Airdate: Apr 21, 2003
Scientist: Daniel Schneider
Hydropower: Learning from Beavers
Beaver dams have inspired scientists to rethink their approach to hydropower.
ambience: rushing water, turbine
Beavers are considered one of nature's most gifted engineers. In fact, beaver dams have inspired scientists to rethink their approach to hydropower. I'm Jim Metzner, and this is the Pulse of the Planet.
Beaver dams are not only a marvel of animal ingenuity, they also have an advantage over the hydroelectric dams that humans build. Now, a beaver dam is never bigger than ten feet high.
"The interesting thing is, the pressure and velocity that are associated with fish in moving through heads of ten feet, is entirely within the physiologic limits of fish to endure."
Unfortunately, says engineer Daniel Schneider, many fish are killed by the blades of turbines in hydroelectric dams or they're harmed by the severe pressure of the churning water. Attempts to protect salmon from dams in the Northwest have been only partially successful. So, Schneider invented what he calls a "linear stair-step" hydropower engine. Water flows, fairly slowly, through a rising and falling series of blades called "foils." As the water turns the cascade of foils, it rotates axles which drive a generator. This new system doesn't need to have tall dams with high pressure to create a lot of energy, and it's very "fish friendly."
"The way this protects fish is by being able to let both the adults and the young ones move through the system as easily as you can move up and down stair steps. It takes that same amount of experience of moving from a high level to a low level, and allows that to be done in steps."
Daniel Schneider says that large hydroelectric dams could be retrofitted with the new low cost stair-step engine, and they'd produce the same amount of power without hurting fish.
Pulse of the Planet is presented by the National Science Foundation. I'm Jim Metzner.