Speculation is/isn't driving up your food prices and mine, and we can't grow enough ethanol to power the US, let alone the whole world.
Just out of curiosity, I did some back-of-the-envelope calculations [no, I'm not going to show my work]. Last year the world produced enough grain and soybeans [I didn't use any other foodstuffs in my calculations] to feed every man, woman, and child on the face of this earth, all 6.6 billion of us, 2000 calories every single day, provided all of it goes directly to feeding humans, no intermediary livestock, and alas, no cat food or dog food. Or saving for a rainy day, or prolonged drought, as the case may be.
This left enough extra corn to make ~30 billion gallons of ethanol, which would provide us, just us here in the US, with about 20% of our gasoline use, assuming a 1:1 substitution of ethanol for gasoline.
In case you're curious, that 30 billion gallons of ethanol would have provided ~120 days food for
the entire world.
dent corn, aka field corn