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The first in a four-part series on electric buses done in partnership with the International Council on Clean Transportation (ICCT) and ITDP.

Clean air has become a rare commodity in the 21^st century. Today nine out of ten people breathe unhealthy air, according to the World Health Organization, resulting in dire consequences. Annual global mortality from ambient particulate matter (PM_2.5) and ozone exposure has increased 24 percent since 1990. Meanwhile global average temperatures in 2017 were 1.17 degrees C above pre-industrial temperatures, second only to 2016 temperatures. The warming component of climate change has contributed to massive wildfires like those that afflicted California in November, in turn causing dismal air quality in the San Francisco Bay Area.

The transportation sector is a major contributor to these twin problems of poor air quality and climate change. In a major polluted city like Beijing, vehicles are now the largest single contributor to ambient particulate matter, reaching 45 percent of total pollutants in 2017. Globally, transportation emission sources contribute up to 23% of average ozone exposure and 12% of average PM_2.5 exposure. In 2010, the transport sector was responsible for 23 percent of energy-related carbon dioxide emission. We can address these challenges in the near-term  with a two-pronged strategy. First, we can initiate an immediate transition to the cleanest soot-free engines, while developing and implementing in parallel an operational shift to low-carbon, zero-emission, electric-drive engines.

Bus fleets are the right place for cities to start the electric revolution. Buses already provide some of the absolute lowest carbon dioxide emissions per passenger-kilometer.  Because more than 80 percent of all buses use older diesel engines and high sulfur fuel, the global bus fleet is responsible for an estimated 15 percent of all particulate matter emissions from on-road transportation.  The International Association of Public Transport (UITP) has set a goal to double the market share of public transit by 2025 in support of international climate change targets. While this target is an effective low-carbon policy on its own, which will require a large increase in bus fleets, at a minimum, bus fleets need to quickly shift to soot-free diesel and gas engines to mitigate hazardous outdoor air pollution as investments in bus fleets expand. A better approach is to leapfrog vehicle technology by operating on zero-emission electric engines, which expand the climate mitigation potential of public transit, improve urban air quality, and increase the quality of public transit service.

Fortunately, bus fleets have operational characteristics that favor the introduction of new technologies, particularly electric drive engines, both to reduce risk and enable broader uptake throughout the rest of the fleet. Bus fleets are publicly regulated, they are centrally fueled, and they receive professional servicing and maintenance. Dedicated electric-drive engines are orders of magnitude more efficient than internal combustion diesel or gas engines.

That superior performance has been proven by on-road experience with Foothill Transit, a public transit agency in Southern California that is in the process of converting to a fleet of electric buses by 2030. Currently, the agency operates 14 buses from California-based manufacturer Proterra that are eight times more fuel efficient than the conventional compress natural gas buses operating in the fleet, according to the US National Renewable Energy Laboratory.

Foothill Transit serves a small population on the eastern fringe of the Los Angeles metropolitan area, but all-electric bus transitions are gaining speed in big cities around the world, including all-electric pioneer Shenzhen, as well as planned roll outs across North America in San Francisco, California and Windsor, Ontario. In October 2017, the mayors of London, Paris, Los Angeles, Copenhagen, Barcelona, Quito, Vancouver, Mexico City, Milan, Seattle, Auckland, and Cape Town signed the C40 Fossil-Fuel-Free Streets Declaration to procure only zero-emission buses from 2025 forward, a pledge for which electric buses will play a key role.

While energy efficiency is paramount, electric buses also provide a better experience for the passenger, as their quiet motors offer a more pleasant ride over their noisy diesel counterparts. They also have fringe benefits for operators. With far lower maintenance costs, electric-drive buses have the potential to deliver lower costs over the lifetime of the vehicle, thus decreasing the costs of providing public transport service. But transit agencies need direct subsidies or changes to their financing models in order to cover the much higher upfront cost of transitioning their fleets to the electric buses. The specifics of that transition, meanwhile, mean that the large-scale leapfrog to zero-emission electric buses presents some questions for fleet operators.

To be continued in part two: “What, Exactly, is an Electric Bus?”