Wednesday, March 31, 2010

Low Tech Clean Tech

Not all the excitement concerning clean energy systems has to do with pushing the efficiency of solar panels, or finding the best way to produce biofuels. Some are actually pretty low tech.
Here in the Pacific Northwest of the US, we are blessed with an abundance of hydropower. The Columbia River in fact is no longer a "river" in the traditional sense of the word, but rather a series of lakes backed up behind dams.

Hydro dams cause big problems for migrating salmon. They block the fish from getting upstream to spawn, and the slack water behind the dams means that the fingerlings spend an inordinate amount of time and energy getting out to the sea. But there is at least one aspect of these operations that is being addressed.

Going through the huge turbines on the way downstream is often deadly for salmon. Well, they don't actually get chopped up the way you might think. The blades actually turn more slowly than that. But they do experience disorienting turbulence and horrifyingly steep pressure gradients. And they do get killed.

Turbulence and pressure gradients cause those smolts that survive the passage to spin out the dam in a very vulnerable state, a situation that a growing menagerie of animals - sea lions, arctic terns, etc. - have become aware of. But the salmon may be getting some help, and the dams can be made less harmful than they are.

The US Army Corps of Engineers, who own and manage the dams on the Columbia River, and the Bonneville Power Administration, which sells the power from the dams, are paying a Pennsylvania firm to design and build a turbine with smoother interior passageways to cut down on salmon fatalities. An aging turbine at the Ice Harbor Dam on the Snake River would be the first to be replaced.

This isn't exactly rocket science, but it's close. High performance aircraft have the same problem with turbulence around their blades as the turbines in the dams do. In the case of the aircraft, the turbulence leads to inefficiency and higher operating costs. But the tools that are being used to re-vision the powerhouse blades for the salmon are the same tools used to model high performance aircraft propeller and turbine fan blades.

The larger problem has been that the turbines are so expensive to replace, that the Corps generally waits until a turbine is "on its last legs" before buying a new one. So perhaps, with the turbines in the dams on Northwest rivers reaching the end of their service lives, we'll finally see an opportunity to do the right thing along with the necessary thing.

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