STÉPHANE HERZOG The Swiss love their cars, but the fact is that the country’s approximately 4.8 million passenger cars spend most of their time immobile. They are parked for up to 23 hours a day, with their battery cut off from the world. In the future, cars – which will soon all be electric – will be interconnected via intelligent electrical networks. They will form storage facilities, as when water is stored in a dam. “Thanks to bidirectional charging which allows cars to either send or receive energy, Switzerland has a massive power reserve at its disposal,” says Volker Fröse, a consultant cited by car-sharing specialists Mobility. In the evening, at dinnertime – when demand for electricity peaks – computers will tell the connected batteries to supply current to the grid. During the day, solar panels will feed power into the cars, treating them like mobile batteries. The entire system will be an example of the vehicle-to-grid (V2G) principle: a network of bidirectional batteries that can receive, store and supply electricity within a local or global network. Recharge your battery overnight “The average car battery can hold 60 kilowatt-hours (kWh), whereas a stationary battery in a house equipped with solar panels holds only 6 kWh. Many people have solar panels but no battery for them. The benefits of using your car as an electrical battery are therefore obvious,” explains Valais engineer Arnaud Zufferey, a graduate of the Swiss Federal Institute of Technology Lausanne (EPFL). A 7 kW charging station takes only one hour to charge ten percent of a battery. “This allows you a lot of flexibility when topping up your battery: you can do it at lunchtime, when In the future, millions of cars will combine their batteries Car batteries, connected to a single network, can create power grids. This will enable solar energy to power electric cars. Mobility, the Swiss car-sharing company, has carried out a full-scale test of the technology. solar energy production is at its peak, or overnight, when charges are low,” he says. So, when will Switzerland, with its love of cars and solar panels, usher in this revolution? Mobility ran a full-scale test between autumn 2022 and spring 2024. The car-sharing company connected up a fleet of 50 electric cars, each fitted with a bidirectional battery. The test involved rolling out these cars all across Switzerland – where they had to be available at any time – and connecting them to different electricity providers, as Mobility explained. During the 18-month test, around 7,000 people drove approximately 800,000 kilometres. When stationary, the cars ‘sold’ electricity to the grid, generating up to 2,000 Swiss francs in revenue per vehicle per year, according to Mobility, although they admit that running a V2G system is not viable for a car-sharing company under current circumstances. “The era of bidirecTo conduct the trial, Mobility had to use vehicles that not only charge from the grid but also feed it with electricity. Currently, the list of electric cars that offer bidirectional charging is limited. Photo: Mobility 22 Nature and the environment
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