Feature: A short drive in the BMW Hydrogen 7

September 9, 2008

BMW Hydrogen 7. Click image to enlarge

Manufacturer’s web site

BMW Canada

Review and photos by Jil McIntosh

Imagine a vehicle that performs the same as your gasoline car, but sends nothing more harmful than water vapour out its tailpipe. Does it sound too good to be true? Some people believe it is; others, like engineers at BMW, think it’s the way of the future, and they say they’ve got the car to prove it.

The car is the Hydrogen 7, and the automaker recently brought several of them to Canada for journalists to drive. They’re part of a fleet that the company is testing, including giving them to high-profile drivers to use in their daily activities, ranging from car collector Jay Leno to opera singer Placido Domingo. These models are actually the sixth generation of BMW hydrogen vehicles, and the first hydrogen car in the luxury class to pass through the standard development process for volume production. But don’t run down to the dealer to trade in your 3 Series just yet: while these cars work, and work very well, it will be a long time before hydrogen vehicles become a daily reality, if they ever get there at all.

BMW Hydrogen 7. Click image to enlarge

“This is about sustainable energy, air pollution and global warming,” said Jason Perron, an engineer with BMW’s Clean Energy Project. “Fossil fuels are finite, and there are geo-political issues surrounding them. Energy independence is important, and this is the direction we are taking. We feel that the internal combustion engine still has a future, especially with renewable fuels like this one. We expect a future with all types of vehicles, such as electric, fuel cells, hydrogen and biofuel capability.”

The Hydrogen 7 is a dual-fuel vehicle with a regular internal combustion engine that burns either hydrogen or gasoline; it carries both, fuelled through separate fillers on its flank. Other hydrogen vehicles, including those currently being tested in real-world conditions by Honda and Ford, use a fuel cell that converts hydrogen to electricity, and then uses that electricity to power an electric motor that drives the car.

There are advantages and disadvantages to the systems. In its favour, hydrogen is virtually free of harmful emissions, sending only heat and water out the tailpipe (putting your hand behind the Hydrogen 7′s pipe is similar to putting it over a kettle). Unlike oil, hydrogen can be produced almost everywhere – even in your driveway, should Honda prove successful with its experimental Home Energy Station, which will produce it from the house’s natural gas supply. And a fuel cell can be combined with a plug-in electric system to produce a car that runs exclusively on batteries charged on household current, and then switches to a clean-emission system to continue driving the electric motor once the batteries wear down. One concept version of the Chevrolet Volt uses this.

But right now, the disadvantages to hydrogen are daunting, so much so that some critics say they are insurmountable.

BMW Hydrogen 7. Click image to enlarge

The price of fuel cells will have to come down considerably before they’ll be viable for consumers: Perron said they’re between $150,000 and $175,000, which is one of the reasons why BMW uses a conventional engine. Secondly, storage is a major problem: the Hydrogen 7 can only carry enough liquid hydrogen to go about 200 km (a button on the steering wheel seamlessly switches between hydrogen and petroleum at any speed, so the car overall has a range of about 700 km). And finding the fuel is almost impossible, as a network of consumer liquid hydrogen filling stations simply doesn’t exist. In order to demonstrate the vehicles in Toronto, BMW had to set up a mobile station. The Canadian National Exhibition grounds, where the presentation was made, has a hydrogen production station powered by a wind turbine, but it produces gaseous hydrogen and couldn’t be used to fill the cars.

There’s also considerable controversy over hydrogen itself, which isn’t necessarily a “green” fuel. It can be made from water, using electricity to crack the hydrogen and oxygen apart; that’s renewable if the electricity comes from water or wind turbines, or from solar panels, but many power plants are coal-fired. Today, though, hydrogen is most commonly (and most cheaply) made from natural gas, which is a fossil fuel; it can also be produced from other sources such as biomass, methanol, coal or oil. Hydrogen is also an energy carrier, not an energy source, and there’s always a question of whether the method used to produce it requires more energy than the hydrogen ultimately provides. The production and distribution of hydrogen may be out of the automaker’s hands, but it will be a major factor in whether vehicles like these are ever a common sight on our roads.

