A report by Imperial College, commissioned by Drax, finds that as a result of the growth in production of greener, renewable electricity, the average year-round emissions from electric vehicles have fallen by half in the last four years and that they are now twice as efficient as conventional cars.
The report uses the Tesla Model S as an example. In the winter of 2012, producing the electricity for a full charge created 124g of carbon emissions per km driven, roughly the same as a 2L Range Rover Evoque. Now the carbon intensity of charging a Tesla has nearly halved to 74g/km in winter and 41 g/km in summer, as the UK continues to break its own renewable energy records.
For smaller EVs, the results are even better. The Nissan Leaf and BMW i3 can now be charged for less than half the CO2 of even the cleanest non-plug-in EV, the Toyota Prius Hybrid.
To meet the challenge of peak-time EV charging, the report says that less carbon intensive power generation, storage and smart power management systems are needed. These include rapid response gas power stations, as well as grid-scale batteries, home-based batteries and demand-side response schemes. As the share of intermittent renewable capacity on the grid increases, more back-up power needs to be available for when the wind doesn’t blow and the sun doesn’t shine.
The report says that a future increasingly relying on back-up generators is far from inevitable, especially if the use of smart technology and smart meters increases. By analysing electricity costs and country-wide demand, smart meters have the potential to ensure EVs only charge outside peak times (unless absolutely necessary), when electricity is more likely to come from renewable or low-carbon and cheaper sources.
Report author Dr Iain Staffell, a lecturer in sustainable energy at Imperial College London, said: "It is widely accepted that electric cars dramatically reduce air pollution in cities, but there is still some debate about how clean they actually are - it varies depending on where the electricity to charge them with comes from."
"According to our analysis, looking at a few of the most popular models - they weren't as green as you might think up until quite recently, but now, thanks to the rapid decarbonisation of electricity generation in the UK, they are much better.