Off Grid Via Slow Moving River?

einstein writes "I live out in the middle of nowhere, and I lose power at the drop of a hat. My house is right next to the Susquehanna river, and all the kinetic energy going past my house makes just want to go off grid. Most homebuilt hydro power is lower volume/high speed. What would be a good, unobtrusive way to generate electricity from a high volume/low speed body of water? I'm between two large hydro dams, so the water level is fairly constant, but does tend to fluctuate 4-6ft in the winter due to ice floes and melting snow. I think maybe a miniature version of one of the recent submerged tidal generators might work... Does anyone have some suggestions on how I might go about this project?" More than a few people have done this before.

Comments

The Romans

[panxerox]

did something similar, they had a line of floating grain mills across the Tiber (no ice there though) in the late empire period. Find a good high current area and build a paddlewheel boat basically with the drive attached to a generator and use anchors in the riverbed. It might not generate a steady high elec current so you might want to put in a bank of batteries and converter for peak demand. Since the paddlewheel is in the back the boat draft would break up at least thin ice. With underwater turbines your talking alot of cost both in construction and maintainance. Hers another option http://www.hydrogenappliances.com/hydromauro.html

High torque

[680x0]

I bet you could build a low-speed, high-torque paddle wheel (it would need to have a lot of surface area being pushed on by the river). Then, using gear ratios, you can convert that to high-speed, low-torque that may be needed by your generator. Not being a mechanical engineer, I'll leave it at that. :-)

does this remove energy from the current?

[polished look 2]

ok, say this person puts in a paddle-boat or what-not which drives a generator. Does this remove energy from the river? will the downstream hydro-electric plant have less energy?

Re:does this remove energy from the current?

[FrankDrebin]

yes, but just momentarily

Huh? Let's not forget the law of conservation of energy. Of course a waterwheel/generator takes energy from the river as it puts out electrical energy. There is nothing "momentary" about it.

But this energy is otherwise "lost" to heat as the water flows downstream anyway. IIRC it was Joule (whose energy scale we use today) that originally did the science on waterfalls, showing the water temerature at the bottom of the falls is higher than at the top. As water flows downhill, it pummels into itself, and the gravitation potenital energy is converted to heat.

A waterwheel simply takes some of this energy and converts it to rotation instead of heat. With a waterwheel in place, the temperature of the water will be ever-so-slightly cooler downstream.

The downstream reservoir has a level, and it is the difference between this elevation and the tailrace (water exit) elevation that determines the amount of energy the hydro plant can extract. The difference is called "head" (I kid you not).

So the energy of the water used by a waterwheel is not "stolen" from the downstream plant... because it would have already been "lost" to heat as it reached the reservoir anyway.

Permits?

[pherris]

While it does sound like an interesting idea I suspect that the county and/or commonwealth will want you to pull somekind of permit. After they stall you for a year or two just to come up with the regulations they most likely want engineering data concerning possible damage to the riverbed and the generator's effect on river currents. Of course this really makes no sense but local politics never did.

Years ago my family spent a few years trying to get a 30' fix pier (that others on our street could use for free) built by our property. Between the hassles of the town, state and MEPA we gave up. Strangely a few years later a neighbor (and state senator) who opposed to our project build his own from our prints 100' away. I guess we didn't grease the right gears.

My advice, make it small, discrete, quite and easily removable. Be forward that running your own generator over a long period is probable cause for the DEA to search your house as a suspected grow-op. It sounds crazy but again it's all about politics.

Bonne Chance.

Re:Stay on-grid while generating power

[vikingpower]

Absolutely: DO stay on the grid. For 2 obvious reasons: 1) what if, you never know, your installation breaks down beyond repair ? 2) it's profitable I am in a monastery in the Netherlands. We are going to generate our own electric power, with windmills ( we are very close to the North Sea shore, have 200+ days of wind per year ). Not only for the monastery-house itself, but also for the candle factory with which we earn our money: heating paraffine eats kilowatts. But even under these favorable circumstances we would be mad to go off the grid.