[BitWielder1]

You're right that it makes no sense burning something else to make electricity to make ethanol for energy purposes.
That leaves solar.
The question of efficiency is still legitimate.
Can they make, install and maintain a field of ethanol generating solar panels that are more cost effective than planting and processing corn?
Or drilling for oil.

[Rebel_Ace]

"...You're right that it makes no sense burning something else to make electricity to make ethanol for energy purposes.
That leaves solar..."

Actually more than just solar. Wind turbines, Geothermal, Hydroelectric, even nukes. If you have some energy source that *might* produce unevenly, or you would like to run one *evenly* for efficiency, and store any excess, this *might* be a way to do it.

"...The question of efficiency is still legitimate.
Can they make, install and maintain a field of ethanol generating solar panels [or other energy source] that are more cost effective than planting and processing corn?
Or drilling for oil..."

Of course. As others have mentioned, it depends upon "what" is supplying the external energy, how long that infrastructure lasts, what materials are consumed in the process, how expensive are the nano structures to produce, how long do the catalysts remain effective, etc, etc.

My comment was more in response to the immediate, "knee jerk" reaction you often get here on FR of ANY announcement regarding research and discoveries in energy production, storage or efficiency gains.

It seems few here take into account that something "interesting" in the laboratory might require 20 years to become a commercial product. You cannot scoff at the baby steps that lead to better things.