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building a waterwheel - your thoughts on a design for my situation?  RSS feed

 
john beattie
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Hello everyone, first off thank you for allowing me to join your forum.

Ok i have an itch to scratch in the way of a water wheel that i can generate some power from, i've probably got a thousand questions but would just like to start with some basic ideas to see what people would recommend, I have a stream running past my house that i'd like to add a water wheel to, it's not a huge amount of water around 60-80 gallon a min, the width of the stream can go from 12" to 36" as it works it way down the hill which is around 9ft head.
What i'm not sure on is should it make a water run from the top of the hill ie like a sluice that will collect and run the water up to the wheel or would i get the same effect if i just made a short run from lower down the hill closer to the wheel, the distance between the top of the hill and where i'd like the wheel is around 150ft so quite a lot of sluice building. i know when using hydro they say the higher the head the better but does this apply in the same way for a wheel.
Any thoughts would be very much appreciated.

I know it's a bad time of year to be asking so don't expect an answer overnight as i say it's just something that i'd like to do next year as a little project so just trying to put a plan together.

Wishing you all a very merry Christmas
Take care
john
 
Roberto pokachinni
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Hi John; Welcome to Permies! 

I'm not the best to guide you on this, but I would say that from what I understand on the subject, and from what you described, you don't really have much in the way of power potential there.  Even so, if you decided to do it, you would need a large wheel, and utilize all of your head (a long sluice raised up to the height of your wheel at it's downhill end) to gears in reduction so that you are spinning rapidly at your power generator.  I would best hope that your home (or the place you are going to use the power) is not far from that production area, as you will lose some power in your transmission lines.  It might be a fun project as a hobby, but I don't know if it will power much.  But like I said, my understanding is limited.        
 
David Livingston
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before you start just a word of warning Where are you ? there used to be a whole heap of legislation in the UK and other places about doing this sort of thing . I would check it out first I know its on your land but alas there are whole departments of folks trying to make you sad out there
 
Roberto pokachinni
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there used to be a whole heap of legislation 
  This is true.  Sound's like your creek is just big enough to be in that category.  Most perennial flows will have some form of regulation.  This is particularly true if 1.) you are diverting the entire flow, or 2.) the stream is fish bearing.
 
Travis Johnson
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Roberto, I can see where you would get this, and you very well may be right, but by me there is a 1790's sawmill museum where they have a stream about this size, hooked up a waterwheel about the size he describes, and saws lumber on an old up and down headrig. I kind of thought it was just set up that way because they used what they had, but it turns out this stream, had incredible torque.

This was an all mechanical drive...actually an all wooden gear drive rig, yet when the dogs fell off the log they were sawing, this log about 16 inches in diameter and probably 12 feet long, was picked up and slammed back down over and over from that water wheel. The building was built from 12 x 12 beams and it was shaking so bad people were running out in fear it was going to collapse. They finally got the rig shut down, but the waterwheel never stopped turning.

After a little thought I realized just how much power that little stream had. Now a garden hose fills a 5 gallon bucket up in about 1 minute  If the stream is moving at 80 gallons a minute, it is 16 times faster then a garden hose. That is really fast, and it is putting a lot of weight on the end of those buckets. How much strength would it take to try and hold up 26 gallons...over 200 pounds of water...all while balancing on the end of a 4-1/2 foot lever? I am not trying to talk down to anyone here, but rather show the physics involved with flowing water and waterwheels. It is a lot more than you would think, but I would not have believed it myself if I had not seen it. There is a lot of power in falling water.

Now the problem is turning that torque into electricity. I would think a custom built generator would be required to get the most juice from all that torque.
 
Roberto pokachinni
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Now the problem is turning that torque into electricity. I would think a custom built generator would be required to get the most juice from all that torque.
  yeah.  Getting direct mechanical force to get a flywheel spinning and run a sawmill or a grain mill is VERY doable.  The problem, as you state is translating that into electricity.  For that to be efficient/worthwhile, you either need a lot more head from what I know.  I don't know of any generator that could translate such low head and low volume into electrical power effectively.  I might be wrong, but I've never heard of anybody doing it besides the engineers at Gaviotas, and they had more volume in their low head systems.  And those guys were really high end thinkers/designers to come up with their power generator. 
 
Travis Johnson
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This is out of my intellect I will admit, but I was thinking...and I might be wrong, that it MIGHT work if the proper generator/alternator was made. I think it would require the proper number of windings and all that. Kind of like along the lines of a locomotive; they don't turn up very high in RPMs, but through torque they produce a lot of electricity.

Still I wonder if there is not a better conversion than electricity for this given plot. Maybe hydro to compressed air or hydro to mechanical power
 
john beattie
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Hi Everyone and thank you for taking the time to reply.

