In school I learned that braking is a waste of fuel as the kinetic energy transfers to sound and heat (which is effectively a loss, right?). So how does regenerative braking recoup some of that energy into the car’s battery?
In: Engineering
Braking is essentially wasted energy in most brakes. This will seem obvious, but the energy you put into your car to make it go fast (“kinetic energy”) will take your car a lot further if you don’t brake. One of the “laws of physics” states that energy cannot be created or destroyed, but only transformed – so where does this kinetic energy go when you brake?
Most brakes work with friction – friction happens when you rub one object against another. If there is a lot of resistance, energy is transformed into heat! Essentially, braking turns speed (“kinetic energy”) into heat(“thermal energy”). This is why cars can overheat if they are driving downhill and braking a lot – the engine isn’t making too much heat, the brakes are.
For a while it was impossible to get this energy back – it just isn’t reasonable to design something that can recreate fossil fuels from brake heat. But this changed when cars started using batteries because we know how to make electricity easily.
Now, instead of wasting energy by converting it all to heat, we can convert the speed back into electricity! And then reuse that electricity to make the car start again.
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