Energy Return on Energy Invested (ERoEI)

For soy biodiesel the generally agreed number is 3.2, that is, the fuel yields 3.2 times the amount of energy used to make it.
The table below is a break down of energy inputs:

Process Stage MegaJoules/t MBTU/gal
Production of rapeseed oil 57% 16356 51.7
Tranportation 3% 511 1.6
Esterification 35% 5706 18.0
Plant construction & maintenance 1% 162 0.5
Storage 1% 214 0.7
Distribution 3% 498 1.6
Totals 100% 23447 74.1

For WVO biodiesel, we get to eliminate at least the first item, production. Using the other energy inputs, this yields an ERoEI of 5.26, which is my working number at this time. If one were to collect the WVO with a biodiesel operated truck, and use biofuels for the operation of the processing plant, distribution, etc, this number could be somewhat higher.