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Forum Index : Other Stuff : Micro Hydro advice
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| brettcrossley Newbie  Joined: 20/07/2010 Location: United StatesPosts: 4 |
Hi, first post here so please forgive some ignorance (I did do a lot of searches before posting at least!) I have a small house on a very fast moving mountain stream. The water is coming down from a very steep valley and flows all year very quickly. It's not a big stream in terms of volume, but really fast flow. I want to try out micro hydro as a test project, and don't have the money to buy an off-the-shelf system (looked like at least $1500 for a decent one). I had an idea: get a smallish outboard motor w/ blown motor, remove the motor, and put a car generator in place of the gas motor. Then just mount the thing straight down in the water flow at a point where rocks force a really fast flow. To give you an idea of the water power you could not stand in one of these places. My thinking was to take the output from the generator and run it up to the house (<100 feet away) then use it to charge a bank of golf-cart batteries and maybe hook up DC powered devices directly to it. I can get the alternator for free/cheap as I have a good friend w/ a large car repair shop. Love to hear any thoughts on this. Brett Crossley |
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GreenD88 Senior Member  Joined: 19/05/2009 Location: United StatesPosts: 104 |
I would think an electric boat trolling motor would be perfect. You will have to keep the alternator dry and I doubt the propeller would have enough power to spin it with any load on it. Licensed Master Plumber / EPA 608 Universal License / 410a Safety Certified / Medical Gas Brazer/Installer |
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| Robb Senior Member Joined: 01/08/2007 Location: AustraliaPosts: 221 |
If that's the case I'd measure up you head and volume and quote some actual figures because that sounds good! You would have to outlay some funds but it sounds as if electric hot water, selling power back to the grid etc could be on the menu  Not with your outboard motor but with some good equipment  |
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| VK4AYQ Guru  Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Brett You should look at an overshot water wheel if you have enough fall they are slow but a lot of torque to gear up for the alternator, if not much fall an undershot wheel would work, but not as well as a overshot wheel. If you can get some 4" pipe and pick up a good head a pelton wheel is a good option, don't waste time on the outboard as you will be disappointed with power out. All the best Bob Foolin Around |
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| brettcrossley Newbie Joined: 20/07/2010 Location: United StatesPosts: 4 |
I'll work on calculating the volume. I found one method that involved seeing how long it took to fill a five gallon bucket. There are a few places due to large rocks where the whole stream flows through a really small cross section, but I'm not strong enough to hold the bucket into the whole flow. At any rate it easily is 5 gallons / second, so I'll call it a conservative 300 gallons per minute. It could be several times that. As for the drop, I guess it depends on where you measured from, but there's at least 20 feet of drop in the short section I just walked. Using topo maps it averages 200 feet of drop for every 1500 foot section. Here's a picture of one section. I like this section because the house is straight up the bank from the creek, maybe 100 feet away. http://media.10footwave.com/production/demoapp/3316_PICT0016 .jpg |
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| brettcrossley Newbie Joined: 20/07/2010 Location: United StatesPosts: 4 |
Is the idea to put one end of the pipe upstream just sitting in the water like a drain, then gravity moves the water down the pipe (the distance of the "head") and that makes the jet for the pelton wheel? What I was thinking of was to capture just a fraction of the shear force of the water that is currently moving in the stream. The idea of the outboard was really just to use it as a waterproof housing for a car generator and take advantage of the prop on the end. I could even imagine removing the prop and bolting a pelton wheel to the prop shaft, turning the whole thing 90 degrees sideways and mounting it down directly in the stream. Here's a link to the area of the stream I was thinking of. It's maybe 2' across, has a foot of water shooting out of it. 
