German Car Zone

Road Testing BMW's Hydrogen 7



By Bruce Gain| Also by this reporter
02:00 AM Nov, 13, 2006


BERLIN -- Jules Verne, in his 1874 novel The Mysterious Island, described hydrogen as an "inexhaustible source of heat and light." A little over 130 years later, BMW is testing the theory with an innovative internal combustion engine that burns the lightest element much like gasoline, only cleaner.


Wired News was invited to test-drive one of BMW's new Hydrogen 7 automobiles recently. It proved a serious step forward in using hydrogen as a potential energy source for cars, while showing defects that make the concept a clear work in progress.
BMW is the only major carmaker to bring a car with a hydrogen-combustion engine beyond the prototype stage.


The automaker's approach is markedly different than the more familiar concept of hydrogen-powered fuel cells, where energy is stored before it is converted into electricity. By contrast, BMW's Hydrogen 7 is powered by pumping hydrogen into a combustion engine and igniting it. The engine can burn both hydrogen and gasoline, and switches between the two at the flick of a switch.


Burning hydrogen is more efficient than converting it into electricity, making it the more practical choice for hydrogen-fueled cars now, according to BMW.
The automaker is taking that premise to the road with a limited test release next year. BMW said it will put 100 of the hydrogen models into circulation in the United States, Europe and Asia. The cars will be loaned to high-profile people, BMW says, such as celebrities and politicians. If the cars become sufficiently popular, BMW says it can go into full-scale production, without commenting how much the model will cost.


The test drive confirmed the vehicles are road-ready. But some major issues need to be worked out, particularly with acquiring and storing the liquid hydrogen fuel.
At 110 mph along the highway on the outskirts of Berlin the sedan handles much like the German luxury carmaker's flagship BMW 7 Series model, on which it is based. In total, the liquid hydrogen tank, heat exchangers and other components add an extra 550 pounds to the car's weight -- and you feel the extra load. However, performance was not drastically different than the 7 Series BMW.


When pushed, the 12-cylinder, 260-horsepower engine emits a high-pitched whine like that of the diesel version of the 7 Series. It is not exactly a speed demon, but it doesn't lack power; after pulling onto an exit ramp, I accelerated from zero to 62.5 mph with two adult passengers in less than 10 seconds.
The car switches from hydrogen to gas mode with the press of a button on the steering wheel. I heard a small click from behind the backseat without any change in my speed or acceleration along the highway.
BMW's first hydrogen-powered car has a lot to be excited about. The byproduct of the engine's combustion process is almost exclusively water vapor, which comes out of an exhaust pipe. However, some nitrous oxide and carbon dioxide are emitted, so the Hydrogen 7 is not a zero-emission car.


CO2 emissions are 1 percent of the maximum emission levels in the United States and Europe, while N2O levels are 30 percent and 2 percent of the maximum levels in those same regions, respectively, BMW says. A planned hydrogen-only model will further reduce N2O emissions to within 10 percent of the maximum levels in the United States, BMW says.


One major challenge is how to keep the hydrogen cooled to minus 253 degrees Celsius (minus 423 degrees Fahrenheit) so it remains in liquid form without boiling off. Despite the double-walled, stainless-steel tank that stores the liquid in high-vacuum conditions with aluminum reflective foil, the liquid hydrogen in the 8-kilogram fuel tank begins to boil after 17 hours if the car remains parked. The tank empties completely after 10 to 12 days.
During the test drive, I pulled over to a Total hydrogen filling station to tank up.


The BMW Hydrogen 7 holds approximately 8 kilograms of liquid hydrogen. The car consumes about 15 miles per kilogram for a total cruising range of 120 miles, BMW says. In gas mode, the car's 74-liter (19.5-gallon) gasoline tank offers a range of about 300 miles.
At $10.30 per kilogram, hydrogen fuel is no bargain, even in Europe, where gas prices are significantly higher than in the United States. Filling up a 74-liter gas tank in Germany with high-test gas costs about $123, which for a cruising range of 300 miles is a much better deal than $82.40 you'll pay to go 120 miles on hydrogen fuel. The price of hydrogen is astronomical compared to the $2.20 or so per gallon price in the United States. However, BMW representatives on hand for the car demonstration in Berlin last week said hydrogen pump prices should be significantly lower if production increases for use as car fuel.


