There are no free lunches
The last weekend I was out visiting my sister. We had a get together with several other relatives, among them a couple of my sisters kids.
As it happened, one of my sisters son and I got into a discussion about the usefullness and the net invironmental imprint the use of ethanol in cars really is.
Yes; Burning ethanol instead of petrol does leave a smaller CO2 imprint- at first sight!
But Making ethanol takes a lot of energy. Besides from the energy used to make room for sugarcane plantations, the work of cultivation, processing, destillery, and abow all- transportation; you have a net loss of energy during the process steps. Thermodynamic laws forbid you to make more energy, and the laws of ever increasing enthrophy states that you never can get out as much energy as you have put in to the process. The net effectivity is seldom more than 20-30%.
The net loss energy has to be taken from somewhere else! Where do we take it from? Well- usually from nuclear energy, or by burning oil or coal or in very rare cases from hydro power plants... (No- do not even get me started about windmills or solar cells!)
Besides that, ethanol has a lower energy effectivness than petrol. All in all this means that burning ethanol makes a larger net CO2 imprint than burning petrol, and that it costs more energy to manufatcure it, than what you'll get out! And we taxpayers are the ones paying the bill- as usual.