Swapping ‘gas guzzling’ cars for zero emission electric vehicles will not solve the UK’s carbon emissions problems on its own, according to a new report from the Royal Academy of Engineering.

Electric vehicles are only as ‘green’ as the electricity that charges their batteries, according to the report ‘Electric Vehicles: Charged with Potential’, which has been written by the UK’s leading engineers.

The report identifies what the Academy calls ‘the serious challenge of ensuring that the electricity supply system can cope with charging tens of millions of vehicles whilst still reducing carbon emissions from power generation’.

The engineers identify four major technical issues:

• The availability of high energy-density batteries at a price and with a long enough cycle life for electric vehicles to be economically viable
• The practicalities of charging vehicles – particularly for users without off-street parking
• The electrical distribution infrastructure to provide power to millions of charging points and
• The need for a national energy system and ‘smart grid’ that can recharge millions of electric vehicles using low-carbon electricity without overwhelming local distribution circuits.

Professor Roger Kemp of Lancaster University, chair of the Academy’s electric vehicles working group, said: “When most electricity in Britain is still generated by burning gas and coal, the difference between an electric car and a small, low-emission petrol or diesel car is negligible.

“We welcome the fact that the motor manufacturers are so ready to take on the challenge of developing mass market electric vehicles. We also welcome the new Government’s commitment to mandating charging sockets for electric vehicles and plug-in hybrids, but establishing these as the technology of choice for personal transport is only one aspect of what is needed to reduce transport emissions.”

The report says that if the UK is to meet its renewables targets and ensure a ‘greener’ power supply to electric cars, a range of new low-carbon energy sources will be needed, including new nuclear power stations, wind farms and tidal barrages.

There are three interrelated policy programmes that are critical to the successful introduction of electric vehicles, according to the Academy: low-carbon energy, universal broadband provision and smart electricity grids. The report says that electric vehicles can only have a serious impact on carbon emissions if the three areas of policy are already in place.

Richard Parry-Jones, a member of the working group and former group vice president of the Ford Motor Company, said: “Electric vehicles could provide a major contribution to meeting the target of an 80% reduction in greenhouse gas emissions by 2050.

“However, they will only be built in mass production numbers when there is a compelling sustainable social and business model for their use to allow manufacturers to plan for a long-term market and when the new vehicles have a real carbon efficiency benefit over the latest internal combustion engines.”

As a result, the engineers conclude: “There are ways to allow electric vehicles and plug-in hybrids to take over most of the present uses of petrol and diesel vehicles but these are unlikely to develop without financial incentives for early adopters.

“In the medium term, the new Government will need to indicate how it intends to replace road fuel taxation as electric vehicles gain market share, to allow manufacturers and potential users to make informed decisions.

“A more likely alternative to widespread adoption of pure electric vehicles with their infrastructure requirement would be the plug-in hybrid. While hybrids have most of the environmental benefits of electric vehicles, they do not rely on such a comprehensive network of recharging points at multiple destinations.

“Plug-in hybrids could be adopted quickly as family cars or executive cars, leaving pure electric cars to achieve initial market penetration as second cars, doing low mileage and thus having little impact on carbon emissions.”