Israel Tests Wireless Charging Roads for Electric Vehicles – Scientific American
Electric vehicles have long been a promising option for sustainable transportation. They come with practical headaches like expensive, bulky batteries that often need recharging, however. Israel is tackling those hurdles by investing in roads that power electric buses—as they ride down the street. The government is collaborating with Israeli start-up ElectRoad to install a public bus route in Tel Aviv, using an under-the-pavement wireless technology that eliminates the need for plug-in recharging stations.
Although still in its infancy, the technology could clear the three biggest hurdles—cost, weight and range—that have held back the widespread adoption of battery-powered vehicles for more than a century. First, though, ElectRoad will have to demonstrate that its “inductive charging” technology can be scaled up cheaply enough to be adopted on roadways worldwide. “It’s exciting because it’s charging without wires,” says Tim Cleary, director of BATTERY, an energy-storage research laboratory at The Pennsylvania State University, who is not involved in the project. “But unless it’s affordable and cost-effective it’s not going to take off.”
ElectRoad is betting it will. Wireless charging means the electric buses can carry a light, inexpensive battery instead of a bulky, costly one—and never have to stop for recharging. And once a roadway is outfitted with the technology, it can continuously power properly equipped vehicles. “You only need to pave for the infrastructure one time, and that’s it. You can use it for all kinds of vehicles, so that’s a big advantage,” says Oren Ezer, chief executive and co-founder of the four-year-old company.
So far, the firm’s only proving ground has been an 80-foot test route at its headquarters in Caesarea. But the technology performed well enough for the company to win a $120,000 grant from Israel’s Ministry of Transport and Road Safety and approval to outfit a portion of a Tel Aviv bus route with their technology, says Shay Soffer, chief scientist at the ministry. The route will be around half a mile long and is slated to open in 2018. If all goes well, the government plans to deploy the technology more widely, starting with an 11-mile shuttle between the city of Eilat and the Ramon International Airport. “Tel Aviv is the biggest city [in Israel], like New York on a small scale. If it will work in Tel Aviv, it will work anywhere,” Soffer says.“I think in 10 years you’ll see a lot of solutions like ElectRoad in our transportation.”
ElectRoad’s Ezer declined to give the price of the Tel Aviv project but says the total cost of construction will be shared by the transport ministry, the city and the company. The cost per kilometer of roadway will be a crucial factor in future years as the company attempts to scale up. Israel joins a growing number of nations exploring the technology. South Korea, for example, already has several wireless bus routes around the country. The European Union is studying the feasibility of widespread wireless charging, too. ElectRoad’s technology is different, Ezer says, because the transformers are less expensive and the installation process is faster and more efficient.
Inductive charging has been around since the 1890s, when inventor Nicola Tesla first discovered he could wirelessly power lightbulbs. Since then it has been used in an array of devices ranging from phones to toothbrushes—but only recently on the scale of a 13-ton bus. The buses are charged and propelled by power from the interaction of two electromagnetic fields. Inverters installed along the side of the road provide power to plates of copper embedded in the road. Similar copper plates are installed on the bus’s underside. As the vehicle passes over the charged roadway, the two fields interact and generate power.
ElectRoad says it can install the technology in an existing road with minimal disruption, using two tractors that can fully equip one kilometer of roadway in a single night. Each bus still needs a small onboard battery for a couple of reasons: The first is to accelerate, because the jolt of energy required to propel a stationary bus is far more than the energy it needs to coast down the street. The second is to provide power on short stretches of road that are not fitted with the technology. ElectRoad’s buses can travel off the charging road for about three miles.
The biggest advantages of wireless charging are that it allows for significantly smaller batteries or the ability to travel longer distances with a larger battery. Both are convenient, says Burak Ozpineci, who works on wireless technologies at Oak Ridge National Laboratory in Tennessee. However, the cost of the infrastructure and materials, especially copper, will likely be expensive, he says. Currently, the metal costs about $2.60 per pound. In addition to costing more, wireless power might not be as straightforward as simply plugging into a socket—the bus could stray from the main strip, becoming misaligned and delivering less power, according to Penn State’s Cleary.
In addition, the advantages of ElectRoad’s technology may become less important as electric vehicle batteries get cheaper, lighter and more efficient. Breakthroughs in engineering and chemistry have made batteries much more cost-efficient over the past 15 years, says Dustin Grace, director of battery engineering at Proterra, an electric bus company. A few years ago a typical electric vehicle battery cost about $1,000 per kilowatt hour. But now many companies are down to $200 to $300 per kilowatt hour, and a few, including Tesla, General Motors and Nissan, are even lower, according to Grace. “I’m in the camp where I see the cost of lithium ions and energy storage just plummeting,” Grace says. “What these auto manufacturers are finding when they’re getting into the $100-to-$200-per-kilowatt-hour range is these vehicles are really on parity with other vehicles. They’re no longer looking at batteries as this challenge that has to be solved.”
Ezer acknowledges battery prices are falling but emphasizes ElectRoad’s solution is not for individual vehicles but for all-encompassing infrastructure that can eventually serve entire cities. That’s where the savings are, he says. And remember that small, light battery onboard? It is only used about 6 percent of the time the vehicle is running, and thus can last as long as 25 years, Ezer asserts. By contrast, conventional batteries in electric buses, like those made by Proterra, last around six years.
Despite the challenges of scaling up, ElectRoad is optimistic about the growing synergies between its vehicles and electric grids that are transitioning to renewable energy sources like solar and wind, instead of fossil fuels. Eventually, the company even hopes to make wireless charging a two-way street: not only from road to bus but vice versa with the energy generated from braking, according to Ezer.
And down the road, the start-up’s dreams are even bigger, Ezer says. “We plan to start with buses, of course, but we believe in revolutionizing the entirety of transportation.”