This is the important line. You don't want to carry around 20 pounds of stuff to get the effect of 1 pound of gasoline. The next hurdle to clear will be how this compares to gas when measured in terms of energy output per dollar. My guess is that gas is still much cheaper; but, as the price of this system comes down, and the price of gas goes up, that threshold will be crossed quickly enough.
Ah, but how much gasoline is used to produce, harvest and transport the starch?