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Sweden Tests Electric Roads to Give EVs Unlimited Range

Overhead wires provide electricity for buses and trains. Could they work for trucks, too?

3 min read
Sweden Tests Electric Roads to Give EVs Unlimited Range
Photo: Scania

Renewables are critical to the future of efficient, clean transportation. For road vehicles, storing those renewables, and then using them only when necessary, is still a major obstacle to commercial success. In Sweden, the government is partnering with the private sector to deploy new technology that could allow electric vehicles to travel on roads indefinitely, without having to worry about lengthy recharging or massive battery packs. Is it fusion power? Dark matter? Black magic? Nope: overhead wiring.

Sweden's latest foray into roads that can provide electric power to vehicles is perhaps one of the least futuristic options possible, but that doesn't necessarily make it any less effective. A two-kilometer pilot stretch of the E16 motorway has been equipped with overhead caternary wires, and trucks modified with pantographs are running tests to see how well the it works.

Power delivery systems like these are nothing new: They've been around since the 1880s, and we still use them all over the place. In crowded city centers, overhead wires are the safest way to provide power to buses and trolleys following fixed routes, and they're also the only way to keep high speed intercity trains fed. Vehicles that run on rails harvest electricity from a single overhead wire, using their tracks to complete the circuit. Buses and other vehicles with tires need a pair of overhead wires instead, and this is the kind of system that Sweden has set up.

The overhead wires provide 750 volts of direct current to the hybrid electric system in the truck through a pair of pantographs. The pantographs can automatically deploy and attach to the wire while the vehicle is traveling at speeds of up to 90 kilometers per hour, meaning that the truck can seamlessly enter and exit a roadway. The truck itself is a hybrid electric, with a 360 horsepower motor that runs on both biofuel and a 5-kilowatt-hour lithium battery pack that provides enough juice to go about three kilometers. That battery storage capacity isn’t much, but it’s easily enough for getting on and off electrified roadways whenever necessary—especially with the biofuel engine as a backup.

This sounds like a great compromise, but before you get your hopes up, it’s not likely that this will happen with your average sedan or light truck. The height required for a safe overhead line (between five and six meters) would render the connection system impractically long for passenger vehicles.

Sweden is also testing a different type of electric road, using conductive transfer technology based on an energized rail embedded in the road surface. The rail is exposed, and special “shoes” underneath vehicles can draw energy from it continuously. The rail is only energized when a vehicle passes over it, and “multiple safety barriers” are in place to minimize the risk of accidental zaps.

Systems like these make sense in the same kinds of situations and locations where you might consider running a freight rail line, except that using trucks on roads instead of trains on rails has a lower cost of entry and is much more flexible. It's also easier to implement on a wider scalee, since trucks don't have to fundamentally change their behavior to benefit. They can follow the same routes at the same times with the same payloads. The only exception: For what is hopefully a significant portion of the trip, they'll be emission free. 

These roads will be undergoing testing through 2018. The Swedish government hopes that it will learn enough about what works and what doesn't to help it make informed infrastructure decisions, with the goal of a completely fossil fuel–free vehicle fleet by 2030.

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To decarbonize road transport we need to complement EVs with bikes, rail, city planning, and alternative energy

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A worker works on the frame of a car on an assembly line.

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EVs have finally come of age. The total cost of purchasing and driving one—the cost of ownership—has fallen nearly to parity with a typical gasoline-fueled car. Scientists and engineers have extended the range of EVs by cramming ever more energy into their batteries, and vehicle-charging networks have expanded in many countries. In the United States, for example, there are more than 49,000 public charging stations, and it is now possible to drive an EV from New York to California using public charging networks.

With all this, consumers and policymakers alike are hopeful that society will soon greatly reduce its carbon emissions by replacing today’s cars with electric vehicles. Indeed, adopting electric vehicles will go a long way in helping to improve environmental outcomes. But EVs come with important weaknesses, and so people shouldn’t count on them alone to do the job, even for the transportation sector.

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