Roberto, when i first looked at this i didn't think there was enough water or head to be able to do anything worthwhile but after looking at some Youtube videos i seen some wheels running with what looks to be very little water so it got me thinking maybe there was something that could be done, now i've said 60-80 gpm but that is just a rough idea, i got this number from damming the stream around a 8" pipe and holding a 3 gallon bucket under the pipe it filled in 3 seconds, there was also extra water passing through the rough dam i'd made, i was thinking 4ft for the wheel size and as i said i wasn't sure if building a long sluice from the hill top would help, i guess it keeps all the water uniform with a steady flow rather than it having to run over rocks ect,  i have approx 80-100ft from where the wheel will be to the end needing the power, i've seen a chap over at Missouri wind and solar saying if using DC i will lose power over distance and the cable i would need to use is much more expensive, as if i used three phase there is very little loss and the cable can be standard flex, i have an Ametek 99 DC motor but not sure if this is the best choice for a wheel and was thinking it may be to big for the water i have, below are some videos i have seen showing what looks like very little water, i have this amount and some.







Dave, thank you for that advice, i'm on the south west coast of Scotland (Dumfries and Galloway) i have permission from my land lord but i know what your saying about council rules and regs so that is worth looking into before i spend any money, the site did have a wheel on it many years back it was run off a dam further up the hill, my land lord has said if i'd like to reinstate it i'm more than welcome but to be honest i don't think it would be worth it as i think i'll need all the water going in to run the wheel so the large volume would be just standing still, it would be fine if just wanting to run the wheel a few hours a day with larger water volume but i'm looking for 24 7 winter running as summer has much less water.
Maybe with there once being a wheel on the stream there will be no objections, all the water is run off from the hills no springs not that i know of anyway there are no fish but you do get wild life so will look into it, so thank you for that.

Travis, thank you for your input, this is what got me a little confused when i watched the above videos, i would have though a large volume of water was needed but it looks quite small, i guess it will also depend on how well you build the wheel and the generator size also the amount of power needed, it's my understanding the more power you pull from the generator the harder it becomes to turn this with a set of pulleys to speed it up could prove hard for the amount of water flow i have, the above videos seem to be just wanting to trickle charge batteries but i was hoping to get some usable power, ideally i'd like 900 watts but i don't think i will get anywhere near that, but was also thinking solar and wind to add as time goes on.

So yes all very interesting and always good to hear what other people think, you have all given me something to think over and all help is very much appreciated.

Many thanks
john


 
David Livingston
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If you are in Scotland you will need to talk to the water board alas or even the Scottish office best of luck mate
 
Roberto pokachinni
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I have seen all of these before.  All good little systems with low electric power potential. 

You can generate power, for sure.  Just not sure how much, or how much it will be worth for the effort for your needs.  Maybe yes.  That will be up to you to figure.

So, as far as basic system designs, and in regards to the videos: 

The third video shows the water hitting the wheel in what I consider a more ideal manor, which is where gravity is nearly maximized, and less of the force is dissipated without translation to positive wheel movement.  Consider your hand turning the wheel.  All you want the hand to do is turn the wheel.  If you are clapping your hands occasionally, or twiddling your thumbs, or texting on your phone, your efficiency at turning the wheel is likely to be diminished.  Same is true with the water.  All you want the water to be doing is turning your wheel, and with as much use of gravity as possible. The pipe could be a little longer, and it could have angled flanges that force more water directly onto the cups. 

From what I can gather by what I see, the one the first video shows sort of chops the water and thus looses some of it's force in the shock blow to the water, and so could be a lot more efficient if the low head wheel was designed differently to avoid wasting this energy potential.  It might just be a matter of angling the paddles so that this blow does not happen as the water enters the wheel area. Also the model in this first video seems to have a huge amount of drag as the wheel is sitting in the post impact water, rather than spinning freely.   

The second was somewhere between; the higher position gives more gravity to the system, and less force is wasted than on the first video, but because the force of water is coming against the wheel's rotation, some efficiency, I think, is lost when the forces collide.  He says that due to geography he can not go higher.  It would be much better, if possible in your system, to be higher, to have the wheel rotate in the other direction to what he has, and have the water gravity drop effective to the rotational direction. Perhaps in his case, a wider wheel that is short enough so that he could get his sluice in the right position would be better?  

In regards to those observations, by dumping above your wheel (hence the long sluice that is higher than your wheel), and dumping in the same direction as your wheel movement (so you have no forces countering each other), you gain efficiency/potential.  

Also one thing to consider is building your wheel wide enough that your cups are catching all of the water that is directed at it (in this way the first system has some, but limited merit).  The more force that is directed to the wheel, be it dynamic kinetic force of flow, or the weight of the water on the wheel, should be maximized.  The other thing to consider is what the wheel is doing.  All you want it to be doing is rotating with positive water forces.  Any other things that effect that, are inefficiencies.

