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 I 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 looked at has been electric buses. Electric buses are 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 gone a certain distance.
The Major Problem of the Electric Bus - Range Anxiety
"Range anxiety", a term coined to describe the fear of being stranded as a major reason why all-electric cars have not sold better to this point, 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 much lower than an electric car has - as little as thirty miles. Since most buses are out on the road for twelve 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 able to be deployed in the nation's bus systems.
Recharging Stations Required, Potentially Causing Delays
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 the layover location to avoid inconveniencing the 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 twenty to thirty miles. This distance may mean that the bus may need to recharge as frequently as after every round trip, but that is not the major problem - what if the bus is late? Right now if a 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, meaning an electric bus that runs late may continue to run late for quite a while. Of course, this outcome will lead to poor system reliability.
Of course, cities and private land owners may complain about the installation of the charging stations, which can kind of 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 the wires.
The Reliability of Electric Buses In Action
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 problems with electric buses that are any different or more frequent than problems with other kinds of buses.
The Cost of Electric Buses
Proterra, a major manufacturer of electric buses, says that although their electric buses cost more than comparably equipped diesel fuel buses, they say that over the lifespan the two costs are comparable. Since they say their buses will save their owner $700,000 in fuel and maintenance savings over a 12 year period, we can infer that their capital cost is $700,000 more than a diesel bus. Of course, this 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 I would expect their cost to come down, but I could not imagine the initial cost to ever be anywhere near the cost of a diesel vehicle.
Use of 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 arena. 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 even see in the printed timetable the short recharging periods at Pomona TransCenter.
Outlook for Electric Buses
Similarly to electric cars, until battery technology develops to the point where a vehicle can comfortably travel 200 - 300 miles on a single charge, it is unlikely that the technology will be adopted broadly by the transit industry. Delays caused by the need for en-route charging will probably prove too expensive for a transit agency, especially the ones that have drivers relieved for breaks rather than count the layover at the end of the line as a driver break. Since these agencies, such as TTC in Toronto and STM in Montreal, frequently have scheduled layovers lower than the time needed for charging adopting electric buses would cause massive schedule rewriting and an increase in operating costs. Of course, the above assumes that a public or private landowner does not mind the installation of the charging stations on their land.
Another big factor arguing against the adoption of electric buses is the 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. 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.
Now that you have read about the electric bus, perhaps you would like to take a look at my electric bus photo gallery .