It is not an easy task to compare the environmental effects of battery powered cars to those caused by conventionally fuelled automobiles. The degree to which manufacture, usage and disposal of the batteries used to store the necessary electrical energy are detrimental to the environment is not exactly known.
Now, for the first time, a team of Empa scientists have made a detailed life cycle assessment (LCA) or ecobalance of lithium-ion (Li-ion) batteries, in particular the chemically improved (i.e. more environmentally friendly) version of the ones most frequently used in electric vehicles.
The investigation shows that if the power used to charge the battery is not derived from purely hydroelectric sources, then it is primarily the operation of the electric car, which has an environmental impact, exactly as is the case with conventionally fuelled automobiles.
The size of the environmental footprint depends on which sources of power are used to "fuel" the e-mobile. The Li-ion battery itself has, in contrast, a limited effect on the LCA of the electric vehicle. This is contrary to initial expectations that the manufacture of the batteries could negate the advantages of the electric drive.
The environmental impact of batteries for electric vehicles
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.
Li-ion batteries 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 Empa's "Technology and Society Laboratory" decided to find out for sure. They 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 to the scrapping of the vehicle and the disposal of the remains, including the operation of the vehicle during its lifetime.
Data with which to evaluate the rechargeable batteries was not available and had to be obtained specifically for this purpose. In doing so the researchers made intentionally unfavorable assumptions. One such was to ignore the fact that after use in a car, a battery might well be used in a stationary setting for other purposes.
Other relevant LCA information was obtained from the "ecoinvent" database (Home
), managed by Empa. The electric vehicles evaluated were equivalent in size and performance to a VW Golf, and the power used to charge the batteries was assumed to be derived from sources representing an average European electricity mix.
A new petrol-engined car, meeting the Euro 5 emission regulations, was used for comparison. It consumes on average 5.2 liter per 100 kilometers when put through the New European Driving Cycle (NEDC), a value significantly lower than the European average. In this respect, therefore, the conventional vehicle belongs to the best of its class on the market
Electric Cars Greener Than Expected