There’s been a lot of talk over the last few years concerning gas-electric vehicles, commonly called hybrids. For all the hype, there hasn’t been much in the way of information concerning how they operate. They save gas, and are better for the environment, but how do they do this? I’ll attempt to give a brief explanation below.
Hybrids commonly make use of two separate power plants: a traditional (though smaller and more efficient) internal combustion engine, and an electric motor/generator. Fuel consumption and emissions reduction are accomplished with a combination of three different mechanisms:
1. Reusing wasted energy through technologies such as regenerative braking.
2. Reducing the size and power of the internal combustion engine and using the better torque of electric motors to compensate.
3. Reducing wasted energy during idle and low output (cruising at speed) modes, generally by cutting power to the internal combustion engine (either partial or total).
Regenerative braking takes the kinetic energy lost during traditional braking and uses it to recharge the batteries and power other electrical systems on the vehicle. This results in free energy for the battery, and also reduces wear on the brake parts.
Reduction of traditional engine size and power results in better performance due to lessened weight of the engine plus optimized performance. The smaller engine operates continually in its ideal power range as opposed to traditional engines, which must operate in a much broader range, while having a narrow optimum range.
Energy is wasted by traditional engines at idle and during times of low power needs. Reducing or cutting power completely during these times reduces the amount of fuel consumption and emissions put out by the vehicle by quite a bit. When power is cut completely, as at idle, the vehicle switches over and runs on its electric motor. Simply pressing the accelerator pedal restores power.
Most hybrids also make use of other fuel saving techniques such as weight reduction. This is an engineering choice as opposed to a benefit of hybrid technologies. Several manufacturers announced that they would incorporate several aspects of hybrid technology. These would not be true hybrid vehicles, but would take advantage of several different aspects of the technology to save on gas and reduce emissions.
Trade offs include lessened power, and increased total vehicle weight due to the presence of the electric motor and battery pack. This weight will not affect the vehicle during urban driving, but will adversely affect fuel savings during highway driving. In short, hybrid vehicles are best suited to driving in an urban environment. Another perceived trade off is in initial cost. There have been rumors for a while now that the fuel savings versus initial cost never truly evens out. This is in fact not true. A recent study by Intelichoice shows that all hybrid models will begin to pay for themselves in a little less than five years.
Most vehicle manufacturers have hybrid models, including Ford, GM, Mazda, Nissan, Honda, Peugeot, Renault and Toyota. Currently the best selling hybrid is the Toyota Prius.
Hybrid Cars 101
Hybrid cars operate using a dual engine design. One engine is a simple, conventional gasoline motor that is almost identical to normal gasoline powered cars. The second engine can be equated to a bigger, more powerful version of the electric golf cart engine.
The secret with hybrid cars is how it shifts effortlessly between the electric motor and the gas powered motor to adapt to whatever driving situation the driver is in. When the hybrid is started up, the electrical system fires up and is ready to supply power to the drive motor as soon as the driver steps on the accelerator.
One of the many nuances of having a hybrid is that there is no noise, vibration, or sound. It is almost like the car is not even on. The only indication the driver can perceive are perhaps the lights from the instrumental panel. When the driver decides to push on the accelerator, electricity flows from the battery to the electric drive motor, and the car moves.
When the going gets tough and the need for speed is necessary, the electric motor disengages as the gasoline engine sparks up to provide more power. At high speeds, the car runs purely on gasoline and no electricity.
At city speeds, the computer calculates if the electric motor can sustain the speeds, and if it can, the gasoline motor is disengaged as the electric motor takes over.
The switch between motors only happen as often as necessary and is meant to maximize fuel efficiency.
Another feature hybrids possess is something called regenerative breaking. When the car is slowing down to a stop, the electric generator engages the wheels in order to recharge the battery, but what is also cool is that it creates drag, slowing down the car as well. So the electric generator recharges the battery as well as help the car brake more efficiently.
In addition to the regenerative breaking feature, hybrid cars also possess another gas saving feature. When the car comes to a full stop, the gas engine is completely shut off, so it does not use gas while it is idling. Once the accelerator is pushed, the electric engine moves the car while the gas engine is fired up again.
On average, hybrids get about 30-40 mpg which is not too spectacular. Some, of course, get more or less than others.
Hybrids also get better mileage in cities compared to highways. To some that may seem strange, but in truth, it makes perfect sense. In the city, a car does more braking and stopping giving the hybrid more chances to recharge its battery. In addition, in highways, a car tends to go at higher speeds, making a hybrid rely more on its gas engine.
The enigma of hybrid cars have eluded many, fascinated others, and bestowed hope to all for a greener future.