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Are Battery-Powered Electric Buses Coming to Your City?

While it may sound like an easy climate win to have buses run on battery power, the technology may not be ready to support such initiatives.

In the last decade, electric vehicles have become mainstream. Having captured a small but growing share of the passenger-car market, and an enormous amount of media buzz thanks to Tesla, the EV industry is now setting its sights on the bus market.

Several companies that manufacture battery-electric buses, or BEBs, are selling the product to cities interested in zero-emission buses that operate without trolley wire. (While many cities already have extensive networks of electric trolleybuses, such as Zurich and San Francisco, these buses require overhead wires to operate.) Manufacturers include the longstanding Canadian bus manufacturer New Flyer, China's BYD, and the American startup Proterra.

As part of generous government subsidies to BYD, Shenzhen has replaced its entire fleet with BEBs. Cities in Europe and the United States are also experimenting with them. Moscow plans on replacing its trolleybuses with BEBs, and small and medium-sized American transit agencies have begun leasing or buying this technology. Part of the rationale behind this shift is to reduce local-diesel bus pollution; part of it is about cutting greenhouse-gas emissions, and part is the perception that BEBs are a futuristic technology.

But is the technology really ready?

There are reasons for skepticism. So far, it looks like BEBs struggle when it's too cold (below freezing) or too hot, and on routes with hills. The global frontier of public-transit innovation in Western Europe is cautious about adopting BEBs and prefers a hybrid form of trolleybuses and battery-electric technology called in-motion charging, or IMC. Some Swiss cities are adding trolley wire at low cost while using IMC to extend the range of their existing trolleybuses several miles beyond the wire.

Range Anxiety, but for Buses

Battery-electric vehicles' biggest problem has always been range. At the dawn of the automobile age, electric cars competed with gasoline and steam-engined vehicles: In 1900, 38 percent of U.S. cars were battery-powered, and only 22 percent boasted internal combustion engines. As late as the 1910s, Thomas Edison was working on an electric car and a network of charging stations. But in time, gasoline-fueled cars came to dominate the market, partly because a car's range on a full tank of gas was far greater than on a full battery charge.

Dramatic improvements to battery technology have fed the recent EV renaissance, allowing such models as the Tesla Model 3 and BYD Qin to travel about 200 miles on one charge. That's helped alleviate the "range anxiety" that keeps many U.S. drivers from considering an electric vehicle.

Still, the energy density of batteries remains well below that of gas. And, unlike most passenger cars, city buses run for the entire day. The big American transit agencies run buses for about 25,000 to 40,000 miles a year, which is two to three times the average distance a car is driven—and buses have a more energy-intensive urban driving cycle (with little highway running), totaling 100 to 200 miles of city running per weekday.

Moreover, the routes most likely to get battery-electric technology are the strongest ones, where fleet utilization is higher, since electric buses are more expensive to buy than diesel buses. This pushes up the required range for operating without midday charging.

On heavy-duty buses, the range has not been enough. Albuquerque provides one example: It found its BYD buses' range to be only 177 miles on one charge, compared with a contractual promise of 275, and this was not enough to run a full day's service. In Vancouver, a BEB trial talks up rapid recharging during layovers—there is no expectation of being able to run a bus for an entire day without recharging. Rapid recharging is labor-intensive, since a worker must supervise it, unlike recharging or refueling at the end of the day.

In Moscow, Mayor Sergey Sobyanin has made a big push for BEBs, which in his view are more modern than the city's expansive trolleybus network. The city recently purchased 100 buses each from two Russian automakers, Kamaz and Gaz. The London-based transit advocate Martin Wright compared Moscow's procurement and operating costs and talked to Russian observers. Wright said (as of early fall) that Moscow's trial routes for BEBs—trolleybus Routes 73, 76, 80, and 83—have had to use more buses just to run the same service, pointing to before and after slides. The four routes appear to have gone from 46 trolleybuses to 82 BEBs without any increase in service frequency, presumably because BEBs have considerable down time for midday charging.

This is not the first time that the adoption of a supposedly game-changing new technology has required expanding the fleet and increasing the associated labor costs. In his paper titled "The Bus Is Young and Honest," historian Zachary Schrag details how, in the 1920s, New York City started replacing its streetcars with buses because Mayor John Hylan opposed the private-rail transit concessions and believed buses were more modern. Transportation engineer John Beeler pushed back, arguing that to provide the same capacity of the 1,002 streetcars serving Manhattan at the time, the borough would need 2,538 buses. But despite Beeler's protests to the contrary, New York replaced the streetcars with buses over the 1920s and '30s, as did practically all American and most European cities in the following generation.

Mixed Experiences

Albuquerque recently made headlines in the urban public-transit world when the municipal transit agency, ABQ RIDE, returned the BYD-made electric buses it had ordered, finding them deficient. The city had paid $1.2 million apiece for these buses, and after it returned them, it bought diesel buses from New Flyer for $870,000 each.

A source who has worked on Albuquerque transit projects and spoke to CityLab on the condition of anonymity detailed the circumstances around the failed BEB trial. Albuquerque is a typical Sunbelt city with low urban density and little historical transit ridership. With plentiful free parking nearly everywhere, few people ride the bus. But one bus corridor is prominent: Central Avenue, cutting east to west across the city. About half of ABQ RIDE's ridership is on this corridor, so it became a priority for bus-rapid-transit upgrades as part of a program called Albuquerque Rapid Transit, or ART.

However, according to the source, the battery was not strong enough for daily service without midday recharging. Central Avenue has a large elevation change (about 1,000 feet), and this could be the reason the battery life was not as long as advertised. Whereas Vancouver's TransLink has layover facilities with rapid charges, ABQ RIDE intended to turn buses around without special facilities.

