Perhaps the real problem with producing ethanol from grains- it makes food too expensive for poor people:
Sheeran (UN) noted that in some countries food was available, but cost too much for the poor to buy it, or, as she put it “markets full of food with scores of people simply unable to afford it. These conditions have triggered food riots from Cameroon to Burkina Faso to Indonesia to Mexico and beyond.”
Food, she reminded the European Parliament, is a geostrategic issue, just as oil is.
“This challenge may be one of the most critical peace and security issues of our time. Fragile democracies are feeling the pressure of food insecurity; food riots have erupted throughout the globe,” she said.
Don't forget about water rights...