Hydrogen's high flammability, compared to other fuel mixes, raises concern for many (especially for me while standing next to the fuel pumps). The Hindenburg and the Challenger both ran on hydrogen, although the fuel mix was not what triggered those disasters. According to BMW, the risks posed by hydrogen are at the very worst comparable to those of gas. At the fueling station, sensors will shut down fuel flow from the pumps if a leak is detected, while the car's engine and hydrogen gas flow will also stop in case of a puncture or leak, BMW says.


Hydrogen is primarily produced from natural gas, a process that generates more CO2 than gasoline car engines. However, solar, wind and hydroelectric generation of hydrogen and its extraction from biomass represent viable long-term options that promise negligible CO2 emission, BMW says.


The automaker concedes its Hydrogen 7 production car is just a start. The model's acceleration and mileage pale in comparison with many ethanol-fueled and gas-electric-hybrid models, such as the latest Lexus hybrid. Company engineers are working to introduce lower pressure in the fuel tank to limit how fast the liquid hydrogen boils off. And they're researching new materials for a lighter and less bulky fuel tank.
The dearth of fueling stations will hamper drivers who need to fill up in the middle of places like Kansas. For the 100 Hydrogen 7s in operation next year, BMW says hydrogen filling stations will be located in the vicinity of where the cars are loaned, albeit probably fewer than 12 worldwide in 2007. Hydrogen trucks will offer mobile fill-ups for the loaned cars, BMW says.


Ultimately, BMW engineers hope to develop an engine that offers acceleration and power comparable to any gasoline internal-combustion engine vehicle. To do that, BMW says it is developing a hydrogen-only internal-combustion engine that will produce 95 kilowatts of power per liter instead of the 32 kilowatts per liter now in the Hydrogen 7, with direct, cryogenic injection in a pure hydrogen tank. On a per-volume basis, cryogenic liquid hydrogen offers 75 percent more energy compared to hydrogen in a compressed gaseous state at 700 bars of pressure, BMW says.


"This will take some time," said Frank Ochmann, head of the Hydrogen 7 project. "We will have (this capability), but the question is when we make the decision to do it."



Source: WiredNews

Cool article... but it shows you that we aren't ready for this technology yet. I didn't know all the hydrogen burns off after only 17 hours of being parked. Not exactly convenient.

Awsome post! Thank you very much.

It doesn't burn off but starts to boil. The tank will get empty in 10-12 days assuming zero driving during that time.

Can it be used to make a cup of latte?

In the other thread Osna asked if it can be used for making tea... But for your question the answer is "no". There is however one extremely expensive espresso machine called Zonda (or something like that) and it is made by famous coffee machine emperor Don Pagani.

If you're talkinga bout when Hydrogen boils it's at an increadably cold temperature - so no. (Thanks for remembering my tea bit bmer)

Great article. I'm very hopeful that Hydrogen technology, presumably along with extraction powered by nuclear energy, will pave the way for a zero-emmission future that doesn't suck.

In 100 years I hope that cars will use nothing but hydrogen and fuelcells.
Can the Zonda make espresso?

No problem, mate! Actually making tea could in theory be possible when the car runs on hydrogen. That's by using the 200 degree celsius water vapour (I think they said 200 C in Autobild test) coming out of the exhausts.

"What is it?



"Ostensibly, a BMW 7-series – a 760iL, specifically – engineered to run on either ordinary unleaded petrol or liquefied hydrogen. When burning the latter, it emits only water vapour and trace amounts of nitrogen dioxide and harmful particulates. That, says BMW, makes it the world’s first super-low-emissions luxury vehicle, and a totally sustainable means of personal transport.



