BMW Hydrogen 7
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| BMW Hydrogen 7 | |
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| Manufacturer | BMW |
| Class | Executive car |
The BMW Hydrogen 7 is a limited production hydrogen vehicle built by German automobile manufacturer BMW. The car is based on BMW’s traditional gasoline powered 7-series line of vehicles, and more specifically the 760Li. It uses the same 6 litre V-12 motor as does the 760i and 760Li; however, it has been modified to also allow for the combustion of hydrogen as well as gasoline, making it a bivalent engine. Unlike many other current hydrogen powered vehicles like those being produced by Honda, General Motors, and Daimler Chrysler - which use fuel cell technology and hydrogen to create electricity to power the vehicle - the BMW directly ignites the hydrogen in its internal combustion engine.
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[edit] Production
BMW claims the Hydrogen 7 is the “world’s first production-ready hydrogen vehicle”; thus far, the Hydrogen 7 has only been released to select high-profile lessees. Only 100 total vehicles have been produced to put their technology to the test, and no more are planned to be produced.[1] BMW says it chose public figures such as politicians, media figures, businessmen and big names in the entertainment industry such as 2007 Academy Award-winning director Florian Henckel von Donnersmarck and the chairman of Sixt AG, Erich Sixt, because “they would be ideal ambassadors” for hydrogen fuel and can help spread awareness of the need for such technologies.[2]
There is doubt, however, over whether or not this automobile will ever be put into larger production, even if hydrogen fuel technology reaches the point of economical and “green” feasibility, as well as to have the infrastructure required to put hydrogen vehicles in demand. The Hydrogen 7 uses more fuel than many trucks (it gets only 16.9 mpg for gasoline on the highway) and is not as green as it may seem.[3] It will also only be more expensive than its sister the 760Li (no retail price has been announced), which is BMW’s biggest and most expensive sedan, with a base price tag of over $118,000, thus further diminishing its widespread appeal. As of November, 2006 there were only five filling stations in the entire world that supported BMW’s filling technology, furthering the obstacles of making this car worthwhile.
[edit] Use of hydrogen technology
The BMW Hydrogen 7 uses hydrogen as fuel differently from fuel-cell-type vehicles. When in hydrogen mode, it injects the hydrogen directly into the car’s air intake manifold (similar to nitrous oxide injection) to be combusted in the engine’s cylinders rather than converting the hydrogen’s energy into electricity to spin electric motors like a fuel cell. BMW says this is a more efficient use of the hydrogen[citation needed]. The car can also switch seamlessly between hydrogen and gasoline at the touch of a button on the steering wheel, and of course will do so automatically when one of the fuels is consumed.
The hydrogen fuel is stored in a large, nearly 30-gallon, bi-layered and highly insulated tank that stores the fuel as liquid rather than as compressed gas, which BMW says offers 75% more energy per volume as a liquid than compressed gas at 700 bars of pressure.[4] The hydrogen tank’s insulation is under high vacuum in order to keep heat transfer to the hydrogen to a bare minimum, and is purportedly equivalent to a 55-foot thick wall of polystyrene Styrofoam.[5]
There is still a downside to the use of liquid hydrogen, however. To stay a liquid, hydrogen must be super-cooled and maintained at cryogenic temperatures of, at warmest, -253°C/-423°F. When not using fuel, the Hydrogen 7’s hydrogen tank starts to warm and the hydrogen starts to vaporize. Once the tank’s internal pressure reaches 87 psi, at roughly 17 hours of un-use, the tank will safely vent the building pressure. Over 10-12 days, it will completely lose the contents of the tank because of this.[6]
[edit] Specifications
The car is powered by a 6.0 liter V-style 12-cylinder engine capable of running on both premium gasoline and hydrogen fuel. It is rated at 191-kilowatt (260 PS/256 hp) and 390 N·m (290 ft·lbf) of torque using either fuel.[7] The car accelerates from stopped to 100 km/h (62 mph) in 9.5 seconds. The hydrogen fuel tank holds roughly 8kg of hydrogen, enough to travel 125 miles. The gasoline fuel tank holds 19.5 gallons, enough to travel 300 miles for a combined total of over 400 miles at cruising speeds. The Hydrogen 7 gets about 4.7 miles per gallon on hydrogen (by comparison Honda's FCX Clarity gets 81 (eighty one) mpg][8]) and 16.9 mpg on gasoline. The curb weight of the Hydrogen 7 is roughly 550 pounds heavier than the 760Li, bringing it to about 5100 pounds. [9]
[edit] Notes
- ^ BMW EfficientDynamics : BMW CleanEnergy : BMW AG
- ^ Coming soon: Hydrogen-powered BMW
- ^ BMW's Hydrogen 7: Not as Green as it Seems
- ^ Road Testing BMW's Hydrogen 7
- ^ BMW Hydrogen 7 Prototype concept car from the Los Angeles Auto Show
- ^ Road Testing BMW's Hydrogen 7
- ^ BMW's Hydrogen 7: Not as Green as it Seems
- ^ Honda FCX Clarity: Car of the century?
- ^ Road Testing BMW's Hydrogen 7
