California’s freeways are famous for having heavy traffic, but soon they will be known for something much better. The freeways will produce energy, thanks to a pilot program approved by the California Energy Commission that will install piezoelectric crystals on several freeways Piezoelectric crystals are about the size of watch batteries, and they produce an electrical discharge when they’re mechanically stress, such as when a vehicle drives over them. Multiply that by thousands of vehicles and it creates an electric current that can be fed into the grid. Scientists estimate the energy created from a 10-mile stretch of freeway could provide power for the entire city of Burbank (population: more than 105,000).