There is no food shortage

There is no food shortage: "It's that the ability to fill up a gas tank with gasoline is, in the 'wisdom' of the marketplace, the highest value use of the food crop."

An article you have to read by Michael Tobis about how the growing gap between the rich and the poor means the rich can buy food related resources and convert them to biofuel or anything they want because their money does the talking for them.

In other words the price mechanism of the market is not capable of allocating resources most efficiently because higher prices means a kilo of meat for one rich person is more valuable than 10 kilos of grain for 10 poor people, since the seller can get more selling 1 kilo of meat than 10 kilos of grain. Of course this probably would not work if every farmer / farm corp. only sold meat. But the general principle is that the "invisible hand" on its own does not satisfy.