A problem with bio fuel is that agricultural production (grain) can be diverted into the production of fuel and away from food production. This may seem attractive to farmers who feel it would be a consistent source of sales for their production, but it has several associated problems:
- crops for bio fuels return less energy for transportation than the energy input for their production once fertilizer, fermentation and distillation is accounted for
- there is a growing world food shortage which would be made worse by diverting grain to fuel
- there is not enough arable land to produce sufficient bio fuel to meet current fuel demands.
Alternate bio fuels using recovered cellulose from plant waste (stalks, waste leaves and crops) does not make as much money as direct to fuel sales of crops, but resolves many of the problems