A few thoughts:
- Not shown is energy needed to produce corn - in the form of fertilizer, herbicides and pesticides, irrigation, the running of farm equipment, and the management of runoff.
- Energy is needed to refine corn to produce ethanol, but I guess you'd need to refine oil to produce gasoline too.
- The corn would probably be genetically engineered, with negative effects to the environment and positive effects to Monsanto.
- In my mind, Distillers Dried Grains With Solubles (DDGS) should not be fed to livestock.
- The growing of corn depletes a rapidly dwindling and valuable resource: water.
- The land upon which the corn grows could be used to feed people, yes. But continuing to burn gasoline spews greenhouse gases which also reduces land to grow food since it contributes to global warming which increases drought and desertification.
- Why corn? I read that sugarcane is more efficient at producing ethanol than corn. But sugarcane doesn't grow well in the US. And using sugarcane as an ethanol source would just transfer our dependence from oil-producing regions to sugarcane-producing regions. (So is ethanol from corn really about going green? or about protectionism?)