Dübendorf, Switzerland – Lithium-ion batteries for electric vehicles are only a “moderate environmental burden,” according to researchers at Switzerland’s Empa Technology and Society Laboratory. The scientists made a detailed life cycle assessment (LCA) of the batteries and found that it is primarily the method used to create the electricity to charge the battery that determines its environmental footprint, rather than the manufacture of the battery itself.

The battery itself has a limited effect on the LCA of the electric vehicle, the researchers said, which is contrary to initial expectations that the manufacture of the batteries could negate the advantages of the electric drive.

The researchers calculated the ecological footprints of electric cars fitted with lithium-ion (Li-ion) batteries, taking into account all possible relevant factors, from the production of individual parts to scrapping the vehicle and 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. The researchers intentionally make unfavourable assumptions, including ignoring the fact that the batteries might be used for stationary storage once they were no longer suitable for automotive use.

The vehicles evaluated were equivalent in size and performance to a Volkswagen Golf, and the power used to charge the batteries was assumed to be derived from sources representing an average European electricity mix. For comparison, the researchers used a new gasoline car that consumed an average of 5.2 L/100 km in the New European Driving Cycle.

The study showed that at most, only 15 per cent of the total environmental burden can be ascribed to the battery, including its manufacture, maintenance and disposal. Half of that figure, or about 7.5 per cent, occurs during the refining and manufacturing of the battery’s copper and aluminum raw materials. Production of lithium is responsible for only 2.3 per cent of the total.

The greatest ecological impact over the vehicle’s expected 150,000-kilometre lifetime is regular recharging of the battery. Charging with electricity sourced from a mixture of atomic, coal-fired and hydroelectric power stations, as is usual in Europe, results in three times as much pollution as from the Li-ion battery alone. If electricity is generated exclusively by coal-fired power stations, the ecobalance worsens by an additional 13 per cent, while pure hydroelectric power improves the figure by at least 40 per cent.

The Empa team concluded that a gasoline-engine car must consume between 3.0 and 4.0 L/100 km in order to be as environmentally friendly as the vehicle studied with Li-ion batteries and charged with a typical European electricity mix.

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