Wireless chargers to power Seattle’s new e-buses en route

Wireless charging e-buses on the layover between routes provides additional range, allowing buses to stay in service for 12 to 14 hours a day

Since the e-buses are continuously recharged, they can be equipped with smaller batteries from the outset, adding up to a “huge cost savings”. KUOW photo by John Ryan.

This article was published by The Energy Mix on March 14, 2024.

By Gaye Taylor

Move over induction stoves, there’s a new kid in town: Seattle’s Sound Transit is the latest to embrace the “game-changing” efficiencies of inductive chargers for their electric bus fleet.

The wireless charging technology pioneered by Pennsylvania-based InductEV will be used by the transit authority’s Stride bus rapid transit (BRT) service, due to be up and running by 2029, reports the Daily Hive. The new BRT fleet will include 15 articulated and 33 double-decker e-buses, which means top-deck riders are in for a treat, view-wise.

But something down below the e-bus will be making all the difference to the efficiency, reliability, and sustainability of their ride: namely, 300 kilowatts’ worth of in-ground inductive chargers embedded at 13 bus-stops and lay-bys along the route.

These inductive charging systems are poised to “bust wide open the wireless EV charging dam,” CleanTechnica recently wrote. Formerly Momentum Dynamics, InductEV has been working on wireless charging for at least a decade, the news story stated, adding that the company appears to have “cracked the code” with a serious business case for commercial fleets. In January, InductEV made a series of announcements about new hires and commitments that signalled it could soon be partnering with the Port of Los Angeles, and then came its February announcement for Seattle.

Back in the cash-strapped world of public transit, that business case appears to be catching on. Sound Transit is now the seventh public transit authority in Washington State to deploy InductEV’s patented charging system, notes the Hive, with some 100 battery-electric buses across the state “using or scheduled to use” the technology. According to InductEV, the wireless charging system has a transmission efficiency of 90 per cent, making its performance virtually identical to plug-in charging.

InductEV wireless chargers for mass transit buses can also be found in California, Oregon, Indiana, Tennessee, and Massachusetts, and taxis in Sweden and Norway are powering up using the company’s charging system.

Simple Design, Big Savings

Wireless charging has been a “game changer,” said Richard DeRock, general manager of Link Transit in Wenatchee, Washington. “They charge our e-buses for a few minutes on the layover between routes and provide additional range, allowing our buses to stay in service for 12 to 14 hours a day—even during the harsh cold of winter,” DeRock said in a testimonial for InductEV. “Buses typically end their day with 40-50 per cent of battery charge still remaining, even on the coldest days.”

That means further savings for fleets that need less redundancy to allowing buses “dead-heading” back to the depot to recharge.

En route charging prevents battery-eroding swings between a full charge and an empty one, InductEV Chief Revenue Officer Brandon Anulewicz told The Energy Mix. And since the e-buses are continuously recharged, they can be equipped with smaller batteries from the outset, adding up to a “huge cost savings”.

He also flagged the cost-saving simplicity of the charger itself, which consists of a modular transmitter unit housed in a shallow, 2.5- to 3-foot cavity in the pavement. The modular means that problems can be swiftly addressed, with an errant module easily swapped out for a functioning one. The same goes for the underside of the bus where the charging receiver is located, Anulewicz said.

And because the bus is charged from below, rather than from above as in the case of a standard pantograph system, wireless charging means the height difference between a double-decker and a standard e-bus is no longer a concern.

The design is also scalable. Seattle’s 300-kilowatt units consist of four 75-kW modules, but Anulewicz said the chargers can be easily adapted to fit taxis and passenger cars (one module), large shuttles and mid-sized delivery trucks (two modules for 150 kW), and even heavy haul transport trucks (6+ modules / 450+ kW).

E-buses can “absolutely” be retrofitted to wireless charging, he said, adding that many of InductEV’s first deployments involved retrofits.

Anulewicz estimated that transit agencies that switch from diesel to electric, and stick to standard pantograph-model depot charging, typically need 20-30 per cent more buses, with a corresponding need for more depot space when the vehicles come back at night.

His company’s wireless system, by contrast, takes up very little real estate—a small power cabinet located a discreet 30 metres from the in-ground charging pad—which is another selling point.

(For insight into how much space standard pantograph charging systems require, see here for Electric Autonomy’s April 2023 deep dive into the electric-retrofit pilot being undertaken by the Société de transport de Montréal at its Stinson Transport Centre. Is STM thinking about incorporating wireless charging into its electric plans? “For the moment, this solution is not part of the STM recharging strategy,” STM spokesperson Kevin Bilodeau told The Mix.)

Simple design also means smaller recurring costs, said Anulewicz. He compared the InductEV wireless system to the standard pantograph that has “so many moving parts”, with different pieces of equipment needing to “talk to one another.” Communication breakdowns can prove “catastrophic” to the effort to keep  the buses running, he added.

The InductEV chargers work in all kinds of weather, apparently unaffected by rain, ice, leaves, or even full submersion. The company maintains the technology works “even under water with no loss of efficiency.”

Chief Strategy Officer John F. Rizzo said transit authorities that make the switch from diesel to wireless charging should find their operating expenses reduced by “at least 50 per cent annually,” with “the total cost of ownership of wireless stations typically 30 per cent lower than plugged stations.”

Wenatachee’s DeRock needs no further convincing. “The cost savings are real and measurable,” he said. “Along with the availability of inexpensive, clean, renewable hydropower from the Columbia River and lower maintenance costs, it makes the expansion of our fleet of battery-electric buses a financially sensible solution to combating climate change.”

Asked whether transit agencies proceeding to retrofit to electric (like Montreal) or build from scratch (Vancouver’s purpose-built Marpole depot) should be prioritizing wireless charging, Josipa Petrunic, president and CEO of the Canadian Urban Transit Research & Innovation Consortium (CUTRIC), said significant improvements in the technology have helped allay earlier concerns about efficiency and safety. “Safety has been a primary concern, and innovators are building in safety measures around the technology,” Petrunic told The Mix.

InductEV, which became a CUTRIC member in August, says it has met key industry standards, including the one laid out by the Institute of Electrical and Electronic Engineers.

“In the fight against climate change, all solutions need to be on the table, and wireless charging is a legitimate technology that likely has reasonable applications in transit agency operations in the future,” Petrunic said. She flagged a “need for piloting, demonstration, and testing to prove wireless charging out in real life,” but noted that “the savings on operational time for buses could also be immense.”

“It doesn’t require an operator or driver to get out of the bus to charge, and that is a huge time and cost savings that most agencies won’t want to ignore,” she added.

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