BMW Hydrogen 7
Encyclopedia
The BMW Hydrogen 7 is a limited production hydrogen vehicle
Hydrogen vehicle
A hydrogen vehicle is a vehicle that uses hydrogen as its onboard fuel for motive power. Hydrogen vehicles include hydrogen fueled space rockets, as well as automobiles and other transportation vehicles...

 built by German automobile
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...

 manufacturer BMW
BMW
Bayerische Motoren Werke AG is a German automobile, motorcycle and engine manufacturing company founded in 1916. It also owns and produces the Mini marque, and is the parent company of Rolls-Royce Motor Cars. BMW produces motorcycles under BMW Motorrad and Husqvarna brands...

. The car is based on BMW’s traditional gasoline powered 7-series
BMW 7 Series
The BMW 7 Series is a line of full-size luxury vehicles produced by the German automaker BMW. Introduced in 1977, it is BMW's flagship car and is only available as a sedan or extended-length limousine...

 line of vehicles, and more specifically the 760Li. It uses the same 6 litre V-12
V12 engine
A V12 engine is a V engine with 12 cylinders mounted on the crankcase in two banks of six cylinders, usually but not always at a 60° angle to each other, with all 12 pistons driving a common crankshaft....

 motor as does the 760i and 760Li; however, it has been modified to also allow for the combustion of hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 as well as gasoline
Gasoline
Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...

, making it a bivalent
Bivalent (engine)
A bivalent engine is one that can use two fuel types. Examples are petroleum/CNG or petroleum/LPG which are widely offered in the European passenger vehicle aftermarket...

 engine. Unlike many other current hydrogen powered vehicles like those being produced by Honda
Honda
is a Japanese public multinational corporation primarily known as a manufacturer of automobiles and motorcycles.Honda has been the world's largest motorcycle manufacturer since 1959, as well as the world's largest manufacturer of internal combustion engines measured by volume, producing more than...

, General Motors
General Motors
General Motors Company , commonly known as GM, formerly incorporated as General Motors Corporation, is an American multinational automotive corporation headquartered in Detroit, Michigan and the world's second-largest automaker in 2010...

, and Daimler AG - which use fuel cell
Fuel cell
A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent. Hydrogen is the most common fuel, but hydrocarbons such as natural gas and alcohols like methanol are sometimes used...

 technology and hydrogen to produce electricity to power the vehicle - the BMW Hydrogen 7 burns the hydrogen in an internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

.

Production

BMW claims the Hydrogen 7 is the “world’s first production-ready hydrogen vehicle”; thus far, the Hydrogen 7 has only been released to select high-profile leasees. Only 100 total vehicles have been produced to put their technology to the test, and no more are planned to be produced. BMW says it chose public figures such as politicians, media figures, businessmen and big names in the entertainment industry such as 2007 Academy Award-winning director Florian Henckel von Donnersmarck
Florian Henckel von Donnersmarck
Florian Maria Georg Christian, Graf Henckel von Donnersmarck is a German film director, best known for writing and directing the 2007 Oscar-winning film The Lives of Others and the 2010 film The Tourist.-Personal life and family:...

 and the chairman of Sixt
Sixt
Sixt is a European car rental company. It has around 3,500 service stations in over 80 countries. Sixt was founded in 1912 by Martin Sixt in Munich.-Company facts:*Revenue : €1.44 billion*EBIT: €153.3 million*EBT: €121.647 million*Employees: 2,015...

 AG, Erich Sixt, because “they would be ideal ambassadors” for hydrogen fuel and can help spread awareness of the need for such technologies.

There is doubt, however, over whether or not this automobile will ever be put into larger production, even if hydrogen fuel technology reaches the point of economical and “green” feasibility, as well as to have the infrastructure required to put hydrogen vehicles in demand. The Hydrogen 7 uses more fuel than many trucks, consuming 13.9 L/100 km for gasoline (petrol) and 50 L/100 km for hydrogen. The following table shows the consumption (L/100 km) and fuel economy (mpg) for both Imperial and US gallons.
Fuel Consumption Table for the BMW Hydrogen 7
Gasoline (petrol) Hydrogen
L/100 km Imp. mpg US mpg L/100 km Imp. mpg US mpg
13.9 20.3 16.9 50.0 5.6 4.7


The difference in fuel consumption is largely due to the different energy density
Energy density
Energy density is a term used for the amount of energy stored in a given system or region of space per unit volume. Often only the useful or extractable energy is quantified, which is to say that chemically inaccessible energy such as rest mass energy is ignored...

 with gasoline (petrol) yielding 34.6 MJ/L and liquid hydrogen
Liquid hydrogen
Liquid hydrogen is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.To exist as a liquid, H2 must be pressurized above and cooled below hydrogen's Critical point. However, for hydrogen to be in a full liquid state without boiling off, it needs to be...

 yielding 10.1 MJ/L. Based on these energy density figures, one would expect 47.6 L/100 km for hydrogen based on 13.9 L/100 km for gasoline (petrol); which is very close to the stated 50.0 L/100 km. Using hydrogen in an internal combustion engine as a source of energy is far from as efficient as fuel cell
Fuel cell
A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent. Hydrogen is the most common fuel, but hydrocarbons such as natural gas and alcohols like methanol are sometimes used...

 technologies; however, this is a system that is in production (albeit limited) now.

