Me and my dad got into a conversation about using cars to produce energy for road lights, we came up with 2 ideas.
My idea was to put piezoelectric ceramic plates under the road and when cars run over the plates it presses on the plates in-order to produce electricity. most piezoelectric stuff is remarkably cheap and could possibly utilize the weight of cars, trucks and 18 wheelers to to produce electricity for various street lights or even more.
His idea was to put magnets under cars and coils under down hill roads, when the cars move down hill the magnets induce currents in the coils in-order to produce power, this would of coarse slow down the car but that wouldn't matter because the car would be traveling down hill and the energy would be drawn from the force of gravity. I told him that it might attract random trash from the road like nails which might help roads be safer, but at the same time it could be dangerous if you picked up a large piece of trash.
Both of these Ideas seem logical to me but we want to get some scientific feed back from you guy's to see what you think.