> It's an Israeli firm that is intending to put piezoelectric
> cells under highways to generate electricity every
> time a car/truck passes over.
That's a really bad idea.
They fail to point out that the laws of physics mean there is no free lunch. The car or truck in question will be slowed down slightly. That's fine if it's used on the approach to a junction (the driver doesn't have to brake as hard) but bad news if used on the exit or an entire motorway. More fuel would be needed to maintain the same speed.
The question then becomes... Are a load of car engines more or less efficient than a power station at generating electricity? I suspect not so this idea would also increase C02 emissions.
It has a limited life as well. Once we all start driving electric cars we'll all have regenerative braking and want to use the energy ourselves rather than give it away to the electricity company.
The only practical application I can see is for powering illuminated road signs out in the country and solar panels might do a better job.