this post was submitted on 24 Aug 2024
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[–] [email protected] 16 points 2 months ago (13 children)

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.

[–] [email protected] 3 points 2 months ago (4 children)

How would a turbine that takes energy from the air current generated by a passing car decrease the energy of the car? The car has imparted the energy to the air, the air has already extracted energy from the car aerodynamic or directly Newtonian forces, and then the turbine would extract energy from the accelerated air from the passing vehicles.

[–] [email protected] 1 points 2 months ago (1 children)

How would a turbine that takes energy from the air current generated by a passing car decrease the energy of the car?

Not sure where you got that idea from, but how would that generate a meaningful amount of energy? It seems very unlikely that such a system would ever recover the energy spent on its construction.

[–] [email protected] 2 points 2 months ago

Not sure where you got that idea from

I think it’s because you said, “Any system that gains some energy from a passing car,” not that anyone mentioned turbines explicitly.

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