Soon, the question may not be "What can you make ethanol from", but "What CAN'T you make ethanol from". The newest I have found: sweet potatoes. Some areas of the world grow corn well, some grow soybeans and some grow sweet potatoes. The trick is to find the best crop in any given area, and use that. This is exactly what some Canadian tobacco farmers have done. According to this article, the number of Canadian tobacco farmers has dropped from 4,000 to a few hundred, as the numbers of smokers decline and imported tobacco became cheap to import.
Farmer Berry Murray went back to school and wrote his thesis on alternative crops for ethanol production. Instead of corn, Murray has plans to build a plant producing ethanol from sweet potatoes. Common practice for corn-based ethanol plants is to use certain residual biomass for animal feed. Alternatively, Murray plans to use the leftover biomass for the production of methane gas, creating additional renewable resources. With these gases, Murray plans to produce electricity using gas turbines to sell to the electric companies.
[Source: The Toronto Star via Treehugger]