LostXOR , 5 hours ago

Last year the California Energy Commission posted the results of a study aimed at assessing efficiency of deploying piezoelectric systems to generate clean electricity from roadways.

“Based on the laboratory evaluations and road tests, the application of the piezoelectric energy harvesting system in one lane of a one-mile-long roadway has the potential to generate 72,800 kilowatt-hours of energy per year,” the team reported.

How is that clean energy, in any sense of the word? Any system that gains some energy from a passing car must necessarily decrease the (kinetic) energy of the car by an equal or greater amount. And the vast majority of cars get their kinetic energy by burning fossil fuels. Sounds like a more expensive, less direct, and less efficient version of a gasoline generator.