Press Release
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Liquid Hydrogen ??????????????????????????????????????? New Energy for Ongoing Mobility in Everyday Motoring.
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High energy density of liquid hydrogen offers long cruising range.
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Vacuum super-insulation allows liquid storage of fuel.
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New momentum for expanding the hydrogen infrastructure.
BMW is the first carmaker in the world to focus consistently on the use of hydrogen as the medium- and long-term fuel for the car of the future.
Now, introducing BMW Hydrogen 7, the BMW Group is presenting the first series-production hydrogen-powered car in the world offering a high level of practical quality.
Such practical quality was indeed an important objective throughout the process of developing and testing BMW Hydrogen 7, encompassing the entire area of vehicle use, that is driving the car, filling up the tank, taking care of both service and repair requirements. Seeking to integrate the car from the start fully in everyday use with all its practical qualities, the BMW Group consistently followed the complete process of series development also for BMW Hydrogen 7.
High energy density of liquid hydrogen providing a long cruising range.
In defining the energy content of hydrogen, we distinguish between gravimetric (related to weight) and volumetric (related to volume) energy density. Compared in terms of its weight, hydrogen has a very high level of energy density about three times the gravimetric energy density of gasoline, and is therefore of great interest for mobile use. The volumetric energy density of hydrogen, on the other hand, is about one-quarter that of gasoline.
With tank capacity in the automobile being limited, we have to increase the level of energy (energy content) related to volume, for which there are two possibilities: Either we compress hydrogen in its gaseous state or we cool it down until it turns into a liquid. Compression of gaseous hydrogen is possible today up to a pressure of 700 bar, while at ambient pressure hydrogen turns liquid when cooled to a temperature of ??????????????????????????????????????? 253 ????????????????????Celsius.
In order to obtain the highest possible energy content on a limited tank capacity, the BMW Group has opted for liquid hydrogen. The volumetric energy density of this liquid fuel, that is the amount of energy related to the capacity or volume required within the car??????????????????????????????????????s tank, is more than 75 per cent higher in the case of liquid hydrogen than with gaseous hydrogen compressed to a pressure of 700 bar. Hence, liquid hydrogen gives the car a cruising range 75 per cent longer. This, in turn, means greater freedom and enhanced mobility for the driver ??????????????????????????????????????? a criterion of particular significance as long as the infrastructure for filling up hydrogen is still in the process of being developed.
Vacuum super-insulation for reliable storage of fuel.
Together with its dual-mode power unit, the liquid hydrogen tank in BMW Hydrogen 7 is the most significant new development in the automotive industry achieved in this case. The particular challenge in storing liquid hydrogen is that the liquefied hydrogen cooled to a cryogenic temperature of ??????????????????????????????????????? 253 ????????????????????C has to be kept at this temperature for a long time. Precisely for this purpose, the BMW Group has developed trendsetting, 30-millimetre (1.18????????????????????????????????????????) thick vacuum super-insulation offering the same thermal insulation effect as a layer of styropor measuring no less than 17 metres or 56 feet in thickness. This provides the option to store liquid hydrogen in the car for a lengthy period of time.
Energy balance for supplying liquid hydrogen.
The liquefaction of hydrogen serving as drive energy in the car initially calls for a higher amount of energy than the process of compressing gaseous hydrogen. In everyday use, however, this balance of energy changes to the benefit of liquid hydrogen, since it is essential, in determining the overall consumption of energy, to consider the overall concept and system of the vehicle.
This overall perspective also considers the fact that compression heat is generated in the process of filling up the vehicle with gaseous hydrogen.
This, in turn, leads to ongoing expansion of the compressed hydrogen gas, with a negative effect on its energy density.
Given this situation, there are two options for reducing the heat generation effect: Either passive cooling by allowing for a break from time to time when filling up the tank ??????????????????????????????????????? an option the customer would hardly accept ??????????????????????????????????????? or active cooling by reducing the temperature of hydrogen at the filling station before pumping hydrogen into the tank. The drawback in this case is that such a process significantly increases the consumption of energy in the ???????????????????????????????????well-to-wheel??????????????????????????????????? cycle, that is the entire process of fuel going from the well in the ground to the wheel on the car, putting gaseous, compressed hydrogen at a substantial disadvantage.
A further point is that hydrogen, on account of its greater density when stored in large quantities, will be delivered in a liquid state to the filling station and stored there also in a liquid state in the long term. Generation of compressed gas directly at the filling station would be inefficient due to the small scale and volume of such facilities.
