With Teutonic pragmatism, BMW opted for working, roadworthy models by going the flexi-fuel gasoline-hydrogen ICE route instead of the fuel-cell stack technology exemplified by the Honda FCX, the Daimler Chrysler F-Cell, and the Ford Focus FCV. Like Daimler Chrysler, BMW decided to employ a proven production model, its flagship 7-series luxury saloon.
A full tank amounts to 8 kilograms of liquid hydrogen kept at minus 253 degrees Celsius in a dual-wall, stainless steel tank insulated by high vacuum and aluminum foil. When low on hydrogen, a driver merely has to push a button to effortlessly shift to normal gasoline-fed ICE driving.
Going the flex-fuel route does have the benefit of leveraging all current expertise in engine production. Wankel did the same with the rotary engine. But the key rationale is that hydrogen combustion is far more efficient than burning it in power plants to produce the electricity that will charge electric car battery packs. And to pre-empt criticism that hydrogen production itself releases greenhouse gases, BMW proudly divulged that solar power is used to convert water to hydrogen gas and compress it to a thousandth of its normal volume.
Doubtless, the emission reduction achieved by the Hydrogen 7 will create the most fanfare in the “Clean Energy” PR roadshow. CO2 emissions are virtually nonexistent, amounting to 1 percent of American and European ceilings. In turn, nitrous oxide discharge is just one-third of the maximum permissible in the United States; BMW revealed, however, that a pure-hydrogen model coming down the R & D pipeline will slash N2O to less than 10 percent.
BMW therefore had reason to be confident in being the first luxury performance sedan maker to demonstrate a public and sizeable commitment to hydrogen by handing over the 100 road-ready Hydrogen 7’s for test drives by media, government officials celebrities, motoring writers and other opinion leaders. The campaign, dubbed “Clean Energy” (“Efficient Dynamics” in North American markets), is meant to draw support for hydrogen hybrid R & D and, ultimately, lower sticker prices closer to today’s mainstream gasoline internal combustion engine (ICE) vehicles.
The principal trade-off in the production test of Hydrogen 7 is the extra weight – amounting to 550 pounds – brought on by the hydrogen tank and heat exchangers. Driving at high speed, say over 100 MPH, the saloon does feel like one is carrying three fairly hefty passengers. However, the 260 horses churned out by the V-12 engine still have plenty of power. Even carrying a passenger or two, the Hydrogen 7 takes less than 10 seconds to go from a standing start to 60 MPH.
All in all, the Hydrogen 7 is “The Ultimate, Now Cleaner, Driving Machine”