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] 7 points 2 months ago* (last edited 2 months ago) (7 children)

It depends. Is this energy the same energy that is already being burned?

Looking at an extremely simple example: Solar powered calculators (the real ones). They harness light from the light bulbs in a room which would be otherwise dark. The only time they are harnessing that power, is when the light is on. They add no extra draw to the light, they are 100% passive. The only time you’d really have to take into consideration how green that power is (explicitly for the calculator) is if you are turning on that light explicitly to power the calculator.

If the tech being talked about is just harnessing the “junk energy” of the vehicles in their normal operation, this would be 100% green energy. If it is adding a load, it is 100% dirty when powered by an ICE. If it’s somewhere in the middle… I hope you get my point.

You’re also ignoring the fact that not all vehicles are ICE.

[–] [email protected] 7 points 2 months ago (2 children)

Ehh it's still a rubbish idea, that money would be much better spent going after primary producers of energy, like solar, wind, geothermal, or nuclear.

Some napkin math and an equivalent area of solar, say over a road or parking lot would produce 3.5 million kwh in a year.

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

Those aren’t always a fit for everywhere. And getting energy from one place to another is an unsolved issue. Just because one option is cheaper than others doesn’t mean that particular option is the better choice. Diversity is very important.

[–] [email protected] 1 points 2 months ago

Diversity is important, but it's still better to go after larger sources of energy first. There's just not much energy to be recovered from falling rain or waste from cars.

Make the cars waste less energy, or the transit system in general is much easier and will actually save money long term.

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