Water wheel building, what size?

Hello everyone,

I am planning a hydro project to help power a small off-grid cabin in Northern Idaho. I have property with a creek currently flowing at a rate of 240GPM. The creek flows for 500 linear feet across my property, however the head is fairly low as a whole dropping only about 1' per 25 feet of run in places, less in others.

I am hoping to get at least 50 watts usable power with a home-made cedar water wheel and a low RPM PMA. I plan on offsetting my additional power needs with a solar array, however the less I have to collect from the sun the better, since my neck of the woods is pretty cloudy all winter.

Some additional background: I am not afraid of building the wheel and a 100' sluice box to get at least a 4' overshot wheel, however I want to know if going longer and higher will be worth the time and energy. I wouldn't want to divert the water the extra distance for small diminishing returns.

My experience lies in woodworking, I have a small sawmill on the property with the ability to build anything I need out of wood for very little overall cost so utilizing a Turbine is pretty much out of the question even if it is a little more efficient.

Any information from people with more abilities in Math or Experience would be great.

Thanks!

Hi Drew; Welcome to Permies!

I have plenty of micro hydro experience, but math...   not so good. So if I've goofed up the numbers please excuse me.
I have hydro & solar as well. You are correct about solar power in N Idaho in winter, it bites.
If I read your post right, your hoping to make 4 amps @12vt ?  = 50 watts ? That is not much.
240 gpm ? How did you come up with this number ?  I think you will be needing the gpm out of your flume, not the creek.

So a low rpm pma ?  What RPM does it start producing?  Does it have a max RPM ?   Voltage ? Direct driven or gear drive?
What kind of battery's were you thinking of using? How far are they going to be from the water wheel ?
How far to the inverter ?


Lots of questions. Tell us what you have in mind.

Thomas, Thanks for the reply!

You are correct on the math, let me clarify some more. My intention with stating a (minimum) of 50 watts would be to produce at least 1.2KWH per day from the system. I realize this is a small amount, which is why I want to make sure I don't create something more useless and completely waste my time. Double that would be better but I'm mainly just trying to find a realistic baseline that I can shoot for with my current situation.

I measured 240GPM out of a 3' Culvert currently located on the up-stream side of the property, and you are correct I would need to measure the flume rate instead. Advice on how large to size this would also be appreciated since I haven't built it yet either.

I was thinking of something like the Wind Blue DC500 PMA and gearing the system to achieve 1200 rpm's (12 volts) ideally. I'm not sure if this is feasible so any input would be appreciated. Max RPM on this unit is 10,000 and with my flow rate I don't think that would ever be an issue. Now that I think about this some more I have no idea if those kind of RPMS are even realistic, and if they aren't would a different alternator system be more functional?

Battery storage would be approximately 80' from the water wheel, depending on the length of the flume of course.  The only two structures on the property are a 12X16 storage shed with larch siding and a 10X20 roof for the sawmill. I have flexibility on where I build a cabin, however it would be ideal to split the difference between viable solar and hydro areas. The creek runs north to south on the west side of the property, with potential build sites not far away at any point. Due to the tree line however ideal solar panel placement would be 80-100' due east (opposite direction from the build site).

These are all factors I'm trying to figure out to establish the correct spot to start the foundation this spring.

A few more notes: I currently live in town with natural gas for backup heat, (primary wood stove) water heater, and range. My normal electricity usage is 4 KWH per day on average. An efficient fridge/freezer combo could easily cut down 1KWH and not having a dishwasher would also save a fair amount(Haven't metered, logged, or calculated actual usage on this) I plan on moving from a 1500 square foot townhouse to a 400 square foot cabin with propane for all the same features I have on natural gas in town. In my mind this puts me at a baseline of requiring approximately 3KWH per day produced through Hydro/Solar. If I can achieve half of that (or more) with the hydro system I would be very happy since I could count on important things like the fridge/freezer/a couple LED lights to be essentially guaranteed. Assuming the water wheel isn't completely frozen over or stuck with branches, or whatever else happens to water wheels..

Please correct me if I'm making any ridiculous assumptions, and thanks again!

Good Morning Drew;
Lets start with the basics. I have been 100% off grid since 1983, I know a whole bunch about what your wanting to do.  Going with propane is a good idea. You need a propane range (home depot)or used , you need a propane water heater, I use on demand but you won't have the water pressure to run one and you need a propane refrigerator. Forget an electric one. They are not nearly efficient enough. And the dish washer has now morphed into being  … YOU...
About propane fridges.  Old servel fridges are practically indestructible. They are small inside and not very efficient, but still worth useing. Lots of plastic newer ones out there,  kinda junky but I used one for years.  Now if you want the best and you can afford it. I use an 18' Diamond brand , made by the Amish. It rocks! Huge fridge, huge freezer and very efficient! Same size as any "normal" home. Delivered cost was almost $2500... see what I mean about afford it...

