Future Transportation Systems - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 265

Hybrid cars are particularly advantageous in large cities, where traffic con-
gestion causes an enormous waste of time and energy and where pollution causes
several diseases and environmental damage [ 11 ].
Future hybrid motor vehicles will remain more expensive than similar cars with
combustion engines, since all supplementing parts of the propulsion must be
doubled, which measure increases the costs of production and maintenance.
However, future vehicles with hybrid propulsion will be more comfortable and
will need less fuel [ 12 ].
17.1.2.2 Electric Vehicles
The propulsion of an electric motor vehicle consists of the engine, the transmission
system, and the power sensor which converts the accelerator pedal's position into
the appropriate current and voltage regulator of the engine.
The main characteristics of electric vehicles depend on the battery type.
Any household electric socket can be used to charge the battery, supplying
electric power of 3.7 kW (3.51 BTU s -1 ) per hour. Charging for one hour can fuel
a trip of approximately 20 km (12.43 mi). Shorter charge times can be achieved by
the use of an industrial current connection which is often used for forklifts in
stores. It takes 100 times longer to recharge a battery than to refuel a combustion
engine to travel the same distance [ 13 ].
The design of the newest lithium-ion batteries is compact, the construction is of
a relatively light weight, and the durability covers approximately 10 years or
600,000 charging-discharging cycles. Some models are surrounded by a cooling
gel and achieve 25-50% higher energy density than conventional nickel-metal
hydrid batteries; see Fig. 17.5 .
Lead-acid batteries are most common in road vehicles. In modern electric cars,
nickel and lithium-ion technology are replacing lead-acid batteries.
The advantages of the lithium-ion technology are the high thermal stability and
the high capacity. However, some elements have to be improved, such as the
cooling unit, the battery management system, and the high voltage connection.
Batteries with organic lithium electrolytic solutions are combustible and can
lead to severe injuries in case of accidents. Therefore, it is important to design
future batteries that do not burn. For this reason, non-flammable lithium-polymer
technology, including an electrolyte solution made of polydimethylsiloxane and
electrodes designed with nanotubes will gain importance in the future [ 14 ].
Fiber-reinforced synthetic materials and metal containers with a strengthened
wall are used to protect against mechanical shocks. The electronic control unit
avoids overcharging the lithium-ion battery, saves it from damage when starting at
high temperatures, and records events which are important for the maintenance of
the system [ 15 ].
In contrast to the internal combustion engine, the electric propulsion must
distinguish between short and long time engine power. The short time power is
limited by the maximum power of the supply. The maximum power is a half hour