Hydro Power

Discussions about Renewable Energy, including photovoltaics, wind, and small scale hydro.
Creating power for your home, off grid.
Emphasis on nuts-n-bolts, hands-on projects.

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Sharkey
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Hydro Power

Post by Sharkey »

The days are getting shorter and darker and I find myself having to use the AC-to-DC converter in the Housetruck to keep the batteries from getting too low each night due to the current draw of the incandescent lights. This really isn't a lot of power, but it irks me to have to purchase utility power when there is so much renewable energy flowing all around me.

To wit: I dug out a project from 12 -15 years ago (maybe longer) and completed it (finally):

Image

It''s a tiny hydro power generator, constructed out of junk box parts! The generator is a permanent magent DC motor that I purchased back in 1993 to power the circulating pump on my solar heated hot tub. The other motor I purchased at the same time actually got used, this one got put on the shelf. Some years back, I bent up some scrap aluminum and mounted the motor, laying out the position of the nozzle, etc.

The Pelton runner is quite a piece of work:

Image

This is the guts from a car washing wand that I adapted to fit on the shaft of the motor using a coupling. The washer had concentric brushes, the internal brush was rotated by water pressure provided by the garden hose. Obviously, I needed a more rugged mounting and a bigger nozzle, so I pitched the wand and housing and built my own, using the bottom of a one gallon water jug for a deflector shield.

This time of year, it's necessary for me to run the water for an hour or so every day before bathing to flush out the sediment that builds up in the pipe running down from the spring. I haven't quite figured out why water standing stationary in the pipe gets murky and running it regularly prevents this, but if I don't run the water, I end up with mud coming out the fixtures in the house.

I've always wanted to capture the energy of the flowing water, but never got much farther than my half-finished hydro generator. I actually toyed with it some the summer before last, but it made so little power that I failed to get enthused about it and it went back into storage.

A couple of days ago, I brought it out again, and over the last few evenings, I finished installing the nozzle (an old bronze high pressure hose fitting) and a valve and pressure gauge. This afternoon, I modified the water system at the house to allow me to install the small plant so that it receives pressure directly from the pipe coming up the hill from the lower pasture. I threw together an ammeter and connected a small gel cell battery as a load, and turned on the water:

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I was hoping for at least an ampere at 12 volts. All I got was .6 amps. Still, this is better than nothing, so I ran some extension cords back to the Housetruck and before it got dark, connected the output of the generator to the nickle-cadmium batteries that power the Housetruck's lighting system. Turning on the water got me .73 amperes, a whopping 10 watts! I'm not complaining, 10 watts is more than the $13,000 worth of solar equipment out in the yard is producing right now. In fact, yesterday was a rainy and dreary day, and I managed to generate only 17 watt-hours with the solar system.

So, improvements: The pipe coming down from the spring is only ¾" in diameter. It has 50 pounds of static pressure. When the hydro is running the pressure at the nozzle is 15 pounds. Obviously, a bigger pipe would allow me to open up the flow considerably, which would raise the power output dramatically. Unfortunately, putting in a new pipe to the spring is not a trivial task, and is one that will have to wait for another day. The "grand plan" is to put in a pair of 2" poly pipes and start consuming more of the estimated 125 gallons per minute that the spring gushes out in the winter. When those pipes are in place, the tiny home-built hydro will be replaced with a small commercial unit that is capable of 2,000 watts of output (given enough water).

In the short term, I could boost output from this plant by moving it down to the lower pasture and running the power back to the Housetruck on long wires. The house has 50 PSI of static pressure, while the lower pasture has 75 PSI, and has about 250 feet less pipe, and fewer joints, turns and valves to impede the flow. The catch in this plan is that the pipe I'm running the hydro from is also the domestic water supply for the house and Housetruck. When the hydro is running, the pressure at the fixtures is pretty pathetic. Some means of shutting off the hydro would need to be fabricated that would allow it to be remotely started and stopped for showers, dish washing and laundry. Oboy, another project.

Normally after installing a small hydro plant, the output of the generator is optimized by "tuning" the system. Alternator-based generating systems will have a field control that would allow the maximum amout of power to be withdrawn from the alternator, essentially a "throttle" which allows the operator to trade off runner speed versus available torque. A simple permanent magnet motor has no method of controlling the magnetic flux in the field magnets, so it just runs at whatever speed the load (batteries) slow it down to.

