BMW Hydrogen 7
Reed Saxon  /  AP file
The BMW Hydrogen 7 sedan, which runs on both hydrogen and gasoline, is unveiled at the L.A. Auto Show last November.
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updated 12/15/2006 10:31:57 AM ET 2006-12-15T15:31:57

America is about to receive the most advanced, greenest and surely the most expensive production-ready BMW in the world, valued at about half a million dollars. If you’re one of the select few to be deemed worthy by BMW, it’ll be loaned to you for free.

An overflowing money clip — on its own — won’t grant a shot at one of the six-week to six-month “leases” BMW will offer on 25 to 30 BMW Hydrogen 7 sedans — all of which are prototypes, not actual production cars — that arrive in the U.S. this spring. Each one will be entrusted to a carefully chosen politician, scientist, business leader, media member or celebrity who BMW thinks can best champion hydrogen as an alternative fuel for the masses.

A total of 100 Hydrogen 7 sedans will be distributed worldwide to countries in Europe and Asia in addition to the U.S. In Europe, interested parties qualified by BMW must lease the car for an amount still to be determined (laws in the U.S. prevented leasing arrangements and so BMW offers the Hydrogen 7 for free). BMW hopes to start selling hydrogen-powered 7 Series sedans in the U.S. by 2020 and roll out the technology on other models thereafter.

The Hydrogen 7 looks nearly identical to the top-of-the-line BMW 760Li ultra-luxury sedan on which it’s based, complete with a 6.0-liter 12-cylinder engine and all manner of pampering amenities. The massive engine, whose power output has been curtailed for better efficiency, was used to showcase the idea of environmentally responsible performance.

BMW has temporarily circumvented the lack of hydrogen in fuel form by making the Hydrogen 7’s internal combustion engine capable of running on gasoline, in addition to hydrogen, with a fuel tank for each. The car can drive about 435 miles with both tanks full — 124 miles on hydrogen alone.

The only emission when running on hydrogen is water vapor, making hydrogen theoretically more environmentally friendly than other alternative fuels and fuel-saving technology. “The public often sees hydrogen and hybrids in the same way, as green vehicles,” said BMW’s director of traffic and the environment, Dr. Klaus Scheurer. “But hybrid technology alone does not solve the problem of sustainable mobility.”

Gasoline/electric hybrids, while a huge leap in the right direction, still use non-renewable gasoline and create exhaust emissions that are harmful to the environment by virtue of their internal combustion engines. Even alternative fuels such as biodiesel, ethanol and natural gas pollute the environment when burned as fuel. But just looking at tailpipe emissions — such as the water vapor produced from hydrogen-powered combustion engines or fuel cells — isn’t enough: Assessing the total environmental impact must encompass the manufacturing of hydrogen, as well, which often requires non-renewable resources, such as natural gas or petroleum, to produce.

Broader fuel debates aside, BMW’s Hydrogen 7 is a marvel. From behind the wheel, the large sedan is as quiet and refined to drive as BMW’s standard 7 Series model, perhaps even more so, with an almost dead silence at idle. There’s a slight click when hitting the steering-wheel-mounted button that shifts the engine’s fuel source from hydrogen to gasoline. A gauge shows when the vehicle is in hydrogen mode. Power is an adequate 260 hp, down from 438 hp in the 760Li, while torque is fine if not overwhelming at 287 pound-feet.

The Hydrogen 7 accelerates to 62 mph in 9.5 seconds, but the hydrogen mode provides substantial low-end power that makes the car feel faster than that, if not as fleet as either the V8 or V12 gasoline versions of the 7 Series.

Filling the car up with liquid hydrogen is done in a normal way, at a fuel pump, which is one of the reasons hydrogen in liquid form was chosen, Scheurer said. A robust Formula One-style, two-handed hose is used in refueling, because the hydrogen is cooled to minus 253 degrees Fahrenheit to give it more energy density.

BMW’s approach to using hydrogen in liquid form is unique in the auto industry; other manufacturers working with hydrogen have all gone to fuel cells powered by gaseous hydrogen. Having made no official announcements as to when it would start producing and selling vehicles that run on liquid hydrogen, BMW looks to get its cutting-edge technology out there as soon as possible as a bridge to the distant zero-emissions future, while retaining necessary logistical links to current gasoline infrastructure.

In opting to develop vehicles fueled by liquid hydrogen, BMW appears to be a green maverick, tackling the many unique storage, refueling and transportation issues that arise with liquid hydrogen.

Pierre Gauthier is hydrogen director for Air Liquide, the French energy giant that sells hydrogen in both liquid and gas forms in North America. It’s used for mainly industrial applications now, but the company is pushing fuel retailers in the United States and Canada to take the lead from their European counterparts and open a hydrogen aisle in current refueling stations.

“The availability of fueling is really an issue with the retailers,” said Gauthier, who says his company is ready to provide hydrogen for vehicles either in gaseous or liquid form — however retailers like Shell want it. Right now, he says, these retailers are leaning toward hydrogen gas, which could complicate BMW’s liquid hydrogen hopes.

“BMW is using liquid, but the other (manufacturers) are on board with gas,” Gauthier said. “As far as we’re concerned, both can be done, and done now.”

The issue of creating infrastructure for hydrogen as a fuel, as well as creating the fuel itself, is a huge hurdle, but there are still other technical issues to overcome. The most significant with BMW’s Hydrogen 7 — and company officials admit it’s a big one — is that there’s no way that any system can maintain the extremely low temperatures necessary to store the liquid hydrogen while the car is shut off and parked. Half of the liquid hydrogen in the BMW Hydrogen 7’s tank burns off per week when the car is turned off and parked between drives — a phenomenon called “boil off.”

“If you’re parked for two weeks’ vacation, when you come back you won’t have any hydrogen left,” Gauthier said.

Still, both Gauthier and BMW say there are viable ways to reduce boil off, just like other manufacturers are working to get the cost, size and weight of their hydrogen fuel-cell vehicles down.

All of these issues conspire to push the hydrogen age out a decade or more. “2015 to 2020 is what everyone is saying,” Gauthier said. And he’s the first to admit that’s still only an educated guess.

© 2013 Forbes.com

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