Swiss researchers demonstrated that charging an electric car could be almost as fast as filling a tank of gas. A whooping 4.5 megawatt charging station is needed though.
We all know what is the main drawback of electric cars. If their range is constantly improving, as battery development is progressing, the long charging times are the only factor that keeps customers away from this technology. Swiss researchers from the Ecole Polytechnique Federale de Lausanne (EFPL) said an EV could be charged in 15 minutes. The only way to make the charging process faster is to increase the power flow going in. But such a quick charge would require 4.5 megawatts of power, or the equivalent to 4,500 washing machines, and this would bring down the power grid. EPFL scientists said they have found the solution to this problem without draining all the power from the system. “We came up with a system of intermediate storage,” said Alfred Rufer, a researcher in EPFL’s Industrial Electronics Lab. The solution is a buffer storage system that disconnects from the grid before releasing the 4.5MW charge to a car. “With this buffer storage, charging stations can be disconnected from the grid while still providing a high charge level for cars.” And this can be done using the low-voltage grid used for residential electricity needs or the medium-voltage grid used for regional power distribution, which significantly reduces the required investment.
Intermediate storage is achieved using a lithium iron battery the size of a shipping container, which is constantly charging at a low level of power from the grid. When a car needs a quick charge, the buffer battery promptly transfers the stored electricity to the vehicle, thus the grid is not even used. To prove the system works, the researchers built a demonstrator together with their science partners. The demonstrator is a trailer holding the intermediate storage battery. It draws power from the low-voltage grid and, in the space of 15 minutes, provides the 20 to 30 kWh needed to charge a standard electric car battery. “Our aim was to get under the psychological threshold of a half hour. But there is room for improvement,” said Massimiliano Capezzali, deputy director of the Energy Center, who coordinated the project.