Renewable energy grids require massive amounts of energy storage - and an electric car plugged into a charging station is a giant, city-wide battery waiting to help the grid. The Dutch city of Utrecht is about to launch a clever way to start bidirectional charging. This idea already has a lot of practice in the home sector - devices such as Toyota's V2H (vehicle-to-home) charging system can convert electric vehicles into high-power backup power, capable of running an entire home for days on end.

Bidirectional charging stations will turn Utrecht's 300 shared electric vehicles into distributed "big batteries" supported by a powerful grid.

Making this a reality on a wider urban scale has been discussed since the beginning of the electric vehicle revolution; the same high power density batteries that allow electric vehicles to accelerate so quickly also make them ideal for sending power back to the grid quickly to smooth out peaks in demand. The problem is, most electric cars are privately owned, and many people are happy to trickle charge from a wall socket at home rather than installing a dedicated charger, let alone one capable of charging in both directions.

This is the beauty of this Dutch plan. The program is a collaboration between the two companies. WeDriveSolar is developing bi-directional clean energy charging technology and is working with Hyundai and Renault to ensure cars can do the job. MyWheels, the largest car-sharing company in the Netherlands, will connect 300 of its more than 3,000 cars to the network through its charging stations.

Two-way charging stations will harness energy from car batteries to smooth grid demand peaks

If each car was a base-model Hyundai Ioniq 5 with a 58-kilowatt-hour battery capacity and a rated discharge of at least 125 kilowatts, then when they were all plugged in, the city grid could theoretically gain 17.4 megawatt-hours of energy and at least 37.5 megawatts of power.

This represents a significant proportion of grid-scale "big batteries," so it should be very convenient for the energy grid, while also potentially providing a new revenue stream for ride-sharing companies. The Ioniq5 has a full-charge range of approximately 220 miles (354 kilometers), so even if the grid load is particularly heavy and the two-way charger sucks up half of the battery, the car can still meet the travel needs of the vast majority of users.

In Utrecht, several Renault and Hyundai cars are already connected to a pilot two-way grid charger, and WeDriveSolar says that by the end of the year, the first 300 cars will be in use, making it "the world's first city with two-way charging."

Very neat, and we'll definitely see more of this as pilot projects like this expand.