BATTERY-POWERED electric cars are often promoted as the ideal solution to the challenges of future mobility since they produce no exhaust gases in operation.
Li-ion batteries have established themselves over competing lead-acid and nickel metal-hydride (NiMH) types because they are lighter and can store more energy.
They are also basically maintenance-free, display no memory effect (loss of capacity when repeatedly charged after partial discharge), have a low self-discharge rate and are regarded as safe and long-lived.
For these reasons, they find use in many products, such as laptop computers. But are they also environmentally friendly? Researchers at the Empa “Technology and Society Laboratory” in Switzerland decided to find out.
They have calculated the ecological footprints of electric cars fitted with Li-ion batteries, taking into account all possible relevant factors, from those associated with the production of individual parts all the way through the running and eventual scrapping of the vehicle and the disposal of the remains.
The upshot of the study was that the electric car’s Li-ion battery drive is, in fact, only a moderate environmental burden.
But the outlook is not as rosy when one looks at the operation of an electric vehicle over an expected lifetime of 150,000km.
The greatest ecological impact is caused by the regular recharging of the battery – that is, the “fuel” of the e-car.
The scientists concluded that a petrol-engined car must consume 3-4 litres per 100km (or about 70mpg) in order to be as environmentally-friendly as the e-car studied, powered with Li-ion batteries and charged with a typical European electricity mix.