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Dam-less HydroPower

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In general, hydroelectric power is derived from the height through which water falls. When we build a dam, we are doing the equivalent of bringing two points along the river close together, to create some desired height.

Think of it in terms of the basically gentle slope of a riverbed, and Points A and B along the length of that riverbed, with B being downstream of A. If we drew a horizontal line from A to B, how high above B would that line be located? Well, when we build a dam at B, the water-level behind the dam is exactly that horizontal line connected to A.

So, it can now be understood that we don't actually need to build the dam! Instead, let's put a large Tunnel Boring Machine at Point B and set it to dig horizontally toward Point A. Once we are beneath Point A, we bore vertically to connect to the upstream part of the river. Now all we need to do is put a turbo-generator into the bore-way, and we will be generating hydropower, exactly as if we had built a dam at point B.

There are some advantages and some disadvantages to this Idea. The main disadvantage is that we won't want to send the whole river down the borehole at Point A --but in terms of a dam, essentially the whole river does generate power at Point B. The two main advantages are that fish are free to swim the whole river (we merely need screens to keep them from going down the bore hole), and that we can build these borehole hydropower systems all along the length of the river, without any need to look for special places to put them (like high canyon walls are needed when building a dam).

I would like to think that the net effect is, we could actually generate more total hydropower from this dam- less system, along the length of a river, than from the normal damming system. To be determined, of course!

 — Vernon, Apr 23 2014

AKA Run-of-the-river hydroelectricity http://en.wikipedia...er_hydroelectricity

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 Very, very baked I'm afraid. Quite often implemented as simply laying a pipe adjacent to (or even in) the flow.

 For the microhydro projects around where my folks live, there are very strict regulations on what percentage of a river can be diverted - any noticeable change to the environment is verboten, so dams are right out.

But it's not just tiny systems that do this, I'm sure you're aware of Dinorwig power station? They dug a tunnel between two lakes, and placed all the generators underground.
 — mitxela, Apr 23 2014

Nope, never heard of Dinorwig before.
 — Vernon, Apr 23 2014

 You also missed the bit where dams act as a battery, allowing the storage and controlled release of power. Where I live has a major dam and canal system to provide for power to (now obsolete) textile mills. Roughly speaking, they would use twice the river's flow for 12 hours, and then shut down for 12 hours. Without the dam, that would not have been possible.

There's also the fact that the major purpose of most dams is not power generation. Hoover Dam, in the US, was primarily built for flood control and irrigation. Power generation is a significant bonus, but not the primary purpose.
 — MechE, Apr 23 2014

Many, many rivers in the world do not run at full strength during the year. In Maine, for instance, a turbine sluice without a dam above it would only work for a few weeks each spring and autumn, when everyone's up to their tits in floodwater and nobody dares to plug in the toaster anyway.
 — Alterother, Apr 23 2014

Yes, very baked, but if you are going to be copying someone, you can do worse than Nicola Tesla, as this is the way Niagara Falls is done.
 — MisterQED, Apr 27 2014

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