Munich, Germany, ... Joining forces with DELPHI Automotive Systems, the largest automotive supplier in the world, BMW is developing an entirely new type of fuel cell able to generate electricity out of gasoline.

Since this innovative energy converter uses conventional engine fuel, it does not require any other source of energy such as methanol and therefore does not call for any elaborate change in on-board technologies and in the network of filling stations.

The new fuel cell is called SOFC for short or Solid Oxide Fuel Cell and converts hydrogen into electricity at a temperature of approximately 800 degrees C or 1470 degrees F via a circonium oxide ceramic transformer.

The first step in this process of conversion is to evaporate the gasoline, obtaining hydrogen through a splitting process in a reformer also operating at roughly 800 degrees C. This hydrogen then reacts with oxygen in the air fed in during the process, generating electricity and, as a waste product, water.

Compared with the proton-exchange-membrane fuel cell (PEM) generally still proposed today, which in theory may also be supplied with hydrogen via a reformer running on petrol, the SOFC is far less sensitive to impurities in the reforming process. A further advantage is that it does not require any expensive precious metal electrodes. Accordingly, the SOFC is clearly superior to the PEM, especially as the latter is subject to the further restriction that it should preferably only be run on pure hydrogen. With the Solid Oxide Fuel Cell, on the other hand, motorists will not have to wait until a comprehensive and widespread hydrogen supply infrastructure is in place.

Fitted in BMW passenger cars, the Solid Oxide Fuel Cell will serve to supply electric energy to the on-board network, thus doing the job for which it is most suitable: generating electricity at a high level of efficiency and operating independently of the engine. The actual drive power for the vehicle itself should in BMW's opinion still be provided by the combustion engine with its well-known advantages.

In the future, therefore, the compact fuel cell battery will merely take the place of a conventional lead battery. With the fuel cell exceeding the power output and capacity of a lead battery by far, however, this fuel-cell APU (Auxiliary Power Unit) is not only able to supply power to all conventional electrical powerconsuming items in the car, but also allows new functions such as air conditioning when the car is at a standstill.

In the long term the fuel cell may even be able to replace the electrical alternator in the car and allow the use of a much smaller lead battery only required for starting the engine and in emergencies. The introduction of the SOFC therefore marks the beginning of a new era with cars requiring more and more electric power in the future.

While the ongoing development of the SOFC in the gasoline-powered automobile will still take another five years or so, BMW will be the first car maker in the world to introduce a PEM fuel cell battery for generating electric power in the car as a standard feature. Starting next year, BMW will be building a small number of 7 Series sedans with a hydrogen-powered combustion engine for the worldwide EXPO 2000 Clean Energy Project. Already carrying liquid hydrogen on board for the power unit, these cars will be fitted with a PEM fuel cell generating electric power from hydrogen and air.

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