The Renewable Transport Fuels Obligation Programme came into effect in April 2008. It  places an obligation on fuel suppliers to ensure that a certain percentage of their total sales is made up of biofuels.

This means that, by 2010, 5% of all UK fuel sold on UK forecourts is required to come from a renewable source. European specifications currently only allow a maximum biofuel content of 5% by volume to be sold on forecourts as standard petrol or diesel.

As the transport sector is currently responsible for a quarter of all UK emissions this should have a big impact on reducing emissions. The Department for Transport expects this measure to reduce the carbon emissions from road transport in 2010 by about 1 million tonnes, equivalent to taking around 1 million cars off the road.

To show they have met the obligation, the fuel suppliers must obtain renewable transport fuel certificates. In order to obtain the certificates, they must report on the greenhouse gas emissions and sustainability of their fuel. The scheme is run by the Renewable Fuels Agency.

If a fuel supplier does not have enough certifictes at the end of the reporting year, it must either buy more or pay a 'buy-out' penalty.