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Hydrogen powered 7 series
2007 BMW Hydrogen 7
Hydrogen-powered 7-series will be leased to U.S. government agencies in 2007.
By Steve Siler & Dave Vanderwerp, October 2006
Automotive evolution can be a bittersweet process: while we break out the bubbly to celebrate the latest safety, emissions controls and creature comforts, such progress seldom comes without a price, usually in the form of sterilization of our favorite cars, sometimes our favorite brands.
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So not only is BMW’s announcement that it is only about a year away from marketing a vehicle that can run on liquid hydrogen, but is it is with great relief that said vehicle is, for all intents and purposes, a plain old 7-series. The hydrogen-powered 7-series prototype you see here (creatively named “Hydrogen 7”) signals that the folks in Munich aren’t planning to do things much differently as the future of hydrogen-powered automobiles become clearer.
Two fuel systems, one 12-cylinder engine
Powering the Hydrogen 7 is a 256-hp 6.0-liter V-12 (the same engine in the 760Li makes 438 hp) with a “dual-mode drive system” that allows it to tap either its 19.5-gallon gasoline tank or a 17.6-pound liquid hydrogen tank for its juice. The driver can switch between fuel sources via a dashboard switch; if one tank runs empty, the system will automatically switch to the other. This complex switching involves not just separate tanks, but unique delivery channels and an additional network of valves in the cylinder head. The hydrogen tank carries enough liquid hydrogen for 125 miles of squeaky-clean motoring, with the gasoline tank good for another 300 miles.
That’s all nice, but at the end of the day, we want to know if it’s still a BMW. The 7-series isn’t light to begin with and saddled with an undisclosed amount of additional weight, the V-12 is said to deliver its driver to 62 mph in a leisurely 9.5 seconds, regardless of which fuel is being used. That’s some four seconds off the pace of a 360-hp 750Li. Top speed is electronically governed at 143 mph.
The regular 7-series is certainly a natural fit to anyone wanting to showcase cutting edge automotive technologies (always has been). But in this case, it literally was a good fit for the numerous hydrogen-related components that had to be installed without cramping the occupants. From what we can tell, the installation was seamless. That said, we somehow think they gave it a four-passenger layout for a reason.
The BMW spokesperson we spoke with suggested that the technology is relatively scalable for application in vehicles of other size categories, although we expect that a hydrogen-drive system in something like a Z4 might have some sort of an impact on interior space.
But does it really help the environment?
Pure hydrogen contains no carbon, so combustion produces no unburned hydrocarbons or carbon monoxide, and BMW says the engine is calibrated to avoid the production of oxides of nitrogen as well. While liquid hydrogen is the densest form of the fuel, keeping it at the required 420 degrees below zero in the on-board storage tank is expensive and difficult. Plus, getting a pound of hydrogen into its liquid form takes roughly six kilowatt hours of electricity. If that electricity comes from a coal-fired plant, it creates as much carbon dioxide as burning half a gallon of gasoline (which contains the same amount of energy as that pound of liquid hydrogen).
So it certainly isn’t the silver bullet, and it may just be an extremely expensive technology that has no positive effect on emissions. Using hydrogen in a fuel cell to produce electricity extracts far more performance from the fuel than do internal-combustion engines.
Still, the Hydrogen 7 is a sign that a green future certainly won’t be a dull future