The following video shows a more idea build/flow pattern, in my unschooled opinion.  Though of course it is small.  You want your wheel to be as big as your system can handle, I think.



I can just see the inefficiencies in the other systems.  I'm no engineer, but that's just how I see it, and I might be wrong. 

As far as gearing and engines, there are better minds than mine for that.  My brains work in terms of bicycles more than cars.  Travis has some interesting ideas and a better and more experienced mind for such aspects, but if you post a general thread on gearing, or alternator/generators then you might get more of those sorts of folks reading/answering.


 
Travis Johnson
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I am not sure about that Roberto, I just try to think about what I/others have and the best possible use. We all use electricity I know, but it can be quite the adversary, sometimes other forms of power work better for a given situation.

Me, I have always loved hydro and micro-hydro, that would be the ultimate build for me...but I am not suited for it here. Maybe someday. I would like to build a cabin out in the woods, off-grid for just the wife and I as our current house is just too big, and still growing. let one of the kids have that and live a more modest lifestyle.

As for bicycles versus cars, I often forget that bike chains and sprockets put man into flight, but it seemed whenever I shifted my 10 speed bike as a kid, I jammed the chain and I landed on my face. Since this was the 1980's, no kid wore a helmet, and unless a bone was showing, dad would not cut a stick with his chainsaw and splint it with duct tape...such was life of growing up on a farm. We just called it being poor of course.
 
john beattie
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Roberto thanks again for your reply, as you say the question is how much power can i get for the money and effort needed, i guess this is what i'm trying to find out, i don't mind putting the time or the money into the project but i need a satisfactory result.
I have thought about using pipe instead of building a more flat waterway thinking it would be much easier and cheaper also i'd think the outlet of water would be more concentrated with more force than say a 12"-16" sluice, i guess the wheel width would have to be matched to the water outlet and was thinking a thinner wheel would be best. the one in your video looks to be quite wide for a pipe also it looks to have quite a lot of water coming up around the back as the wheel turns, i'm thinking this is not a good thing and you really need the buckets to empty as much a possible before they return to the top, i guess there is a lot of trial and error with this kind of thing so i'm thinking about starting with just a cheap made wheel and a short sluice/pipe then see what we have, i will need to find out how to measure the torque from the shaft then work out how much torque i'll need to turn a bunch of pulleys and the power unit.

Take care
john
 
Roberto pokachinni
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Hi John, the video that I posted was mostly to show that the position of the water outlet of the sluice was in the right position, and that the wheel was wide enough to take all of it as it drops. 
quite a lot of water coming up around the back as the wheel turns, i'm thinking this is not a good thing and you really need the buckets to empty as much a possible before they return to the top,
You are right to point out the water coming up the back of the wheel.  It looks like there are two possibilities for that problem.  11.) The water underneath is being picked up by the cups as the wheel spins, which means the wheel needs to be higher.  2.) The design of the cups is flawed as they are not getting rid of all their water after the vertical drop.  The water coming up the back is a huge source of inefficiency as the weight will be slowing the wheel's potential to spin.  Good eye.
i guess the wheel width would have to be matched to the water outlet and was thinking a thinner wheel would be best. 
I'm not sure.  The thicker wheel would guarantee that you get benefit from all the water and gravity, where as a thinner wheel will have more splash off, or water that misses it altogether.  If your bushing is good (so there is limited friction in spinning your axle), the width shouldn't matter much for creating inefficiencies, if that is why you think that a wide wheel is not best.
 
Roberto pokachinni
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Hi Travis.  I was mostly referring to my perception that you may be more mechanically inclined than I.  All the gearing for this could be done with bicycle parts.  The alternator/generator/engine aspect is where I am pretty lost, and I figure you might have a better knowledge base.  Funny story about the duct tape splint.     
 
Troy Rhodes
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Here is a nice little calculator to get a "back of the napkin" idea of what rate of energy production you could expect.

And let's assume a back yard engineered alternator overall efficiency of 40%.  A highly engineered and optimized generator/alternator might approach 85% efficiency, but way way more money.

http://www.engineeringtoolbox.com/hydropower-d_1359.html


There are not-too-difficult ways to measure your flow.


The density you don't have to fiddle with, because water is always 1,000 kg per cubic meter.


