Electric vehicles as mobile energy stores

With the increased use of solar and wind power, the demand for flexible energy storage systems is also growing. Are electric cars with their batteries a sensible and economical solution for this? And under what conditions is implementation possible? These are the questions Dominik Storch, a graduate of the Master's program in Automotive & Mobility Management at Technische Hochschule Ingolstadt (THI), pursued in his final thesis. He was supervised by Prof. Dr. Thomas Becker, Professor for Digital Automotive Management at the THI Business School.

In his master's thesis, Storch investigated the potential of so-called bidirectional charging, which enables electric vehicles to not only draw electrical energy from the public grid, but also to feed it back into the public grid (Vehicle to Grid: from the vehicle to the grid).

The starting point for the analysis: Up to ten million electric cars are predicted on Germany's roads by 2030. On average, a vehicle is only used for one hour a day. Assuming that ten percent of the available battery capacity is used for grid storage services over the remaining 23 hours, the additional storage capacity would theoretically be able to supply around 135,000 four-person households with electricity for one month, according to Storch's calculations.

According to Storch's analysis, large-scale implementation is currently not yet possible due to technical and regulatory barriers: Both electric vehicles and charging stations would first have to master bidirectional charging in order to convert direct current into alternating current (and vice versa). Similarly, the Renewable Energy Sources Act does not yet take electric cars into account as mobile electricity storage devices. The current consequence for the vehicle owner, according to Storch, would possibly be a possible double taxation of the energy drawn and the energy discharged.

Earning opportunities for owners of electric vehicles

In order to be able to charge bidirectionally, e-car owners are currently still having to invest in a charging station and an energy management system. According to Storch, the expenses for the user are not yet profitable. With increasing market penetration of e-vehicles, according to the analysis, investments in infrastructure will also decrease. It is therefore quite realistic in perspective that owners will earn money with their own car. The income would vary depending on the type of contract; according to Storch's calculations, an annual profit in the low to mid three-digit range is feasible.

THI's adaptive battery systems as a technological solution

Researchers at the THI around Prof. Dr. Christian Endisch are already working on a technological realization of bidirectional charging. The learnable battery systems researched at the Institute for Innovative Mobility (IIMo) in collaboration with Audi AG can not only absorb energy from the grid, they can also feed energy into the grid and, according to the researchers, without the expensive charging infrastructure currently required. Learning-capable battery systems combine data evaluation by artificial intelligence algorithms with a highly flexible topology in the hardware. This flexibility enables them to adapt to external conditions, they accept almost all voltage levels and can be operated with direct current as well as alternating or three-phase current.