For reference it's a 12 liter bucket in the picture. I guess I was thinking the simplest way to make energy from this is something I put right in the flow of it. |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Brett It looks like a beautiful place you have there, but not enough solid water to work a turbine, boat propeller. In an outboard motor the generator run to slowly in and not provide enough rpm to produce much electricity, also the diameter of the prop is a bit small to absorb the water energy. If you want to use a propeller as a turbine, you will need to mount it in a tube with close clearance to minimize losses around the outside of the propeller and direct the flow of the creek through that. This system works on flow volume and low pressure while a pelton wheel works on low flow high pressure, a pelton wheel in the creek would be useless as it takes at least 50 psi water pressure to make them work. Looking at your picture I think this would be an ideal place to mount a undershot wheel as the flow is concentrated through the rocks, or an overshot wheel if you can run a water race for a few feet to drop over the top of the wheel. or the propeller in a tube and use this point as a pickup, but you will need some water filter on the inlet to reduce damage to the prop and stop animals and kids getting sucked in, All the best Bob Foolin Around |
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| Robb Senior Member Joined: 01/08/2007 Location: AustraliaPosts: 221 |
I'v no connection with this company but their calculator program may be of interest. http://www.energyalternatives.ca/Downloads/MicroHydroCalc.ex e It works on wine if your not into windows. I tryed it |
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| davef Guru Joined: 14/05/2006 Location: New ZealandPosts: 499 |
How much drop do you have access to along the stream? It looks like a sizeable flow rate, 5 gallons (about 20 litres/sec) over a drop of say 10 metres is about 1.5 KW/hour times generation efficiency of 50% = 750Watt/hour. That's serious power. I am hoping to exist on about 1/4 of that. Are there issues with putting in a penstock and pelton wheel? http://tech.groups.yahoo.com/group/microhydro would be worth a look. |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
One thing i notice that keeps popping up in this thread is quoting the use of a car alternator. Firstly you need to look outside of using one of these, as it is one of the worst sort of generators you could pick for a RE application. It might look to be a cheap option, but a useless one for this sort of application. If it was that easy and they worked worth having, then we all would use them, i doubt if you will find one person here using one without lots of modds. It dont matter if its wind or hydro, it all comes down to 3 things.... energy supply, efficency of the generator and the losses within the system. I would not place the generating system in the stream, Pipe or plumb the water away from the stream, use the water and return it to the stream. You can almost bet that soon as you get something set up, it will flood down and wash it away (murphys law) or the stream will dry up (second murphys law) At least if you plumb it, you can set up in a safe enviroment and have prolonged use from you work. There is no short cuts in RE that are worth taking. (or murphy will get you for sure) Pete. Sometimes it just works |
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| brettcrossley Newbie Joined: 20/07/2010 Location: United StatesPosts: 4 |
I just came to that conclusion myself based on reading a bunch of stuff on this and other message boards and looking over replies of these experienced folks. I guess a lot of people (like me) start out thinking they will just do something experimental and don't want to spend a bunch of money since they are unsure of the results. Then after figuring out how it can really work you get the confidence to plan something more costly but more feasible. Thanks for the reality check! |
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SSW_squall Senior Member Joined: 20/03/2010 Location: AustraliaPosts: 111 |
Hi brett, That a very nice stream you've got there - you may want to check out my thread "new F&P micro hydro" if you havn't already... It's a pelton turbine and is only running about off about 15psi of head and genrates 135W contineously. You have *WAY* more water than i could dream of, it looks like at least 40L/s if you can get even a quarter of that flow in the picture into a pipe down a 10m (30ft) drop you are talking serious quantities of energy. A pelton machine would work but you'd need a couple of jets to make use of the flow, of course the higher the head the more energy generated for the same flow A crossflow or turgo machine would be better suited to the medium head that it looks like you have availiable Check out Energy systems and design ltd The turgo machine would be the way to go if you can install a pipe or penstock to get a decent fall Or you could go for the low head propeller machine, which would not require a pipe, but would need a open channel to carry the water horizontally to get a fall of a 3 feet or more. In any case I wouldn't bother stuffing around with the outboard motor, even built into a tube the results are likely to be less than ideal. Regards AB Einstein: Everything should be made as simple as possible, but not one bit simpler |
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| neil0mac Senior Member Joined: 26/12/2009 Location: AustraliaPosts: 210 |
Brett. Looking at the picture of the section of the waterfall that has caught your imagination, it strikes me that there is a second (or more?) drop a little higher up. Does not the kinetic energy of the higher fall get totally absorbed by the intermediate pool? Why not use a pipe/race to preserve some of that energy and run it into a vertical sluice pipe with your 'generator' at the bottom? For that matter, why not have two impellers/generators in the system as gravity will soon replace the energy absorbed by the higher generator? Just for you to think about, and others to comment on. |
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natures helper Newbie Joined: 03/10/2010 Location: AustraliaPosts: 8 |
Hya everyone as I have just joined this site forum I thought I eould post here as I have a similar situation as Brett has. A mountainous rainforest perennial creek which I have already have in place 2" poly gravity feed going upstream with easily a head of 30 metres or more. I have purchased a perm magnet low rpm dc motor. I currently am designing and building an overshot waterwheel. My maximum outflow rate I guadged at 2 litres per second or about 120 litres a min. My thinking has come to creating a wheel with an 800mm diameter and a width of 380mm running 12 buckets made from very rugged 100mm diameter poly pipe cut in 1/2 lengthwise... the wheel side are made from high quality 5mm plastic sheet so there will be no rust or rot. I took my time measuring out and cutting wheel side in pairs but i was wondering with an overshot wheel do I need to apply a certain offset pitch to the buckets to maximize tourque. It does look as though i will need to run a 3 step gearing ratio to achieve the rpm needed for the dc motor to charge a battery...i am making the bucket mount so they can have an adjustable pitch of + / - 5 degrees off square to centre of hub...In nother day or 2 ill take a few pics to better explain what im doing. I dont plan on hooking to grid or inverting to ac as I only wish to generate 12 volt power for outdoor night garden lighting... More to come Mud is just wet dust |
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| davef Guru Joined: 14/05/2006 Location: New ZealandPosts: 499 |
natures helper, 30 metres of head, nice. What is the flowrate? 1 Litre/sec is about 200Watt mechanical (using a pelton wheel of the correct runner diameter) or 100+Watts of DC into a battery per hour. 2.4KW/H per day is capable of lighting up more than your garden! Do you want the overshot for visual reasons? My neighbour wants to build something similar and thought of a way to get rid of the gears . . . run the motor off the edge of the outer rim of the wheel. Look forward to some pictures. Dave |
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| natures helper Newbie Joined: 03/10/2010 Location: AustraliaPosts: 8 |
Hya Davef, Yes the waterwheel was initially thought of for visual effect but realyzing that some power can be generated with the mechanical workings. With the 2"poly (normally used for irrigation) can be positioned anywhere I choose meaning I dont run the risk of flood damage being well away from the natural watercourse. It takes 5 seconds to fill a 10 lire bucket so im sure the volume is enough to drive an overshot wheel. I did look at a pelton wheel but its not asthetic given the location I have chosen... Am a bit unsure about direct drive off of the wheel given the possibility of getting water into the motor. The idea is to use a large sprocket eg. a go-cart sprocket (as these can have 100 + teeth)bolted to the side of the wheel and run at a reasonable distance to a sheltered housing for the motor and battery bank. This isnt intended to supply power continuously but only for night time illumination. 
