Wiggling Plastic at River Bottom to Generate Electricity

Aug. 26, 2008 -- For centuries humans have dammed rivers and streams to grind grain and later, generate electricity. Now a new, more subtle form of freshwater power is about to make its debut in the old steel town of Vandergrift, Penn.

Using a grid of electricity-generating smart materials on the bottom of the Kiskiminetas River, combined with a host of energy conservation efforts, Vandergrift hopes to generate between 20 and 40 percent of the city center's electricity.

"Vandergrift is trying to be the model green town," said Lisa Weiland, a scientist at the University of Pittsburgh who is involved in the project.

Vandergrift, which is northeast of Pittsburgh, was originally supposed to be the model steel town, but now, as Weiland says, it is "reinventing itself and going for sustainability."

That sustainable power will most likely come from a grid of undulating strips made of polyvinylidene fluoride or PVDF, a material that generates a slight electrical current when it is moved, in this case, by the currents and eddies in the Kiskiminetas River. Such materials are described as piezoelectric, and the resulting electrical current would pass to small substations along the river's edge before charging a group of batteries.

"There are other materials that give better performance or have higher energy densities," said Weiland. "But we're willing to sacrifice a little power to keep the ecosystem happy."

The Kiskiminetas River, or the Kiski, as it's more informally known, is about 40 yards wide where it passes Vandergrift. Weiland currently plans to lay a grid, 30 yards wide and about a mile long, down on the river bed to help power the city.

The exact details about how dense the grid would be, how long the PVDF strips will be, or even when the grid would be laid down, are still being worked out. But whatever the final plans are, the researchers claim they will maintain the health and appearance of the Kiski, which is used for fishing, canoe trips and other recreational activities.