A hybrid vehicle contains an electric motor and battery as well as a petrol (or, occasionally, diesel) engine. Either fuel source can be used to power the vehicle.
Advantages of Hybrid Vehicles
Hybrid vehicles combine the advantages of electric vehicles and petrol vehicles while helping to overcome some of their main disadvantages. The main problem with electric vehicles is that they have limited range and can usually only travel 80 to 160 kilometres before they need to be refueled. While that might be fine for everyday commuting and running errands, it limits the usefulness of an electric car on long journeys. A hybrid vehicle can switch to using petrol as its main fuel source when the battery runs low on charge, allowing it to make trips of any length as long as there are standard refueling stations along the way. On short journeys, however, the vehicle uses electricity, therefore avoiding the environmental problems associated with petrol and diesel cars.
How Hybrid Vehicles Work
There are two types of hybrid vehicles: parallel hybrids and series hybrids. Each type has a slightly different structure and works in a different way.
Parallel Hybrid Vehicles
In a parallel hybrid vehicle, both the engine and the electric motor can drive the transmission simultaneously. The engine is fed by a fuel tank, while the electric motor draws power from a set of batteries. If the batteries run out of charge or the tank runs out of fuel, the other fuel source can continue to power the vehicle. When the batteries are charged and the tank contains fuel, both the electric motor and the engine can contribute to the vehicle's propulsion, effectively giving it greater horsepower.
Series Hybrid Vehicles
In a series hybrid vehicle, the petrol engine is not directly connected to the transmission. Instead, it powers a generator, which can either turn the electric motor that drives the transmission or charge the batteries. This kind of set-up can be useful as it keeps the batteries charged even when there is no charging station available, but it is less efficient when the car is cruising at high speed because power is lost in the connections between the engine and the generator. Having the engine directly drive the transmission reduces the amount of power that is wasted due to inefficiencies.
Modern Hybrid Vehicles
Most modern hybrid vehicles, including the Toyota Prius and the hybrid versions of the Honda Accord and Honda Civic, are parallel hybrids. One notable exception is the Chevy Volt, which uses a series hybrid system.
Hybrid vehicles are popular with buyers who want the environmental benefits of an electric car, but who don't want to be limited by range. Parallel hybrid cars are by far the most common type of hybrid on the market, thanks to their improved efficiency over series cars.