"Freedom of Choice" Feature Article, October 2004

FEATURE FOCUS: The Hybrid Auto Bandwagon

freedom of choice

The fuel cell vehicle has a long way to go. Maybe those part electric-powered, part gasoline-burning cars will help clear the way.

by Paul Sharke, Associate Editor

Clean, pure water dripping from the exhaust of a fuel cell vehicle, we are told, is the only waste product in an energy chain that one day will include making hydrogen, storing and transporting it, and converting it chemically into electricity. Yet, for fuel cell researchers working today, benign water turns up almost "always in the wrong place," according to Francis R. Preli of UTC Fuel Cells in South Windsor, Conn. Preli spoke at the Rochester Institute of Technology/ASME fuel cell conference held in upstate New York this past June.

In winter, the water freezes; in summer, it evaporates, Preli said. Starting a fuel cell in zero-degree weather remains an issue despite the progress in managing fuel cell water that researchers have made over the last five years, he said.

Another speaker, Andrew Bosco, from GM Global R&D in Honeoye Falls, N.Y., told the audience that today's fuel cells were still too costly by an order of magnitude to compete with internal combustion engines in mobile applications. He expected advancements in materials to eliminate the complexity of today's fuel cell systems.

He said that computer diagnostic tools, such as computational fluid dynamics and finite-element analysis, are helping to uncover the ways in which the various media that make up fuel cell stacks compress and how they respond to bipolar plate stresses, to name but two examples of research. Experimental measurement tools were helping researchers to visualize flow, measure temperatures directly, and understand compression distribution, he said.

The Ford Escape Hybrid (above) began life with great fanfare. PZEV versions of smaller cars (below) hardly even drew whispers.

Much engineering remains before the fuel cell takes over as the principal power plant on our cars and in our buildings. Its acceptance may come about through a series of incremental steps rather than from one great technological leap. The success that hybrid autos are enjoying today may be the first of many such steps the buying public will have to make before we transition to a full hydrogen economy sometime in the next quarter-century, according to fuel-cell conference keynoter JoAnn Milliken, a Department of Energy technology development manager.

The path will probably take us down many technological byways. For instance, the DOE is about ready to decide the fate of on-board gasoline reforming as a way of producing hydrogen for proton exchange membrane, or PEM, fuel cells, Milliken said. A crucial issue there is the time necessary for a reformer to warm up. A 30-second delay is about all the majority of drivers will tolerate, Milliken said.

Indeed, while PEM fuel cells are generally considered the sensible choice for automotive power, they may not be the first type of fuel cell to come into popular automotive use. Delphi Automotive Systems and BMW have been developing a solid oxide fuel cell, or SOFC, that will provide an auxiliary power unit for a car's electrical needs, which, as one conference speaker put it, are today about three times what the Apollo missions needed to put men on the moon. Delphi Corp.'s Steven Shaffer gave conference attendees an update on this APU.

The idea is to use a high-temperature SOFC to generate electricity and free the engine of this chore. A smaller, more efficient engine could then be used to propel the vehicle. The SOFC would run on the same gasoline or diesel fuel that powers the engine because the fuel cell does its own reforming. The 5 kW fuel cell would keep the air conditioner and car's electrical system operating even while the engine shuts off for a light, à la hybrid.

Although the SOFC might never be the fuel cell of choice for mobile operations, because of a lengthy warmup period, it represents a novel approach of introducing the public to fuel cells without exposing anyone to the technological risks of a full-blown production fuel cell vehicle.

If the success of hybrids is any indicator, such an approach might just work.

Riding the Hybrid

Chrysler plans to offer front-wheel-drive hybrid vehicles by 2006, according to an announcement from the Chrysler Group chief executive, Dieter Zetsche. The announcement came a week before Toyota said it would raise prices on its hybrid Prius to better match supply with demand. Ford is now producing its hybrid Escape, joining Honda and Toyota in the North American hybrid electric vehicle market.

A 2.3-liter four-cylinder engine and 65 kW traction motor combine forces to produce in the Escape hybrid what Ford called the equivalent output of a 200-hp V6 engine. Mileage improves by 75 percent in city cycles compared with a conventional Escape XLT, the company claims. The vehicle includes a 110-volt outlet that can recharge a laptop computer.

Ford calls the Escape a "full" hybrid, meaning that the motor can move the car forward on battery power alone, like Toyota's car. The Honda moves only when the engine is on. A start/stop circuit shuts the engine off at traffic lights.

Hybrid economy kicks in mainly when the cars are stopped or crawling in heavy traffic. In these conditions, ordinary automobiles probably could do nearly as well, mileage-wise, if a driver was willing to shut the engine off every time traffic stopped, and forgo music and heat or air conditioning during the stop.

Years ago, the National Safety Council published a tip on making it to a distant gas station on very little gas. The idea was to turn on the engine, bring the car up to 10-15 mph, then shut off the engine and coast to a stop. This technique really stretched out fuel economy, the article claimed. At some level, hybrids are manifesting this idea, with an orchestration of complex controls, in the everyday setting of stop-and-go driving.

The Delphi/BMW solid oxide fuel cell (top) could provide electricity for cars without the finicky hydrogen purity needs of proton exchange membrane fuel cells. A Toyota worker (middle) installs the battery pack in a 2004 Prius. Escape Hybrid powertrain (sans cover, bottom) gives performance and efficiency, Ford claims.

