The government should be encouraging the growth of dedicated 'energy crops', especially on land unsuitable for food production or housing, a new report says.

Crops such as willow and miscanthus or elephant grass are grown specifically to make fuels and provide an alternative to conventional petrol and diesel.

The report by the Royal Academy of Engineering also said transport fuels made from waste such as cooking oil or dregs from whiskey manufacture will be needed to help the UK meet targets to cut carbon emissions.

These 'second generation' biofuels were found to be significantly cleaner than fossil fuels, and more effective than food crops used for fuels such as sugar beet and maize.

Professor Roger Kemp, one of the report's authors, said while electric technology could help to cut emissions from cars and light vans, biofuels could play a 'much bigger part' in achieving the same for aviation, HGV and maritime transport.