Originally posted by: Brent Kline
We have damns all over the US. Why are we not converting these to hydro electric plants. Seems to be the best choice over wind or solar ? any ideas ?
Most of the dams already are hydroelectric plants. The biggest ones date back to the Great Depression, when many of them were more make-work projects than responses to actual need--for instance, the Tennessee Valley Authority dams, Hoover Dam, Grand Coulee Dam, etc.
What I consider kind of amusing is that we deem ourselves to be the geniuses of the world and where we are globally because of our derring-do and pluck and the good ol' 'MURRICAN way, but the truth is, we've been ridiculously lucky. I mentioned Grand Coulee Dam--when it was built, most of the Pacific Northwest didn't even have electricity--only the largest cities. So now there was this massive amount of electricity being generated by the dam--without nearly enough customers to buy it all. Then what happens? Aluminum-fuselage aircraft---and the ultimate wartime buildup. What's the only problem with aluminum? It takes massive amounts of electricity to make it. And just as we need to build thousands and thousands of planes...Grand Coulee Dam is completed. When the dam was planned, no one dreamed there would be such a huge demand for aluminum.
Unfortunately, hydroelectric power isn't all that environmentally friendly. Dams choke off fish migration routes, and the "fish ladders" don't help. The areas behind the dams are, of course, completely flooded. And the throttled river downstream is drastically changed as well---Glen Canyon Dam has had a profound effect on the ecosystem of the Colorado River within the Grand Canyon.
The Canadians LOVE hydroelectric power (in fact, "hydro" is the word they use to refer to electricity). But in their case, they have a LOT of empty land with many large rivers flowing through it. The James Bay Project in Quebec harnesses rivers that flow into Hudson Bay, and it generates so much "hydro," the bulk of it is sold to the US. If that series of dams ever failed, there would be blackouts all over the northeastern US.
The problem we face is that all the good damsites have been used up. There's no river remaining that we could practically block with a dam and get enough power generation to make the enterprise worthwhile.
Yet another problem is siltation. The area behind the dam gradually fills up with silt, and eventually what you have is not a lake, but a huge stinky mud flat, with the river cascading over the lip of the dam rather than going into the silted-up penstocks. The Bureau of Reclamation was advised early on that the dams on the Colorado were a bad idea because the Colorado flows through soft sandstone formations that produce a lot of silt (which is red--hence "Colorado"). Lake Mead, for example, has about half the capacity it did in 1932 when the dam was completed, which means that in another hundred years, it will be a hundred-mile-long, 800-foot-deep mud plug.
So as far as hydro--been there, done that, used it up.