Only if you ignore the energy required to make ethanol or biodiesel. Don't forget diesel is required to run farm tractors to plant and harvest corn. Energy is required to distill pure ethanol. The cost of producing these fuels would increase if there were a shortage of oil coming to the US. They would hardly make us independent of Middle Eastern oil.
Petroleum production and refining use energy as well.
But you bring up an interesting point. How many BTUs of energy are needed to produce one BTU of Ethanol vs. one BTU of gasoline or diesel?
I know fermentation itself releases energy- that's why barns full of too-wet hay catch fire.
With modern technology, how much of the heat from the evaporation process can be recaptured?
Well, one could run a still on solar power - it does not take that much, just mirrors. The Brazilians have found ethanol marginally economical - not from grain, though, but from biomass, IIRC.