How car-sharing vehicles can contribute to the energy transition

An innovation project by the University of Applied Sciences Northwestern Switzerland FHNW and the OST - Ostschweizer Fachhochschule shows for the first time how car-sharing fleets can contribute to grid stabilization as flexible energy storage systems. Together with the energy suppliers AEM, ewz and Primeo Energie as well as the Mobility Cooperative, they investigated how bidirectional charging can be integrated into existing electricity grids in a technically and economically viable way. The conclusion: bidirectional charging electric cars are a practicable and worthwhile building block for the energy transition - both for grid operators and for vehicle fleet operators.

From car to active network participant

The core question of the project was: Can electric vehicles not only draw electricity from the grid, but also feed it back into the grid in a targeted manner - and thus reduce the load on the power grid? The answer is yes - and not just in theory. In several real field tests, Mobility vehicles were controlled in such a way that they postponed their charging processes at certain times in order to feed electricity back into the local distribution grid in a targeted manner. Result: In up to 60 % of cases, grid loads were successfully reduced. Flexible control proves to be a valuable lever, especially in times of high demand or high PV surplus.

Intelligent forecasts with machine learning

Intelligent forecasting models predict when and for how long a vehicle will be available - based on millions of real booking data from the car sharing system. In addition, the state of charge of the vehicle batteries was analyzed to find out how much energy can be stored or fed back into the system. On average, around 9 to 12 kWh of usable flexibility was available per vehicle - enough to buffer relevant grid loads with several vehicles in total or to store PV electricity temporarily in a meaningful way.

Easy integration into the power grid possible

The product model developed for marketing charging flexibility is a particularly practical success of the project: it can be easily integrated into existing systems of distribution grid operators, can be standardized throughout Switzerland and focuses on two applications:

• "Charging when there is excess electricity" (e.g. during high PV generation)
• "Regenerative power supply for grid load peaks"

Distribution grid operators can use various types of control systems to activate the flexible power - from existing ripple control systems to modern load control systems. The model provides for remuneration for both the provision and the actual use of flexibility and works on a quarter-hourly basis - adapted to grid requirements. This represents a decisive step towards the market-driven integration of e-mobility and electricity supply.

Added value for everyone: the environment, grid operators and users

The project clearly shows that decentralized e-vehicles are more than just a means of transport. They are mobile, controllable energy storage systems - and therefore a key to successful sector coupling of mobility and energy. For grid operators, this means lower costs due to peak load reduction and grid stabilization. For society, it means progress towards a climate-friendly, decentralized energy landscape. And for car sharing providers such as Mobility, it opens up new business models in the area of grid-supporting services.

Source: FHNW School of Engineering and Environment