Honda's Clarity Puts Fuel-Cell Technology in Limelight

It's a safe bet Sir William Robert Grove had nothing like this in mind when he successfully combined hydrogen gas and oxygen in 1939 to produce electricity in the world's first fuel cell—a device he called the gas battery.

In the hands of engineers and designers at Honda Motor Co., Grove's gas battery – albeit with a modicum of refinement – has become the heart and soul of an ultra-modern, clean, fuel-efficient green car: the FCX Clarity.

Honda introduced the production version of its newest hydrogen-powered, fuel-cell electric car at the Los Angeles auto show earlier this week and on Friday gave a few journalists the chance to delve a bit more deeply into the fourth-generation technology that makes this most advanced of the alternative fuel vehicles work.

The company will begin leasing the limited edition car to select customers in mid-2008. Lease terms will be three years, at $600 a month, and the car will only be available to Southern California residents who live near existing hydrogen fuel pump facilities in Irvine, Torrance and Santa Monica.

As more hydrogen fuel becomes available, additional vehicles could be leased in other regions of the country, Honda executives said.

(Honda won't sell the Clarity because, although technically a production model, it still is largely hand assembled and is crammed with expensive technology that likely would require Honda to charge close to $1 million a copy to break even on.)

The sleek, garnet-red sedan (green is its mission, not its color) was designed by Masura Hasagawa.

His exterior features a short, dropped nose and rear deck that show off a long, glassed-in cabin further delineated by powerful fender and character lines. It's an all-new look, based on the show-stopping FCX Concept introduced at the Tokyo auto expo in 2005.

"We needed people to see what we could achieve with this new technology just by looking at the car," Hasagawa said. 

The four-place interior by Hasagawa's fellow Honda designer Yozo Takagi, features individual seating "cocoons" with heated and cooled front bucket seats upholstered – like the rest of the interior -- in a Honda-developed biofabric derived from corn.

A small lever mounted on the right side of the instrument cluster housing – about level with the driver's right hand when it is grasping the four-way adjustable steering wheel – "shifts" the electric motor/gearbox from "Park" to "Drive" or "Reverse," as needed.

It's an electronic shift-by-wire system and there's only one forward speed because electric motors deliver their torque more efficiently than internal combustion engines and don't need to be mechanically geared up and down.

A 3-D power display on the floating, padded instrument panel lets the driver monitor the electric drive and fuel-cell system goings-on via vividly colored icons.

They include a "pulsating ball" fuel economy icon that grows in size and changes color -- from blue, for high efficiency, through yellow, for average mileage, to an angry amber that lights up the screen when you put the accelerator pedal to the floor for rapid acceleration.

But attractive as it is inside and out, it's what is under the hood, and center console and rear seat and the floor of the surprising spacious trunk, that makes the Clarity so special.

Other automakers are still developing their fuel cell systems. Honda says that, for all practical purposes, its system has arrived.

The major obstacles to going retail are lack of a fueling and service infrastructure, and the high cost of components, which will only drop as demand increases; demand, of course, being largely dependent on fuel availability. (Honda is working with partner Plug Power Inc. to develop a home fuel maker that could use residential natural gas service and electrical power to produce and compress hydrogen for refueling a  car overnight.)

One criticism of fuel-cell technology has been that making  hydrogen fuel from natural gas, the most prevalent method in use worldwide today, uses so much energy and creates so much carbon dioxide that it  would negate the emissions and fuel efficiency benefits of the fuel-cell vehicle.

But Ben Knight, vice president of automotive engineering at Honda R&D Americas, says the company's studies show that for the Clarity, CO₂ emissions in the so-called well-to-wheel cycle, which includes production of hydrogen fuel from natural gas, is "less than half that of a gasoline-fueled vehicle, and less than that of a battery-electric vehicle."

The new system's fuel efficiency, the tank-to-wheel cycle, is three times that "of the best gasoline engines," Knight said, "and twice that of a modern hybrid." 

The heart of the system is a 100-kilowatt fuel cell stack that's so small it fits in the center tunnel beneath the console separating the front seats.

The stack, which produces electricity by passing hydrogen and oxygen through a permeable membrane coated with a platinum catalyst, is 65 percent smaller that the stack in the experimental 2005-model FCX minivan that Honda has been leasing to a few cities and two Southern California retail customers for the past few years.

Its cells, Honda won't say how many but there are hundreds, are arranged vertically. Previous fuel cell stacks were made of cells piled one atop the other in a horizontal pile that created a very wide but relatively lat package; the new one is long and narrow, which made it possible to package it in a sedan.

The vertical arrangement also promotes more efficient cooling, electricity "generation" and cold weather operation, said Knight. 

A unique feature of the system is its "auto stop" function: to improve fuel efficiency, the flow of hydrogen to the fuel-cell stack is shut down when the car is idling. It's the fuel-cell vehicle version of the internal combustion engine shut-down feature of an idling gas-electric hybrid.

When it is making electricity, power from the fuel cell flows to a 288-volt, lithium-ion battery pack and, when the battery is not needed for extra boost, directly to the electric motor-cum-gearbox mounted transversely under the hood.

The battery pack is 40 percent lighter and 50 percent smaller than the ultra-capacitor that stores electrical power in the 2005 model.

The motor delivers 134 horsepower and 189 pound-feet, or 256 Newton meters, of torque. The peak level is delivered in the zero-to 20-mph range. It's enough to give the Clarity a top speed of 100 miles per hour with off-the-line acceleration that pushes you firmly back into the seat. 

The motor-gearbox has been downsized considerably from the unit used in the '05 FCX. It is almost a foot narrower and 9.5 inches shorter than the '05 version, which allowed designers to style the car with its very short and steeply sloped nose.  

The entire power plant is 397 pounds lighter and 45 percent smaller than the system in the previous-generation FCX.

Fuel is carried in a single, cylindrical tank mounted behind the rear seats and above the rear axle. It carries abut 3.9 kilograms of gaseous hydrogen compressed at a pressure of 5,000 pounds per square inch. The tank has far fewer parts -- valves, regulators, filters -- than the previous twin-tank system, and carries more fuel in a smaller space.

With estimated fuel economy equivalent to 68 miles per gallon, the FCX Clarity has a maximum range of 270 miles on a single fill-up, Honda says.

Sir William, a Welsh-born, Oxford-educated barrister and chemist, would be proud, were he still around to gaze at what has become of his little invention.

Posted by

John O'Dell November 17, 2007, 4:08 AM

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Alternative Fuels, Fuel Cell, Honda, Hydrogen