What prevents cities from adopting electric buses en masse is a mix of technological, financial, and institutional challenges, according to a pair of reports from the World Resource Institute looking at efforts in 16 cities at various stages of adopting e-buses.

An electric bus in France. (Photo: Jean Liou/Getty Images)

There were about 425,000 electric buses in service in the world's cities last year. Almost all—99 percent of them—were in China. The booming industrial city of Shenzhen, in particular, is one of only a few cities to have fully electrified its fleet. The rest of the globe, meanwhile, is racing to catch up, and falling further behind.

It's not the lack of ambition that's stopping them: With the goal of curbing carbon emissions in mind, municipal leaders all over have pledged to partially, if not fully, replace their city's fleet with e-buses over the next decades. A number of cities, from large metropolises like Mexico City to more modest ones like Philadelphia, have started pilot tests.

What prevents cities from adopting electric buses en masse is a mix of technological, financial, and institutional challenges, according to a pair of reports from the World Resource Institute looking at efforts in 16 cities at various stages of adopting e-buses. That first report focuses on three major types of barriers, while the second highlights how to overcome them.

The cities studied range from Addis Ababa in Ethiopia—where there's been "no substantial planning" around electric buses—to cities like Philadelphia and Campinas, Brazil, which, respectively, are running a pilot test and expanding its number of e-buses, to successful cases in Shenzhen and the nearby Zhengzhou. They vary geographically, with some in developed nations like Chile and Spain, and other in emerging countries like India.

The biggest takeaway is the cities that want to hop aboard the e-bus revolution need to completely rewire their thinking about electricity and vehicles. "Understanding that electric vehicles are about more than just vehicles is one of the hardest barriers for people to cross over, in both the energy and transportation sectors," says Camron Gorguinpour, one of the lead authors of the twin reports. "It's hard on people who have gone through their whole careers thinking that vehicles and electrical systems are [separate] to now internalize that these things are one in the same."

That means when cities consider adopting electric buses, they need to understand the power grid upgrades and charging infrastructure required, and challenges associated with that. Failure to do so is the most common mistake, according to Gorguinpour. Many cities just set up their charging stations thinking that things would "work themselves out."

That's why he says one of the most overlooked stories from Shenzhen's experience is the city's long process in setting up the charging infrastructure to support more than 16,000 electric buses. Each bus has a range of about 124 miles on a single charge of 252 kilowatt hours (KWh). In total, the fleet can eat more than 4,000 megawatt-hours (MWh). For comparison's sake, 1 MWh is enough to power about 300 homes for an hour. "That's an insane amount of power required, not to mention real estate," he says. "And the process to identify what land is available, then to work with the utilities—even just figuring out the optimal location—is a hugely important task, and incredibly challenging."

That's what Philadelphia discovered when it decided to expand its existing fleet of e-buses with newer models—ones that featured bigger batteries. The city failed to recognize in the early planning process that it would be prohibitively expensive to acquire land in its busy downtown area for charging stations along the bus routes. So they decided to install all the charging infrastructure in the bus depots.

"They made that decision without realizing that [it would cost] $1.5 million to upgrade the electrical system in that one location to install a substation that can power 20 vehicles," Gorguinpour says. "These things can get out of control real fast."

That gets into the financial barriers. Cities across the globe often cited higher expenses as the primary challenge to procuring a fleet. While cities that adopt e-buses do end up saving money over the longer term in things like fuel (not to mention the harder-to-quantify value of cleaner air and fewer greenhouse emission), the upfront costs represent significant challenges. In the case studies, the price of a new e-bus ranged between $300,000 and $900,000 per bus, with the report noting that the prices vary dramatically depending on the manufacturer, specifications, and the location of the transit agency. In the United States, an electric bus averages around $750,000, while a conventional diesel bus is around $435,000.

When cities decide to implement electric buses, Gorguinpour says the cities focus too much on those upfront costs and not enough on the "life cycle cost." That could mean delaying the the adoption process altogether or funding small pilot tests—sometimes with just a handful of buses—without a larger plan to scale up. "We encourage cities to do whatever they can afford," he says. "But if you're going to get five electric buses in your city, you should work with a group of stakeholders to come up with a strategy, to say, 'How am I going to learn enough from these five buses to construct a plan to get me to 500 or to thousands of buses?'"

Or, in the case of Belo Horizonte in Brazil, to get operators on board with full adoption. The city and its bus operators are locked into a long-term contract that provides no requirements or incentives for operators to replace its diesel-bus stock. After the city ran a pilot program without any involvement from the operators—in hopes of showcasing the technology—the report notes that, "to date, no operators have expressed interest in investing in what is seen as an expensive and risky endeavor."

That cautionary tale illustrates the importance of bring all potential stakeholders together before making any decisions—something that WRI's second report, which offers a roadmap to adopting electric buses, strongly emphasizes. That includes not only transit officials, but also utility companies, bus operators, and organizations that can help the city finance such a costly endeavor. That includes multinational and national development banks, which Gorguinpour call the "obvious places to start." In some cases—as in Chile's capital city of Santiago, which has the largest e-bus fleet outside of China—it's utility companies, not transit agencies, that have stepped up to finance the projects.

For cities that have already started its procurement process, this second report provides guidance for various stages of the process, including the stage at which a city is ready to scale up. In all those, the report stresses one major step: "A lot of these reports are about city officials going out and getting all the stakeholders in a room to build a comprehensive plan," Gorguinpour says. "It's a lot harder to do anything in large scale in a silo, because the technology is so interdependent on other things."

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