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Will there ever be a silver bullet that will get us out of our fuel crisis, one catch-all solution that delivers the energy efficiency and independence we so sorely need? One fleet manager isn't waiting to find out; he's trying everything.

Ralph Knight, director of transportation for Napa Valley Unified School District in Napa, CA, has been dabbling in alternative fuels and power systems for years, for purely pragmatic reasons. "We don't get money to replace equipment," Knight explains, "so alternative fuels is where we had to look to get rid of some stuff."

That's right: the State of California doesn't have money available to help school districts buy new school buses, but it does have money available for the purchase of alternative fuel vehicles--go figure.

"It's up to the schools to take care of their own dollars and cents to replace," Knight says. By comparison, the neighboring State of Oregon pays 85 percent of the cost of a bus replacement.

Electric Charge

Knight's conversion to alternative fuel and powertrain advocacy began in 1997, with the availability of two new types of buses: one with a traditional diesel engine powered by natural gas, and another with an electric drive system powered by batteries.

When the battery-powered buses became available first, Knight jumped at the chance to acquire some, and at one time he counted four all-electric buses in his fleet. Well, actually, he still has them, but the last one was taken out of service halfway through the 2007-08 school year, when its batteries finally died.

"We had three and a half years of service out of that bus," he recalls. "It was flawless: one day the bus was out of service, and that was due to a mechanical issue that we didn't have parts for; it had nothing to do with the electric drive."

The bus in question was one of the first electric models offered by Blue Bird, with an electric drive system by Solectria (now Azure Systems) powered by 112 lead acid batteries. Knight recalls that when it was first delivered the bus "fell flat on its face" after only 100 miles, and it took Solectria a year to address the problem. After that, he says, the bus ran beautifully. "I would like to repower that bus with a new set of batteries and get it up and running again," he says, "because it was very driver-friendly and it ran every day." There's just the minor matter of finding $10,000 in the budget for 112 new batteries…

Sorry Stories

The three other dead electric buses on the lot have even sorrier tales to tell. Two were powered by Siemens drive systems, with "Zebra" batteries. "They're excellent drive systems, very, very expensive drive systems," Knight says, "but the Zebra batteries did not do what everybody hoped they would do."

Each Zebra battery had 1,000 cells, and, according to Knight, one percent of the cells died within two months. When the battery reached 90 percent capacity it was as good as dead.

"They were changing batteries so often…" Knight recalls. "They felt that the issue may have been in the charging, because they were charging them as a gang very hard with the charger on the ground out here. They felt that maybe it should have been individual on-board chargers, instead of hitting them so hard like they were."

Electric bus #4 was intended as a test bed for nickel-metal hydride (NiMH) batteries, but because the drive system was flawed, Knight says the bus was a failure. "There was a quarter million dollars' worth of batteries in that bus, and I kept telling them that they were using the old drive system that didn't work to start with, so why put those batteries in something that could be a bus problem and not a battery issue?" he asks. "But nobody wanted to go to the extent of putting in a new drive system, they just wanted to test the batteries. Well, once again it failed because the bus would run, if we were lucky, one day a month. And now I've got a quarter of a million dollars' worth of nickel-metal hydride batteries sitting in a bus out there."

Natural Gas Conversion

Within a few months of beginning his electric bus odyssey, Knight was able to acquire natural gas-powered "transit" style buses. These he was able to get through his local Air Quality Board for a song.

"I got rid of some buses in this yard that were 32, 33, 35 year-old Crowns," he recalls. "We had 220 Cummins and 671 pancake Detroits in them, and there was no such thing as smog control on those things at that time. When they did start smogging, at that point they became dogs to run.

"At some point, we had to get rid of equipment, and the local Air Quality Board was practically buying us new buses 100 percent," he says. "I could get up to a million dollars a year in buses through grants from the local Board, and that was getting me seven or eight buses a year. Out of close to seven or eight million dollars in buses, we paid for one bus out of that, roughly $130,000."

Life Expectancy

The CNG buses have been a hit in Knight's fleet, because of their clean operation and their durability. The first two CNG buses added to the fleet are still going strong with "well over" 150,000 miles on each, and when asked about the life expectancies of the engines, all Knight can say is that they haven't hit it yet. The John Deere CNG engines run so clean, Knight's technicians only change their oil once a year--and that's overkill, according to John Deere, which recommends draining the oil every other year.

"We dump it every year just to be safe, and that oil comes out just as clean as it was when it went in--you cannot tell the difference between the new and the old," Knight says.

Only two minor events have spoiled the CNG campaign: John Deere discontinued the engine that Knight had grown to love, and the local Air Quality Board stopped giving away bushel baskets of money.

"I'm a big fan of the John Deere engine, but that's gone, unfortunately," Knight says. "John Deere stopped production of the 8.1 natural gas engine. The dollars and cents just weren't there. They're saying they're going to stand by these buses until they're off the road, but right now we don't have a natural gas engine that we can get in the back of a school bus." And as for the funding source, "They changed their policy to only cover incremental costs, and that's when everything came to a screeching halt. We had to find new ways to pay for this."

Alternate Route

After the failure of the all-electric buses, you might think that Knight would be reluctant to go down that road again, but in August of 2007 he added a diesel-electric hybrid bus to the Napa Valley fleet, and this story has a happy ending.