So I'm thinking of a waterwheel for electricity

Big Lar

Beside my house is a stream that has ran there for many years, so many years thats its about 10 feet below the ground, I made a little clay dam in around Christmas and put a 300mm pipe in as an overflow, I have a very nice steady flow of water coming out of the pipe and I'm thinking to myself that a small 7 - 8 foot water wheel might be the business.

I have in my head that the water wheel is going to drive a motor but the speed is going to be variable, I am wondering how can I get power from that to work in tandem with my existing electricity supply ?

I am kinda just playing with this in my head at the minute, so I have no plan set in stone yet.

BryanF

http://www.boards.ie/vbulletin/showpost.php?p=77451975&postcount=3

gman2k

Good info on this site
http://www.powerspout.com/

Big Lar

gman2k wrote: »

Good info on this site
http://www.powerspout.com/

Indeed there is, It seems that I need to convert my power to DC or use a DC motor and then use a Grid-Tie inverter to sync it up the incoming ESB supply.

gman2k

Loads of videos on youtube re micro hydro

Coles

You really need to know the available flow and how it will vary over the year. If you have a flow of 20 Litres per second and an available head of 3 meters you might be able to make a waterwheel system that is 50% efficient to give a maximum output of 300 watts. A flow of 100 Litres per second would give you 1.5kW and it would start to look feasible.

Big Lar

Right so some day next week I think I'll stick a barrel in underneath the pipe and see how long it takes to fill

Coles

Big Lar wrote: »

Right so some day next week I think I'll stick a barrel in underneath the pipe and see how long it takes to fill

And try to get as many readings as possible over a reasonably long period of time.

Big Lar

Coles wrote: »

And try to get as many readings as possible over a reasonably long period of time.

Will do, this project is a few months down the line.

Big Lar

Coles

That's a 300mm pipe, right? You have a flow of between 3 and 5 litres per second at the moment. You'll have significantly more during rainier periods, but I think you'll probably find that the flow at the moment is close to the mean flow. It's fairly simple to work out the theoretical capacity of a resource...

Flow(m3/s) x Head(m) x G(m/s/s) x Efficiency(%)

The difficulty with small flows and low head sites is that the efficiency is normally quite low (40-50%) so in this case we are looking at...

0.005 x 2.5 x 9.81 x 50% = 61 Watts

That might look like a tiny amount of energy (and it is!) but over a year that's 537 kWHrs, or about 15% of the electricity use of a house.

Not feasible in my opinion.

PyeContinental

I have used solar panels to charge car batteries, to use for charging mobile phones, laptops, running radios, charging torches, and anything else that can be powered or charged by DC power. The car batteries are 12 volts DC, but you can step them up or down as required.

If had a water wheel, I would attach a belt to it and connect a car alternator, which is already optimised to provide a constant voltage, irrespective of the fluctuations in the speed of the wheel (approx 14 volts over a range of approx 600 to 8000 revolutions of a car engine). If you had enough waterflow to allow you to gear the waterwheel to turn the alternator to mimic the amount of turns it would receive from an idling car engine, you should achieve an unvarying voltage from the alternator.

I would consider this experiment as the first step in the "proof of concept", and the conversion of the DC power into AC and integration of this system into the house-hold power supply as a separate project.

Coles

Good advice, but the difficulty with a waterwheel is that they turn so slowly (5-8 RPM typically) and the gearing up to 1500RPM(?) for a car alternator would be extremely inefficient.

PyeContinental

It looks like it's possible to gear the slow revolution of the waterwheel to suit an alternator. I found this site http://www.reuk.co.uk/Building-a-Waterwheel.htm - have a look at the pictures down the page, and there's a video of it working (although it's a not a great quality video).

They use this alternator: http://www.windbluepower.com/Permanent_Magnet_Alternator_Wind_Blue_Low_Wind_p/dc-540.htm - I think they might be implying that it has beeen customised to produce a higher voltage at lower rpms, but not sure, I just scanned over it. Noticed it says that it has a remote rectifier (converts AC to DC) whereas a car alternator would have one built in. If you were wanting to add the output to your home's supply, it might be advantageous to have the option not to convert the AC to DC and back again.

Big Lar

Coles wrote: »

The difficulty with small flows and low head sites is that the efficiency is normally quite low (40-50%) so in this case we are looking at...

0.005 x 2.5 x 9.81 x 50% = 61 Watts

That might look like a tiny amount of energy (and it is!) but over a year that's 537 kWHrs, or about 15% of the electricity use of a house.

Not feasible in my opinion.

Thats a bit depressing, 537 KWHrs is a saving of about €75.00 for the whole year, Not what I had hoped at all .
But disappointing as the replies were, thats why I asked, so thanks for your input Coles

PyeContinental wrote: »

It looks like it's possible to gear the slow revolution of the waterwheel to suit an alternator. I found this site http://www.reuk.co.uk/Building-a-Waterwheel.htm - have a look at the pictures down the page, and there's a video of it working (although it's a not a great quality video).

Ah great link and in fairness the price is right for the waterwheel, I may just build a bigger one from 3/4 in the coming months. Its a fairly cheap experiment

Coles

Great link. I've had some dealings with REUK and they are very decent to deal with.

That PMA would be ideal but you still need to get the revs up to 1000RPM to make best use of it. Still expensive with the charge controller.

The plywood waterwheel is a terrible idea and it would be a far better job to make it out of mild steel and weld it all together. Not too complicated either. Another option would be to make it out of aluminium box section, 2mm sheeting and rivet it all together..

A2LUE42

I know I'm digging up an old thread here. But did you do this in the end op? Or does anyone know if it is possible to buy a kit version of something like this. Just a hobby idea, not intended to power a house.

Coles

There are a number of simple off-the-shelf hydroelectric systems, but not usually waterwheel types. Waterwheels are almost always custom built to suit a site. If you were handy with a welder you could make your own one easily enough, but on a hobby budget it's probably best to familiarise yourself with the different generator and transmission options so that you can design the whole system to suit whatever bits and pieces you can find. If you have to buy a particular gearbox or gearset brand new to exactly suit your wheel and generator that could cost a fortune, but you could easily find one for free that you could design the wheel to suit.

A2LUE42

I was doing some searching for off the shelf options and seem to find the type that are designed to run a garden hose through,which are too small, or much larger ones that are beyond the scale of what I was trying to do. I have a stream that is walled on both sides for a part of the garden about 4 feet above the water height, where the water would be about 8-12 inches deep and about 4 feet wide, with a reasonable flow.