A leading scientist was today due to claim that biofuels are not as environmentally friendly as the government says.

Professor Roland Clift is expected to label the government’s promotional policy for transport biofuels as a “scam”.

The environmental technology professor at Surrey University sits on the Department for Environment, Food and Rural Affairs’ (Defra) environmental scientific advisory council.

During a seminar at the Royal Academy of Engineering, he planned to reveal that promoting the use of biofuels is likely to increase greenhouse gas emissions, not reduce them. Professor Clift said: “Biodiesel is a complete scam because in the tropics the growing demand is causing forests to be burnt away to make way for palm oil and similar crops.

“We calculate that the land will need to grow biodiesel crops for 70 to 300 years to compensate for the CO2 emitted in forest destruction.”

Clift also condemns plans to make biodiesel in Britain from rapeseed.

He points to research that shows the crop produces large amounts of nitrous oxide which is an even more potent global warming agent than CO2.

Professor Clift’s comments represent a direct challenge to government minister David Miliband, who published the strategy to promote biofuels as part of the government’s push to support the technology.

The Renewable Transport Fuels Obligation (RTFO) demands that 5% of all fuel sold by 2010 is biofuel.

Defra chief scientific adviser Professor Howard Dalton is expected to defend biofuels at the same event.

Last week, Department for Transport adviser Professor Roger Kemp also said that using biofuels in transport would have no impact on cutting emissions.

“We would need to plant a land area twice the size of Britain to get enough biofuel crops to halve our emissions,” said the professor of engineering at Lancaster University.

“The numbers simply do not add up.”

Both professors say the rise in interest in biofuels comes from a false belief that there must be a technical solution to climate change.

“Underlying this all is the assumption that we have to preserve the mobility and freedom to travel that we now enjoy at all costs,” said Professor Kemp.

“However, when you look at the science of climate change it is clear there are no such simple solutions. Humanity has to accept that.”