The Kings Canyon Unified School District of San Joaquin Valley, California made a splash last week when it put the first electric school bus into service. Those green bumpers sure look snazzy and "85% emissions reduction" sounds great. But nobody seems interested in publishing how much the buses actually cost.

Short-range vehicles that operate in loops, like school buses, seem like the perfect application for electric power based on our current technology. Motiv, Trans Tech, and the California Air Board (CARB) think so too, and they all collaborated to bring the project to fruition. The figure of "$11,000 in annual savings" for the school using the electric-retrofitted TransTech E-450 based SST bus, simply called the SST-e, keeps resurfacing but it doesn't add up based on what I was able to find out.

The SST-e was a long time coming, the Kings Canyon school spent four years working on the project, and somebody convinced CARB to kick in "around $400,000" to bring four electric busses into service.

That school district must be pretty big, because they have a "transportation manager." He's a gentleman by the name of Jason Flores, and he made it pretty clear the environmental angle was his primary objective picking up the electric buses.

"KCUSD has taken major strides to reduce diesel particulate emissions by as much as 85 percent. Going electric with these new green school buses is just one more important step in KCUSD's ongoing portfolio of measures to protect our children, serve our community, and be good stewards of our environment. We hope other school districts will follow our lead to protect children from diesel particulates and protect themselves from rising diesel costs."

The school ordered four SST-es with green bumpers and wheels to really drive that point home; "green means good!" Foster City, CA-based company Motiv Power Systems fitted what they call a "flexible electric Powertrain Control System" (ePCS). Their main claim to fame before the Kings Canyon school bus was Chicago's first electric garbage truck.

But you really want to know if the damn things are cost-effective, right? Trans Tech's President John Phraner claims an electric bus will save "16 gallons a day," which he worked out to "$11,000 a year," over a conventional bus "not to mention the cost of maintenance." But what kind of usage are we talking about, and where?

Electric powertrain builder Motiv's CEO Jim Castelaz was similarly vauge when asked about the SST-e's real price.

"The buses cost about twice as much as a comparable gas bus, but cost 1/8 as much to fuel (power) and 1/3 as much to maintain. In the life of a school bus, 2-3 times the cost of the vehicle is spent on fuel and maintenance."

To me, that just raised more questions than it answered. What's a comparable bus? What's the lifespan we're talking about? What sort of maintenance are we assuming?

Motiv was willing to elaborate a little, but they remained guarded on how much has really been invested. They confirmed the bus in question was a "Type A," and that their cost comparison was to gasoline-powered versions of the same. Motiv placed the lifespan of the Type A bus at "20 to 30 years," which sounds like an awful hard figure to place a comparison on considering that "to" makes a 33% difference.

Bottom line is, they don't want to publish the cost because the four they built were part of a pilot program that factored in a lot of government funding. The pricing structure for the pilot project didn't include scalability, so Motiv doesn't have enough data to provide an MSRP.

I can understand that— if another school orders a batch of SST-e buses from Motiv, the situation will be largely different and so will the price, so Motiv doesn't want to paint themselves into a corner by committing to a figure. But that doesn't diffuse our curiosity about what those first four buses at Kings Canyon cost, and if they'll actually save the district dollars in the long run.

"We give the price that way because most people don't have context for how much a regular school bus costs. Unlike buying a family car, the industry and price points are completely different. We hesitate to throw out a number, as most readers will not have the proper context," said Castelaz.

Since the real prices remain a secret, we can only speculate how the economics of the SST-e break down based on what we know and what we have to infer.

Let's go with the low end of Mr. Castelaz's statement and say a gasoline-powered Type A SST bus lives for 20 years and costs twice the initial price to maintain over that time. The first new gas-burning TransTech SST I found for sale was $66,000, so by Motiv's estimate it would cost another $132,000 to fuel and maintain for a twenty year life.

I don't know for certain what a 2014 E-450 would end up costing in repairs annually, especially fifteen or twenty years down the road, but for the sake of comparison here let's call it $750 per year. That should balance the first few years of routine-only oil changes and tire rotations with the brake jobs and major component replacements an E-450 is going to need in its twilight years. What's left then must be fuel costs.

If that's the case and the SST-e really does have an eighth of the gas version's fuel and a third of its maintenance cost, the twenty-year breakdown should look something like this:

† Assumed Cost of electric SST-e based on statement provided by Motiv above

* of 2014 TransTech SST with a 5.4 V8 that looks just like the "electrified" version.

Based on this rudimentary estimate, it's $46,425 cheaper to run the electric bus for a twenty year lifespan than to run the gasoline version. That's $2,321.25 broken out annually, making the "savings of about $11,000" asserted by TransTech's president sound a little off.

I didn't factor in depreciation, and there's no mention of changes in insurance and registration fees. More importantly, I wasn't able to factor in government tax credits and rebates that may or may not be associated with running the SST-e. But "tax credits" don't make costs go away... it just puts the bill on the government's tab which gets picked up by taxpayers.

After seeing my speculative figures, Motiv offered to elaborate once again on how they came to their conclusions:

We look at numbers that KCUSD is willing to share with us as follows:

Kings Canyon Unified average annual route miles traveled 14,000 per bus

14,000 divided by 6mpg = 2,333 gallons

2,333 X $4.00 = $9,333 per year

Many school buses in our fleet get less than 6mpg The same 14,000 annual miles are be run from electricity at roughly $0.10/mile, or $1,400 annual fuel cost (note that this is 15%, or roughly 1/8th Maintenance savings can be simplified (and likely under-estimated) by counting only the forgone oil changes, transmission flushes and brake changes. On a diesel bus, the former two happen annually and the latter every other year, resulting in an average cost of $700/year that is avoided.

Total annual savings are $9,333 + 700 = $10,033 in gross yearly savings, or $8,633 in net savings.

John Clemens from the Kings Canyon Unified School District's Transportation Department put annual maintenance savings at closer to $1,300, based on the school's arrangement to have repairs performed at $55 per hour and get parts at cost.

Based on my estimate, a $2,000 estimated annual savings for an extra $66,000 up front cost seemed like a tough sell in most school districts, but the new information provided by Motiv at least gets us to where their numbers make a bit more sense. Though I'm still not convinced school buses really see duty for two to three decades, they definitely didn't in the Boston 'burbs I grew up in.

Motiv's CEO did have a lot to add about the environmental significance of the SST-e electric bus, which I'll share . But the thrust of his message was:

"We estimate GHG as pound of CO2-equivalent, or CO2e. In California, one kilowatt-hour of electricity produces about 0.89 pounds of CO2e. That amount of electricity will move the vehicle about 1 mile, including all losses (generation, transmission, battery charge and discharge, etc). To move the vehicle 1 mile on gasoline requires about 1/6th of a gallon."

In general, I'm a fan of exploring alternative propulsion sources. Especially in public transit applications. But I'm also a fan of transparency and comparison charts. After all that, do you think electric buses could be the future of people-moving, or is the SST-e just a tree-hugging PR stunt?