Always 'on the horizon,' fuel-cell vehicles now 'around the corner'

  • 05-Dec-2013 06:55 EST

The Hyundai Tucson fuel-cell vehicle mounts the stack, motor, and controls in a single under-hood package.

The old line about the fuel-cell car being "on the horizon and always will be" may be about to become outdated. The technology, using hydrogen to produce electricity, dates back to 1838, but its high energy conversion efficiency (more than 40%) and near-zero emissions have made the fuel cell (FC) increasingly appealing. However, the technology has made its way into no more than handfuls of leased vehicles for over a decade.

The California mandate that 15% of vehicles for sale in 2025 be of the zero-emissions type changes the picture, as fuel cells "emit" just water vapor. Hyundai announced a production car for next spring, and both Honda and Toyota said they would have fuel-cell cars on the U.S. market by 2015.

The Hyundai and Honda announcements came at November's Los Angeles Auto Show, Toyota's at the simultaneously running Tokyo Motor Show. Range of all three is more than 300 mi (480 km), which alleviates range anxiety, with refueling time for 4-5 kg (1.8-2.3-lb) tank(s) being 3-10 min at pumping pressure of up to 70 MPa (10 ksi). Fuel economy is over 70 mi (113 km) per kg. Hyundai tried to make the point that its fuel-cell vehicle is a practical approach, that the company will produce as many as it can market—recognizing that the present refueling infrastructure is limited to a small part of southern California.

Hyundai put a price tag on the vehicle, albeit for a three-year lease, of $2999 down and $499 a month, including free fuel, maintenance, and road service for a total of about $21,000. There is no leasing target, but "we can make them in substantial numbers," said a Hyundai executive. The lease price is comparable to the $600 per month Honda has been getting for a three-year term on the lower-volume Clarity, a fuel-cell car it introduced in 2008—a figure that also includes fuel and the service package.

Both Honda and Toyota are talking very small numbers, although that could change if Hyundai is successful.

$50,000 price point seen

Hyundai made the point that it sees a slow advance for lithium-ion battery technology, and that it believes a fuel-cell vehicle would be just a more practical, lighter alternative to the battery-electric vehicle (BEV) with a large battery pack. The cost to produce reportedly is greater than a long-range BEV such as the Tesla S, but the gap is closing. Hyundai is projecting a selling price in the $50,000 range for its next-generation model, similar to what Toyota's projections.

Current packaging has the FC stack, controls, and drive motor in a single assembly under the hood of a Tucson SUV, the result of aggressive development program to reduce stack cost and size. The latest stack represents a 40% cost reduction from 2010, which itself was 70% less than in 2005. Hyundai sees another 50% reduction possible by 2016, primarily in use of new materials, reduction in those that can't be substituted, and savings from moving to production-based construction. Such improvement would make the technology scalable for most vehicle sizes.

These FC vehicles will not be performance models. The Tucson FC, built on the same production line as a gasoline-powered model, is rated at 100 kW, and like the Honda of the same rating it comes with an auxiliary high-voltage lithium-ion battery for acceleration assist—so in effect it's an all-electric hybrid. Li-ion storage capacity is just 0.95 kW·h, enough for its limited use for acceleration and climbing hills.

Instant torque of the electric motor is 300 N-m. Hyundai declined to announce power density of its latest stack, although Honda and Toyota have: 3.0 kW/L. The 2010 Hyundai stack was rated at 1.6 kW/L. Packaging the latest version completely under the hood indicates significant progress in reducing size/increasing density, however. A 12-V battery, for lights and accessories, is in the back.

Safety, durability testing

With the Hindenburg blimp disaster of 1937 still well known, questions of the safety of hydrogen in the tank (pressurized to perhaps 5000 psi/34.5 MPa) will arise. Hyundai performed 35 mph (56 km/h) 40% front offset and 52 mph (84 km/h) 70% rear offset crash tests—both in excess of conventional vehicle testing but deemed necessary for customer assurance.

The Tucson-based FC has been tested for up to 140,000 mi (225,000 km) and the company reports just 15% power degradation. The FC stack was validated for cold-weather performance in an environmental chamber at -4°F (-20ºC), also in Korean mountains at -2.2°F (-19ºC). It was evaluated at up to 117⁰F (47.2°C) in 0-20% relative humidity in Death Valley, CA, and passed a Hyundai hot-weather, high-load test in a 20-min drive up a 6% upgrade. Earlier-stage fuel cells were very temperature-sensitive, but that's nearly a non-issue today.

Honda's long experience

Honda, which has promised its new FC for 2015, has long industry experience, having leased a small number back in 2002, and its last generation, named the Clarity, continues to be available (perhaps two dozen in U.S. use). The new Honda FC is a highly styled car, but as with the Hyundai the complete package (stack, controls, and electric motor) is under the hood, thanks to a 33% reduction in stack size. There is no announced lease price, although it's likely to be competitive with pricing for the Tucson FC and its own Clarity, and it will also include maintenance, roadside assistance, and fuel.

The striking feature of the forthcoming Honda is surely its aero styling—even more futuristic than the Clarity. The current model packages the FC stack down the center ("transmission tunnel " in a conventional rear-drive car). Inasmuch as Honda has entered into a technology agreement with General Motors, the FC storage system also might be shared, to provide economy of scale for a 2020 time frame. However, it was emphasized by Tetsuo Iwanura, CEO of American Honda, that the company is "developing our own" overall FC system.

Toyota's FC concept—not yet shown in the U.S.—is, like the Honda, an aero-shaped sedan. However, it packages the stack in the underbody, the motor and controls under hood. The system also is rated at 100 kW.

Refueling infrastructure, pricing

The big question for hydrogen has been the refueling infrastructure, in a country that already has infrastructures for fuel (gasoline/diesel) and electricity. A comparable infrastructure for high FC volume is a long way off, effectively limiting the geographic reach. Honda has been working with Toshiba, its fuel-cell supplier, and a Japanese home builder on a system to use household natural gas to produce the hydrogen, but the project reportedly is not nearly ready.

Hyundai is refueling its prototypes at an Orange County Sanitation District sewage-treatment operation, where methane byproduct is used to produce hydrogen. Although California has announced a project for 100 hydrogen refueling stations by 2024, government-sponsored projects have a history of slippage en route to completion. So for an FC vehicle to truly eliminate range anxiety, developing that infrastructure is as important as reducing vehicle production cost to mass-market level. Any significant number of FC vehicles likely would require producing hydrogen with natural gas, a process estimated by the U.S. Department of Energy at a cost per kilogram (equal to a gallon of gasoline) of $3.67 to $4.49. Those figures cover compression, storage, and pumping, and vary with cost of the natural gas, but don't include federal, state, or local taxes.

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