Engineering & Product Development: California Studies Piezoelectric Highways
An exciting new engineering endeavor could make America’s busiest highways more than just a way to travel. The California Energy Commission recently took bids to begin testing piezoelectric generators embedded in roadways as a source of renewable energy. The project is part of California’s plan to use renewable energy sources to create 50% of their electricity by 2030.
What is piezoelectricity?
It’s long been known that certain crystals in which the atoms are not symmetrically arranged, like quartz, produce electrical charges when compressed. Pressure makes the atoms in the crystal move, causing the existing negative and positive charges that normally cancel each other out to move to opposite ends. This allows electricity to flow through the crystal. See an animated demonstration of how it works, here.
Piezoelectric transducers are already used to change pressure and vibration into electricity in electric igniters for gas appliances, ultrasound equipment, quartz timepieces, and microphones.
Piezoelectric generators in roads and walkways.
In 2009, Israel was the first country to test using the weight and friction of vehicle traffic to produce electricity by putting generators with adjacent batteries under the asphalt of a ten-meter section of Route 4. The Green Optimistic reported in October of that year that the test “generated some 2,000 watt-hours of electricity.” The Los Angeles Times reported in September of 2016 that the project was an apparent failure, prompting Italy to scrap a similar project. However, the East Japan Railway Company was successful using piezoelectric flooring in a railway station. The energy generated by crowds of travelers walking through the station currently powers the ticket gates and displays there.
Implementing the system in a way that would produce electricity at costs competitive with established systems will be challenging, but the CEC is optimistic. As reported in the Huffington Post, “scientists estimate the energy generated from a 10-mile stretch of four-lane roadway can power the entire city of Burbank, which has a population of about 105,000.”
The CEC will award 2 million dollars from the California Public Utilities Commission’s renewable investment fund to testing contractors in the early 2017. Lab testing is expected to take at least 2 years.