OK, with a tag like "triboelectric nanogenerator", who doesn't want to love this new idea? But then: Physics.
Popular Science, of all sources that should maybe know better, touts this very-small-generator-inside-your-wheels as "... pulling latent electricity from the ground itself." Really, guys?
Researchers tested the TENGs by securing six strips of the material on the back wheels of a electric toy car, which also had six LED lights attached. The power generated by the toy car in motion lit all six LED lights, and at its peak, reached 1.79 milliwatts. However, the wattage increases with the weight and speed of the vehicle used, so researchers believe the output will grow with the size and weight of the tires used, according to the paper published in Nano Energy.
Nanogenerator tire at work
Why are we so skeptical? Just remember, nothing is free, and energy has to come from somewhere, and for every action there's an equal and opposite, right? Your motor pushes your car. Your tires go bouncy bouncy over the bumpy bumpies. They absorb the impact of the bumps, making your ride more comfortable, which is absorbing energy (and pretty much turning it into heat - ever feel your tires after a good drive?). Simply put, you try to recover that energy, you're going to make your tires stiffer. Riding on rocks is best left to Fred Flintstone. Just an opinion. Remember regen suspension? Like that.
To keep this all in perspective, remember, they're called "nano" generators for a reason. They're very small - and there are certainly viable applications in terms of powering pacemakers and other small things... but EVs? We remain skeptical.
If you want to read about how this "self-powered technology makes the periodic battery replacement or recharging no longer necessary", go to nanowerk.com. If you want to read Dr. Wang's free e-book on nanogenerators, here it is. Also, Georgia Tech's 2010 video explains some of the practical applications: