Driver Tim Mabry eases his foot onto the pedal, and what appears to be a plain white Freightliner tractor moves ahead briskly, making only a faint whirring sound. We are being propelled through an industrial neighborhood in Rancho Dominguez, Calif., by an electric motor

that gets its energy from 204 lithium-ion-phosphate batteries charged by a pair of hydrogen fuel cells mounted under its hood. It has no diesel engine and no clutch or transmission.

"It's like driving an oversized golf cart," says Mabry, the only person authorized to operate this $270,000 machine. It's owned by his employer, Total Transport Systems Inc. (TTSI), and for this brief demonstration, it's pulling an empty sea container that sits on a beam-backboned trailer chassis. The tractor regularly hauls containers out of the ports of Los Angeles and Long Beach. "It's performing awesome down at the port. It does everything it's supposed to do," he says.

It's called Tyrano by its maker, Vision Motor Corp. of El Segundo, Calif., which installed the fuel cells, batteries and electric components in a Freightliner Cascadia glider kit. This one's a prototype, from which TTSI has been shaking out bugs and gaining operating lessons. If it continues operating as well as it has been and financial factors fall into place, many more will join the fleet.

Tyrano exists because the ports' authorities began a Clean Air campaign about five years ago. TTSI responded by buying clean diesel units in 2007, followed by liquefied-natural-gas-powered tractors in 2008 and 2010 - 159 clean machines in all. LNG is cleaner, safer and cheaper than diesel, and various government grants offset their higher purchase prices. But natural gas is still a fossil fuel that results in emission of some greenhouse gases, notes TTSI President Vic LaRosa. The Tyrano's powertrain emits nothing but water vapor, which makes it really attractive to him.

Its cleanliness is beyond what the ports' managers had expected, and they didn't quite know what to do with it. "The ports didn't have a category for registering this," LaRosa says. "We had to wait three or four weeks for them to change their programs to get it registered." That and a special sticker allow the tractor to operate out of the ports as a drayage truck. The sticker says "exempt" because the Tyrano is free of any operating restrictions related to exhaust emissions.

Vision Motor calls it a Zero Emissions Terminal Tractor, or ZETA. It's the right thing for southern California because of its benefits to people's health, says LaRosa, citing lung and respiratory diseases blamed on exhaust smoke from internal combustion engines.

Reducing illness is a long-term gain, but the tractor's cleanliness and quietness make immediate sense at the highly regulated ports and in neighborhoods where people otherwise object to heavy truck traffic because of fumes and noise.

Fuel cells can run on various fuels, including diesel, which is broken down to obtain hydrogen.
But it's cleaner and more efficient if fueled by hydrogen in the first place. It's got to be 99.9% pure or it'll damage the cells, which together produce 33 kilowatts. The cells were made by Hydrogenics in Canada and should last eight to 10 years, the manufacturer says.

Siemens says the motor should run for 30 years with little or no attention. The lithium-ion-phosphate batteries come from China; li-ion batteries have been reliable and long-lasting in hybrid cars and trucks and should be in the Tyrano, too, LaRosa says. When they weaken, they can be used for stationary power storage or recycled and a new pack bought for maybe $10,000.
Hydrogen itself is not as exotic as some folks might think. It's long been used in industry, and it fuels piston engines in transit buses in Palm Springs, among other things.

Theoretically, its abundance is infinite, as hydrogen is the most abundant element in the universe, and it powers the sun. However, it doesn't occur naturally on Earth, so it has to be extracted from earthly compounds.

One is water - H2O - and that's what drips out of the fuel cells when hydrogen is chemically combined with oxygen from the air. The cell's process is the reverse of electrolysis, which splits water molecules by applying electricity, so the cells' other product is electric energy.

Another compound containing hydrogen is natural gas. That's where TTSI's supplier gets it through special refining, and sells it at a station in Santa Monica. That's off the carrier's usual routes, so the tractor isn't used as much as it could be. The supplier, Air Products & Chemicals, plans to erect another hydrogen station much closer, and that should allow greater utilization of the Tyrano.

Exotic or not, hydrogen was selling in January for $2.25 to $2.50 per equivalent gallon, or two-thirds to one-half the cost of diesel fuel.

On this day the Tyrano's tanks are low on H, which is one reason Mabry is going easy on the go pedal and declines my request to take it out on the freeway. The tank gauge registers only 2,200 psi vs. 6,250 while full; at maximum pressure, the tanks hold 28 kilos (61.6 pounds), enough for a range of 200 to 250 miles. Converting the H to diesel-equivalent gallons results in a mile-per-gallon figure of 3.3 to 4.2. That doesn't seem overly economical - until we factor in hydrogen's low price and the low maintenance required by the truck.

With no engine, there are no oil changes, no water-jacket cooling system to watch, no EGR plumbing or particulate filter to worry about and no transmission. Brake expense should be 50% lower because the motor becomes a generator that charges the batteries during deceleration, meanwhile slowing the truck like a hybrid. LaRosa thinks the Tyrano's cost of operation over 10 years will be half that of a diesel tractor.

Power is certainly no problem. The electric motor is capable of making as much as 3,300 pounds-feet, or almost twice the torque of the biggest truck diesels.

To save the drivetrain, the 320-kilowatt (429-horsepower) Siemens motor's output is electronically limited. The motor is directly linked to the rear axles; they have 2-speed differentials that allow 42 mph in Low and 100 mph in High, but the vehicle is electronically governed at 57 mph, Mabry says, and even with normal output, he seldom uses Low range.

The shift selector is labeled D-P-R, with D and R meaning what you think while P should read N for neutral, as there's no parking pawl. A normal air parking brake is among the many common parts on the chassis.

If unbridled, that immense torque makes the Tyrano really quick off the line. Once, after a Siemens technician turned off the limiter, a punch on the pedal lit up its drive tires, Mabry says.
It gets attention at the ports just acting like a normal drayage tractor because it's not normal, he says. Other drivers see the special "Hydrogen Powered" lettering on the hood, "and then they notice that it's not a diesel and they want to get close, trying to read everything else on it."

From a distance the Cascadia looks pretty much like any other modern Freightliner tractor, until you spot the behind-cab cabinet that houses the gas bottles or the lettering on the hood.

Underneath the hood is a different story. Tilt it and you see a large metal box that contains electrical controls. Low and to the rear of that are the boxy fuel cells. The motor is out of sight under the cab's floor. The only sound is the whirring of a cooling fan. There's no diesel and no diesel noise, and the engine compartment has become a large locker for electrical gear.

Now we're done and Mabry