Much of Hollywood has fallen for hybrids. And why wouldn't it? In that make-believe world, an extremely complicated automobile can be sold profitably for a few thousand dollars over the cost of a simpler design.

Look at hybrid technology's much-touted regenerative braking, for instance. Engineer Jim Lux estimates the kinetic energy of a 3,000-pound car running at freeway speeds to be around 500 kilojoules, about the energy needed to travel a quarter-mile. Most of that energy is expended in overcoming air resistance, Lux said. Putting that energy back into a battery has to occur quickly, which heats up the batteries and shortens their lives. It also requires a big generator, one much larger than the motor a hybrid requires to simply accelerate the car and move it around. Bigger means heavier and costlier, he added.

PZEVs, or partial zero emissions vehicles—introduced with little fanfare so far—may offer a better bet for the average engineer not making the equivalent of a Hollywood star's salary. They cost little more than the stock vehicles from which they evolve, but offer drastic reductions in emissions, equal to that of hybrids and natural gas vehicles, according to the California Air Resources Board.

Ford, Chrysler, Honda, and many of the other automakers sell PZEVs in California and in the states that follow its stringent environmental model. The Ford Focus PZEV, to cite one example, moves the catalytic converter nearer to the exhaust manifold to decrease the time the catalyst takes to heat up. A special exhaust gas recirculation system shunts inert gas into the engine to reduce NO_x. Butterfly valves in the intake manifold increase the turbulence of incoming air to improve the air/fuel mix while the engine is running throttled.

Because the Focus is already an economical—that is, small—car, it delivers good gas mileage without resorting to the eye-watering complexity of the double-drive hybrids. Recently, this writer logged about 30 mpg over a 1,000-mile loop through New England, driving a rented 2005 Focus mostly on highways with the air conditioning on and the car hovering mostly just above the speed limit. Had there been any traffic, mileage would likely have suffered somewhat, of course.

Gas mileage, although better in hybrids, remains a hard sell in the United States, even as the price for a gallon hovers around $2.

Indeed, the Department of Energy calculates that a Honda Civic hybrid saves only $150 annually over the standard 1.7-liter Civic LX model driven 15,000 miles a year, 55 percent of the time on the highway. At that savings rate, it would take a hybrid buyer a long while to recoup the several-thousand-dollar premium he shells out for the car. For that money, he could buy the plusher Accord PZEV.

Under-the-hood shots of the Escape (top) and the Prius (bottom) sandwich a view of the Ford assembly line. Both cars can move on electric power alone, although not at highway speeds. Honda hybrids must restart their engines in order to resume movement.

The 2005 Chevrolet Silverado and GMC Sierra hybrid pickup trucks will be sold in a handful of states in the West and in Florida. Drivers of these trucks couldn't care less about emissions or fuel economy, although GM claims up to a 10 percent improvement in city driving over comparable vehicles for the two models—amounting to about a couple of miles per gallon. Instead, the pickup trucks replace conventional alternator/starters with more powerful motor/generators that quickly restart engines stopped for traffic lights. When not used for mobility, the generator provides contractors a 14,000-watt electric source from four 110-volt, 20-amp outlets. The truck will generate for as long as 32 hours before shutting down automatically, leaving enough gas in the tank for a refueling run.

Having that kind of power available during a blackout could keep food cold or a basement dry. Still, there has to be a much cheaper way of generating a dozen kilowatts during the infrequent, though always inconvenient, blackout.

If we're going to incorporate beefed-up generating capacity in our vehicles, having use of it while the car or truck is parked makes sense. Some fuel cell aficionados have been promoting this idea for years.

Meanwhile, a few power companies have been investigating plug-in HEVs as the next step in the hybrid evolution. For them, it's a good way to sell off-peak power; so far, automakers haven't taken up the cause. It's refreshing now to watch automakers go after stationary generation, balancing the efforts of some stationary power producers to create concept cars.

Crossing Over

It has been five years since Honda introduced its hybrid Insight to U.S. shores. Experts at the time were saying that stationary power would be the gate by which fuel cells would one day enter the mainstream. The higher cost of a watt of power in that market made stationary power a better entry point for fuel cells struggling to bring down per-kilowatt costs. Now, the situation has flipped, as power generators wait for the automakers to bring out their cells. Fuel cell longevity has become an issue of concern, but less so for automakers than it is for stationary generators.

Fuel cells haven't become the simple solid state devices that were predicted initially. Hydrogen hasn't become any more readily available than it was five years ago. No one's expecting a fuel cell car by 2010 any more.

Yet, as we continue to drive sport utility vehicles and other behemoths, the nation is reminded constantly about its diet of foreign oil.

Supporters of the hydrogen economy are viewing their vision as the long-term solution to the nation's energy needs. As fuel-cell conference speaker Mark Williams of the DOE's National Energy Technology Laboratory put it, "Hybrids are a bridge to reduce foreign oil dependence until the hydrogen economy is in place," which he predicted will be in 2040.

It's hard to decide whether "bridge" is the appropriate metaphorical element to describe the role of the hybrid automobile in the world today. On one hand, bridges are usually permanent. Some would argue that hybrids will compete so successfully with fuel cell cars in range and cleanliness that they'll never be outdone by solid state technology.

On the other hand, bridges weigh little compared with the land masses they ordinarily connect. Hybrids may never reach the sales volume that traditional internal combustion engine cars now enjoy, or that fuel cell cars may one day reach. But they could very well provide a way to go from one huge market to the next.