A company in Great Britain recently installed special tiles which generate electricity when pedestrians walk on them. The generated electricity can be used to light up the pavers themselves using high-efficiency light emitting diodes (LEDs) or wired to remote lighting or even be fed into the electrical grid.
An engineer by the name of Laurence Kemball-Cook came up with the idea and has established a company to exploit this technology. His company Pavegen manufactures tiles which are made of a combination of recycled concrete and rubber from recycled tires.
When one of the tiles is stepped on, the surface is slightly compressed about a 1⁄5 of an inch. This compression is converted to electricity via the piezoelectric effect (pronounced PIE-EE-ZO).
Actually, the work done to deform a crystal is converted to electrical energy. The effect is taken advantage in the igniters in stoves, barbeque grills, and cigarette lighters. The reverse effect functions to create the timing device in quartz watches. In this case an electric current is used to make the quartz crystal deform, that is vibrate. The frequency of the vibration is used to measure time.
This technology has applications wherever there is pedestrian traffic, indoor or out as the tiles are waterproof. Pavegen is currently installing its device in a pedestrian area adjacent to the stadium in London which will host the Olympic games this summer. Tens of thousands of foot falls will light up an adjacent mall. Numerous other applications of the technology include shopping malls, playgrounds, airports and train stations and urban sidewalks.
If the piezoelectric tiles were placed in highways they could generate energy to power street lights, traffic control signals, etc. The energy could power devices which could warn motorists of the presence of ice on bridges and overpasses. The power could conceivably be used to warm the surface enough to prevent icing in winter.
Another application of the piezoelectric effect is being developed for shoes and clothing. The military has experimented with piezoelectric boots which could power personal gps devices for battlefield management. Civilian technology could include piezoelectric clothing — say a jacket or pair of pants which when worn and thus in motion could generate energy to charge a cell phone, a music player or even a portable computer. Until the advent of nanotechnology this has not been possible because the piezoelectric electric materials were too brittle to be woven into fabrics.
The solution to our waning supplies of fossil fuels and the attendant problem of global warming from the use of those fuels will require many ideas big and small to create clean energy and a sustainable future. All this energy from piezoelectric devices is not free. It comes from energy expended by the people wearing or stepping on them. In our overweight society, however, that may not be a bad thing.