" The fuel required to transport biomass to a processing plant, covert it to fuel and transport the fuel to an airport is about equal to the fuel created from biomass."
I see this claim again and again. Yet we manage to transport crude oil half-way around the globe for a net energy profit. Is the energy density of biofuels so much less or is this an economic argument in disguise?
Now I can't find precise figures but according to the Wikipedia "oil tanker" article "the average cost of oil transport by tanker amounts to only two or three United States cents per 1 US gallon". (Yes there's a citation for that.) With crude oil at 1$100 per barrel (42 gallons) three US cents buys something like one hundredth of a gallon. That's a ratio of 100 to one even assuming no other costs.
OK, if you transport the raw biomass rather than processing it on site the ratio would decrease significantly but why would you do that? You harvest the material, process (or refine) it and ship it out in a concentrated form.
Sorry, but these efficiency arguments are just a red herring. There is no theoretical constraint. At the moment oil is cheaper because it's cheaper (an economic constraint). But it's not getting cheaper and never will while biofuels certainly will.