As you can see I carefully designed and cut out bucket support yolks (24 of them)to hold and sdjust the pitch of each bucket...the whole lot is then assembled with 12 threaded rods (marine grade stainless. I will endeavour to get a few pics today to show the creek nature and the location of this setup.... 
Mud is just wet dust |
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| davef Guru Joined: 14/05/2006 Location: New ZealandPosts: 499 |
Looks interesting. Yes, more pictures as you progress please. If you had a small diameter wheel running on the outer surface, covered in a strip of rubber, then thru a shaft you might be able to keep the water out of it. But, then again you are not too worried about some gear loss. My neighbour wants to do it for visual reasons as well and to power a night for the chickens in order to extend the laying season! Dave |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Brett Just a quick 2-cents from a plumber of over 40 years: The more head height (read that: distance between the highest point you can collect water to the point of use--preferably the lowest point on your property) the better the results of such a venture. If you own the land at the top of this little stream, think about installing a PVC pipe run (buried if possible to avoid animals including humans and UV sunlight degradation) from the top to the bottom. Once you've directed the flow and (hopefully huge) pressure gain from the head height difference, the water can be returned to the stream. Remember, you are likely not going to remove any more than the amount of static flow through a 4" pipe at best, so the results "seen" at the stream will be minimal, if any. Just an idea. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| natures helper Newbie Joined: 03/10/2010 Location: AustraliaPosts: 8 |
Thanks Brett for your 2 cents but the 2" poly is subject to minimal uv exposure due to a dense canopy of rainforest growth an to bury it would be near impossible due to the rocky nature of the area. I am aware of the limit of static/friction given the length of pipe verses the head. Most of the system was already laid out prior to my arrival and all I corrected was the areas which caused air locks due to uneven terrain and gullies that the poly crossed... For the time being this is merely a first attempt of making a working micro hydro setup to determine if I should and can improve what minimal effort I have already accomplished. The poly was put down primarily for gravity feed irrigation but in times of "purge" when its raining or at night ect I want to utilyze the water flowing through to run this waterwl (overshot) I have the wheel fully assembled bar the central hub axle as I have yet to determine the length and diameter as well as the type of steel avaliable to me that is most cost effective...So far I have spent 150 dollars australian 1/2 for the motor/generator and 1/2 for the marine grade stainless steel threaded rod and nuts/ washers. The plastic sheet and pvc pipe for the buckets were free..(recycled) I do find this site very interesting and informative ..pity im a real dummy when it comes to electrics but a horticulturist shouldnt have to know how to wire up a generator lol so ill be lookin for advice once I get to that part. Mud is just wet dust |
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| natures helper Newbie Joined: 03/10/2010 Location: AustraliaPosts: 8 |
Now on for more updated pics.... First off this is the creek im working with... 
the 30 metre head is about 400 metres further up and takes about 20 mins to get to on foot..which is why i know im limited to static/verses length..but it is a good little hole that wont dry up even in the drier spells.. next we have location ... 
the water once worked through the overshot wheel will re-enter here. Of course there will be a bit of tidng up to do and I dare say some concrete footings as well... this is my water flow rate as it come unrestricted out of the 2" poly pipe ... 
a closer look.... 
Now onto what the wheel looks like at this point..... 
Notice the individual yolks 2 for each bucket these were the most time consuming to do as I did them in pairs from a seperate template...The idea is to have an adjustable pitch and set screw to adjust the hydrodynamics of the wheel... 
well enough pics for now but has anyone else tried mounting the buckets/vanes in such a manner? Mud is just wet dust |
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