Hydrogen Power: Live

What is the future of the hydrogen-powered car? If you ask BMW, the future is now. As we told you in the previous installment of our two-part feature, there are good reasons for the vaunted German technology company to feel that way. After all, hydrogen is abundant, and pound for pound, it packs more energy punch than most other fuels. Further, when used as a fuel, it produces only clean water vapor and no "greenhouse gases." What's not to like?

Unlike many car manufacturers, though, BMW doesn't think that hydrogen power should be viewed as an exotic technology for the far-distant future. In fact, the company has built a string of hydrogen-powered 750hL luxury sedans to prove that premise, and those sedans are in the midst of what it calls the CleanEnergy WorldTour that will eventually conclude in Berlin after visiting four continents.

Lest you think that the world tour is just a quickly planned publicity stunt, the BMW Group has worked very hard for more than 20 years to obtain what many believe is its international lead in hydrogen technology. Over the course of those 20 years, BMW engineers not only gained expertise in hydrogen-powered engine technology, but also in the extraction, fuelling and storing of hydrogen. Actually, those final three issues are harder to perfect than using hydrogen as a fuel for the internal combustion engine.

Interestingly, while others are looking at hydrogen fuel cells to power future vehicles, BMW seems ready to stick with a more conventional engine technology.

"We place our bets on the internal combustion engine, because we are convinced that our customers will attach great importance to range, dynamic performance and comfort in the future too," said Dr. Burkhard Göschel. "However, we want to cooperate with the other automobile manufacturers on the topic of alternative drive. We have a common aim, which is the Zero Emission Vehicle. And both thinkable solutions, the electric car powered by electricity from a fuel cell as well as our vehicle with spark ignition engine, have the main thing in common: hydrogen as the source of energy."

While others just talk about hydrogen, BMW has built a small fleet of hydrogen-powered cars, and they are about as far from Buck Rogers as you can get. The truth is they seem so much like current BMW 7-Series luxury sedans that it is hard to tell them apart. Running on hydrogen, the 12-cylinder engine delivers 204 horsepower, and the biggest difference between the hydrogen engine and a conventional BMW 12-cylinder is the intake system that features additional injection valves for the hydrogen. (The 750hL's are configured to run on gasoline as well, since hydrogen is not readily available yet.)

The hydrogen-powered car accelerates from standstill to 62 mph (100 km/h) in 9.6 seconds and achieves a top speed of 140 mph (226 km/h). It has a range of more than 200 miles on a hydrogen fill-up.

The most exotic aspect of the 750hL may well be the 140-liter "Cryo" fuel tank. The hydrogen is stored cryogenically (in super-chilled and liquid form) at minus 250 degrees Celsius in a double-walled steel tank behind the rear seatbacks. Two safety valves ensure controlled ventilation in case of excess pressure.

Because hydrogen can be extremely volatile, the BMW engineers have worked long hours on ensuring the storage system is safe. Numerous crash tests have shown that even in the case of a massive rear-end collision, the tank's steel cylinder with its double walls will not leak. Not leaving anything to chance, the BMW engineers say the tank cannot explode even in very severe crashes "that would leave very little chance for occupant survival." For an explosion to occur, they assure us, hydrogen and air would have to mix but due to the higher inner pressure of the hydrogen, air cannot enter the tank. The 750hL's also feature hydrogen fuel cells in place of typical lead-acid batteries to power accessory items.

These demonstration vehicles are all part of BMW's design, said Goschel, "that BMW will be the first automobile manufacturer in the world to offer series production hydrogen cars." It could happen as soon as 2005.

A native of Boston, Tom Ripley reports on automotive and technology issues from his home in Villeperce, France.