An ABQ RIDE spokesperson confirmed that the buses' batteries did not have the agreed-upon range, and added that they also had safety problems, such as door malfunctions, which led the city to sue BYD. "It's clear that the buses are not safe, and we are not going to place residents at risk," municipal chief operating officer Lawrence Rael said in a statement. BYD did not respond to requests for comment.

In the Twin Cities region, the Minnesota Valley Transportation Authority, a small agency serving the southern suburbs of Minneapolis, leased a BEB from Proterra at no cost for a trial last winter. A source in MVTA (again, speaking on condition of anonymity) spoke positively of the physical aspects of the bus, such as the chassis and ride quality. Moreover, when it wasn't so cold, electricity consumption was low: The battery only drained 2 percent, the source said, while sitting in traffic for nearly an hour.

But when it got cold, the bus's performance suffered. At the freezing point, the range was already below target. At 20 degrees Fahrenheit, the source said the driver had to take the bus back to the garage, lacking enough charge for an entire day's worth of work. On Super Bowl Sunday it was 5 degrees F, and the battery allegedly lasted for 40 minutes, covering only around 16 miles. The agency had to bring a generator to the transit center to recharge the bus.

When asked if this version of events is accurate, an MVTA spokesperson responded only that "the range was not as long as we expected." For its part, a Proterra representative wrote in an email that, on Super Bowl Sunday, its data showed the bus drove 61 miles and could even go 120 on one charge, but had to be charged more often because there was not enough time to charge it all the way from empty to full.

Minneapolis' major agency, Metro Transit, is still interested in BEBs, but, according to Energy News is still uncertain about how well they will perform in the cold.

According to a Reuters story from last winter, similar problems have been found in other cities. Transit officials in Worcester and Springfield, Massachusetts, complained that BEB technology performed poorly in the cold and snow, while a report in Phoenix said that the buses did poorly in the summer heat, because of the demands of running cooling equipment. Similarly, the Minnesota source claimed that, over the three-week trial, electricity consumption was 70 percent heating and only 30 percent motion.

Worcester Regional Transit Authority, however, told CityLab that its Proterra BEBs have not been problematic. (It did have to shut them down for a blizzard last winter, but the city's entire bus system shut down.) Among cold-weather agencies, there is a spectrum from MVTA's disappointment, through Metro Transit's cautious interest, to WRTA's support.

In-Motion Charging

There is an alternative, combining the best features of BEBs (flexibility) and trolleybuses (reliable power and range): in-motion charging, or IMC. A trolleybus with IMC has a small battery, with enough range for a few miles off-grid, and mechanisms for recharging while driving under the wire. It still requires some trolley-wire infrastructure, but not on 100 percent of the route: Italian manufacturer Iveco claims that 60 to 75 percent of the route needs wire. While this may still seem high, there are some places in the U.S. where buses could run on one wired trunk and then branch to many unwired streets (for example, in Roxbury and Dorchester, two Boston neighborhoods).

But this technology is virtually unknown in North America, where transit agencies treat the trolleybus as a dinosaur, even in cities with extensive networks such as San Francisco, Boston, and Vancouver. The California Air Resources Board's regulations mandating electrification of the state's bus network to curb pollution focus exclusively on BEBs and fuel cells: The mandates give agencies full credit for every BEB already in use, but only one-tenth of a credit for every trolleybus. The state's analysis of its bus fleet in support of the new regulation ignores trolleybuses as well, never mind that San Francisco has about 300 of them, compared with 71 other zero-emissions buses statewide.

However, IMC is gaining currency in Europe. In Switzerland in particular, a very large proportion of public transit runs under wire, a legacy of cheap hydroelectric power and World War II-era shortages of fuel. The Swiss rail network is entirely electrified, and some cities, especially Zurich, have more ridership on their streetcar and trolleybus systems than on diesel buses.

So far, IMC is mostly restricted to Central Europe. German manufacturer Kiepe has sold IMC buses to nearly all the major cities of Switzerland, as well as to some secondary cities in surrounding countries, such as Parma, Linz, Esslingen, and Limoges. Seattle and San Francisco have bought IMC buses as well, but Kiepe claims only that these have enough battery to get around obstacles and complex junctions, whereas its main European product can travel five to seven kilometers off-wire, or about three to 4.5 miles.

In tandem with IMC, Swiss cities are expanding their trolley-wire networks where it is warranted. The Swiss rail advocate and enthusiast Max Wyss has given some examples of recent extensions of trolleybus and streetcar systems. St. Gallen, a small city east of Zurich, is extending its trolleybus network, and the cost of the overhead wires is about $2.7 million per mile, and closer to $2 million after adjusting for the country's high living costs.

By contrast, ART (the Albuquerque project for which ABQ RIDE intended to buy BEBs, but will debut as diesel BRT instead) cost $135 million over Central Avenue's 16-mile stretch, or more than $8 million per mile. If ART were IMC, some of the costs could be avoided and some would remain necessary, but even taking the costs as a given, adding wire would only raise the price by about a quarter.

Is This Technology Ready?

BEBs are not really ready yet. The battery isn't good enough if there's any problem along the way, such as a climb or cold weather, and the extra infrastructure for midday charging is expensive.

Battery costs are going down, helping explain the growth of battery-electric propulsion in the passenger-car market. This should give transit advocates and city planners hope that, in the future, BEBs may have a place. But the technology is not yet mature, and some of the most innovative cities in the world when it comes to public transit purchase trolleybuses with IMC instead.

This story originally appeared on CityLab, an editorial partner site. Subscribe to CityLab's newsletters and follow CityLab on Facebook and Twitter.