Big Assumption & Simplifications.
The energy to make it comes from fossil fuel! It probably has to to start with, but as long as the energy produced is more than twice the cost to make it, it can be self sustaining. 50/50 is sustainable but hardly economical. It requires a much lower energy consumption to make it effective. On the other hand I didn't see any comparison to the amount of energy it takes to recover and refine crude. You also have the potential to use solar energy or wind energy as the source rather than the biofuel itself. Long term we have to get more direct conversion of solar or other fusion energy into transportable/usable fuel such as H2.
Regards,
Mark