total amount of ethanol that could be produced by converting the entire 2005 U.S. corn crop into ethanol would be about 31.1 billion gallon, which equals only 22% of U.S. gasoline consumption in 2005.
Also, energy potential of ethanol is misleading as a large amount of oil and natural gas is required to produce ethanol from corn. Several researchers have investigated the energy return on energy invested (EROEI) of corn-based ethanol and the consensus is that it probably is between 1:1 and 1.5:1 – i.e., it has a small net energy yield at best.
"Ethanol is being billed as the leading supplement/alternate for gasoline. The U.S. produced approximately 4 billion gallons of ethanol in 2005, which equals about 2.9% of gasoline consumption. With current technology, a bushel of corn will yield 2.8 gallons of ethanol in a dry mill. Therefore, the total amount of ethanol that could be produced by converting the entire 2005 U.S. corn crop into ethanol would be about 31.1 billion gallon, which equals only 22% of U.S. gasoline consumption in 2005.
Also, energy potential of ethanol is misleading as a large amount of oil and natural gas is required to produce ethanol from corn. Several researchers have investigated the energy return on energy invested (EROEI) of corn-based ethanol and the consensus is that it probably is between 1:1 and 1.5:1 – i.e., it has a small net energy yield at best."
Good statistics and your assumption of using corn for the ethanol product is correct. Switchgrass which grows in plenty over millions of acres in the mid-west can also add another estimated 20% of gasoline production and is much cheaper to produce. I think the biggest challenges are shipping, storage and building nuclear plants to power the conversion of raw materials so we dont use oil or nat gas.