The European Union has a major drive to turn all kinds of waste into energy, particularly from biogas. There are two main incentives for this, the first being the geological feature that natural gas is in finite supply and world production of it is expected to peak within the next few decades, and secondly that burning fossil carbon contributes to the atmospheric concentration of CO2, which some believe will cause global warming and climate change. To address either issue, finding a renewable (non-fossil) source of methane is encouraged.
The claims over how important biogas could be to help secure Britain's energy future are certainly extravagant, and Mark Fairbairn from the National Grid thinks that it could provide for half the country's gas by 2050 in substitution for natural gas . Given that the UK gas consumption is around 103 billion cubic metres  of natural gas annually (i.e. around 3.6 trillion cubic feet, tcf) 50-odd billion m^3 (1.8 tcf) of biogas would need to be produced per year to meet this projection. This, roughly (assuming that 6,000 cubic feet of natural gas has an energy equivalence of one barrel of oil) amounts to an equivalent of 300 million barrels or 41 million tonnes of oil. That does sound rather a tall order - to put it mildly.
In Germany biogas is already being fed into into the national gas grid and in Sweden and Spain, vehicles including buses are run on biogas, but they still use an awful lot of oil overall and most of the small number of gas-powered vehicles are run on petroleum-gas. In Yerevan, Armenia, where I was last May, I noticed buses and lorries resplendent with rusty-looking cylinders of gas as their fuel supply, which is more cheaply obtained than liquid fuels, but I emphasise that it is petroleum gas (mainly propane and butane) that is used there and not biogas.
Also in Germany, there are aerobic digesters which are fed by maize (corn) rather than waste and so the same argument would arise over growing crops for fuel or for food as applies to biodiesel production and must ring an eventual death-knell for both biodiesel and biogas, if the latter is made from food too. It is ridiculous to compromise indigenous food-production in any nation, since all nations will find it increasingly untenable to import food on the vast scale most currently do, in the absence of cheap oil or gas.
It is true that a small amount of biogas is produced from landfill and sewage and used for energy in the U.K., but it is anticipated that "new incentives" (i.e. forms of financial encouragement; tax-breaks maybe?) will mean that this kind of conversion of waste into fuel would find more extensive applications, including the use of compressed biogas for transport. It sounds great but I question the usual scale-up and engineering required to inaugurate a huge infrastructure based on biogas. In my opinion, like solar energy, the greatest opportunity for the technology is in providing energy for small communities rather than as some attempt to preserve the energy status quo, which is simply unsustainable without fossil fuels, including gas.
 "UK joins European drive to make energy from waste." By Gerard Wynn. http://www.reuters.com/article/GCA-GreenBusiness/idUSTRE5981HY20091009