is to use waste heat from power plants and factories to power the distillation process. You don't need really high temperatures to distill high concentration ethanol, something like 65 degrees Celsius if memory serves. By using heat that's currently being thrown away, a technique sometimes called cogeneration, we can cut the cost of distilling ethanol quite a bit.

Still, the majority of energy used to produce a gallon of ethanol is probably used to power the farm equipment needed to raise the corn. This might be a natural application of genetically altered crops that would be designed to grow quickly, produce high yields per acre, be insect resistant (less cost and energy used for spraying), and prehaps need less care than crops like corn that are intended for human consumption.