Can regenerative brakes reduce air pollution?

It’s time for us to open our metaphorical mailbag and see what you’ve been sending our way. John got in touch after listening to last week’s show, and he said -

You were discussing the particulate air pollution coming from cars as they brake. I am wondering whether regenerative braking could help with this?

Chris Smith shared his thoughts...

Katie - Now it's time for us to open our metaphorical mailbag and see what you've been sending our way. John got in touch after listening to last week's show and he says, "you were discussing the particulate air pollution coming from cars as they brake and I'm wondering whether regenerative braking could help with this." So Chris, what do you think?

Chris - Yeah, he's absolutely right that as we embrace more electric cars, electric cars don't brake in the same way that traditional cars do. When we put the brakes on in a traditional car you are literally rubbing a brake pad against a surface, and the friction turns some of the kinetic energy of the car into some heat; but it wears out the brakes in the process, generating the particles that we then breathe in, and they're bad for your lungs.

In an electric car, though, there are traditional brakes that work like that, so you can put the handbrake on, for example, but you can also do regenerative braking, which is where when you take your foot off the accelerator, or you put your foot on the brake, the motors, instead of consuming electricity, then turn into generators. And so you convert the kinetic energy of the car into electricity, which can then be put back into the battery or into a capacitor to store that, and then reused to start the car moving again. So instead of converting the kinetic energy of the car into heat and brake dust, you actually convert it back into useful electricity. So we're actually going to see probably this solution being at least in part solved by the use of technology that's coming along, which is a good thing.

Katie - Is that a manual brake or is that an automatic brake?

Chris - The cars do have a manual brake, which you can apply, and it will give you an additional braking effect; but a lot of the time when you put your foot on the brake you can use the electric motor to brake the system. And that will actually be much more efficient than wearing out brakes, which we do at the moment.