 
Jane Johnson
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Yes!!! I've been thinking just along those lines - I don't know if a large water wheel is the best way to use the energy from a small river or stream (facing the same problem) and I've been working on the idea of using magnetic rods going across the stream bed, threaded through coils - tubes, slid through tumblers   like larger cotton reels with magnets (waterproof) and IMMERSED in a flowing water stream - from the smallest stream to the largest river. None of this using the tons of energy to lift a great big wooden wheel as the reels could be quite small and light - either a non-oxydising metallic or light wooden structure (balsa? Or why not actual cotton reels in series?) - or else something like plastic sheeting, cut, and fixed like kids' windmills, or large bobbins made with magnets attached to blades integral to the turbines, all sizes to suit the flow, turning immersed in the water itself and the coil in the (2 - one inside the other) metal tubes around which the turbines roll. The kinetic and electrical energy could then be recouped and stored (wires from the tubes/rods go to series of 12 vv batteries on the banks in insulated boxes, then cabled to storage/ or transformers. The river maintains a perpetual flow - haven't worked it out yet but someone's going to!
 
David Livingston
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Something else to consider is the overall cost and maintenance.
Solid state photovolaic cells are now much cheaper than ever before . Work out you budget for your water wheel etc and then look at the cost of the cells . I suspect that the cost of the cells will be much less watt for watt
 
john beattie
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Roberto, i was thinking wide wheel 12"-16" just because i was thinking wide sluice and thought an even spread of water over the wheel would be best, when i seen someone using a pipe i did think that the water would be more powerful as it leaves the pipe so more power hitting the wheel but as you say if you have water splashing all over it's a waste as you need to keep it in the buckets to help pull the wheel around so that's why i was thinking less width on the wheel if using a pipe, so i wasn't really sure what would be best which is why i was asking to start with if using a sluice should it start at the top of the hill or can it start much closer to the wheel, i know if using pipe the pressure builds up the more head just didn't know if an open sluice would work the same, the method in my madness was if i can start the sluice half way up the hill or less i could maybe build another wheel just before then start the water run from the top that way i get two wheels running off the same stream, just a thought i know that it won't be as simple as that. i have a lot to learn and think about and as i say i think there will be a lot of trial and error.

Troy, thank you for the calculator that's very handy, i've seen one or two of these but never been sure how they work, is the value given the power in electricity or is it the power of the wheel at the axle ? i can't understand how they can come up with a watt output without knowing what kind of power unit is being used so i'm guessing it's axle power which was going to be one of my questions on how to achieve this.

Jane, i've seen a few videos where people have made small wheels around 24",  in the water they turn real fast but as soon as they connected the generator they stopped solid, i may be wrong but one of the problems we have is running speed of the generator, most dc motors or alternators need high RPM to achieve voltage so a pulley system is needed to bring a say 10RPM wheel up to 1000 rpm and to do this you need torque at the wheel shaft, large wheels give more torque but need more water so i guess it's about building your system around what water you have.

David, Yes i have also looked at solar but my main problem is we need the power in winter and in this part of the world (Scotland UK) we don't get much sun in the summer never mind the winter, if we could collect power all summer and store it to the main grid then have it back in winter that would be the way we would go, but there isn't any scheme to allow us to do that not that i know of anyway. i still would like to have a play around with a few panels just out of interest to see how they work. maybe have some connected to the house hot water tank.

Take care
john
 
Travis Johnson
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Be that as it may, I doubt it would be possible to beat the efficiency of a micro-hydro project because it is producing power 24/7/365 instead of only in daylight hours. Even if the water wheel only produced 300 watts, in 24 hours that is 7200 watts. A 300 watt solar array would produce half that at the height of summer, and yet over the length of a year with cloudy days, fog, rain, snow...

I think the initial cost would be higher up front with micro hydro, but the return on investment would be greatly shortened in the long term.

Myself, I have a potential stream, and it drops right off into a ravine giving me some flow, but incredible head. I am currently working on clearing land in the headwaters of this stream and while it is only 30 acres, void of trees, and with a lot of ditching (and most likely drainage tile), I can envision getting more run off into the stream bed. This will not only help me glean more power, but allow my soon-to-be fields to dry out for farming. It is however located well away from my house, but someday I want to build a cabin there for just me and the wife and let one of the kids have this monstrosity of a home (and all the cleaning it requires).

 
David Livingston
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well you could get some panels for free http://www.which.co.uk/reviews/solar-panels/article/how-to-buy-solar-panels/free-solar-panels if you have a south facing roof . This would help I think
I think its a good deal not with out risks but if you are not thinking of going totally off grid it might be worth looking at . Going off grid at the moment to me looks a none starter as the cost of saving or storing electricity seems prohibitive unless you totally reduce your electric usage .

David
 
john beattie
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Thanks for that David, we don't own this house but the landlord is very interested in this kind of thing and we have more than enough roof space even land space if they can be fitted on the ground, i'll have a read through and have a chat with our landlord

Take care
john
 
Troy Rhodes
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The efficiency figure you put in accounts for the kind of generator/transmission/wheel, etc.  So, a guess, but it still gives you data to refine your idea.

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