With a tank storage facility of medium size (and wherever pipelines are not practical for reasons of sales), hydrogen would also be delivered in liquid form, in the same way as other types of gas already liquefied today for purposes of distribution. Hence, the fuel would first be liquefied before filling up the tank with hydrogen gas, then evaporated and compressed prior to the fuel pumping process. Clearly, this would mean a significantly greater effort requiring far more complicated and complex technology for providing compressed gas at the filling station. So in comparison with liquefied hydrogen, the overall amount of energy required for filling up the tank with hydrogen gas would ultimately be greater.
Momentum for developing a hydrogen supply infrastructure.
The process of filling up the tank of BMW Hydrogen 7 with liquefied hydrogen is conceived and laid out to be fully compatible with everyday requirements, with the driver only having to perform roughly the same operations as when pumping gasoline into the tank. And since suitable storage tanks and dispensers for hydrogen could be added to existing filling stations without substantial problems, there will be no need to build new filling stations from the ground up.
The process of filling up a car with liquid hydrogen differs from pumping in gasoline mainly by the fact that it requires a pressure-tight and low temperature-proof coupling instead of the usual gas pump. The actual operation as such, on the other hand, is almost the same as before:
Once the driver has connected the hydrogen tank coupling with the tank filler manifold in his car, the coupling is locked in position, the tank is filled, and the coupling is unlocked by automatic system control. The entire process takes less than 8 minutes and is cleaner and no more hazardous than the conventional process of filling up the tank with gasoline, since no fuel is able to escape in an uncontrolled manner and no ignitable vapour or any other kind of gas reaches the environment.
Presenting BMW Hydrogen 7, the BMW Group is clearly proving that the process of switching over to alternative drive energy does not require any concessions in terms of sheer driving pleasure, motoring comfort, or everyday driving quality. Indeed, BMW??????????????????????????????????????s Hydrogen Saloon sets a clear sign proving the everyday qualities of liquid hydrogen as a source of energy in the production car.
BMW Hydrogen 7 has gone through the entire process of series development with all the testing processes required by law. Following the complete process of product development and creation, the BMW Group, together with the T?????????????????????V South Germany Inspection Authority, subjected BMW Hydrogen 7 to a comprehensive range of all round tests with the focus in particular on the car??????????????????????????????????????s liquid hydrogen components. And then, as a result of these tests, the South German Technical Inspection Authority arrived at the conclusion that the Hydrogen Saloon is at least as safe in practice as a conventional gasoline-powered car.
All this clearly confirms that BMW Hydrogen 7 as a vehicle running on liquid hydrogen is fully able to meet all the requirements of everyday motoring.
But despite the wide range of tests carried out on the new model, user-friendliness can ultimately only be confirmed in practice in all the details involved. And this, in turn, requires the appropriate infrastructure, which is currently being established and put into place. The BMW Group, therefore, is the forerunner in this process.
To promote the establishment of the appropriate supply infrastructure, the BMW Group entered into powerful partnerships with other companies and organisations at an early point in time. One of these alliances is the Clean Energy Partnership (CEP) Berlin, conducting one of the most important demonstrating projects in Europe in developing alternative forms of energy in the automotive industry. This consortium of the automotive industry, the supplier industry and public transport services established in 2002 now comprises not only BMW, but also Aral as a supplier of petroleum and mineral oil, DaimlerChrysler, Ford, General Motors/Opel, Volkswagen, Hydro, Linde, Total, Vattenfall, and the Berlin Transport Authority (BVG, Berliner Verkehrs????????????????????betriebe). The purpose and objective of the CEP is to demonstrate the practical feasibility of an appropriate hydrogen supply infrastructure, to further develop hydrogen in technological terms as a source of energy, and to expand the options for using hydrogen for everyday purposes. One of the project??????????????????????????????????????s highlights is the operation of two public hydrogen filling stations opened in Berlin in 2004 and, respectively, in 2006. A further fully integrated filling station will be opened in Munich before the end of this year.
The BMW Group makes a worldwide commitment.
The BMW Group is contributing the know-how it has gained in the research and development of hydrogen to the German Government??????????????????????????????????????s National Innovation Programme. A further point is that BMW Group associates have been appointed as consultants to the Advisory Council and the Top Management of the Deployment Strategy Panel of the European Hydrogen and Fuel Cell Technology Platform (EHP) as a special body initiated by the EU Commission in 2004 serving to promote the development and operation of cost-efficient, competitive European energy systems based on hydrogen and fuel cell technologies.
Yet another international commitment by the BMW Group is its participation in the Research Alliance of the Department of Energy as well as the initiation of a hydrogen feasibility study and an information campaign on this subject matter in China. Here, joining forces with Chinese scientists, BMW Group experts are searching for ways and means of creating and building up a full-scale hydrogen supply infrastructure.
