By Christoph Hammerschmidt, Contributing Editor
Many see electric driving as a technology of the future. But it’s not that simple: An analysis by consulting firm Oliver Wyman warns of widespread power cuts if electromobility quickly finds too many friends.
The study predicts that the low-voltage grid will be overloaded if electric vehicles exceed 30 percent. According to the current regulatory framework, this would be the case in five to ten years’ time. Comprehensive problems are to be expected from around 2032 onwards.
Although the study explicitly refers to the German electricity supply network and the regulatory framework conditions that apply here, the problem is likely to arise in other industrialized countries in a similar form, albeit with different parameters.
The authors of the study assume that from 2035 onwards, more than one in three cars will be driven by battery-powered vehicles. These cars charge their energy via public and private charging stations, which are powered by the low voltage grid (400V to 1000V AC in most European countries). The low-voltage grid is not designed for this number of electric vehicles.
An example shows that in particular suburban and rural areas are susceptible to power outages caused by charging electric vehicles: With a local network size of 120 households, 36 electric cars are already sufficient to overload the network at certain points. Without preventive measures, power outages across the board are to be expected from 2032 onwards. In order to avoid this, operators would have to invest up to 11 billion euros in the expansion of their networks under the current framework conditions and with an electrification of 50 percent of the automobiles.
Thomas Fritz, author of the analysis, explains: “There is already an urgent need for action on the part of network operators, since network expansion requires considerable lead times and high investments.”
As an economically more attractive alternative to the slow and expensive expansion of the grid, the authors of the study propose to make charging processes more flexible. The charging processes of electric cars are usually so short that they are connected to the mains for the longest time at night without being actively charged. Most charging processes therefore have time flexibility. You do not necessarily have to start at the moment the car is plugged in. Instead, the charging process can also begin later at night without an electric car user having to forego his fully charged vehicle the next day.
Jörg Stäglich, head of the energy team at Oliver Wyman: “Due to the increased flexibility, network utilization is spread over a longer period of time so that there is no network congestion. This minimizes the risk of a widespread power failure. Above all, an intelligent software solution is required for implementation.”
Even if only 30 percent of electric vehicles take part in the flexible charging process, the peak load drops significantly. The higher the percentage of electric cars with flexible charging processes, the lower the likelihood of network congestion. If the network operators succeed in winning at least 92.5 percent of the owners of e-vehicles for flexible charging, there is no need to expand the network, even if the e-vehicle quota is 100 percent. According to Fritz, flexible charging is thus a “real alternative to conventional grid expansion”.