DETROIT - Gasoline- or methanol-powered fuel cells may be a hot technology, but researchers at BMW are cold to the devices.
'We are not so optimistic about fuel cells,' says Christopher Huss, director of BMW's environmental research and traffic activities.
'We are in contact with each fuel cell company, and we have come to the conclusion that the unknown price, the unknown manufacturing technology, and the unknown cleanliness of fuel cells means it could take more years to predict when they will be suitable for automobiles,' he said.
Fuel cells convert hydrogen to electricity while emitting harmless water vapor and carbon dioxide. If methanol or gasoline is used instead of pure hydrogen, it must be reformed in a complex process that produces other unwanted byproducts.
That is one reason BMW is leaning toward liquid hydrogen for burning in conventional internal-combustion engines, says Huss, who addressed Detroit's Automotive Press Association last month.
Super-clean emissions dominated by oxygen and water vapor make it worthwhile to solve the drawbacks of hydrogen as a fuel.
Those drawbacks are numerous. For one, liquid hydrogen must be stored at the extremely low temperature of -248 degrees Celsius and under pressure. BMW's design uses special double-walled tanks with 70 layers of overlapping aluminum for insulation. The tank pressure is kept constant to prevent the hydrogen from boiling back into a gas, while burst discs prevent pressure buildups and Hindenburg-like explosions.
BMW's latest hydrogen-powered prototype is a 7 series sedan with a 2.8-liter, six-cylinder engine. It will go into testing as a Munich airport courtesy car later this year. The vehicle will travel 250 miles on 37 gallons (100km per 34.8 liters) of liquid hydrogen, but also runs on gasoline fed from a separate tank.
The car requires an expensive refueling infrastructure with robotic pumps to avoid accidental human contact. As a liquid, hydrogen can freeze a limb to ice almost instantly. Huss says technicians initially needed one hour to refuel the car, but now have it down to three minutes. BMW plans to open its first hydrogen fuel station at the Munich airport this year. A gallon (3.8 liters) of liquid hydrogen will cost $3.70 to $5, he says.
The automaker is opposed by fuel cell advocates, who believe it would be easier to convert drivers to a new powertrain rather than a new fuel. But technology analyst Jim Hall of AutoPacific Inc. in Southfield, Michigan, believes BMW may be right.
'The hydrogen-powered car could be the way the hydrogen infrastructure gets built,' he says. 'It would probably be an easier sell in a marketing sense - all you are doing is changing a fuel. With a fuel cell, you are changing a power paradigm.'
But Huss believes the fuel industry must also use clean methods of producing hydrogen. The gas can be manufactured using solar power and electrolysis, but man-made hydrogen is mainly produced during oil refining and in special plants that add steam to natural gas.
Says Huss: 'We need to take the carbon (in fossil fuels) out of the equation.'