I'm still kind of confused on this. In all the examples of energy expenditure, we assume that the energy comes from ethanol in the first place. The plants aren'

I'm still kind of confused on this. In all the examples of energy expenditure, we assume that the energy comes from ethanol in the first place. The plants aren't magically creating more carbon, so if you grow the same amount as you burn, that carbon should be absorbed back. That leaves deforestation for planting, which is a problem since human energy use isn't the only source of CO2. But if deforestation is avoided (this is where GMO crops would come in, grow more fuel in a given amount of space) or we implement other methods of CO2 sequestration (impractical now, but perhaps not in the future) we could still minimize that risk.