The effects of climate change are becoming increasingly noticeable. In this context, the e-vehicle is gaining more and more popularity in Germany – many people expect it to have a better climate footprint than conventional combustion engines. This thinking is promoted by statements like this: “E-vehicles are three times more efficient than combustion engines”. This claim is mostly true.
The quote originates from a tweet posted by Marion Tiemann, who is a Greenpeace climate activist campaigning for an ecological traffic turn and who studied Environmental Policy and Planning in Berlin. In this tweet of April 13, 2022, Tiemann hyperlinked a blog post of the German ministry of environment protection. But the original data source is a collaboration of the German think tanks Agora Verkehrswende and Öko-Institut. The way electric vehicles work makes people say that they are more efficient than conventional cars. But why is that?
Figure 1: The WtT efficiency starts with the extraction of raw materials for fuel production and ends at the gas station where the customers can refuel their vehicle (data source: gmobility).
To analyse the efficiency of a vehicle, experts often use the so called “Well-to-Wheel” efficiency. This calculation consists of two parts: The Well-to-Tank (WtT) and the Tank-to-Wheel (TtW) efficiency.
All types of fuels can be measured in this scheme (e.g., gasoline, hydrogen or electricity). Researchers calculate the presumed CO2 emissions required to extract the raw material, process, store and transport it to the filling station.
The TtW system, on the other hand, evaluates the efficiency of the vehicle itself and how much of the resources it uses to fulfil its purpose and get from A to B. This can be very different, depending on the vehicle’s technology, for example if it is a gasoline engine or an electric vehicle. The WtT and the TtW analysis summed up from the WtW analysis.
E-vehicle causes less emissions while driving
Through the WtW analysis, the differences in greenhouse gas emissions of vehicles and the efficiency of electric vehicles, even when considering the European electricity mix and not assuming that the e-vehicles are powered with green electricity, become visible (cf. Figure 2).
Figure 2: Emission comparison of different vehicle types stated as CO2 equivalents. CO2 equivalents are a unit of measurement for standardising the climate impact of different greenhouse gases (data source: FIS)
The graph reveals that the CO2 emitted on the way from the energy source to the gas pump (WtT) is even lower in case of combustion engines than it is in case of e-vehicles. In terms of TtW efficiency, the electric car therefore performs better because it does not emit any carbon dioxide due to its alternative driving technology. The electric car would win the well-to-wheel efficiency decision even clearer if the electricity came from renewable energies – then it would emit only two grams of CO2 per kilometre. The infographic is based on the European power mix.
Figure 3: The production of e-vehicles emits nearly twice as much greenhouse gas emissions as the production of gasoline engines.
Gasoline engines cause less emissions in production
Compared to gasoline powered cars, the production of e-vehicles is significantly more energy intensive due to emissions from the production of the batteries. Summed up, e-vehicles are only more environmentally friendly than conventional cars as they do not emit tailpipe emissions. However, it is true that their use causes less greenhouse gases depending on the electricity used. Assuming the German electricity mix and a progressive energy transition, an e-vehicle purchased today has 15 to 30 percent lower greenhouse gas emissions in the overall balance of production and use than a gasoline powered car.
Figure 4: The contributions of the different materials to the greenhouse gas emissions of the battery of an e-vehicle.
Lifetime of the car determines its effect on climate change
In future, the demand for the raw materials required for the production of battery cells will continue to increase. However, the extraction of these materials is often accompanied by environmental and social burdens. That is why raw material requirements need to be reduced, for example through innovative production technology and greater material efficiency. Increased recycling also contributes to this – many materials in a battery can be recycled at the end of its life. Therefore, looking at the total amount of resources actually consumed, the amount of gasoline used by an average gasoline engine over its lifetime is equivalent to 300 to 400 times the amount of metals consumed by a battery cell.
Conclusion
In general, Marion Tiemann’s statement is correct as it refers to the well-to-wheel efficiency of electric vehicles. However, it needs to be noted that she is only referring to a small part of a bigger picture. For example, she does not consider the emissions produced by the extraction of materials for the production of electric cars, the production itself and the final disposal. In fact, the production of an average electric car produces about twice as many greenhouse gases as the production of gasoline cars does. Only the emissions saved during the use of the electric car make it less polluting in total than other vehicles in this comparison (cf. Fig. 2). Assuming that the energy policy and the expansion of renewable energies in Germany proceed as planned, it holds the opportunity to save emissions during the use of electric cars as well as during their production. Therefore, the electricity used for production and charging of the vehicles must be provided by renewable energy sources.
RESEARCH | ARTICLE: Franziska Kircher & Meg Löffler, Hochschule der Medien, Stuttgart (Germany)
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