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Experts agree that hydrogen is the only source of energy with the potential in the long run to replace fossil fuels in road traffic.

With its chemical symbol H, hydrogen is one of the components that makes up water and nearly all organic compounds, meaning that it is part of the biological cycle and therefore fully compatible with the environment.

And as the most common element in the universe, hydrogen is available for all practical purposes in virtually unlimited quantities.

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The dual-mode combustion engine powering the first series production luxury hydrogen saloon is the decisive, revolutionary new development in BMW Hydrogen 7: This muscular engine is based on the twelve-cylinder gasoline power unit displacing 6.0 litres and featuring VALVETRONIC technology in the BMW 7 Series. Maximum torque is 390 Newton-metres/ 287 lb-ft and comes at an engine speed of 4,300 rpm.

Running on gasoline, the engine operates with direct fuel injection, while in the hydrogen mode the fuel/air mixture is formed in the intake manifolds. The new injection valves developed for this purpose make the greatest conceivable demands in engine development in terms of their construction and integration. Conceived and designed for gaseous hydrogen, the valves are not only larger than conventional gasoline injection valves, but also cover a far wider variation in size and range in terms of their volume flow, operating at different levels of system pressure and at the same time with both very short and longer gas injection times required for hydrogen gas.

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The hydrogen tank in BMW Hydrogen 7 takes up approximately 8 kilos (about 170 litres or 45 Imp gals) of liquid hydrogen, the conventional gasoline tank has a volume of 74 litres or 16.3 Imp gals.

Used as drive energy, liquid hydrogen involves a particular technical challenge in the construction of the tank: Since hydrogen under normal ambient pressure has to be cooled to – 253 °Celsius in order to turn into a liquid, innovative vacuum super-insulation is required to store hydrogen fuel in the car over lengthy periods.

Hence, the hydrogen tank in BMW Hydrogen 7 has double walls with several layers of aluminium and glass-fibre in the space in between measuring 30 millimetres or almost 1.2 inches in thickness in order to avoid higher temperatures entering the tank.

The highly efficient insulating effect offered by the tank is also ensured by a vacuum in the intermediate section between the two walls avoiding any kind of airborne heat transfer. And last but not least, the mounts holding the inner tank in position are made of carbon-fibre-reinforced plastic bands reducing thermal conductivity to a minimum.

Super-insulation is a very effective way to minimise the intrusion of higher temperatures and equals a 17-metre-thick layer (56 feet) of styrofoam in its insulating effect. Filling hot coffee into the tank, for example, you would have to wait approximately 80 days until the coffee has dropped to a temperature suitable for drinking.

Boil-off management limits the inner pressure inside the tank and, when exceeding a defined level of ideal pressure, ensures controlled removal and conversion of hydrogen. Gaseous hydrogen released in this way is mixed with air in a venturi pipe and oxidised into water in a catalytic converter.

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The concept for filling the hydrogen tank is likewise easy to handle in everyday use and, in principle, hardly differs from the usual way a motorist fills up a gasoline tank. Basically the only new feature is the pressure-tight and low temperature-proof tank connection for liquid hydrogen placed by the driver in the liquid hydrogen filler manifold of BMW Hydrogen 7 like a regular fuel pump and then connected by manual pressure. Then the connection is fastened fully in position and the tank is filled in a process controlled by the system.

To open and close the tank filler flap, all the driver has to do is press a button in the cockpit next to the steering wheel, the entire process of filling the tank then taking less than 8 minutes.

Given the simple handling procedure and system control in filling the tank, the process of filling hydrogen into BMW Hydrogen 7 is just as easy, straightforward and harmless as filling a tank with conventional gasoline fuel, and is in fact even cleaner.

Teaming up with the TÜV South Germany Technical Inspection Authority, the BMW Group has successfully tested BMW Hydrogen 7 in a large series of the most demanding trials and test procedures focusing in particular on the car’s hydrogen components and going through all the homologation requirements made of a regular production vehicle.

The BMW Group has also put BMW Hydrogen 7 through a complete programme of crash tests going beyond the usual legal requirements. These crash tests include frontal offset collisions in accordance with EURO NCAP at an impact speed of 64 km/h or 40 mph, rear-end collisions with 100 and 40 per cent overlap, as well as side-on collisions at the car’s most sensitive point directly on the fuel filler pipe.

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To promote the development of hydrogen filling stations, the BMW Group has been involved in the Clean Energy Partnership (CEP) Berlin ever since its establishment in 2002. Today, leading companies such as Aral, the Berlin Transport Authority (Berliner Verkehrsbetriebe, BVG), DaimlerChrysler, Ford, General Motors/Opel, Volkswagen, Hydro, Linde, Total, and Vattenfall Europe all belong to the Clean Energy Partnership Berlin.

The Clean Energy Partnership Berlin is part of Germany’s national Strategy of Sustainability, one highlight of the CEP’s projects being the practical examination of fuel supply scenarios. To conduct this study under realistic conditions, two hydrogen filling stations were built in Berlin in November 2004 and March 2006, with a third hydrogen filling station scheduled for completion in Munich before the end of this year.

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