Nonetheless, hydrogen fuel (whether converted to energy in fuel cells or burned in an internal combustion engines) is not green as it may seem; particularly so when you also consider that producing liquid hydrogen requires vasts amounts of energy. (Unless however, the energy to produce the hydrogen is obtained through renewable sources, like solar or wind and subsequent electrolyzation is the method of production). It will also only be more expensive than its sister the 760Li (no retail price has been announced), which is BMW’s biggest and most expensive sedan, with a base price tag of over $118,000, thus further diminishing its widespread appeal. As of November, 2006 there were only five filling stations in the entire world that supported BMW’s filling technology, furthering the obstacles of making this car worthwhile.

Use of hydrogen technology

The BMW Hydrogen 7 uses hydrogen as fuel differently from fuel-cell-type vehicles. When in hydrogen mode, it injects the hydrogen directly into the car’s air intake manifold to be combusted in the engine’s cylinders rather than converting the hydrogen’s energy into electricity to operate electric motors like a fuel cell. BMW says this is a more efficient use of the hydrogen. The car can also switch seamlessly between hydrogen and gasoline at the touch of a button on the steering wheel, and of course will do so automatically when one of the fuels is depleted.

The hydrogen fuel is stored in a large, nearly 30-gallon (110 liters), bi-layered and highly insulated tank that stores the fuel as liquid rather than as compressed gas, which BMW says offers 75% more energy per volume as a liquid than compressed gas at 700 bars of pressure. The hydrogen tank’s insulation is under high vacuum in order to keep heat transfer to the hydrogen to a bare minimum, and is purportedly equivalent to a 55 feet (16.8 m) thick wall of polystyrene Styrofoam
Styrofoam
Styrofoam is a trademark of The Dow Chemical Company for closed-cell currently made for thermal insulation and craft applications. In 1941, researchers in Dow's Chemical Physics Lab found a way to make foamed polystyrene...

.

To stay a liquid, hydrogen must be super-cooled and maintained at cryogenic temperatures of, at warmest, -253 C. When not using fuel, the Hydrogen 7’s hydrogen tank starts to warm and the hydrogen starts to vaporize. Once the tank’s internal pressure reaches 87 PSi, at roughly 17 hours of non-use, the tank will safely vent the building pressure. Over 10–12 days, it will completely lose the contents of the tank because of this.

Specifications

The car is powered by a 6.0 litre V12 engine
V12 engine
A V12 engine is a V engine with 12 cylinders mounted on the crankcase in two banks of six cylinders, usually but not always at a 60° angle to each other, with all 12 pistons driving a common crankshaft....

 capable of running on both premium gasoline and hydrogen fuel. It is rated at 191 kW and 390 N.m of torque using either fuel. The car accelerates from stopped to 100 km/h (62.1 mph) in 9.5 seconds. The hydrogen fuel tank holds roughly 8 kg (18 lb) of hydrogen, enough to travel 125 miles (201.2 km). The gasoline fuel tank holds 19.5 gallons, enough to travel 300 miles (482.8 km) for a combined total of over 400 miles (643.7 km) at cruising speeds. The Hydrogen 7 gets about 5.6 mpgimp on hydrogen (by comparison Honda's FCX Clarity gets 81 mpgimp) and 16.9 mpgimp on gasoline. The curb weight
Curb weight
Curb weight or kerb weight is the total weight of a vehicle with standard equipment, all necessary operating consumables , a full tank of fuel, while not loaded with either passengers or cargo.This definition may differ from definitions used by governmental regulatory agencies or other...

 of the Hydrogen 7 is roughly 550 pounds (249.5 kg) heavier than the 760Li, bringing it to about 5100 pounds (2,313.3 kg).

See also

  • CleanEnergy
    CleanEnergy
    BMW CleanEnergy vehicles have both a hydrogen and a petrol tank. If one of the tanks is empty, the bivalent BMW engine unit switches over automatically to the other fuel system. One decisive advantage of the combustion engine is bivalence...

  • Bivalent (engine)
    Bivalent (engine)
    A bivalent engine is one that can use two fuel types. Examples are petroleum/CNG or petroleum/LPG which are widely offered in the European passenger vehicle aftermarket...

  • List of hydrogen internal combustion engine vehicles

External links

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