According to the Digest of UK Energy Statistics (DUKES) 2010 published by the UK Government we use nearly 7M tonnes of diesel and 15.5M tonnes of petrol or gasoline in our cars and taxis. So how much electricity would we need to generate if we replaced all our national fleet of fossil fuel powered vehicles with electric ones?

7M tonnes of diesel and 15.5M tonnes of petrol contains 277 TWh of energy. According to the same report, the UK electricity industry delivered 326.1 TWh of energy to its users – simplistically we’d need to increase our capacity by 85%.

However an electric car is far more efficient than one powered by an internal combustion engine (88% vs 35%) so it does far more useful work for the same amount of input energy. 277 TWh put into a fleet of ‘normal’ cars will do 97 TWh of useful work, whereas an electric fleet will do the equivalent useful work with only 110 TWh of input energy.

So what if all cars became electric?

Allowing for transmission and distribution losses across the grid, around 9%, we find we need to generate 122 TWh of electricity – equivalent to roughly 25,000 wind turbines or 34 nuclear power plants.