Li-ion battery has surprisingly small ecological footprint

Swiss research institute EMPA now has calculated the ecological footprint for lithium batteries as the most popular energy source for electric cars.

According to EMPA, lithium batteries are highly competitive under ecological aspects. The Li-ion battery has relatively little impact on the eco-footprint of the cars; what affects the environment much more than the battery is the electric energy required to recharge the battery.

If this energy is generated by means of today’s energy mix most common across Europe (hydro power, wind energy, fossil energy and nuclear energy), during an anticipated electric car life cycle of 150.000 km, the generation of the electric power causes three times higher environmental burden than the battery.

Only 15 percent of the electric car ecologic footprint accounts for production, operation and disposal of the battery. Of this figure, 50 percent points (7.5 percent of the total ecological footprint) is associated to the production of raw materials such as copper and aluminum.

The extraction of the lithium accounts for a surprisingly little percentage of only 2.3 percent. “Lithium-ion accumulators are not as bad in terms of ecology as many thought,” said Dominic Notter, one of the authors of the study.

Also in comparison to conventional vehicles, electric cars are rather competitive when it comes to their ecological impact. The researchers said the total eco-footprint of an electric car – given an average electric energy generation mix – is comparable to a vehicle with conventional internal combustion engine which burns 4 liters of gasoline per 100 km of distance. This corresponds to a fuel efficiency of 58.8 miles per gallon.

The Swiss researchers said they included all relevant factors into their model, from the production of the components to operational lifetime of the battery and the effort required to recycle or scrap the energy storage.

Since no data to this end were available, the team had to gather them in an extensive process. In this context, the researchers deliberately used figures and assumptions unfavorable for the battery. For instance, they did not take into account that Li-ion batteries typically have a second life as stationary energy storage after their degradation makes them unacceptable for vehicle use.

For their calculations, the researchers used data of a compact class electric car. They compared the ecological footprint of this vehicle with the data of a best-in-class conventional vehicle with regard to fuel efficiency. The result: The electric car provides better energy efficiency.

While it used the abovementioned equivalent of 4 liters per 100 km, the gasoline-driven vehicle burned 5.2 liters per 100 km according to the NEDC standard (New European Driving Cycle).

By Christoph Hammerschmidt,