Series electromobility: Climate assessment of electric vehicles

Electromobility is a central research area of the FfE and is part of numerous research projects. In the following series of articles, different topics are presented. One focus is on scenarios for electric vehicles and charging stations in Germany. Furthermore, the different charging plugs are explained and different possibilities of grid integration by controlled and bidirectional charging are described. Finally, the climate footprint of electric vehicles is discussed.

This article is the last in a series of 7 articles which will now be published successively on our website.

 

Overview of the topics of the article series on electromobility
1.   Development of electromobility
2.   Charging points
3.   Plugtypes
4.   Private and public charging
5.   Smart Charging
6.   Use Cases for bidirectional charging
7.   Climate assessment of electric vehicles

 

The perception of electric vehicles (EV) has changed in the past between "panacea" and "placebo". However, to achieve the ambitious greenhouse gas reduction targets of 40 % by 2040 and 80-95 % by 2050 compared to 1990 [1] of the Paris Climate Agreement, the integration of renewable energies in the transport sector is required. For that purpose, electromobility is currently the only significant alternative and its expansion has irreversibly picked up speed. The question arises as to what real contribution EV can make to meet these targets.

It is undisputed that an electrically powered vehicle is considerably more efficient than a vehicle with an internal combustion engine. But this advantage is reduced due to the higher cumulative energy expenditure for the production of EV batteries. The energy requirement in battery production is subject to uncertainty and, according to [2], is usually in the range of less than 10 to almost 170 kWh per kWh of battery capacity produced. Furthermore, the emissions associated with this electricity demand are strongly dependent on the electricity mix prevailing at the location of battery production.

Figure 1 shows the results obtained from the study “Carbon footprint of electric vehicles –a plea for more objectivity” of FfE [3], where GHG emissions of total battery production in kg CO2 -equivalent per kWh battery capacity as a function of the electricity required for battery production and the emission factor for the electricity used in battery production are displayed.

 

Energy related GHG emissions from battery production

Figure 1: The question arises as to what real contribution EV can make to meet these targets.

Moreover, the “payback period” of an electric vehicle compared to a conventional combustion engine vehicle has also been analyzed [3]. GHG emissions for the production of the gasoline vehicle in Germany were obtained from [4] and amount to approx. 6.6 t CO2-eq. For an EV with a 30 kWh battery system produced as indicated in [5], emissions amount 10 t CO2-equivalent. Finally, the results of the comparison shown in Figure 2 apply to vehicles with consumption values of 5.9 l/100 km for the petrol vehicle and 17.3 kWh/100 km for the electric vehicle.

 

Climate effectiveness of a gasoline and a battery electric vehicle

Figure 2: Climate effectiveness of a gasoline and a battery electric vehicle of the compact class as a function of driving performance and charged electricity (DE: German electricity mix, EU: European electricity mic, PV: Photovoltaic)

It is shown that the electric vehicle, when charged with the German electricity mix from 2015 (emission factor: 0.58 kg CO2 eq./kWh, renewables share: 29 %), performs better than the gasoline vehicle from an emissions perspective over a distance of approx. 50,000 km. For an average annual mileage of approximately 14,000 km, the calculated distance accounts for an amortization period of 3.6 years. This is reduced to just under 2.8 years for the EU electricity mix (0.46 kg CO2 eq./kWh) and to 1.6 years for electricity from photovoltaics (0.1 kg CO2 eq./kWh). The results also show that even if the electricity mix is still very much dominated by conventional power plants, the additional emissions for the production of the electric vehicle are offset by the lower emissions during operation.

 

Literature:

[1] Sechster Monitoring-Bericht zur Energiewende - Berichtsjahr 2016. Berlin: Bundesministerium für Wirtschaft und Energie (BMWi), 2018. 
[2] Ellingsen, L. et al.: Identifying key assumptions and differences in life cycle assessment studies of lithium-ion traction batteries with focus on greenhouse gas emissions. In: Transportation Research Part D: Transport and Environment 55, 82-90, 2017.
[3] Regett, A. et al.: Klimabilanz von Elektrofahrzeugen – Ein Plädoyer für mehr Sachlichkeit. Munich: Forschungsstelle für Energiewirtschaft e.V., 2020.
[4] Hawkins, T. et al.: Comparative environmental life cycle assessment of conventional and electric vehicles - supporting information. In: Journal of Industrial Ecology 17(1), 53-64, 2013.
[5] Thielmann, Axel et al.: Energiespeicher-Roadmap (Update 2017) - Hochenergie-Batterien 2030+ und Perspektiven zukünftiger Batterietechnologien. Karlsruhe: Fraunhofer-Institut für System- und Innovationsforschung (ISI), 2017.

 

 

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