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Oslo Metro Takes Greener Track

New trains share power captured by regenerative braking

2 min read

Oslo has one of the world’s smallest carbon footprints for a city of its size, but it wants to get even greener. To that end, it’s replacing 63 of the T-bane Metro’s trains with new three-car trains from Siemens that are 30 percent more energy efficient than the best cars currently in service there. The key is in the trains’ ability to generate electricity while braking and transfer that power to other trains.

When a train’s operator applies the brakes, the four 140-kilowatt, 750-volt dc electric motors are engaged as generators that use the kinetic energy of the turning wheels to send current back into the metro’s power grid. This technique, called regenerative braking, allows the trains to recover up to 44 percent of the energy used to bring the trains up to speed.

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This photograph shows a car with the words “We Drive Solar” on the door, connected to a charging station. A windmill can be seen in the background.

The Dutch city of Utrecht is embracing vehicle-to-grid technology, an example of which is shown here—an EV connected to a bidirectional charger. The historic Rijn en Zon windmill provides a fitting background for this scene.

We Drive Solar

Hundreds of charging stations for electric vehicles dot Utrecht’s urban landscape in the Netherlands like little electric mushrooms. Unlike those you may have grown accustomed to seeing, many of these stations don’t just charge electric cars—they can also send power from vehicle batteries to the local utility grid for use by homes and businesses.

Debates over the feasibility and value of such vehicle-to-grid technology go back decades. Those arguments are not yet settled. But big automakers like Volkswagen, Nissan, and Hyundai have moved to produce the kinds of cars that can use such bidirectional chargers—alongside similar vehicle-to-home technology, whereby your car can power your house, say, during a blackout, as promoted by Ford with its new F-150 Lightning. Given the rapid uptake of electric vehicles, many people are thinking hard about how to make the best use of all that rolling battery power.

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