Modelling the Weekly Electricity Demand Caused by Electric Cars

As transport is one of the big sources of carbon dioxide emissions, it is natural to seek for solutions reducing the carbon dioxide emissions in transport as well. Replacing cars powered by a combustion engine by battery electric vehicles may be one measure to achieve this goal, at least as long as the electricity consumed by these cars is produced carbon neutral or in a low-carbon manner. In Germany, the Federal Government aims at a stock of one million electric vehicles in the year 2020. This goal is very ambitious, since customers are reluctant to buy battery electric cars, probably most of all due to their limited range. A possible solution to the limited range problem is the use of Plug-in Hybrid Electric Vehicles or Extended Range Electric Vehicles (EREV), combining an electric battery with a combustion engine or a generator. These solutions overcome the range limitations while at the same time allowing driving on electric power for the majority of the total mileage.In this paper, we analyse the effects of an increased use of EREVs and battery electric vehicles using the travel demand model mobiTopp. For three scenarios with different rates of market penetration of electric vehicles, the travel demand and car usage is simulated over a simulation period of one week. The results show, that for 65 up to 70 percent of the mileage, EREVs can be driven in battery-only mode, demonstrating the usefulness of the EREV concept and indicating a substantial potential for the reduction of carbon dioxide emissions. The results, however, also show that with an uncontrolled charging strategy, i. e. every car recharges immediately after accessing a charging location, the peaks of electricity demand for charging the electric cars occurs when the general electricity demand is already high. During these periods, additional electricity demand is typically covered by gas-fuelled power plants, thus using fossil fuels. Therefore, the concept of introducing electric vehicles in order to reduce total carbon dioxide emissions can only succeed if combined with intelligent charging strategies.