Comment by wizardofdos

3) you contribute to loss of biodiversity through increased land use for intensive farming (monoculture, high chemical use)

4) co2 balance of those 'biofuels' is way worse than fuels refined from extracted fossil fuels

5) additional supply of these fuels lowers fuel prices thereby slowing shift to renewable energy sources (i.e. renewable electricity)

6) simply paying farmers for fallow fields is a much simpler solution to the problem