Gaseous biofuels including biomethane, which has been shown to be more environmentally beneficial than liquid biofuels, should contribute to meeting the challenging UK targets set for the supplying of biofuels to the road transport fuel market. Under the Renewable Transport Fuel Obligations the financial incentives for the supply of biofuels have been volatile, e.g. 2008/2009 saw Renewable Transport Fuel Certificate values fall to zero. Any shortfall from the maximum value has significant implications for all biofuels. It is demonstrated that biomethane can be produced at a cost which is competitive with liquid biofuels and fossil fuels within the UK. Technologies such as water scrubbing, pressure swing adsorption and physical and chemical absorption are available to upgrade biogas generated by anaerobic digestion of organic wastes to transport fuel quality, and technologies such as membrane separation and cryogenic distillation are being modified for such an application. The manufacture and sale of biomethane as a transport fuel is also financially competitive with Combined Heat and Power. One limiting factor may be the additional cost of purchasing and maintaining biomethane fuelled vehicles. Support in this area could lead to the rapid expansion of biomethane transport fuel infrastructure and bring significant long term environmental and economic advantages.