Bio-fuels were once regarded as a major contributor in “fighting climate change” and cutting emissions.  Then several problems were recognised.

First, there is a considerable energy input in growing bio-fuel crops.  Diesel for tractors, fertilisers and pesticides.  This must be off-set against the supposed emissions savings.

Second, burning food crops reduces the tonnage of food available to feed people, at a time when hunger remains a global problem.  It also raises food prices.  There have been riots over food prices in a number of countries.  The extent to which bio-fuels raise prices is disputed, but clearly they must have a significant effect.

Thirdly there is the question of “Indirect Land Use Change” or ILUC.  If people use agricultural land for bio-fuels, this will put further pressure on other land.  It may cause the clearing of rain-forest or other forests, or the use of peat-lands.  The extent to which this occurs…