Of the non-battery methods of providing power for an electric car, only fuel-cell generation and flywheel storage provide sufficient power to operate an electric car over a commercially useful range. Recent developments in fuel-cells make them a more likely power source for the shorter term than flywheels. The proposals for fuel-cells which can run directly on methanol or gasoline, rather than as at present having to use reformers to convert these fuels to hydrogen, make fuel-cells a potentially more attractive short-term proposition than hitherto. If this development is successful we could see significant numbers of electric vehicles using this technology within ten years. The successful development of an infrastructure for supplying clean hydrogen direct to vehicles could, however, change the emphasis to the use of hydrogen storage on the vehicle. These issues are discussed. Flywheels still have a large safety hurdle to overcome. Before they can be accepted in production vehicles it will have to be shown conclusively that the flywheel containment system can cope with all the accidental failure mechanisms which can occur in a vehicle in use on the public roads, and that the gyroscopic effects both in normal use and in a catastrophic failure do not increase the danger to the user. The other energy sources described in this chapter cannot, with perhaps the exception of compressed air storage, store sufficient energy to propel a vehicle over a distance great enough to be of interest. However, because of their generally high power density, they can be very useful when hybridised with other energy storage methods such as chemical batteries, which have a high-energy density but low power density (for example metal-air batteries); or with other primary power sources such as internal combustion engines. The use of these technologies in hybrid vehicles is discussed in more detail.
Energy sources 2 - Other technologies, Page 1 of 2
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