Brazilians have reduced their dependence on imported oil by increasing production of sugar cane–based ethanol. American politicians and activists argue that the U.S. should emulate this "energy independence miracle." But would increasing ethanol production make much of a difference in the United States?
If it were to produce more ethanol using current technology, the U.S. would need to grow vastly more corn and use huge swaths of land in the process. The U.S. already produces about 4.5 billion gallons of corn-based ethanol—the same amount Brazil produces. It meets only about 3 percent of U.S. transport fuel needs. (One bushel of corn yields about 3 gallons of ethanol.) The country's entire corn crop could produce 35 billion gallons of ethanol, an amount equal to about one-fifth of the gasoline Americans burn each year, leaving none for food and only residues for animal feed. Growing another 12 billion bushels would require plowing up an additional area double the size of Illinois.
Faced with these limits, biotechnologists are trying to find alternatives to corn and sugar cane as ethanol sources. In his 2006 State of the Union address President George W. Bushsuggested that switch grass might be a good source of cellulosic biomass to produce ethanol. But the U.S. Departments of Energy and Agriculture estimate it would take 1 billion tons of dry biomass to produce enough ethanol to replace one-third of U.S. demand for transport fuels. That would mean harvesting 100 million acres of land for fuel, an area about the size of California.
If it required no energy inputs to produce, ethanol might replace about one-third of the oil the U.S. imports annually. The amount of energy required to produce a gallon of ethanol is contested, but let's make the heroic assumption that the process produces twice as much energy as it uses. Ethanol could then replace one-sixth of the oil the U.S. imports each year. That's not nothing, but it's not "energy independence," and it's not much of a miracle either.