An Introduction to Electric Buses

How They Work, How Much They Cost, and Where They Operate

Electric bus pulling over for passengers

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Due to concerns about diesel-powered buses causing poor air quality, transit systems in the United States are increasingly looking towards different propulsion systems. Though natural gas-powered buses are quickly becoming the norm (a trend that one would expect to accelerate in the future, as an enormous amount of natural gas supply has been discovered in the United States, causing a significant decline in the price of the gas) another alternative being considered is the use of electric buses. They're powered solely by batteries, and should not be confused with hybrid buses, which are powered both by batteries and either a gasoline or diesel engine that activates after the bus has traveled a certain distance.

An Introduction to Range Anxiety and Electric Buses

"Range anxiety," a term coined to describe the fear of being stranded, is a major reason why all-electric cars have not been bigger sellers. This fear can also be applied to electric buses. Due to the much larger mass of a bus than a car, electric buses have an effective range that is much lower than an electric car — as little as 30 miles. Since most buses are out on the road for 12 hours and 150 miles or more per day (on their way to 12 years and 250,000 or more miles), it is clear that without some ability to recharge en route, electric buses will not be deployed in the nation's transit systems.

Recharging

Because the electric bus battery range is so low, buses will need to be charged periodically at a convenient place along the route, preferably at a layover location to avoid inconveniencing passengers. Although necessary charging time has been reduced as battery technology advances, the bus may still need to charge for as long as five minutes after the bus travels for about 20 to 30 miles. This distance means that the bus may need to recharge after every round trip. But even that is not the major problem. What if the bus is late? If a traditional gas- or diesel-powered bus arrives at the end of a trip late, it can immediately begin the return trip to make up for the lost time. An electric bus, needing to charge, will not have that option. This means an electric bus that runs late may continue to run late for quite a while. This outcome will lead to poor system reliability.

Cities and private landowners may complain about the installation of electric bus charging stations, which can look like a rain shower head. Usually, the electric bus will park directly underneath the charging station, and a collector is raised to connect with the station in a similar way that a trolley bus connects with wires.

Reliability

Operational reliability is important, of course, but what about the vehicles themselves? Do they break down a lot? Range anxiety aside, there have been no major reported mechanical problems with electric buses that are any different or more frequent than problems with other kinds of buses.

Cost

Proterra, a major manufacturer of electric buses, says that although their electric buses cost more than comparably-equipped diesel fuel buses, over the lifespan the two costs are comparable. They say their buses will save their owner $700,000 in fuel and maintenance savings over a 12-year period. The cost of an electric bus does not include the cost of necessary charging stations, which can be up to $50,000 each.

As the technology advances and the electric bus is put into more widespread use, one would expect the cost of these buses to come down. However, the initial cost is unlikely to ever be anywhere near the comparatively low cost of a diesel vehicle.

Electric Buses in the United States

Electric bus usage in the United States is still small and mainly concentrated in the airport and other short shuttle route arenas. One notable counter-example is found in the service area of Foothill Transit, a provider that covers the far northeastern suburbs of Los Angeles. Foothill Transit operates several electric buses on Route 291, and you can find short recharging periods included in the printed timetable.

Outlook

Like electric cars, electric buses are used on a small scale. Until battery technology develops to the point where a vehicle can comfortably travel 200 to 300 miles on a single charge, it is unlikely that electric buses will be adopted broadly by the transit industry. Delays caused by the need for frequent charging will probably prove too expensive for public transit. Adopting electric buses would cause the need for massive schedule-rewriting and create an increase in operating costs. Of course, this is assuming that a public or private landowner does not mind the installation of charging stations on their land.

Another big factor arguing against the adoption of electric buses is the relatively recent discovery of massive amounts of natural gas in the United States. These discoveries have already driven the price of natural gas down, and will likely keep the cost down for years to come. Natural gas may prove to be a cheaper source of bus propulsion than electricity, especially in states like California where the cost of electricity is high. Unfortunately for electric bus proponents, it is places like California — where pollution concerns prevent the purchase of diesel buses — where electric buses are likely to hold their greatest appeal.

Source:

Kevin Bullis. "Electric Buses Get a Jump Start." MIT Technology Review, June 16, 2011.