Waterwheels Generating Power.

[paddy]

Does anybody here know anything about Waterwheels for producing electricity?????????

[Jack]

Gidday

If I only had running water with a decent fall I would be doing that.
A 6 foot fall running a 4 inch pipe will give you a constant 2 horsepower which with storage is enough to run any domestic situation.

[revdode]

No one apart from maybe Dick Strawbridge does water wheels these days. If you do a search for WATER* turbine suppliers you will find the modern take on water power. More efficient, less romantic and more susceptible to crud in the water supply.
If you are lucky enough to have a decent head and reliable flow of water micro hydro is probably the best micro-renewables solution. The fife earth ship has wind, solar and micro-hydro, until someone desturbed the flow of water the hydro was responsible for the majority of generation. If you get in contact with the folks at sustainable communities initiiative 'm sure they would give you details of the supplier (www.sci-scotland.org.uk).

The range from Navitron gives you an idea of how little space you need for modern gear.

http://www.navitron.org.uk/hydro_power.htm

*edit - oops

[paddy]

Straight in and on the ball.

Thanks alot both for your quick and informative replies.

[Wombat]

G'Day Paddy,

I saw a design once for a pelton wheel that was home made and based (I think) on teaspoons!

Depends on how much fall and flow you have as Jack said. If you are interested I will dig through my mounds of stuff and see what I can come up with.

Nev

[Muddypause]

I reckon that for a waterwheel to produce useful amounts of power, it needs to be pretty big. But the way the water interacts with the wheel will be crucial. For example, it makes a big difference whether it is overshot or undershot. There's probably all sorts of general info on the web.

But I reckon Revdode is right about a water turbine (I'm assuming that 'wind turbine' was a typo) being the way to go. I used to visit a community in Scotland (probably 20 - 30 people) who had their own hydropower, and a reletively small unit was able to supply most of their needs.

[Jack]

Gidday

If you have a bigger flow and small head then the undershot will win, but the other way around I think it's the overshot.

Just a 6 foot wheel with a 4 inch pipe and you get 18kw of power per day if my maths aren't too far out.

[Muddypause]

Gidday

If you have a bigger flow and small head then the undershot will win, but the other way around I think it's the overshot.

Just a 6 foot wheel with a 4 inch pipe and you get 18kw of power per day if my maths aren't too far out.

I wouldn't wish to dispute your maths, Jack, which may well be better than mine, but a kW is a rate of energy, not a quantity, so saying 18kW per day is the same as saying 18kJ per second per day, which I'm struggling to get me 'ead around (imagine saying that a hose pipe delivers 18 liters per second per day). Do you mean that it can produce electricity up to a maximum rate of 18kW? This would make sense, but seems rather high (= 24 horsepower).

Also, does your calculation account for the efficiency of the wheel? I've absolutely no idea how efficient a waterwheel would be, but intuitively I would say not very - not all the energy in the water is going to be usable at the shaft of the wheel. I believe a turbine, OTOH, can offer efficiency of 80% or more.

But a water wheel does have the advantage of being buildable yourself, without needing to get involved in precision engineering and difficult materials. This is an important factor in terms of self-sufficiency. And what an interesting project, too.

[Cheezy]

I have for years hankerd after a water wheel, well before Dick Strawbridge came on to the scene.

It's widely recognised as the only way to generate electricity with a quick pay back. mainly as Muddy say's its do-able yer sel.

Wind turbines are for the hair shirt bragade, they don't make ecomonic sence, but do make environmental sence.

PV cells are for the deep pocketed, and the enviromental impact of all those silicon /glass/ electronic cells is a bit iffy.

But a water wheel could be maunfactured from recycled wood/metal by yourself, very sssish.

Right all I have to do now is find a nice bit of land with the ideal low C house on it (especially as Gordo Brown is making them 0% stamp duty), a nice stream which I can get an abstraction right on, which doesn't flood, and a bit of wild meadow, plus a few acres wood and I'm sorted.

....Any one got a spare couple hundred thou' under the matress they don't need?

[juperwort]

OK, mad non thinking idea I know. But how about catching all your rainfall high up, and regulate it slowly through a mini water turbine to a lower tank.
Pretty much no use, but might charge an AA battery !

