density overcomes the inherent disadvantage of the internal-combustion engine
in which 80% of the energy is wasted in combustion and heat with only 20% of
the available energy getting to the wheels.
A renewed interest in the production of electric cars occurred during the mid-
2000s due mainly to concerns about rapidly increasing oil prices and the need to
curb greenhouse gas emissions.
There are two types of electric cars available today:
- PLUG IN VEHICLES (PEVs), which only run on rechargeable batteries and
have a finite distance they can travel before needing to be recharged - HYBRID ELECTRIC VEHICLES (HEVs), which are able to run on either
rechargeable batteries or gasoline power
With HEVs, as the car is running on gasoline, it is at the same time charging
the batteries.
Pros
■ The operating costs of an electric vehicle can be much lower due to the
low price of electricity relative to the price of conventional fuel (e.g., the
Chevrolet Volt has a combined city/highway 100 miles per gallon
equivalent rating compared to conventional gasoline-power vehicles).
■ Advanced electronics allow the electric motor to act as a generator. When
it needs to, the motor can draw energy from the batteries to accelerate the
car. When acting as a generator, it can slow down the car and return
energy to the batteries. In other words, the electric motor on a hybrid car
can put energy into the batteries as well as draw energy from them.
■ Tax credits may be available when purchasing PEVs or HEVs.
■ Since electricity prices are more stable than oil prices, increasing the use
of electricity for transportation can make costs more predictable and
reduce the negative economic impacts caused by fluctuating oil prices.
■ Significantly less tailpipe emissions. One gallon (4 L) of gasoline weighs
6 pounds (2.7 kg). When burned in a traditional internal-combustion
vehicle, the carbon in it combines with the oxygen in the air to produce 20
pounds (9 kg) of carbon dioxide. Both PEVs and HEVs produce
significantly less CO 2.
■ The driving range for running on the batteries only is about 50 miles,
which is adequate for most people living in urban areas.