To “Spinoneone” the equation is about the efficiency of converting solar energy to fuel. It takes a substantial amount of energy in the form of ammonia fertilizers, etc. to farm corn, ferment and distill the product. As a result you get about 1.2 times the energy out that you put in. Most if not all the biodiesel crops are more efficient in their conversion ratio. Consider the efficiency of a ham sandwich as a photocell you attach electrodes to the top and bottom slices of bread and you get about the same total energy of the ham sandwich plus generated electricity when you eat it. The same cannot be said for fabricated silicon solar cells. While I have not attempted to eat one, the generated electricity is not insubstantial over the life of the cell. So conversion efficiencies are important since in the long run you are converting solar energy (either stored as fossilized coal, ng, oil, produced by plants, produced by the hydrolic cycle, or whatever) to energy. No magic wands, just different efficiencies.
