12 Developments Towards the End of the 20th Century

During the latter part of the 20th century there have been changes which may make the electric vehicle a more attractive proposition. Firstly there are increasing concerns about the environment, both in terms of overall emissions of carbon dioxide and also the local emission of exhaust fumes which help make crowded towns and cities unpleasant to live in. Secondly there have been technical developments in vehicle design and improvements to rechargeable batteries, motors and controllers. In addition batteries which can be refueled and fuel cells, first invented by William Grove in 1840, have been developed to the point where they are being used in electric vehicles.

Figure 1.4 Electric powered wheel chair

Environmental issues may well be the deciding factor in the adoption of electric vehicles for town and city use. Leaded petrol has already been banned, and there have been attempts in some cities to force the introduction of zero emission vehicles. The state of California has encouraged motor vehicle manufacturers to produce electric vehicles with its Low Emission Vehicle Program. The fairly complex nature of the regulations in this state has led to very interesting developments in fuel cell, battery, and hybrid electric vehicles. (The important results of the Californian legislative programme are considered further in Chapter 10.)

Electric vehicles do not necessarily reduce the overall amount of energy used, but they do away with onboard generated power from IC engines fitted to vehicles and transfer the problem to the power stations, which can use a wide variety of fuels and where the exhaust emissions can be handled responsibly. Where fossil fuels are burnt for supplying electricity the overall efficiency of supplying energy to the car is not necessarily much better than using a diesel engine or the more modern highly efficient petrol engines. However there is more flexibility in the choice of fuels at the power stations. Also some or all the energy can be obtained from alternative energy sources such as hydro, wind or tidal, which would ensure overall zero emission.

Of the technical developments, the battery is an area where there have been improvements, although these have not been as great as many people would have wished. Commercially available batteries such nickel cadmium or nickel metal hydride can carry at best about double the energy of lead acid batteries, and the high temperature Sodium nickel chloride or Zebra battery nearly three times. This is a useful improvement, but still does not allow the design of vehicles with a long range. In practice, the available rechargeable battery with the highest specific energy is the lithium polymer battery which has a specific energy about three times that of lead acid. This is still expensive although there are signs that the price will fall considerably in the future. Zinc air batteries have potentially seven times the specific energy of lead acid batteries and fuel cells show considerable promise. So, for example, to replace the 45 litres (10 gallons) of petrol which would give a vehicle a range of 450 km (300 miles), a mass 800 kg of lithium battery would be required, an improvement on the 2700 kg mass of lead acid batteries, but still a large and heavy battery. Battery technology is addressed in much more detail in Chapter 2, and fuel cells are described in Chapter 4.

There have been increasing attempts to run vehicles from photovoltaic cells. Vehicles have crossed Australia during the World Solar Challenge with speeds in excess of 85 kph (50 mph) using energy entirely obtained from solar radiation. Although solar cells are expensive and of limited power (100 Wm-2 is typically achieved in strong sunlight), they may make some impact in the future. The price of photovoltaic cells is constantly falling, whilst the efficiency is increasing. They may well become useful, particularly for recharging commuter vehicles and as such are worthy of consideration.

Hybrid Cars The Whole Truth Revealed

Hybrid Cars The Whole Truth Revealed

Hybrid Cars! Man! Is that a HOT topic right now! There are some good reasons why hybrids are so hot. If you’ve pulled your present car or SUV or truck up next to a gas pumpand inserted the nozzle, you know exactly what I mean! I written this book to give you some basic information on some things<br />you may have been wondering about.

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