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For the past few years, researchers have been actively building and experimenting with hydrogen-powered cars. These infinitely more environmentally-friendly vehicles could be on our streets sooner than we think, largely due to high oil prices and demand for cleaner energy sources.
(Published on April 2006 – JEC Magazine #24)
One of the largest concerns surrounding the development of the hydrogen-powered car is safety. Many fear that an accident or a small spark could ignite a powerful explosion, making these types of cars more dangerous for the driver, despite their environmental benefits. However, as advances are made into the technology of these vehicles, the engineers are managing to find ways to safely store the car’s hydrogen, and much of this has to do with the use of composites as the material for the storage tanks. Many researchers are saying that composites are putting the hydrogen car on the same level of safety or risk as a traditional petrol-powered vehicle.
Using hydrogen safely
A great deal of research has gone into the safety of running a vehicle powered, by hydrogen. In today’s hydrogen cars, there are a number of different safety applications that have been repeatedly tested to make the substance highly manageable. One example is the flame arrester, which has been installed in the vehicle’s tailpipe to prevent any kind of flame from spreading into the exhaust system. But the area subjected to the most safety research has been the hydrogen storage tanks. In most vehicles, these are made out of aluminium or stainless steel. For hydrogen cars, however, composites have come into play because of their ability to withstand high pressures.
Dr Erwin Wuchner, who works at Daimler- Chrysler’s research centre in Nabern, Germany, said “One has to clearly understand the special characteristics of hydrogen and act accordingly. Then it’s just as safe an energy carrier as is gasoline or natural gas.”
Composite storage tanks for the fuel of the future
The tank holding the hydrogen is in the form of a large cylinder and was crafted by Dynetek Industries, a company that produces alternative-energy fuel-storage cylinders and systems. It is made primarily out of aluminium, but is coated with carbon-fibre composite. Information on the exact type of composite used for these tanks remains classified, as several of the world’s largest automakers, such as BMW and GM, are in stiff competition. BMW and GM are currently looking at composites for their storage tanks as well, and are tight-lipped regarding which materials have worked better than others.
However, DaimlerChrysler did acknowledge that it was using a carbon-fibre composite. Its reasons for the choice were related to the carbon fibre’s ability to reach the necessary tolerance for pressure and shape, while at the same time remaining very lightweight.
The carbon-fibre composite layer contributes to the tank’s strong pressure-resistance threshold of 800 bar – more than twice the normal operating pressure of 350 bar