A laboratory energy harvesting device

Aug. 26, 2008 -- Discovery News -- For centuries humans have dammed rivers and streams to grind grain and later, generate electricity. Now a new, more subtle form of fr 5b4 eshwater 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 t 594 o 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.

"If you looked down at [the grid] it wouldn't look that different from seaweed," said Weiland.

According to Christopher Lynch, a smart materials researcher from the University of California, Los Angeles, this is the first freshwater hydroelectric power project of its kind.

Usually freshwater energy comes from damming a river and flooding large areas behind it, said Lynch. That creates enough pressure to turn a turbine which then generates electricity. It's an effective way to capture the river's energy, but it also has severe ecological consequences.

Weiland's method likely wouldn't generate as much energy as a hydroelectric dam but would keep the river intact and healthy.

"The whole idea is very interesting," said Lynch. "Harvesting energy from rivers, ocean waves and currents are going to be an important segment of our overall energy generation in the future."

Weiland's smart materials project is only one small part of the larger effort to turn Vandergrift from steel town to green town. A farmer's market, solar panels, and education programs on energy conservation have been or will be put in place to further help reduce the town's energy consumption.

If all of those efforts are successful Weiland estimates a PVDF-based smart materials grid could generate as much as 40 percent of the town's power. But the cooperation and motivation of the town are essential to reach that mark, said Weiland.

"Smart technologies can take us an important part of the way [towards sustainability]," said Weiland. "But they can't do all of it."

See this story and video at: http://dsc.discovery.com/news/2008/08/26/river-power-energy.html