IMHO Biofuels [Ethanol] are totally unnecessary under any circumstance. They are extremely expensive to make [food producing land has to be converted or virgin soil used] lots of water used in its production and it is less powerful and more corrosive [to most current aircraft engine pipes etc] than Avgas or Mogas less biofuel additions. And the biofuel percentage gets raised by the next Green Garbage Government/EU Directive.
Many biofuel crops, such as corn, are grown with the help of fossil fuels in the form of fertilisers, pesticides and the petrol for farm equipment.
One estimate is that corn needs 30 per cent more energy than the finished fuel it produces!
Another problem is the land required to produce it. One estimate is that the grain needed to fill the petrol tank of a 4X4 with ethanol is sufficient to feed a person for a year.
It also has an affinity for water - not really a good idea.
I'm all for Carbon Contrafibularities. Thanks to Blackadder.
If I were in charge I would ban its production. And no CO2 taxes of any kind, no Carbon Offset Trading, nothing.