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Electric Mobility in Germany: Carbon Emissions Depend on Charging Power - Emissions Reduction Would Require Additional Expansion of Renewables

Press Release of April 22, 2015

Joint press release from the German Institute for Economic Research (DIW Berlin) and the Institute for Applied Ecology (Öko-Institut)

Even if the use of electric road vehicles (EVs) were to increase significantly, the total annual power consumption of EV fleets would be small compared to overall power demand. However, uncontrolled charging, which involves the vehicle being fully recharged as quickly as possible after being connected to the power grid, could result in problematic peak loads in the system. This would not be the case with a charging mode that optimizes system costs, such that EV charging is primarily carried at night when demand is lower and at midday when solar power generation is high. The source of the additional power generated and the resultant net CO2 emissions of EVs depend on the charging mode and assumptions about the future power plant fleet. If renewable power generation capacities were to be expanded beyond current targets – enough to meet the electricity demand of EVs – this could result in a net reduction in CO2 emissions of up to 6.9 million tons per annum in 2030. These are the findings of a recent study conducted by the German Institute for Economic Research (DIW Berlin) and the Institute for Applied Ecology (Öko-Institut) as part of a European research project analyzing the impact of electric mobility on the German power system and the CO2 emissions of EVs using various scenarios. “The introduction of electric mobility would only result in a significant reduction in carbon emissions if linked to a more extensive expansion of renewable energy sources than is currently envisaged,” say the authors of the study, DIW Berlin’s Wolf-Peter Schill and the Öko-Institut’s Peter Kasten.

German Institute for Economic Research (DIW Berlin)

The German Institute for Economic Research (DIW Berlin) is one of the leading economic research institutions in Germany. Its core mandates are applied economic research and economic policy as well as provision of research infrastructure. As an independent non-profit institution, DIW Berlin is committed to serving the common good. The institute was founded in 1925 as Institut für Konjunkturforschung (Institute for economic cycle research). Since 1982, the Research Infrastructure SOEP (German Socio-Economic Panel Study), a long-term study, is affiliated to DIW Berlin. The institute has been headquartered in Berlin since its founding. As a member of the Leibniz Society, DIW Berlin is predominantly publicly funded.

Institute for Applied Ecology (Öko-Institut)

The Öko-Institut is a leading independent European research and consultancy institute working for a sustainable future. Founded in 1977, the non-profit institute develops principles and strategies for realizing the vision of sustainable development globally, nationally, and locally. The Öko-Institut has three offices in Germany: in Freiburg, Darmstadt, and Berlin.

The German government plans to expand the current fleet of EVs – that is, passenger cars that are powered, at least in part, by electricity from the grid stored in batteries – from the current approximately 20,000 vehicles to one million by 2020 and continue to significantly increase that number thereafter. According to the simulations, the annual energy requirements of approximately five million EVs would be similarly modest in 2030 (1.6 percent of total electricity consumption). Whether the German electricity grid will easily be able to cope with the additional charging requirements of EVs, however, depends largely on how the vehicles are charged. If charging is carried out in an uncontrolled mode, this could result in dangerous increases in peak loads in the power system, particularly during the evening. Experts at DIW Berlin and the Öko-Institut are therefore calling for a charging mode that optimizes system costs, carried out primarily during the night when demand is lower and the period around midday when solar power generation in high. Such optimized charging would, however, use a particularly high share of power from hard-coal- and lignite-fired plants since these can generate electricity at relatively low cost and also have high availability during the periods of optimized vehicle charging. In order to prevent above-average levels of specific carbon emissions of the charging current, it would make sense to adequately plan for an additional expansion of renewable electricity generation capacities. “From a system perspective, it is immaterial whether the additional power generated by renewable energy sources is absorbed entirely by EVs by means of a dedicated charging strategy, or whether the additional power is used to meet other electricity requirements,” says Schill.

Carbon Emissions Shift to Power Sector

The introduction of electric mobility means that carbon emissions are shifted from the transport to the power sector. Electric mobility can only have positive net carbon emissions if the use of electric vehicles results in a greater reduction in emissions in the transport sector than the increase in the power sector due to the additional electricity generated. Assuming the current policy framework conditions remain in place, in 2030, any transport-related reductions in carbon emissions resulting from the expansion of the EV fleet would be overcompensated by additional emissions in the power sector of up to 1.6 million tons of CO2 – in other words, overall emissions would rise by approximately one percent of current passenger car emission levels in Germany. However, if renewable power generation capacity were to increase beyond current expansion targets – enough to cover overall EV energy requirements – this would result in a net reduction in carbon emissions of 6.9 million tons by 2030 which equates to a good six percent of Germany’s current passenger car emissions. “Only an expansion of renewables of this magnitude would enable us to fully exploit the potential of electric mobility to reduce carbon emissions,” says the Öko-Institut’s Peter Kasten.

Contact Person DIW Berlin:
Wolf-Peter Schill
T: 030/89789-675

Contact Person Öko-Institut:
Peter Kasten
T: 030/405085-349

Press Contact DIW Berlin:
Sebastian Kollmann
T: 030/89789-250

Press Contact Öko-Institut:
Romy Klupsch
T: 0761/45295-222