Another method of tuning is to change the size of the nozzle. In my case, the high pressure nozzle has a 3/16" hole in the end. This may or may not be optimal for my conditions. A smaller nozzle will restrict the flow, but cause the escaping jet of water to have greater velocity, possibly spinning the Pelton wheel faster. On the other hand, this generator hits maximum output long before the valve that controls the water is fully opened. It could be that a greater volume of water at a lower speed will produce more current.

Tomorrow, I'll stop in at the hardware store in town and see what options I might have for changing the nozzle to something else, perhaps a cheap plastic nozzle that I can drill out and throw away if it doesn't work better. Commercial small hydro plants sometimes use "Rain Bird" sprinkler nozzles, which screw into a threaded fitting. Having a small collection of these might allow tuning.

If I get very bored, there is the possibility of installing one or more additional nozzles.

Moving the nozzle closer to the turbine might help some, the distance in this unit was simply what the parts on hand allowed me to put together. When I messed around with this project last year, I found that the proximity and position of the nozzle didn't make a lot of difference in the output power.

My impression is that the durability of this hydro plant is probably pretty poor. The motor has only sleeve bearings and the brushes aren't likely to last for a very long time. The plastic Pelton runner will certainly erode from the sediment in the water. Even the commercial runners made of silicon bronze wear out over the course of a few years. If the whole thing holds together for a month, I'd be surprised, but if it gets me hooked on water power, I can always step up to a more robust machine in the future (once the money starts rolling in, that is).

At any rate, the plant is running right now, contributing about two thirds of the power needed to light my desk lamp. I used incandescent lights in the kitchen while cooking dinner and didn't bother turning on the AC converter. By bedtime, I'll have consumed 5 or 6 ampere hours out of the battery, which is a very low value compared with a normal night's consumption. Overnight, the hydro plant will charge the batteries back up, perhaps fully. If that is the case, the 12 volt system solar panels won't need to see much if any sun tomorrow. Yay!
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Post by TMAX »

Sharkey, you mentioned using a cheap plastic nozzle that you could drill out. Just a thought.. how about a short piece of PVC with a cap that you drill with the hole size of your choice. Even less cost.

Also, what about using an automotive type alternator. I recall that the one in my Geo was really small, not much more in diameter than a 1 pound coffee tin and considerably shorter.

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Post by Sharkey »

Drilling a hole in a plastic cap would be the simplest, but I'm attempting to do as much as possible with the small amount of water that I have. Using a high pressure nozzle like the one on the generator means that the water is subjected to a smooth, tapered reduction in the size of the pipe, ending in an orifice. A hole drilled in a pipe is going to be an abrupt change and the water would exit the hole as a spray instead of a stream. Having a smooth, laminar flow of water is important, kind of like the difference between regular light and laser light, you want the force to all be in one direction with as litle turbulence as possible when it hits the Pelton cups.

A car alternator would be a good choice, it would mean that I could tune the field strength with a simple rheostat. Many small commecial hyrdo plants such as the Harris are based on truck alternators. In my case it was a matter of what I had the tools and materials to work with. Adapting the 5/8" shaft of an automotive alternator to the 7mm shaft of the Pelton would be easy if I had a metal lathe, but I don't.

It's possible to purchase either plastic or bronze Pelton wheels that are already bored and threaded for alternator shafts, but if I get that serious about it, I'll probably purchase a complete unit with multiple nozzles. For that matter, if I got really serious, I'd probably dump the DC regime altogether and get a small plant based on an induction motor. Run the voltage back to the house at 480 volts 3Ø and step it down with transformers, less loss, no brushes to wear out.
TMAX
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Post by TMAX »

Oops! Forgot the need for a tapered hole for a stream. I have an older type nozzle that is similar to the one your using, only it is about 6 inches in length. Problem is the threads are not too straight. There is difficulty in getting it on and off the the hose end. Still, would you be able to use an item like this?

With enough 3 phase power, you could be on the air with K-SHRK in no time.

TMAX

P.S. The spell check feature seems to have checked out.
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Dennis The Bus Dweller
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Post by Dennis The Bus Dweller »

I have a great electric motor that I think came from a power wheel chair. When I put a drill on it I get close to 90 volts. Id like to do this same kind of thing or maybe put a prop on it. It’s been sittin on a shelf in the barn for a couple of years now. Im waiting for it to do something to itself I guess :lol: It spins really easy so I guess it would work fine. How would I regulate it?
Peace along the way
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Sharkey
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Post by Sharkey »

As expected, there is a lot of high-end theory involved with the design of Pelton Wheel hydro installations, and mine is only haphazardly poking at the arithmetic.

