Electric Buses: How Plugs and Batteries are Replacing Wires and Diesel

, senior policy and legal analyst, Clean Vehicles | January 28, 2014, 10:14 am EDT
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Cities breathe. They take deep breaths in the morning as commuters rush to get to work and exhale in the evening as workers travel away from the city center. According to the U.S. Census Bureau, the population here in D.C. grows from 584,400 to over 1 million people on a daily basis and the population of Manhattan nearly doubles from 1.5 million to 3.0 million during the work week. This amazing phenomenon is made possible, in part, by city buses, which carry hordes of passengers along concrete arteries toward the heart of the city.

But enough romanticizing urban bus commutes. In reality, buses are slow (the slowest bus lines in New York City average 3.4 miles per hour), and tend to be inefficient. Though fuel economy varies depending on the type of bus and the route, an average bus in D.C gets a paltry 3.76 miles per gallon (mpg), and that’s up from 2.96 mpg in 2005! Considering that D.C. buses cumulatively travel nearly 50 million miles each year, cleaning up bus fleets is a critical way to reduce the burden of air pollution, fuel costs, and our oil use.

D.C Metro's bus fuel efficiency increased by 27 percent over eight years, reducing fuel costs, emissions, and oil use.

D.C Metro’s bus fuel efficiency increased by 27 percent over eight years, reducing fuel costs, emissions, and oil use.

Moving beyond conventional diesel buses

Over the past several decades, cities have invested in buses that run on alternative fuels such as compressed natural gas (CNG) and diesel-electric hybrid drivetrains. The initial transition away from conventional diesel buses has been swift. In 2011, more than 35 percent of U.S. public transit buses used alternative fuels or hybrid technology, and that number is set to grow.

In addition to hybrids and CNG buses, city bus fleets around the world are preparing to introduce electric buses that use advanced technology. There are three main types of electric buses; plug-in hybrid electric buses that use rechargeable batteries to run on both electricity and diesel, battery electric buses that do not use any diesel fuel and create no tailpipe emissions, or fuel cell buses powered by hydrogen.

Benefits of commuting on electricity

Though electric buses are not new—the first was introduced in Berlin in 1882—older models frequently required wires to hang over each bus route, marking bus paths through city streets. Growing up in Cambridge, Massachusetts, I remember hearing loud pops as sparks flew from an intersection of overhead electric bus wires near my bedroom.

Today, however, electric buses are being developed that do not require any overhead wires. Instead, they are powered by lithium-ion or iron-phosphate batteries that can be recharged from central stations prior to beginning each route or by hydrogen-powered fuel cells.

A double-deck electric bus in Reading, England in 1966. Buses like these needed overhead wires to provide electricity.

A double-deck electric bus in Reading, England in 1966. Buses like these needed overhead wires to provide electricity.

This technology—though in it’s infancy—could be a game changer. Volvo claims its plug-in hybrid buses can operate on electricity alone more than two-thirds of the time, and reduce diesel emissions by 70 to 80 percent compared to older buses. And if the relatively small amount of diesel fuel used by these buses is replaced with sustainably-produced biodiesel, the climate emissions could be reduced by as much as 90 percent. Better yet, battery electric and fuel cell buses produce zero tailpipe emissions, and can use renewable resources like solar and wind power to charge their batteries or produce hydrogen to power fuel cells. Moreover, as I’ve previously mentioned, driving on electricity is cheaper compared to driving on oil. The expected operating cost-per-mile of an electric bus in New York is $0.20 to $0.30 cents, compared to $1.30 per mile for an equivalent diesel or natural-gas powered bus. Electric buses are also nearly silent, require less maintenance, and can improve air quality through reducing emissions compared to their all-diesel counterparts.

A fuel cell bus rolls down the streets of Berkeley, California.

A fuel cell bus rolls down the streets of Berkeley, California.

No wonder why companies like Volvo and BYD are beginning to take advantage of the many reasons why cities are shifting bus fleets to rely on electricity instead of diesel. Pilot programs for electric buses have sprung up all over the world and are demonstrating the viability of advanced electric buses from BogotaBrazil, and Hong Kong, to New YorkLos Angeles and London.

Electric buses may be coming to a city near you

Though modern electric or fuel cell buses still have a ways to go to reach commercial scale, state and federal policies are helping the transition to cleaner bus fleets. The U.S Department of Transportation recently announced the availability of $24.9 million to put more zero-emission buses into service across America, and the Federal Transit Administration has provided $13.6 million for eight projects to advance the commercialization of American-made fuel cell buses.

These incentives are important for helping further develop electric bus technology by reducing the upfront costs that remain a barrier to the widespread adoption of electric and fuel cell buses. California, a usual suspect in the race for investing in clean transportation, is working to meet its air quality improvement and emissions reductions goals through developing the market for electric buses through state policy objectives, analysis, and incentives. Developing additional policy levers on the state and federal level can help take battery electric and fuel cell buses beyond pilot programs and onto city streets near you.

Help your city breathe cleaner (and get involved yourself) by discovering why driving on electricity is a part of the UCS plan to “Half the Oil.”

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  • Max Wyss

    With all due respect, but the advantages of trolleybuses are completely downplayed here. When it comes to performance, the trolleybus is top, bei it for capacity (double articulateds by Hess or vanHool, in use in several cities in Switzerland, for example), be it for steep grades, where any bus with autonomous energy supply (diesel, diesel electric, etc.) can not maintain a reasonable speed (for example Lausanne, Zürich, San Francisco, or Seattle).

  • At this time, the number of batteries needed for a full day is very large. There are two ways to approach this; “Big battery” buses, or “Fast Charge” buses. BYD is an example of the big battery bus, and the Volvo Plugin Hybrid and Proterra all-electric buses are examples of the fast charge variety. Each has their advantages and disadvantages. The battery in the Volvo is about 1/10th the size of the BYD, and has essentially unlimited range since it charges at each end of the route for about 5 minutes. The BYD charges at night so the chargers are in the depot instead of in the street like the Volvo.
    BYD owns their own battery factory, so they have been able to roll out buses at a decent price. Other bus companies don’t have this luxury of making their own batteries, so will likely adopt the fast charge system to keep prices down.
    The Volvo in particular will be very competitively priced, likely just a small premium over their existing “normal” hybrid. The charging stations (like the Opbrid station) are essentially oversized car chargers, with an overhead connecting system to make the charging process automatic. Installing them is about like installing a Tesla Supercharger plus a lamp post.