Next you need to think about building a rocket mass heater for your cabin.  If you don't know about them, than check the rmh forum out, here at Permies. Buying the RMH builders guide is the next step, less than $30 from Amazon.  Properly support your floor as your building the cabin to hold the weight.

OK now lets think about your hydro.  To start, in my opinion you should concentrate on building your cabin , setting up your solar, and all those propane appliances.Then start working on your flume and hydro.
The PMA your looking at , 10,000 max rpm but you need to know what the minimum output rpm is.  You also need to know that an alternator spins quite easy with no load but that changes as your batterys need power. I.E.) that 1200 rpm will drop bunches when connected to a low battery. Another little tidbit of alternator info... If it is spinning, an alternator MUST be connected to the battery... if not it will overcharge and fry internal components quickly.
My hydro is high head low flow. I have 125 psi down here at the house, I flow apx 3gpm thru one nozzel , I make 6-10 amps @ 12vt around 100 watts .
Here is a site that tells you about low voltage line loss)  www.zetatalk.com/energy/tengy10s.pdf .  As you see your batterys need to be close by your inverter AND close by your hydro... food for thought.

I think I have fed you enough info to spark your interest or to totally bum you out (i hope not)
I have one more question.  What area of N. Idaho are you building in ? Clark Fork ? Bonners Ferry? Sandpoint?  or down south ?

Thanks for the additional info Thomas,

I have seen the prices on ranges/fridges/heaters, etc.. So I do have an idea of the additional cost involved. My property is West of Sandpoint toward Laclede, I venture over to the Elk Barn in Trout Creek a few times a year for work, I'm guessing you know where that is.

I am in a fairly convenient location where I have pressurized water from a 100GPM well already installed on my property. (I dug the 800' trench and installed the pipe last year) I have family nearby that are grid-tied which powers the well pump, I'm just trying my hardest not to pay the utility company $14,000 for an install plus the minimum monthly payment for the rest of my life. That being said my water pressure will be just fine for a propane water heater, plus I wont have to run an electrical water pump to maintain pressure in the house. I know it's cheating but maybe you'll forgive me.

I realize the dishwasher will be me, I was only using that as a comparison between my current usage, and potential usage once I am living in a cabin where I will definitely NOT be installing a dishwasher.

Do you have any thoughts on the new SUNDANZER Refrigerators? The 10.2CF DC Electric model (DCRF290) claims to only use 0.5KWH per day in a 70 degree space. Price tag is $1,400 but it seemed like a decent option to me.

I realize my hydro situation is not ideal being low head, but with all the snow on my property right now it's going to be a while before I can break ground on the cabin project. I have some free time in the next couple of months and was thinking about fabricating the wheel ahead of time. I'm sure you're right though I should wait and do things in a sensible order, like building my flume and sizing the wheel to the actual head once I have more established at the property.

I didn't realize that about alternators, and will definitely be more careful during the testing phase than I would have been.

Thanks for the suggestion about the RMH, I've been reading a little bit about them since I found this site (a couple days in all). I've always used normal wood stoves which seem to put out enough heat and provide some level of ambiance in the house. I'll give them another look though to consider all possibilities.

I'm definitely far from burned out, I've been doing a lot of reading on my own and it's nice to talk to someone with experience about my situation.

Hey Drew;
Yup, you could say I know where Trout Creek is... that's my zip code!  The Elk Barn is the Fitchet's place over in Heron.
No cheating involved, your well, using power from the relatives place that's awesome!  Full water pressure and its not using up your power … very good!
With full water pressure I recommend a Paloma tankless water heater. I've had nothing but flawless service from them , I've had two in the last 33 years , no problems ever. Only replaced the one to get a larger size.  Beware other ones that want power hooked to them. They are noisy and don't work half as good as a simple Paloma.

As far as time on your hands and a desire to build a water wheel, go ahead and build one. Heck its snowing all the time, why not.  With a little research on design, decide on your diameter & width and give it a try. The flume and mounting of & gearing of the wheel are the way bigger job.


Sundanzer has been around a long time. I would trust their products.  I have never owned one yet , but have my eye on their 13' chest deep freezer , also $1400 plus shipping.  I already have 4 brand new 180 watt panels I purchased , waiting in the dark for that.  I want my chest freezer at home and on its own dedicated stand alone system.

For your lighting look into led flat panels.

You haven't mentioned battery's yet?  What were you thinking of using ?

I assume your intent is to invert this power to 110 ? Or were you thinking 12 vt ?


Rocket mass heaters. I have 2...  No creosote ever , no fire all night long , hardly any ash, less than a cord would keep you roasty toasty all winter long,  no smoke other than steam, at all …  I could go on and on about that subject.  

Hey Thomas,

I realized my mistake not long after posting, I'm familiar with quite a bit of Western Montana, make it as far as Thompson falls/Libby pretty regularly in the Summer and Whitefish/Bigfork other times of the year.

Thanks for the suggestion on the Paloma water heater, I haven't done a huge amount of research on tankless propane heaters but I do know the options are a bit overwhelming. I'll put that one on my list so I know where to look when I'm ready to buy.

