The Hindu Business Line : Hybrids, stepping on the gas

Hybrid cars are becoming more and more popular because of their ability to offer better mileage. But that was not the main reason why they were developed in the first place.

Hybrid cars have been in the news for a while now and are increasingly being seen as practical alternatives to cars that run solely on conventional fossil fuels.

Despite the recent counter claims that have put down the fuel-efficiency advantage of the hybrids in real world conditions, the cost-benefit equation that these cars offer will surely be appreciated as crude oil prices continue to rise.

In the big, mature markets of the US, Europe and Japan, hybrids have completed the migration from being technology concepts to become mainstream automobiles.

But the higher price of the hybrid (compared to the same car's conventional fuel model) has meant that, at least till now, the buyers seem to be those who like to wear their tech `savviness' and environment consciousness on their sleeve.

Hybrid cars are becoming more and more popular because they offer better mileage. But that was simply not the main reason why they were developed in the first place. The key driver was vehicular pollution.

Hybrid advantage

On a broader definition scale, a hybrid car could have denoted a vehicle that runs on a mix of two or more different types of fuel or power sources.

But since their introduction in the late-1990s and their subsequent runaway popularity, cars powered by conventional petrol or diesel engines and an electric motor have become synonymous with the name `hybrids'.

Such cars have redefined fuel efficiency benchmarks and set new standards in lowering emissions.

The surge in the price of crude oil the last few years has put hybrids in the spotlight. So, while alternative fuel technologies, such as hydrogen fuel, have remained concepts, hybrids have done the transition to the real world due to their practicality.

What is more, with hybrids showcasing the possibility of dramatically cutting down fuel consumption, many countries are now willing to offer tax-breaks to make these cars more affordable.

The principle behind how hybrids manage to offer the two benefits of higher mileage and lower emissions is so disarmingly simple, you would think that the technology should have been developed long back. This simply is why the hybrid technology could become the norm for all cars within the next decade or so, at least in the major automobile markets.

Hybrids focus on the very essence of an internal combustion engine's fuel burn characteristics. Whether the engine is petrol or diesel powered, the phases of high fuel consumption take place when the vehicle is accelerating from standstill or during periods of peak power demand, such as when the driver is overtaking.

Not stopping with just aiding in cutting fuel consumption during these phases, hybrids also optimise energy usage in the car by reconverting the engine's kinetic energy into electrical power to recharge the batteries, when the car is coasting and decelerating. To achieve this, hybrid cars employ a power-split device to route power to the wheels from the twin sources and by the addition of a generator to ensure that the battery can be recharged or to convert power to be directly routed to the electric motor.

How they work

Hybrid technology for cars essentially involves the use of an electric motor to augment and assist the other source of power, which could either be petrol or a diesel engine. Though the technology sounds easy to implement, integrating these two sources to work in tandem and seamlessly requires the use of high-end electronics and an extremely complicated battery pack and control system.

Modern hybrids are more complicated than the previous generation editions and incorporate advanced systems with even more powerful, but compact battery packs, which enable the electric motors to power the car, standalone, unlike part hybrids, where the electric motor only assists or supplements the fuel-powered engine during the drive. The more complicated, newer full-hybrids also feature proprietary technology that allow the electric motor to constantly send power back to the battery pack even as it is consuming battery charge to power the car, a kind of multi-tasking enabled by the command unit.

In most hybrid cars, the electric motor draws power from the battery pack to get the vehicle to move.

Full hybrids, which feature powerful electric motors, manage to get the car rolling from standstill without any help from the engine, and the latter takes over only after the vehicle has reached a preset speed of, say, 20 mph. In older generation part-hybrids, the electric motor would only assist the fuel-powered engine to get to cruising speed quickly and with lower fuel consumption.

From this stage, the regular engine takes over right through to cruising speeds and the electric motor kicks back to life only when there is a sudden surge in demand for more power, such as during an overtaking manoeuvre.

Another important feature of hybrids is that, in addition to the regular alternator style recharging of the battery power when the engine is operating at cruising speeds, hybrids incorporate technology for replenishing battery charge through a process called `regenerative braking'.

Regenerative braking refers to the unique process where the electric motor's performance is reversed to send power back to the battery pack during times when the vehicle is decelerating or, in more advanced hybrids, simply when the driver lifts his foot off the accelerator pedal. Hybrids incorporate much larger and more powerful battery packs to enable the electric motors pull forward vehicles as bulky as the SUVs.

Because of the combination of regenerative braking and the regular recharging during peak engine performance, the hybrids battery packs eliminate the need for plug-in style recharging that normal electric vehicles require.

Further, since hybrids use the additional assistance provided by an electric motor, they manage to offer better performance even with smaller, more fuel-efficient engines. Not surprisingly, the Japanese, who have always been focused on fuel efficiency and high-end engine electronics, were the first to develop the hybrids.

Toyota and Honda were among the first to offer this technology, with the Toyota Prius and the Honda Insight being the most popular. While initially, the hybrid technology was being exclusively offered only in these models, increasingly many of the existing models (such as the Toyota Camry and the Honda Civic) are being offered with hybrid variants.

The practicality of the hybrid technology is being appreciated by other manufacturers too, which have till now been pouring funds and research efforts into less practical alternatives such as fuel cells. Other manufacturers such as Ford and Nissan have now developed their own hybrids.

In the Indian context, while companies are attempting to develop hybrid variants, it will continue to remain in the concept realm for a few more years to come due to the high cost of the technology.

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