Many find the idea of generating electricity from our roadways very appealing. People went nuts over the idea of solar roadways, even though that’s a singularly terrible idea. There’s actually a much better way to extract energy from roads, and California state officials agreed last week to provide $2.3 million for two test projects that will use piezoelectrics embedded in roads to turn the passing of cars on the road into power.

Piezoelectric materials are ones that generate an electric charge when they encounter mechanical stresses, like the sort of stress a car would apply to a road while driving. It’s easy to see how roadways with embedded piezoelectric arrays would be a great way to capture and repurpose energy from passing cars that would otherwise be wasted. The cars are going to exert a force on the road no matter what; why not harvest it?

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The two projects to be funded are a 200-foot stretch of pavement on the UC-Merced campus, which will be filled with tiny piezo arrays stacked “like quarters” in the road surface. Some estimates suggest that as little as 400 cars per hour would be needed to make the system economically viable. In California’s urban areas, that’s a laughably easy number to hit.

The second test will be undertaken by a company called Pyro-E, and will use a half-mile of highway to potentially harvest enough power for 5,000 homes.

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There’s concerns about what the equipment may do to road surface longevity and wear, and these tests will help find answers to those questions.

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This sure seems worth trying; last time the Bureau of Transportation Statistics checked in 2013, there were 1.3 million miles of paved road in the U.S. That’s a lot of free energy waiting to be harnessed.