Energy conservation is probably not the first thing that comes to mind when you think about freeways jammed with idling vehicles.
But in California, which has some of the most congested freeways in the country, that's about to change. The California Energy Commission has approved a pilot program in which piezoelectric crystals will be installed on several freeways.
Piezoelectric crystals, about the size of watch batteries, give off an electrical discharge when they're mechanically stressed, such as when a vehicle drives over them. Multiply that by thousands of vehicles and it creates an electric current that can be harvested to feed the grid.
In fact, scientists estimate the energy generated from piezoelectric crystals on a 10-mile stretch of freeway could provide power for the entire city of Burbank (population: more than 105,000).
Piezoelectric-based energy-harvesting technology is already being used in other countries. Since 2009, all the displays in the East Japan Railway Company's Tokyo station have been powered by people walking on the piezoelectric flooring. Italy has signed a contract that will install this technology in a portion of the Venice-to-Trieste Autostrada. Israel is already using this technology on some highways, which is how Gatto got the idea for the pilot program in California. A friend returning from a trip to Israel raved about a road that produced energy.