That's good to hear about the Sundanzer, unless I hear of an equally efficient and long lasting model for a cheaper price I'll probably go for that option.

I did a little bit of looking at LED flat panels, do you have them installed? They almost seem like overkill for lighting. I was kind of just assuming I would mainly do recessed lighting that would take replaceable low wattage LED bulbs. I'll admit I definitely don't have the design figured out though so I appreciate the suggestion.

Oh yeah batteries, this is probably my most dreaded subject. I want the ones that last 50 years but don't cost very much, and don't require any maintenance (I'm not that delusional). I understanding wiring in series/parallel, so beyond getting some 6v deep cycle batteries and wiring them to my desired voltage, I really don't have a solid plan yet. I realize I have to size my battery system to allow for non-power generating downtime, so I'm leaning toward lead-acid because I doubt I can afford anything else at the storage capacity I need. Brands and specifics though? Work in progress.

I definitely plan on using an Inverter unless there are specific items that run solely off DC, like that Sundanzer? I plan on having all outlets and lighting be inverted to 110. Also haven't decided on a size for this either.

Finally to the Rocket mass heater. I'll admit I was skeptical. I briefly read about them on this forum, saw your post about them and read again briefly. After that I mulled it over and started watching some videos and really started to grasp the concept. I feel pretty silly for not taking the idea seriously sooner, because I will definitely be building one of those. In my 16X24 Cabin plan I've been struggling a little bit with where to put a small woodstove without taking up too much space. I love the idea of the efficiency of the stove (who wouldn't?) and having a heated area that doubles as a place to sit along the wall? That's awesome, functionality and efficiency. I explained the concept to my wife as well and she's also pretty excited about it.

I'll be spending more time on this forum when it comes to design and materials for the heater, but I'm definitely on board.

Cheers!

This is so funny because i just opened click bait with a waterwheel!

Not real clickbait ot was a link to jalopnik.

https://jalopnik.com/kentucky-mastermind-powers-his-house-using-a-car-altern-1786863522

Hi Drew;
Yes , use led recessed for general lighting, but use the flat panels to light up an area. I have them in our kitchen, bedroom  and office they rock!
Battery's are a huge subject when it comes to off grid. Bigger is always better. 6 volt min, 2 volts are better.  Stay away from 12 vt
Inverters , pure sine wave only. Again bigger is generally better.  I use a Magnum energy it does the job well.  Outback solar inverters are an industry standard.  

Rocket Mass Heaters ,  When you are back over this way next summer you are welcome to see mine.

I realize this thread is 11 months old but it came up randomly in my news feed.  I’ve put together some math for a small scale water wheel and a couple links of where that math came from.  I also tested the torque of my creek with a home made paddle and torque wrench and it matches the math which is a good sign.  Took me a couple days to sort it all out in my mind but it’s actually fairly simple if you can measure how fast your water is or can move and factor in how many square inches or feet of that moving water you can use.  I’ll paste the info below and the links also.  I did math to power an electric car but it’s easy to covert or simplify.  


Water wheel car charger calculation estimates
Need about 400 square inches of contact in water moving at 5 FPS to get about 600 continuous watts.  600x24=14.4KWH

That’ll produced about enough energy to basically get her free miles on a Tesla Model 3 electric car with my average of 15000 miles per year.  

Calculated about 15KWH of battery use on average per day.  In this scenario.

4 inch pipe has an area of about 50 sq inches @ 5fps=75W or 1.8KWH per day
4 ft drop = 15 FPS or 225W 5.4 KWH day


6 inch pipe has 113 sq inches
5fps = 150w. Or 3.6kwh day
4 foot drop 15 FPS 450W or 10.8kwh day

An 8 inch pipe has 200 square inches.  
5 FPS should be 300w or 7.2 kWh day
4 ft drop 15 FPS 900w or 21.6 kWh day

Need an 8 inch pipe and a 2-4 foot drop to create enough power from a water wheel to fuel the Tesla model 3 I don’t have yet, year after year


https://www.backwoodshome.com/design-calculations-for-no-head-low-head-waterwheels/


http://wentec.com/unipower/calculators/power_torque.asp

Hi Chris;  Welcome to Permies!
Thanks for sharing the math on water wheels. It is sure to help someone out.
Lets hope you can get that Tesla soon and then get your water wheel built to power it for free!

Come back often, there is lots of cool stuff to read about here!
Don't forget to check out Rocket Mass Heaters... you've already met the group leader...

Drop in when you can.
We will leave the light on for you.

Hey all,
I realize this thread is older but I thoroughly enjoyed reading it. Very insightful. I’ve lived in 5 states but it’s always been a dream of mine to get off grid in Montana or Idaho. Recently I found a 355 acre property in yellow pine ID with two rivers flowing through it. Perfect for hydro power and its cool to see others are doing it and proving success in that area/climate. If it’s ok, I’d like to keep in touch with you both. Maybe email a question or two as I build mine. Email is
Levimarcus94@gmail.com
Thanks again for the info.
Levi