[Muddypause]

Juperwort - it would all depend upon how much water you can collect. Mind you, it is surprising just how much water comes off a modest roof during a downpour. But it's only going to be useful while it's raining, and I suspect you may be right to limit your expectations to a small battery's worth..

Here's another idea (I may actually have posted this before; can't remember):

Two large storage tanks, one on the roof of your house (house may need reinforcing), one below ground. Wind pump pumps water from the underground tank to the roof tank. Flow of water back down again via turbine.

With large enough tanks, and the underground one burried deep enough, this may produce viable amounts of electricity. Maybe it could even be combined with ground-source heating.

Cheezy, when you find that bit of land, let me know, and we'll combine resources - I'd be up for building the low C house from scratch.

[Cheezy]

I like your thinking Muddy on the tanks, obviously there's going to be losses in efficency, but if you could perhaps combine as many things as possible into the one idea, so when we build our low C house it'd all come in together.

Like you say bury the tank as deep as possble under ground for ground heating. How about using a solar water heater between the pump and top tank as well, seeing as hot water rises this shouldn't be too much of a problem, I've also wondered about fitting heat exchanges in chimneys, this could heat the water in the top tank.

Then you could let it drop going through under floor piping for the under floor heating, fitting a turbine in the last section, the under floor heating would slow the flow and therefore reduce the power out, but you would gain in heat.

What you think?.

[juperwort]

Maybe you only 'open' the top tank when you need it. Shed light for example. Then just go straight to light bulb, no charging

[Thomzo]

Shame you can't make em small enough to fit into each downpipe and the outlets for the shower, toilet (umm maybe not), washing machine etc.

Does kind of link in with my thread on water features though.

http://selfsufficientish.com/forum/viewtopic.php?t=5153

If you pump the water to the top and let it go down through a feature wheel how much of the original water could you pump back up using the electricity you generate on the downwards part of the cycle?

Zoe

[Muddypause]

I like your thinking Muddy on the tanks, obviously there's going to be losses in efficency

There will be losses - probably the greatest in the windpump. A decent water turbine can be quite efficient (I would guess more efficient than a wind turbine), and you would avoid the need for either a lossy inverter, or very lossy storage batteries.

I've also wondered about fitting heat exchanges in chimneys, this could heat the water in the top tank.

I suspect that there would be an increasing problem of overall efficiency by adding more and more sources of heat into the same system, but I guess there could be all sorts of ways we could reclaim energy that we otherwise chuck away. For example, an interim holding tank for the outlet of baths, showers and sinks, where a heat exchanger could reclaim that lost heat. The trick is to make it all economically viable.

Then you could let it drop going through under floor piping for the under floor heating, fitting a turbine in the last section, the under floor heating would slow the flow and therefore reduce the power out, but you would gain in heat.

What you think?.

I would suggest a separate system for reclaiming the heat from a chimney - the heat exchanger running its own underfloor heating, for example, or its own radiators. But maybe the most efficient thing to do is to redesign the chimney, so that the hot flue gasses are diverted around the areas where the heat is most needed.

Maybe you only 'open' the top tank when you need it. Shed light for example. Then just go straight to light bulb, no charging

You got it exactly. The idea is to avoid the need for storage batteries. A bit of technical wizardry would regulate the flow rate according to demand on the turbine.

If you pump the water to the top and let it go down through a feature wheel how much of the original water could you pump back up using the electricity you generate on the downwards part of the cycle?

Oh dear, this should maybe go in the same thread as the perpetual motion machines that keep cropping up in this forum.

If the waterwheel is (say) 50% efficient, and the generator is perhaps 90% efficient, and the motor that drives the pump is 90% efficient, and the pump itself that lifts the water back up is, guess, 75% efficient, and any other gubbins that are required to make the thing work (electrical and mechanical) account for maybe 20%, you get back about a quarter of the energy that you put into the system. So, for evey 100 liters that you use to turn the wheel, you could pump back around 25 liters.

But, don't make things more complicated than they need to be. Use the wheel to drive the pump directly - that way you cut out the inefficiencies of the generator and the motor. That could nearly double the efficiency (or, perhaps more accurately, halve the inefficiency). But this is all guestimating.