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Researchers from Lancaster University are looking to pave the next generation of smart road surfaces — with piezoelectric ceramics. When embedded in road surfaces, the tiles convert vehicle vibration into electrical energy.

Interest in piezoelectric-driven power has grown in the last decade. In 2008, the East Japan Railway Company installed a footstep-sensing floor at Tokyo station, harvesting the crowd's kinetic energy to operate ticket gates and display systems.

Italy, in 2011, signed a contract to place piezoelectric crystals underneath a stretch of road on the Venice-to-Tieste Autostrada. Even a club in San Francisco has taken the technology to the dance floor, using energy-capturing panels to power lights.

But are piezoelectric sensors truly road-ready?

A Piezoelectric Test Drive

Piezoelectric devices create an electric shock, or charge, when compressed. Think of a home grill that lights up with the press of a button, or a pilot light that initiates your hot water heater.

Lancaster engineers are looking at advanced road materials that could generate electricity from passing traffic.

The crystalline structures, when impacted, turn the mechanical stress into power. As cars roll over the sensors, the vibration creates electricity that can run through a wire to a battery, transformer, or central collection point on the side of the road.

The Lancaster University team, led by Professor Mohamed Saafi, will deploy tests on a one-mile road in the UK and Italy. The project aims to recover one to two Megawatts per kilometer under normal traffic volumes — approximately 2,000 to 3,000 cars per hour.

The energy produced will be stored in a battery to power street lamps, traffic lights, and electric car charging points, according to Saafi. The biggest challenges for the team, the professor told Tech Briefs, are cost, durability, and compatibility with materials like asphalt and concrete.

“The pavement must not affect the performance of vehicles in terms of gas consumption and safety,” said Saafi.

Lancaster University’s energy-harvesting project has received approximately £195,000 in funding. The research is part of the SAFERUP (Sustainable, Accessible, Safe, Resilient and Smart Urban Pavements) program, which has been funded by the European Commission’s Horizon 2020 fund and is directed by the University of Bologna.

California’s Piezoelectric Project

Piezoelectric tests are happening in the U.S. as well. In April of 2017, California’s Energy Commission awarded grants to two organizations eager to demonstrate the technology: PYRO-E, LLC and the University of California, Merced.

Using 2-centimeter-wide piezoelectric generators, about the size of two stacked half-dollars, the UC Merced team will perform tests on a 200-foot span of asphalt. Pyro-E, a solid-state technology manufacturer based in San Jose, CA, will also demonstrate the readiness of its electrical harvesting systems on a half-mile area of highway.

Piezoelectric initiatives from groups like Lancaster University and the California Energy Commission are still very much in the development and experimentation phase. The teams are experimenting with the placement of the road devices to see which configurations achieve the maximum amount of energy.

Mike Gravely, team lead for energy system research at the California Energy Commission, wants to ultimately establish if the products provide economical, large-scale power outputs.

“We want to determine whether or not it’s a realistic project or what I call a ‘science project,’" said Gravely. "You can do a science project and it’s a nice project, but it’s not necessarily cost effective or commercial."

California's grant recipients expect to test their technologies over the next two to three years as the state seeks to achieve its far-reaching energy goals. One target for California: getting 50 percent of its energy from renewable sources by 2030.

"We’re not going to get there with current technology," said Gravely. "We’re always looking for new technology like [piezoelectrics] to try out, and our job is to help those companies grow, and to encourage more people to enter the market.”

What do you think? Can piezoelectric technology provide large-scale power? Is a piezoelectric highway possible? Share your comments below.

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