Electric Busology 101

Any transit fan who rides an electric bus will admit to admiration of the strong silent acceleration and the total absence of tailpipe emissions. To appreciate the role of the ETB in transit systems, however, we need to step back and get the bigger picture of what these systems are.

By definition, the systems are large. They maintain service that has been provided, in many cases for over a century, and the equipment they use is intended to last 25 years, implying the continuance of service. In many cases they include a large sunk investment that can’t be recovered if service ends, they usually have many large things on quite a bit of real estate, and when they drink fuel, they don’t use a soda straw.

Consider the railroads in the age of steam. To generate steam you needed coal and water, so each railroad had two parallel structures to provide the coal and water. Steam locos liked to eat and drink every hundred miles, and these frequent stops were more convenient in the days of hotboxes and wayside setouts of cars.

Thus, every steam railroad was a series of small towns, with coal and water storage, and often a railroad hotel or YMCA for train crews. At the end of the age of steam, the steam loco still had a greater thermal efficiency than the diesel, but the cost of maintaining the fuel and water supplies was prohibitive.

Maintaining the fuel supplies for the railroad, indeed, requires an investment so great it becomes a matter of long-term financial planning. Fuel stocks must be maintained to provide service in case of disruptions, and to hedge against market spikes. In the age of coal, this meant mountains of coal stockpiled in the summer months against the anticipated strike of the miners in the winter months. In the age of diesel fuel it means tanks in the ground and contracts for guaranteed deliveries. Large electrical users need to be sure the grid can overcome local disruptions or that they can generate their own essential energy.

In many respects electricity is the best energy source. You don’t need to keep tanks of it on hand, you don’t need to pump it into buses in the morning, you don’t need to carry the weight of the electricity around with you, and you don’t need to deal with the problems of leaks, fire danger, and emissions. An enormous world manufacturing base is constantly trying to improve the performance of electric motors and transit systems have already tried just about everything, so there’s a lot of experience to draw on.

The problem with electricity is that it requires a very large capital investment to deliver the electricity to the bus, usually by overhead wires. That’s a big problem for a transit system, but is it a problem or an opportunity for the society it serves? That’s probably a good topic for another post on electric buses.

5 responses to “Electric Busology 101”

  1. mSkehan

    I look forward to follow-on comments on ETB’s, now as a retired ETB driver of some years. I find it hard to rationalize in my own mind some of the percieved costs and benefits to trolleys – especially the fact that some think electricity is 100% green. Not true, go to the EPA, find the section on “Where does my electicity come from” and enter your zip code. About half is from fossil fuel in Seattle.
    I love trolleys, but they have their limitations and extra costs compared to diesel or hybrids. Decision makers need to make good choices for all the right reasons.

  2. tvjames

    To me, it’s the middle ground be between buses and light rail. Having a chance to get away for 24-hours without the children, we made our way up to the big city, spending time in Freemont, Queen Anne Hill, Crown Hill and downtown. As we sat in a great restaurant in a very walkable part of Queen Anne, we looked at the overhead lines and watched the buses come by with regularity. Like the rails for light rail, the electrical lines hung over the street saying “There’s a transit line here that we’ve committed to” even when there wasn’t a bus passing by.

    (On the other hand, there was also a million Microsoft connector buses so I guess committing to an area with transit and then actually meeting the resident’s needs might not be the exact same thing.)

  3. Chaz

    That data is from a 2005 report and returns regional data (about five states i think) not the specific mix that we in the Puget sound area have. The 2007 fuel mix data that Seattle city light provides the stat claims that in about 90% of the mix was hydro. (See:http://www.seattle.gov/light/FuelMix/)

  4. Anandakos


    Congratulations on the correct use of a very obscure term of art from railroading, “wayside setouts of cars”. You know your stuff.

    And that is a great post on the Starlight. Ben and I got into a pissy fit about rerouting the Starlight down the beautiful Nalley Valley instead of along the Narrows. Ride it now, because when the stimulus money comes flooding in thanks to Patty Money, the Bypass will be on us in a flash.

  5. variable

    For a lot of regions the vast majority of energy comes from fossil fuel, Washington, Oregon and Idaho all get their bulk of electricity from renewable hydroelectric. Including Seattle…

    Other utilities, for instance Puget Sound Energy get a higher percentage from coal but the EPA has Washington among states that get at least 85% of total electricity from renewable.. http://blog.epa.gov/blog/2009/09/11/where-does-my-electricity-come-from/

    Certainly it’s not all green energy but the vast majority of energy produced and used in the Pacific North West is clean and renewable.