Alternative energy will become increasingly important as fossil fuel supplies will inevitably be depleted or environmental damage will awaken consumer awareness. The search for a viable alternative energy will continue until these alternatives can address the dynamic demands of the electricity grid and storage limitations. Piezoelectric devices, used to collect vibratory energy from roads and walkways due to traffic, can produce predictable (traffic-based) and locally storable electrical energy.
Piezoelectric devices generate electrical energy through a piezoelectric crystal. The glass, located about 5 centimeters below the surface of the asphalt, deforms slightly when vehicles travel across the road, thereby producing electric current. These devices have been implemented by the East Japan Railway Company (under the gates of the pedestrian subway station) and by Innowattech (under Israeli roads). Innowattech has announced that these devices, if planted along a one kilometre stretch of road, could provide an average of 400 kW of power, enough to power 162 Western-U.S. Households. These data suggest that piezoelectric energy collection is a competitive and clean alternative energy source. In response to these findings, in 2011, California State Assemblyman Mike Gatto proposed the Bill 306 Assembly to develop this technology for Californian highways. However, it is unclear whether the data actually reflect the physical limitations of the piezoelectric energy harvest.