From oil shrills. We grow more than enough food for the world, so that land would not be better to grow food since we don't need anymore. For that matter biofuels are themselves a byproduct of producing food - soybean oil to make biodiesel is a left over from making animal feed. Ethanol is a primary use of a lot of corn, but it leaves behind high protean animal feed which is in demand.

If you only look at biofuels for the fuel value they still produce more energy than growing consumes (even the oil shrills admit this, but they do it in such a a way as to confuse people into thinking it isn't true). Though the amount of added energy is not great, it is more efficient than burning oil directly.