The drive to switch over to biofuels could lead to rising food prices and deforestation, a report has warned.
Rapeseed oil can be used to produce bio-diesel
The government and EU have said by the year 2020 they want 10% of all fuel in cars to come from biofuels.
But a study by the Co-op Insurance Society suggests achieving this could have a severe environmental impact.
It comes days after a UN report with similar warnings said that biofuels are more effective when used for heat and power, rather than in transport.
Biofuels can be anything made with vegetable matter that burns.
They are seen as a potential solution to climate change because they can reduce emissions of greenhouse gases.
The Co-op report claims there is a future for biofuels, but current targets for growing so much fuel could have unintended consequences, BBC correspondent Damian Kahya says.
Professor Dieter Helm, a senior advisor to the British government, told the BBC: "The sort of targets being set for biofuels will have quite radical effects on agriculture and therefore will have very substantial consequences for food prices and agriculture more generally."
The report says that around nine per cent of the world's agricultural land may be needed to replace just 10% of the world's transport fuels.
This means the production of biofuels could lead to a decrease in land available for food production in countries where famine already exists.
"People are felling rainforests to plant crops to grow energy fuels, biofuels," Professor Helm said.
"Think of the energy involved in felling those rainforests. Think about the damage to the climate being done by the loss of those trees. Think about the ploughing and the cultivation of fields.
"Think about the transport of those fuels, and you start to realise the carbon imprints are about much more than simply what happens to grow in a particular field at a particular point in time."