Had a look at the Wikipedia page on Pelton Wheels:

http://en.wikipedia.org/wiki/Pelton_wheel

...and learned that the velocity of the stream of water is best calculated to be twice the speed of the rim of the wheel. Since the speed of the runner is regulated by the output voltage of the generator, that is pretty much a constant in my installation. Varying the speed of the water entering the runner is probably more important than varying the flow.

Friday, I stopped by the hardware store to see what they had that I could use for changing the nozzle in the small plant that I built. They had a small brass "driveway washer nozzle" (high pressure fitting) and a plastic "sidewalk tunneling kit" that looked like I could cut it down and cobble something together. I bought them both.

The easiest change was to simply unscrew the nozzle I was using and screw on the small brass replacement. This new nozzle has a 5/32" hole instead of a 3/16" that the original had. Turning on the water produced .78 amps of current, or 11 watts, a 10% improvement. The water pressure at the nozzle ran at about 25 PSI, an improvement for the rest of the domestic supply.

At first, I was rather confused as to why a smaller orifice produced more power, but considering the stream velocity being the most significant factor, I guess this makes sense. Since Pelton runners work by diverting the flow of water, rather than simply by the impulse of the water hitting the runner cups, this makes sense. More water does not necessarily mean more power. Using the water entering the runner cup more efficiently does mean more power.

I did look around at the hardware store for Rain Bird nozzles, but they didn't carry them as replacement parts. I may have to try the bigger stores next time I go to the city.

I'm thinking that multiple small(er) nozzles would produce more power than one big one. Matching the water velocity to the runner speed will give best output for the least water used. If a smaller nozzle produces this desired speed, then several smaller nozzles would add additional power output. It's all about torque, not speed, the speed is fixed by the battery voltage. More nozzles = more torque = more power.

Now I have to figure out how to support the generator with a box or structure that allows me to mount and align four nozzles. Oy, more projects.
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Post by stuartcnz »

My father generates all of his electricity with a pelton wheel. He does so, in AC, with no battery system. I think he can generate something like 3 KW at 240 volts. when their is enough rain fall. I'm not sure of the specifics of his system, though know that it is pretty basic.

Small reservoir at the top of the water fall, hose, tap, pelton wheel, alternator, amp meter.

When he originally set it up, he spent literally months reading up on it. The one thing that I remember as being the most important aspect, particularly if water quantity was not high, was having the highest amount of head possible.

The water on my fathers system has a vertical fall of over one hundred meters from the top of the system to the pelton wheel.
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Post by AccordGuy »

Hi Sharky!

There's a great photo story here of an old water mill being resurrected as first an industrial air compressor and now a grid tied generator.

http://s990.photobucket.com/albums/af26 ... aterwheel/
Sharkey
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Post by Sharkey »

I guess it's time to be surprised, as the tiny $7.50 hydro plant is still cranking out power. Most days I have to shut it down by mid morning as the batteries are fully charged from the previous night's consumption.

Since this leaves me with a surplus of power, I have run the extension cords across the yard a couple of days to the 24 volt grid-tied system and run it during the daylight hours. The plant puts out .45 amperes at 26.7 volts nominal, about 13 watts. This makes me think about an automatic change-over that switches the hydro plant to the 24 volt system when the 12 volt system comes up full. I still have the custom designed and built charge control that I used to use to divert excess PV power into the RV refrigerator, it was designed to run an external relay and operate on hysteresis so the relay doesn't chatter. Just the thing to integrate the two systems to charge from one source.

Went up to the spring today and there's a load of water coming off the hill that I can't capture or use. A larger penstock pipe is a must, as it a more industrial pelton and alternator.
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Post by Sharkey »

Just came out the warm end of a full week of freezing temperatures. Today was the first that the temperature was above freezing for 24 hours.

The neighbors lost their water last Monday. Apparently, running my little electric plant and keeping the water flowing at full volume kep me from having freeze issues. Every year until this one, I had some kind of a failure in cold weather, in spite of running the water at the taps in the house. Nothing like wide-open delivery to keep things liquid.