A special mobile filling station was set up (top); The hydrogen tank sits in the trunk. Click image to enlarge

They certainly weren’t during my test-drive, and the car got more than its share of stares, although it was due almost entirely to the large decals put on the doors specifically for such events: normally, only discreet badges and the large chrome secondary filler door give any clue as to the Hydrogen 7′s alter ego. Inside, the only differences are the hydrogen/petroleum button on the wheel, a gauge in the driver information centre that indicates the remaining hydrogen, and slightly less legroom in the rear seat, which has been moved forward to accommodate the hydrogen tank. (Although the system can be fitted to any model, BMW chose its largest sedan because it could hold the largest possible tank.)

That tank mounts in the trunk, and even if it has a long way to go before it can hold enough hydrogen for everyday use, it’s certainly a marvel of engineering. To stay liquid, hydrogen must be a beyond-bone-chilling minus-250C. BMW says the tank has an insulating effect equivalent to a 17-metre-thick jacket of Styrofoam, and if it held regular ice, it would take around 13 years for the block to thaw completely. I don’t know about you, but I’m seeing a tremendous market opportunity for BMW-brand beer coolers.

A button on the wheel switches between hydrogen and gasoline. Click image to enlarge

The tank has also been extensively crash-tested – including being hit from behind by a truck – as well as dropped and shot, but the company says it has yet to rupture one (tests on the “injuries” to the crash-test dummy suggest that the tank even helps provide extra rear crash protection). Should it be necessary, an emergency system expels hydrogen through safety lines in the C-pillar and out through a vent in the roof; if the car lands on its top, there are secondary lines to a vent in the bumper. Special lock buttons on each door are hooked to sensors that continually check for hydrogen in the cabin, and should any be detected, the buttons will flash a red warning. (It isn’t hazardous to breathe gaseous hydrogen, but any spark will ignite it.) Perron says that hydrogen isn’t any more or less dangerous than gasoline, “just different.”

Driving the Hydrogen 7 is similar to driving the regular model, except that the V12 engine has been dialed back from 438 hp to 260 hp to run smoothly on both fuels. It also takes longer to crank over when it starts, because it’s purging the system, and there is a slight clattery noise when it switches from one fuel to the other, because the port injection system lacks sound insulation (it’s inherent to this particular engine, not to hydrogen itself). Overall, it’s business as usual behind the wheel, with smooth acceleration and performance on par with a luxury sedan; only those familiar with the V12′s regular rocket acceleration will notice any difference. It’s tough to give an exact figure because hydrogen is measured in kilograms, but the engineers estimate that the car averages the equivalent of 13.0 L/100 km on hydrogen, which is about what the regular 760Li gets on gasoline.

The filler clamps securely to the vehicle (top); BMW says the filling system may one day be completely automated. Click image to enlarge

Fuelling it up is another story. The hose clamps to the car’s filler neck, purges the system, and then dispenses the liquid hydrogen. At the temporary station, it takes between six and eight minutes to go from empty to full; at permanent stations, which BMW has available in Munich, a cryo-pump pushes the fuel in, requiring only three to four minutes. The company says that the fuelling process can be done by the driver and doesn’t require a trained attendant, such as with propane; in future, stations might be completely automated, with hoses that find the filler necks and fuel the car without the driver getting out from behind the wheel.

But if such a service station is still in the future, so is the car it will eventually fill. BMW is already looking ahead: its next hydrogen vehicle will be a version of the new X6. And it’s not the only one, as the U.S. Department of Energy recently announced up to US$15.3 million over the next five years for hydrogen storage research and development, part of an overall US$1.2 billion the government has committed to hydrogen fuel cells. Perhaps one day you might put a fuel made from water into your tank, and get the same back out from the tailpipe. But don’t give up your gasoline card just yet.

Review by Chris

Posted on September 9, 2008 by Chris

September 9, 2008

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