So what have Munich’s engineers done to this symbol of conspicuous consumption to turn it into a potential climate-saver? Well, surprisingly little. Externally, the Hydrogen 7 is identical to a long-wheelbase 7-series but for its 'Hydrogen' badging and slightly tweaked rear valance styling.

Under the bonnet is where you’d expect most of the hard work to have been done, but actually BMW hasn’t had to do that much to its 6.0-litre V12 to make it accept hydrogen as readily as it does unleaded. It runs a slightly lower compression ratio than the standard V12, has a hydrogen injection system and an aluminium-lined induction system specifically designed to deal with the fuel. Otherwise it’s unchanged, and knocks out a steady, if slightly underwhelming 256bhp whether it’s running on petrol or hydrogen.



Where you won’t fail to identify this Seven from an ordinary 760iL, however, is when lifting the bootlid. This is where BMW has accommodated the 165-litre aluminium tank necessary to store the liquid hydrogen for the engine, and that gives the car a 120-mile hydrogen range, on top of its 300-mile petrol range. The Hydrogen 7 does have a boot, but it’s greatly reduced in size – and there’s four inches less legroom in the back than in any other long-wheelbase Seven – another compromise made for the hydrogen tank.


So what's it like?
Once it’s started up, so well-insulated is this car’s engine that you really wouldn’t know it was turning over at all, let alone be able to identify the fuel it’s burning. On the road, it’s not the most convincing exponent of BMW’s "ultimate driving machine" philosophy, and that’s because it weighs 250kg more than standard car as well as being less powerful. Performance is acceptable, though; 0-62mph taking just over nine seconds. Top speed is limited to 143mph.



BMW’s real achievement here is one of refinement rather than outright performance. When running on hydrogen, the Hydrogen 7 delivers its power just as freely and responsively as it does on petrol – and that’s a considerable success when you consider that hydrogen burns 10 times as quickly as petrol, and is therefore much more difficult to control during combustion.

You can switch from one fuel to another while the engine is running at the touch of a button on the steering wheel; there’s a momentary interruption in drive, but nothing more intrusive than a gearchange might otherwise be. And although the engine takes on a more hard-edged induction note when it’s consuming hydrogen, it remains as refined as most diesel engines, even at high revs.

Should I buy one?
Well, you can’t. BMW is only making 100 Hydrogen 7s, and will retain ownership of every one. If you’re a forward-thinking captain of industry or an environmentally-aware celebrity, you might be offered the chance to lease one for a few months – but the rest of us will have to continue to drive fossil-fuelled cars for the time being.

That's not such a bad thing, of course, because only a handful of filling stations in continental Europe sell the liquefied hydrogen needed to run the car. Even if they did stock the right stuff, it'd cost you three times as much to run your BMW on it right now as it would ordinary unleaded. Worse still, since that hydrogen would probably be extracted from natural gas rather than from renewable sources, you'd actually be doing more harm to the environment by doing so than you would by burning the equivalent petrol in your tank.

Nevertheless, BMW should still be congratulated. The Hydrogen 7 is a fully homologated and type-approved production car; as such it's been put through every relevant crash and stress test, and proves that hydrogen-powered cars can be made safe for our roads, produced in the same factories as any other car, and can provide levels of performance and refinement that are within touching distance of their petrol-powered siblings. The rest of the world may not be ready to accept it, but BMW certainly seems ready and able to make a near zero-emissions car.

Matt Saunders"

How much?
Price when new TBA
Price as tested £150,000

How fast?
0-62mph 9.5 sec
Max Speed 143 mph
How thirsty?
Combined 20.3 mpg
CO2 emissions 332 g/km

How big?
Weight 2460 kg

Engine
Layout V12, 5972 cc
Max power 256 bhp at 5100 rpm
Max torque 287 lb ft at 4300 rpm