Of course, this means that there is a lot of water to get rid of, and a lot of ice that can build up. Witness the iceburg that the hydro plant manufactured during the freeze:

Image

The spray of water exiting the wheel built a kind of ice dome around the exterior of the housing, while the inside was completely open. I almost busted my butt a couple of times approaching the area to shut the plant down for showering, it was pretty slick all around.

Of course, having a proper enclosure for the plant and a spillway to conduct the water away from the vacinity would make sense, but I keep thinking I'll move it down to the lower garden and add a nozzle or two. Besides, old bricks and 2x4's are much less effort to construct.
Tim Clevenger
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Post by Tim Clevenger »

Hey Sharkey.

Here's a bucket-based mini plant that might generate a little more power. Unfortunately it's pictures only.

http://blog.makezine.com/archive/2008/0 ... ctric.html
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Post by Sharkey »

Hi Tim, that's the hydro plant that was featured in a short description in a past Home Power article. The photos on the site you linked to are more descriptive.

The runner is constructed from a 5 gallon bucket lid and 8 PVC angle couplings cut in half attached to the plastic lid with rivets. It must have been a job to get them all aligned correctly, otherwise the balance would be whack when the plant was running.

Not sure I understand how they keep the permanent magnet alternator fron getting waterlogged, the parts list describes parts used to make a "splash guard".

I've been thinking about how to better mount and support the generator I have now. If I add nozzles to it, I need more and better attachments, and it would be nice to have something more stable than an old cinder block as a foundation. A better enclosure would make the operation quieter as well, not that I have a big objection to the white noise of water. A square bucket or aluminum enclosure of some sort with the generator mounted on top of the lid would allow the machine to be opened up for inspection and make exchanging nozzles a lot easier.

Eventually, I'll get my big tax return, and I've already decided that a small part of it will get invested in a commercial hydro plant. There are quite a few choices, I have 180 feet of head, with about 125 gpm in the winter. Thinking of a pair of two-inch penstocks. Return line to the house would be about 600 feet.

Today was cloudy and drizzly, and my 12 volt PV array would never have been able to recharge the batteries from last night's consumption. It's almost 4PM and the NiCd's are just now coming up to full after the hydro plant ran all night and all day, perfect timing for tonight's consumption.
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Post by Sharkey »

Looks like my predictions about the longevity of this project were based on sound reasoning. I had to take the hydro plant off line a day or two ago due to wear and breakage in the Pelton assembly. The plant had been getting noisy very fast, making kind of a rattling/clattering racket when it was running. It was still making full power, but it sounded like a hollow gourd filled with beans being rolled around.

Inspection of the Pelton revealed that the attachments for little buckets had become badly worn due to the motion of the buckets while running. This Pelton wheel is assembled with the small buckets held in place by a locking tab attached to the stem of each bucket. The buckets stems sit in a groove in the top wheel and are secured by a mating bottom wheel cover. There was a tiny amount of motion in each bucket when I put the plant into service, but after 1,200 hours of running, the mating parts of the buckets and wheels are showing some wear. Two of the buckets had broken part of their retainers on the wheel and were kind of flopping around when the water jet hit them.

I removed the Pelton runner and after removing the bottom wheel cover, I had a handful of worn parts laying in a pile.

Image

I wanted to get started on this project today, but guess what, without the hydro plant keeping the water lines cleared, I had to go up to the spring and do the cleaning and draining thing on the head end of the system.

After I figure out what kind of plastic the wheels and buckets are made of, I'll either cement or solvent weld the buckets back into place on the wheel and probably pot the whole mess with more cement to make it a solid block of plastic. No going back after that step, the next time it needs repair, it's into the trash can with the whole thing.

As for the power I'm not making with the plant down, I miss it already!
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Post by Bob »

What a great thing to be getting charged at night as well as the daytime! I don't have a stream but I have been thinking the same thing..right now I have 6 6volt golf cart batteries that when fully charged have no trouble with the night time consumption ( and I am a night owl) but my 4 75 watt panels don't generate enough amps to keep up. I saw a rig in the desert the other day with a wind generator that was zipping REALLY fast!!!! Then and there I decided to get one too...charging all night long....WOW!
Do you also use wind with your machine? Between the midwest storms, living in the desert and traveling up the coast it is a perfect addition to my system. I am going to look into the small ones and see what kind of amperage they supply.
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stuartcnz
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Post by stuartcnz »

Bob, just a quick note on wind turbines. The ones that have square ends on the end of the blades are much quieter than the ones with pointy ends, which can produce an incredible amount of noise.
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