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Water Wheel versus Turbine

 
Posts: 15
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Hello!
My wife and I have been taking the steps to get our homestead up and running. We are not currently off-grid but plan to be within the next year or two. We are planning on utilizing the two four-season creeks we have on the property for power (along with a Vertical Wind Turbine). Currently, we are trying to decide what to budget for, water wheel or turbine. The neighbors have a pond above ours that feeds one of our pond/streams. I estimate the neighbor's pond to be about 10-14 ft above ours and I have no clue water the gpm is. The flow is constant, but it's not high pressure. I could probably fill a 5gal bucket in under 30 seconds. The spot is hard to get to right now with all the foliage. We're trying to decide what would be the most efficient use of our time and money while having reasonable maintenance requirements. I've found a low-rpm perm. magnet generator that claims to put out 5kw at 450 rpm and felt this was a reasonable speed for a water wheel but again I don't know much about electronics. On the other side of that, I've found micro-hydro turbines that claim 1.5 kw and they are a complete setup and designed for the wet conditions the equipment will constantly be in. We kind of just need a direction to go in as we don't know what we're doing any help or resources would be appreciated.
 
gardener
Posts: 3772
Location: latitude 47 N.W. montana zone 6A
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Hi Joe;  
I have lived with micro hydro power since 1996. I use a permanent magnet pelton wheel.  I have high pressure with a low flow.  125 psi at the house and I flow about 3 gpm with it to make 120 watts
I suggest a turbine rather than a water wheel.
When it comes to water power its all about pressure and flow.   If you don't have high pressure then you will need high flow.  
The other consideration when using a hydro is where and how you will control the waste water.  Ideally it would go back into the creek.
Mine is plumbed down across the road and goes first to my pigs for fresh water and then out in our field to create a wetland draw for water fowl.

As you will be a low pressure system , your going to want to figure out how much water you can flow without depleting the pond.
Battery management with hydro and wind requires a constant diversion regulator.   Much different than a solar system alone.
solar-hydro.JPG
[Thumbnail for solar-hydro.JPG]
 
Posts: 6
Location: dfw, TX zone 8
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The formula for hydro power is:
power in Watts = Head x Flow / 5.3   (for units of feet and gallons/min)

Usually we can count on inefficiencies and friction losses to reduce that a lot, its better use 10 instead of 5.3

From your data given:

Power = 10 to 14 feet of head times 10 gallons/min divided by 10 = 10 to 14 Watts
That is ... not much.

Any hydro system you build will be very expensive in a dollars per Watt calculation, because there are so few Watts available from your power source. Better to go with wind, but only if you have strong winds, on top of a hill, and a tall tower. Even then, solar is almost always cheaper. The disadvantage of solar is that it is often strongest when you dont need it, and weakest when you need it most (long cold winter nights after a cloudy day).

 
pollinator
Posts: 3113
Location: Massachusetts, Zone:6/7, AHS:4, Rainfall:48in even Soil:SandyLoam pH6 Flat
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Before we can move on we have to determine how much power you can get out of your current system.

Power = 1/10 x Flow x Head
Power = 1/10 x 10gallon per minutes x 10ft
Power = 1/10 x 10 x 10 Watts per hour
Power = 10W/H or 0.01KW per hour

A system that generates 24KWH per day (1KW per hour for 24hrs)
Power = 1000W per hour
Power = 1/10 x 10000
Power = 1/10 x 100gpm x 100ft
Power = 1/10 x Flow x Head, where Flow=100gpm and Head=100ft

Even a system that only has a head of 20ft and flow of 50gpm would produce 100W per hour or 2.4KWH per day and would still be very useful. I think that once you go below that, the system becomes more geared to single device/direct drive

 
gardener
Posts: 2640
Location: Fraser River Headwaters, Zone3, Lat: 53N, Altitude 2750', Boreal/Temperate Rainforest-transition
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Calculations based on approximates will be better to become a lot more precise, and one of these can vary considerably depending on the time of year.  

There will be times of the year that are specific low flow times and those that are high flow.  In my neck of the woods, we have two times of the year that are low flow, one is at the end of summer (when winter snowmelt on the mountains has been exhausted but before fall rains and cool weather increase the flow a bit again), and the other is about three quarters the way through winter (when most of the flow has frozen and not started yet to melt).  This will be different depending on where you live.  This will also vary slightly as to which week it is in a given year but knowing the basic time of year to calculate low flow is key to starting (as low-flow is about as close as can be measured to calculate the power that you can be pretty much guaranteed year-round).  

Build a simple weir on the creek where (or at the basic height) you are putting your intake.  This can be as simple digging a slot into each side of a small creek and cutting a piece of plywood to length to fit the width of the span of where you slotted in the banks.  With such low flow, you can probably get away with cutting a notch in the plywood, so that all the flow goes over the notch, and then fill 5 gallon pales, or whatever, as your measuring device.  A more precise measurement might happen if you were to fasten and seal a pipe in the plywood, and channelled that water into a container through the pipe.  The less excess or splash the more accurate your measurement.  Do a few trials to make sure of your accuracy, and once you have your method down, do three or four tries, three or four times during a couple of week period and make an average to figure out your guaranteed flow.  

Find someone with a transit or other device to properly calculate your drop  (Head).

Check out this video, which is a fun project done by a guy in Oregon who is playing with water coming off his roof into a rain gutter.  He shows the way to calculate your power properly around 3:47.  
 
Joe Burton
Posts: 15
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Thanks for the input everyone! We are clearing more land every day so hopefully, I'll be able to actually measure the flow from the source but it looks like we may be using solar/wind combo.
 
Roberto pokachinni
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Posts: 2640
Location: Fraser River Headwaters, Zone3, Lat: 53N, Altitude 2750', Boreal/Temperate Rainforest-transition
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The great thing about having a hydroelectric source is that you are guaranteed your minimum flow 24/7.  'That can be a huge plus when other sources can be quite variable.  The minimum flow tops up your batteries, all night long, on miserable cloudy days, or on days when there is no wind.  Just something to consider.  You've probably already considered it, Joe, but I write it here for the good of the community who might be reading it.
 
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