We do not believe that largescale production of fuel from food crops or from most tropical oil crops is a sustainable practice: indeed, by contributing to the rise in world food prices it is also a contributor to famine in some countries.

However, some biofuels do not impact in this way. There are some biofuel options on which the picture is unclear at present; we will revise our criteria in response to global developments. At present we would in principle list producers of any of the following:

• bioethanol from cellulose, produced from wood and/or crop stems only, provided that the designer of the process can substantiate an Energy Return on Investment of 2.5 or greater.
• methane of suitable purity for burning in internal combustion engines, from anaerobic digestion only, provided that the digester was designed and used with mixed input (i.e. both animal and vegetable waste)
• biodiesel primarily produced from waste vegetable oil.