August 24, 2016

Freeways to provide electric power

Ecowatch - The California Energy Commission has approved a pilot program in which piezoelectric crystals will be installed on several freeways.Piezoelectric crystals, about the size of watch batteries, give off an electrical discharge when they're mechanically stressed, such as when a vehicle drives over them. Multiply that by thousands of vehicles and it creates an electric current that can be harvested to feed the grid.

In fact, scientists estimate the energy generated from piezoelectric crystals on a 10-mile stretch of freeway could provide power for the entire city of Burbank (population: more than 105,000).


Boffin said...

This is pretty stupid. The physics isn't even close to working-- not to mention mammoth costs in engineering, installation, and maintenance.

In short - if you are generating power by having the vehicle climb small hills and push them down, you are also increasing the rolling resistance. The energy comes from increased fuel consumption in the vehicles, and with a huge efficiency penalty.

Unknown said...

Piezo electriciticy is generated by applying force to, or squeezing, a special kind of crystal. Thus, imbedding the crystals in the roadbed will generate an electrical current when vehicles roll over them, and no hills, large or small, are required.

Boffin said...

Whether piezoelectric or any other method, it still creates energy from mechanical work, equal to force times distance. Simply exerting a force creates no energy - it must be a force exerted over a distance.

The vehicle has to be climbing hills and pushing them down, whether on a small scale or a large one. The power generated will be less (for piezos a lot less) than the increase in power expended by the car.

So you get a bumpy, dangerous ride on an expensive and fragile road, consuming more fuel to produce a tiny amount of electricity. The whole scheme is ridiculous -- and could only be promulgated by someone with a limited understanding of physics and engineering.

What's frightening to me is seeing how bad the press can when covering a topic I know well - and extrapolating that to all the stories for which I have less knowledge.