Hydrogen BMW 7 Ready For The Road
One of the most important vehicles that BMW will be displaying at the Mondial De L’Automobile in Paris at the end of the month probably won’t be grabbing eyes like a lime-green supercar, or a decked-out SUV concept. No, the BMW Hydrogen7 looks like a normal, long-wheelbase 7-Series, with a standard silver paintjob and no stickers. Its unadorned exterior is deceiving, however, as it’s not only one of the most advanced vehicles to debut at the show, but will be BMW’s first production hydrogen automobile, a vehicle six years in the making.
Because hydrogen fueling stations are few and far between (even in Germany), the Hydrogen7 was designed as a dual-fuel vehicle, with separate tanks for gasoline and hydrogen. The car maintains a 74-litre (19.5-gal) gasoline tank, which is good for a range of 500 km (310 mi), as well as a hydrogen tank that’s capable of holding 8 kg worth of liquefied hydrogen that has a range of 200 km (125 mi).
As its appearance might suggest, the Hydrogen7 is closely related to the 760Li long wheelbase, but there’s a reason for this. BMW chose the extended version in order to accommodate both the gas tank, as well the 8 kg hydrogen tank, which is stored in front of it. As such, 115 mm (4.5 in) of cabin space has been compromised, which makes it slightly less roomy than the standard LWB 7-Series (but plenty roomy by normal standards).
A bit more on the H2 tank that the 7 uses; it is a special fuel tank developed by Magna-Steyr, which is comprised of several sandwiched layers of high-tech thermal insulation. The reason that this is done is to prevent the liquid hydrogen from heating up and vapourizing, whereupon it cannot be used by the engine. BMW claims that the tank is so thermal efficient that a cup coffee would take approximately 80 days to cool down from boiling to a temperature that wouldn’t burn a drinker’s mouth.
Inevitably, the design is not 100-percent thermal efficient; heat does manage to penetrate the tank. When pumped in, liquid hydrogen remains at -250C (-418F), but, because the tank is not actively chilled, evaporation occurs at a rate of a half tank per nine days. Imagine leaving the 7 fully fueled at the airport, while only to come back after a week of traveling to find that half a tank had disappeared. This issue might still need a bit of work.
Aside from the engine’s adaptation to run on liquid hydrogen, which includes new injectors in the manifold, the 6.0L V12 is more or less the same as the standard motor. Running on hydrogen, it produces significantly less power at 256-hp, and 288 lb-ft of torque (versus 445-hp, 443 lb-ft). This is good enough, mind you, to give the Hydrogen 7 a 0 to 100 km/h time of nine seconds (approximately three seconds slower than the 750Li and four seconds slower than the 760Li), and a top speed of 230 km/h (143 mph).
As with the hydrogen-powered Mazda RX-8 and Honda FCX, the BMW Hydrogen 7 will be leased to selective customers, though its fleet will be capped at 100 units.
