Hybrid Vehicles are vehicles
propelled by two or more sources of power.
Most hybrid vehicles
on modern automobile markets are Hybrid Electric Vehicles (HEV). A
typical HEV consists a conventional internal combustion engine (ICE)
and a rechargeable energy storage system (RESS).  There are also
various other forms of hybrid vehicles.
Other sources of power also includes hydrogen,
propane, CNG (Compressed natural gas),
and solar energy.
For road vehicles, power required in different running condition varies a lot, combustion engine in conventional vehicles rarely works on it's
most efficient condition due to this reason, thus some fuel are
relatively wasted in these situations.
Modern Hybrid Electric Vehicles are usually powered by one power
source on open road and the other power source only work when
maximum power is needed, for example when the vehicle is going
uphill or overtaking other cars. Very high
acceleration can be achieved by internal combustion engine and
electric motor are working at the same time if needed. Engines can
run in a more efficient speed with the aid of electric motor. The internal
combustion engines of the Hybrid Electric Vehicles can be shut down
by computer control system when they are idle or redundant engine
power can be used to recharge batteries.
The engines needed are usually smaller than those in conventional vehicles,
engines that are more efficient but with lower torque engines may
also be used .
Batteries are recharged by regenerative braking or electrical generator driven by internal combustion
engine, usually no external recharging resource is needed.
braking is also one of the major advantage of Hybrid Vehicle, when
the car is braking or going down hill, kinetic energy can be
converted to electric energy and recharge the batteries by electric
motor, while conventional vehicles have to slow down via braking
system which will convert kinetic energy to useless heat, when it is
going down long hill engine braking has to be applied to avoid
overheating of the braking system, which would also cost fuel. All these facts
clearly indicates that HEVs can reduce the emission and fuel
consumption by a large scale.
Main categories of Hybrid power:
Parallel hybrid In this type of HEVs, electric motor and ICE can either
run on their own or work in parallel. Electric motor usually
works alone in low power situation like reversing or low speed
running. The internal combustion engine only comes in for higher
speed situation or when battery needs to be recharged.
On open road, internal combustion engine will be the main
power source for the vehicle, usually for maximizing the battery
life. electric motor will come in when maximum acceleration or
propulsion is required.
Mild hybrid The electric motor in mild hybrid vehicles doesn't run
independently, it only assists the internal combustion engine
when extra power is needed.
Plug-in hybrid electrical vehicle (PHEV)
This design usually provides a larger electricity storage
capacity, it emphasis the ability of recharging the battery from
external sources rather than from the internal combustion
In series hybrid vehicles, combustion engine doesn't provide
energy directly to the wheels. Instead it is running on its most
efficient speed and drives a electric generator and indirectly
provides electricity for recharging the battery, recharging the
capacitor and drives the electric motors. Theoretically a series
hybrid vehicle does not necessarily require a battery, a
capacitor is enough for the operation.
The video below gives a basic demo of the
excellent illustration of hybrid vehicle can be found
The following table shows a comparison of
fuel consumption (miles per gallon) between Hybrid and
The table below shows the comparison of fuel cost and emission of the most
common Hybrid vehicles on sale at the moment.
Honda Accord Hybrid
Honda Civic Hybrid
Lexus GS 450h
Nissan Altima Hybrid
Saturn Aura Hybrid
Toyota Camry Hybrid
It is clearly shown that hybrid models have
obvious advantages in fuel consumption rates. It has no doubt that
Hybrid vehicles is an excellent choice for more economical and
environmental friendly solution.