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hakonnissen

Turbines - Where to Start?

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Hi All

 

We have a small guest farm in the Swartberg mountains, which I'm looking to electrify. What may seem like useless sources to others at least provide me with SOMETHING.

 

I have a natural spring coming out of the mountain 40m higher than my guest cottages and I'm looking at installing a permanent magnet alternator with a pelton wheel on it to generate around 400W. I have scoured the internet and something like the Powerspout from New Zealand looks perfect, but will cost me close to R30,000 delivered to my door! That's an expensive prototype, when I'm not even exactly sure of the capabilities of my system.

 

Does anyone know of a local supplier of such alternators / generators? All the US / NZ websites refer to Fisher & Paykel washing machine motors, but I can only find the Samsung SmartDrive's locally, and haven't found a decent used one yet.

 

Regards

Hakon

Cape Town

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Hi Hakon

 

Welcome to the forum I have not replied to your post because I was looking for my notes from a couple of years back. I cannot find them so we'll start again.

 

Pelton wheels can be very efficient returning up to 90% of available energy as electricity. Having given us the height, the next most important variable is flow rate. I off hand can remember that for 400W we had to have a flow rate of 2.5l a sec and we did not have a flow rate like that. The flow of a garden hose is about 30a minute.

 

My cousin had a 3kW Pelton wheel high up in the mountains here in the Karoo and had all sorts of interesting variable loads to draw off excess power since you cannot switch it off. Unfortunately that farm has since been sold and I know the system was allowed to fall into disrepair.

 

One of the options is to take the water past the cottages and so increase the height and then bring the electricity back up to the cottages.

 

I will PM you my cousin's details.

 

Give me your flow rate and I can calculate the energy you could generate. It is sometimes a bit disappointing unfortunately.

 

Chris.

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I seem to recall seeing guys using washing machine motors (or some such) to generate electricity from water in streams.

 

Maybe a old alternator ... just throwing ideas out here.

Alternators (the automotive kind) need too much speed before they make anything. That's not to say that you cannot make it work, I just remember reading about this problem on the forums where people tried to make wind turbines from old car alternators. If you take the alternator apart and rewind the various windings, you can apparently make it work at lower speeds. I have no idea how well this would work, google it yourself (or jfgi as the young ones say ;-P )

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For less than R 1000 I bought a magnetic rotor and a 36-pole stator from LG in Montagu Gardens about 3 years ago. I guess the price might have gone up somewhat, but far less than R 30 000.
I'll try to upload some pics of my attempt to make a wind generator. Perhaps you could use a similar setup for your stream of water with your pelton wheel.

 

The case is a U-shaped box with two plumber block bearings and a steel shaft. The magnetic rotor is mounted on the shaft and the stator with coils is mounted directly to the box, BUT needs to be centered so that the rotor magnets do not touch the pole pieces of the 36 coils. Not to difficult.

Aming at the wind.zip

Edited by SOLARWIND

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Alternators (the automotive kind) need too much speed before they make anything. That's not to say that you cannot make it work, I just remember reading about this problem on the forums where people tried to make wind turbines from old car alternators. If you take the alternator apart and rewind the various windings, you can apparently make it work at lower speeds. I have no idea how well this would work, google it yourself (or jfgi as the young ones say ;-P )

Hi,

The problem with a car alternator is that it cogs seriously and is difficult to start turning it. The LG and F & P washing machine motors are designed with virtually no cogging. This also makes them very quiet.

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There seems to be a serious misunderstanding in the efficiency of hydro turbines. Everyone claims the efficiency of a hydro turbine is in the 96 - 97 percent range. This is an engineering efficiency. It excludes anything that they don't see as a viable option for their efficiency figures. If you do a true scientific efficiency of a Hydro power system you will find that they rarely exceed 15%. This means that a hydro system loses 85% of its energy in the form of the accelerated mass of water. Do you truly want a 100% renewable energy world? Dump the turbine!

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Where does the 85% go? :-)

I understand that there will be losses. Pumping losses, and water molecules stick to each other (and to the wall of the pipe) so there will be some "friction" involved too, aka heat losses. But 85%? If that was true, I can hardly see why it would be popular for pumped storage schemes.

A bit of lazy google research suggest that pumped storage schemas get back 75% of what was put in. This is large scale hydro tech though, the stuff us consumers play with will probably do worse. The only upside to pumped storage would be the excellent cycle life. If you have the space for that much water :-)

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Thanks@PaulF007. I've dealt with ZM before. They gave me very helpful input.
@Tim in my research and experience your 15% is WAY off the mark. I typical micro hydro system operates at about 50% efficiency, but can increase dramatically with scale (ie large hydro generators could be 75-80%).
A hydro system is complicated. The first loss of efficiency is to friction in your feedstock (pipeline). This varies greatly depending on pipe size & type. My pipeline is running at about 98.9%. The 95+% which ppl generally quote is the efficiency of the turbine itself in converting the linear flow of water out of the nozzle into rotational energy on the turbine shaft. Then u loose efficiency to friction in the shaft (negligible), electrical conversion (about 65% efficiency, if memory serves) and lastly electrical transmission (about 98%+ efficiency). This will give you about 50-60% efficiency to get AC electricity. You will have further losses if you need to rectify to DC (theoretical 80% efficiency), and battery storage is a separate issue which also has inherent losses in storage turnaround. My rule of thumb for my system is 50% efficiency.

Sent from my HUAWEI GRA-L09 using Tapatalk

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