HYBRID ELECTRIC VEHICLES

5.0 HYBRID ELECTRIC VEHICLES

Hybrid Electric Vehicles (HEVs) combine two or more energy conversion technologies (e.g., heat engines, fuel cells, generators, or motors) with one or more energy storage technologies (e.g., fuel, batteries, ultracapacitors, or flywheels). The combination of conventional and electric propulsion systems offers the possibility of greatly reducing emissions and fuel consumptions, while giving consumers both the extended range and convenient refueling they expect from a conventional vehicle. HEVs can either have a parallel or series design. In a parallel design, the energy conversion unit and electric propulsion system are connected directly to the vehicle's wheels. The primary engine is used for highway driving; the electric motor provides added power during hill climbs, acceleration, and other periods of high demand. In a series design, the primary engine is connected to a generator that produces electricity. The electricity charges the batteries and drives an electric motor that powers the wheels.

The Toyota Prius and Honda Insight were two models of hybrid electric vehicles introduced in the United States in 1999 and 2000. Other auto manufacturers are working on developing and commercializing HEVs in the market.

5.1 Advantages of HEVs:

The advantages of HEVs are:

- HEVs are two or three times more fuel efficient than conventional vehicles.
- Good emission benefit.
- Extended vehicle range.
- Easy and rapid refueling.
- Compensates the shortfall in battery technology.
- Application of regenerative braking helps minimize energy loss.
- HEVs can run on alternative fuels thus can reduce the dependency on fossil fuels.

5.2 Disadvantages of HEVs:

Hybrid electric vehicles enjoy many advantages overruling the demerits associated with it, if any. As these vehicles are very recently introduced in the market, data on their on-road performance and servicing requirements are yet to be analysed.

5.3 Indian Initiative on HEVs:

In India, Ashok Leyland has developed a model hybrid bus in collaboration with ER&DCI. This hybrid bus has been displayed in the 2002 Auto Expo. Indian manufacturers are investing in R&D to bring out some HEV models.