The river keeps flowing, and flowing ...

We're constantly worried about the generation of power. This is because we're constantly coming up with new and cool things to do with that power, but it's also because we (as a society) are becoming increasingly aware of the negative impact that power generation has on our environment.

I'm amazed and shocked at how little use is made of water power (much of what I say can also be said about wind power). Long before we used coal, and the resultant steam power, effectively, waterwheels were grinding grist. So why are there so many dams that only serve as flood control? Why doesn't every one of those have a hydroelectric powerplant built in?

Water power is amazing in its infinitness. If I take a lump of coal and burn it, I might generate 100 megawatts of power (ok, it's a really big lump of coal). If I take that 100 megawatts, it might equate to a million gallons of water flowing through the hydroelectric generator of a dam.

The amazing thing about that million gallons of water is that I can go a few miles downriver and build another dam, and generate another 100 megawats of electricity, from the exact same water!

Try to do that with the lump of coal. Go ahead, gather up all the smoke and ash and burn it again and see how much power you can generate from it. I'll bet it's somewhere near 0.

But it doesn't stop there ... I can go a few miles downriver and generate another 100 megawatts of electricity from the exact same flowing water that generated the first 200 megawatts.

This floors me. It's like an infinite source of power for free. Sure, you have to build the dams and spend all that construction money, but you'd have to build a coal-fired powerplant as well.

I'm further amazed by outrageous projects such as the Itaipu and the Three Gorges dams. Sure, each of these generates an enomous amount of non-polluting power, but at what cost? How many acres of land were needlessly flooded to build these bohemiths? As a kayaker, I weep at the thought of how many exciting rivers and creeks are now at the bottom of a flat, boring lake. There's also an exciting danger: if either of these dams were to experience a catastrophic failure, due to earthquake, neglect (think Johnstown flood), or whatever ... the devastation downstream would be incomprehensible.

How much different would the total power output be if we made many little dams along the rivers and streams comprising that watershed? Overall, the same amount of gallons per minute would be available, but much of it could be used multiple times!. And the environmental impact of each of those small dams would be considerably less than that of one big dam. Not to mention the safety of having multiple flood control dams along the river to back each other up in the case of one failing.

The logic behind this escapes me. Perhaps there's some overall picture I'm not seeing here, but I can't imagine what it is.