Sir

In his Correspondence 'Choosing between batteries or biomass to stay on the road' (Nature 457, 257; 2009), Lucien Trueb presents figures that do rough justice to the potential of the battery-powered car.

The fully electric car is five times more efficient than the hydrocarbon-guzzling alternative (D. J. C. MacKay, Sustainable Energy — Without the Hot Air UIT Cambridge, 2008), which takes some of the sting from batteries' lower energy density. And the energy density Trueb quotes for petrol makes no allowance for the mass of the internal-combustion engine: replacing this half-tonne lump with its weight in batteries allows electrification without sacrificing performance. For example, a range of 350 kilometres and acceleration of 0–96 kilometres per hour in less than 4 seconds is obtainable today in commercially available all-electric vehicles for which the price tag, although high, is affordable.

If biofuels are to be the alternative, we will have to sacrifice more than 10% of the world's agricultural land to powering the world's cars, or greatly increase our production of suitable 'waste'. Even then, using bio-hydrocarbons to generate electricity in power stations is roughly twice as efficient as burning them in combustion engines.

The electrification of transport is crucial if we are to break our addiction to fossil fuels. Unlike biofuels, electricity production can be scaled up to keep pace with increased car usage. Electric cars are the only long-term solution to comfortable personal transportation.