The environmental benefits of electric cars are denounced as "fiction" by new research into green methods of transport.
By Melissa Kite, Deputy Political Editor Last Updated: 6:25PM BST 18 Apr 2009
The amount of energy used by coal fired power stations to create the electricity to recharge electric vehicles makes them half as efficient as diesel cars, according to the research.
Britain's carbon emissions could even go up if there is a sudden surge in demand for electric cars, the new research warned.
It will call into question a £250 million government scheme announced last week offering consumers £5,000 subsidies to buy a new electric car.
The research conducted by the group Transport Watch found that diesel powered vehicles emit approximately half as much CO2 as electric cars when the use of fossil fuels to produce electricity is taken into account.
The research paper says: "We conclude that the notion that electric cars will reduce emissions is a fiction."
Factors making the rechargeable cars less efficient include the amount of electricity lost on the journey between the coal fired power stations which generate it and the point where it recharges the car, and the energy lost by the batteries and the motor.
The researchers calculated that of the energy burned in a power station, only a quarter reaches an electric car after leakages and losses along the supply chain are considered, giving the vehicle an energy efficiency score of 24%.
A modern diesel engine, by contrast, achieves 45% efficiency.
The research suggests that if fossil fuels are to be burned, it is much more efficient to do it within the engine of a vehicle rather than at a power station and then try to send it via the National Grid, where a lot of energy is wasted, and finally to store it in a battery which in itself might leak power.
Currently the bulk of the electricity used to charge the batteries of electric vehicles is generated by fossil fuel burning power stations.
Only 20% of UK electricity is generated by 'clean' methods such as nuclear power.
The research by Paul Withrington of Transport Watch concludes that CO2 emissions could actually go up if there is suddenly a big demand for electricity to recharge batteries as it would have to come from existing fossil fuel power stations.
He calculated that in China, where most generation of electricity is coal fired, electrification of diesel powered transport would double the emissions from that sector.
There are also big financial and environmental costs involved in setting up a battery charging network.
Mr Withrington said: "The government should re-examine their assumptions and should not encourage this until they have decarbonised the generating industry. At the moment, it is nuts. If you bought an electric car now you would be looking at generating the same amount of carbon or more."
The Government's plans have also drawn criticism from motoring groups.
Philip Gomm, of the RAC Foundation, said: "Electric vehicles are not a panacea. They are good for generating headlines but not necessarily at saving the planet, at least not in the short term. For today and tomorrow, a lot more attention needs to be paid to refining existing petrol and diesel technology, and making cars smaller and lighter as a way of saving fuel – something recognised by the Committee on Climate Change. These are proven solutions to an immediate problem."
The RAC has also questioned where the Government derived its £5,000 incentive per vehicle figure, when previous grants to buy electric cars have been £1,000.
The research can be viewed in full at http://www.transport-watch.co.uk/transport-fact-sheet-5c.htm