BMW 745h. Click image to enlarge
by Tony Whitney
The recent news that General Motors is asking the U.S. government to spend U.S.$10-billion to U.S.$15-billion on hydrogen supply infrastructure is focusing attention again on this gas as an automobile fuel. According to GM, it wants to sell a million hydrogen-powered cars by the middle of the next decade.
The belief is, quite understandably, that nobody is going to buy any vehicle powered by a fuel that is not generally available. A vast infrastructure to supply gasoline and even diesel fuel is already in place in North America and it will take a lot of dislodging, even if prices keep rising and its very availability is threatened by instability in many countries that supply the fuel.
Also, vehicles powered by gasoline have never been cleaner and billions have been spent to make them so over the past 30 years or more.
As most motorists know, hydrogen is the fuel most associated with fuel cell technology, though all kinds of other fuels can be used to power these cells, which create electricity to power motors by a chemical action, rather than by a combustion process.
Even gasoline has been talked about in fuel cell applications, though many members of the public would ask what the point was, since most of the excitement around alternate fuels has been centred on hydrogen. Hydrogen is sustainable as an alternate fuel source for vehicles while gasoline is not, although world supplies seem to be in no right now danger as far as basic resources go. Most gasoline price hikes seem to be prompted by political influences, rather than supply problems.
Putting all the political implications aside, though, it’s worth mentioning that fuel cells are not the only way to use hydrogen as a vehicle fuel and many automakers have been experimenting with the gas in more conventional applications – especially BMW. Perhaps the motoring public is growing tired of being told that fuel cell vehicles are “just around the corner” only to discover that they are still very much in the experimental stage and any vehicles that are on the streets are development models farmed out for local government use on a trial basis. Each year it seems, the advent of the fuel cell age seems to get bumped along again and this has been going on for a decade.
Mini Cooper Hydrogen with internal combustion engine. Click image to enlarge
The use of sustainable hydrogen simply as a substitute fuel for gasoline could also get a boost from fuel cell delays. Any gasoline engine can theoretically be adapted to use hydrogen fuel and provide the various benefits offered by the gas in the type of vehicles we’re already driving.
It’s worth revisiting BMW’s experiments with hydrogen as a fuel for internal combustion engines – a project that has been going on for many years now. The Bavarian automaker is so convinced of the viability of hydrogen that it’s into its fifth generation test sedan using that fuel. In fact, BMW has made a serious commitment to the future of hydrogen as a vehicle fuel and is claiming that its small fleet of hydrogen-fuelled sedans are the first such vehicles in series production in the world.
I once rode from downtown Munich to the city’s airport (a lengthy trip) in a fourth generation BMW 750hL and even “filled up” at a hydrogen service station located right on the airport property. It was an interesting experience, but a common enough routine at Munich airport where many of the vehicles used around the facility, including apron buses, are hydrogen-fuelled.
BMW has been operating 7-Series hydrogen-powered sedans on a daily basis in both Munich and Hanover. When running on hydrogen, the 750hL 12-cylinder engine develops 204 horsepower, tops 100 km/h in 9.6-seconds and is capable of a top speed of 226 km/h. The car’s 140-litre cryogenic hydrogen tank gives the fully-equipped luxury car a range of 350 km. The cars are “dual fuel” units capable of being run on gasoline when needed. After all, you won’t find a hydrogen filling station on every street corner just yet.
BMW 745h. Click image to enlarge
The latest BMW hydrogen car is the 745h, which uses a 4.4-litre V-8. The only major modifications to make the big BMW’s engine run on hydrogen involve the intake ports, which have additional injector valves for hydrogen. The engines come off the same production line as other BMW powerplants and are installed in the vehicle using the same assembly techniques. BMW has also produced a concept Mini powered by hydrogen.
BMW says that its hydrogen vehicles are just as safe as gasoline-fuelled cars. The hydrogen is stored in a double-walled steel tank behind the rear seat back – resulting in some loss of trunk space. The fuel is “cryogenic,” or in an ultra low-temperature condition of minus 253 deg C. Safety has been assured by numerous crash tests. BMW points out that even in a very severe nose-to-tail collision in which the colliding vehicle reaches the hydrogen tank, the double-walled tank would not leak. Even in the severest possible crash, which would probably involve little chance of occupant survival, the hydrogen cannot explode, according to BMW.
Interestingly, the 750hL was also claimed the world’s first production car with a fuel cell and the 745h uses a similar system. The BMW hydrogen sedans have their on-board power supplies generated by a fuel cell. A compact fuel cell takes the place of the usual lead-acid battery and supplies power to the heater, air-conditioner and other ancillaries. Since the air conditioner is independent, the car’s interior can be cooled even when the engine is not running.
Hydrogen is a clean, efficient fuel and can be produced in any desired quantity from water. Combustion in the engine results in nothing but water or steam emerging from the vehicle’s tailpipe. If the electricity used in producing the fuel is generated by wind, water or solar energy, the result is an energy source that’s just about as environmentally friendly as it could possibly be. BMW’s “ideal scenario” is hydrogen produced by solar power.
Munich airport hydrogen filling station. Click image to enlarge
At Munich airport’s unique filling station, hydrogen is produced right on the premises in a facility comprising just a couple of small shipping container-sized buildings. The hydrogen is dispensed automatically using a robot arm which reaches out in response to inserting a credit card and probes for the filler location. It even lifts and replaces the “gas cap” flap.
The downside to all this is cost, though it should be borne in mind that if hydrogen was in wider use, the price per litre could drop dramatically. At the Munich airport filling station last time I checked, hydrogen costs close to 80-cents a litre and the energy density in the fuel by volume is a quarter that of gasoline. You need four litres of hydrogen to travel the same distance you would in a gasoline-powered vehicle on one litre.
BMW clearly believes that hydrogen has a big future and is certainly investing heavily in it. Even so, cars like the 745h, as with fuel cell vehicles, are some way off and the best interim answer right now is probably one of the gasoline/electric hybrids that several manufacturers already have at the dealerships.