Green Electricity From Cars

This week an Israeli firm Innowattech performed a successful trial of their alternative energy system that generates "green" electricity from vibration caused by passing cars. The system was installed on a 10 meter strip of asphalt on a highway and powered the street lights set up next to this strip. It used special piezoelectric generators embedded in the asphalt 2 inches below its top level. The generators were mounted with electronic cards that fed voltage into a storage system.

Piezoelectric effect in general is the generation of a voltage by certain solid dielectric materials when a mechanical stress is applied to them. It has been known for more then a century, and is widely used in piezoelectric transformers for high-voltage power supplies, various transducers, sensors, cigarette lighters, and other low-power applications. The Innowattech's system called IPEG™ is probably the first practical high-power application of piezoelectricity. According to the company, the installation of their system stretching one kilometer would produce 200 kW per hour on single traffic lane, or 1 megawatt on a four lane highway. Installation of the piezo-generators and electronic cards can be performed during paving of new roads or during the maintenance work. The "traffic energy" can be either supplied back to the drivers by powering the road lights or fed into the electric grid. A variation of IPEG™ can also produce power from pedestrian movement. Harvesting energy from the vibrations created by people walking on the floor is also being researched by East Japan Railway Company, who installed “Power-Generating Floor” in a Tokyo station.

Innowattech estimates the cost of energy harvesting from roads, railways and runways via IPEG™ to be 3 to 10 cents per kilowatt, which is comparable to the cost of renewable energies.