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Driving Towards the Electric Era

Cars have been driving us around for a century now and we already have the 100% electric vehicle on our streets. Mobility is becoming electric, creating great improvements in fuel efficiency. Welcome to the new era.

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2013/03/04

Hybrid cars are now second nature

Do you remember those experiments at school? You know, those science classes where you would connect a battery to a motor to make a small model car move forward.

This kind of simple "car" works by using the motor to convert electrical energy into motion: Channel electricity through a motor and it turns. Well, the opposite is also possible. Turn the motor by external energy and it can generate electricity.

Using a motor to convert energy into electricity

In an automobile you will find an engine. We're familiar with the word but what does it actually do in the car? Well, it burns fuel (gasoline) and then uses that heat to create kinetic energy to drive the car. In recent years, though, car-makers have been developing vehicles using another kind of kinetic energy source: A motor powered by electricity, just like those models we all know from our school days.

In a car you press down on the accelerator to power the engine and speed up. To do the opposite, you should then just reduce the kinetic energy and slow down. When you brake or take your foot off the accelerator, there is friction and air resistance on the vehicle, kinetic energy is lost and so speed decreases. By skilfully manipulating these inputs a driver can adjust the speed of the vehicle he or she is driving.

Surely there is a way to recover even just part of this kinetic energy lost when we slow down? Yes, there is with a motor. When the driver's foot is taken off the accelerator and the vehicle is gradually slowing down as it coasts, or when the brake is applied, it is possible to convert the kinetic energy into electricity by turning the motor with the energy from the wheels. In this way, we can make electricity from the motor without using fuel. We call this energy regeneration, and the power can also be stored in the battery for later use.
New Forms of Electrification
This page introduces the example of the Nissan Serena. The diagram illustrates the current of recovered energy
shev_main_en.gif
※Red arrows: Energy current Yellow arrows: Electrical energy current

①Helping us start to move off
Engine power is particularly required when the vehicle starts to move and it also uses a lot of fuel here. Using the electric motor at this point helps the engine do its job and this also improves fuel efficiency.
②Running the navigation etc.
The stereo and navigation can be run just by the electricity stored in the battery. Even just this greatly raises fuel efficiency.
③Preserving energy
The electrical power recovered by energy regeneration is then stored in the battery.

A diverse "electric" world

There are now all kinds of EVs and hybrid cars on the market.

Hybrid cars combine both an internal combustion engine and electric motor, and by utilizing energy regeneration they try to moderate how much we use the engine. For example, when the vehicle is parked (or "idle"), the engine is shut down and the electricity from the battery is used to power the car stereo and navigation system (a so-called "start-stop system"). But not only at these times, when the car is moving the electric motor is also helping the engine to run.

If there is one problem here it is that many hybrid cars are still expensive. And, since the car needs an engine plus a motor and large battery, it requires a special design layout and the amount of space left inside the car will often suffer as a result.

However, recently the "electric choice" has been greatly expanding. Even with a motor and battery in the car, there are now small EVs whose compact size is unaffected by the “extras.”

The re-launched Nissan Serena is one example. Naturally, if compared with hybrid cars with large motors and batteries, the volume of electricity the 2012 Nissan Serena can generate is limited. Yet fuel consumption has been greatly improved and without raising the price, meaning it remains a low-cost vehicle with no sacrifice to the space inside the vehicle.

This is the era that we have arrived at today, one where we can choose cars within a variety of "electric" stages according to our mobility wishes.