No-Head Water Wheel Tidal Dynamo / Motor Question

I have an Idea that you could use but I have not drawn it out on paper to see if it will work.

You could forget using special (expensive) bidirectional generators and just use gears to keep it running the same direction.

I might even just set it up with bicycle gears. If you use two bicycle chain systems with the pedal crank sprocket on the wheel and the wheel end on your generator, and make one cross in a figure 8 it will make the gear at the wheel end rotate the opposite direction.

That way when the river makes the wheel spin clockwise it will crank one set of gears while the other freewheels. When the river reverses it will do the opposite and the generator will always spin the correct direction. You could even use the gears to control the speed of your generator.

I will try to draw this out later if nobody else confirms my idea as plausible.

Drew

How about fitting a bridge rectifier to the electrical outlet so that, no matter which way the dynamo is turning, the electricity comes out the same way up?

Hi

AC or DC ?

No Polarity issue if AC.

I would think the chain would make contact/wear at the crossing point.

Maybe a belt would be better,Any mechanical scheme is going to waste energy.

Direct drive is always best.(Although you may have to gear up rpm. for this setting).

Electrically you are really just rectifying extremely long period ac to dc.

Use rectifier.Power scr. or similar device.

thanks drew, that sounds great.

i think we could be able to get our heads around it. it would be great to see a picture, but dont want to ask too much of you. :)

but if you like to draw up plans for fun, then that would be great.

i am sure if you were ever in london you would be made welcome as a guest at the boat project.

i am glad i found this website.

i will keep you posted on our progress.

thanks drew,

alex.

The more practical way may be to use an alternator system that charges up battery's and then runs an inverter system off of them.

Being your water power source is variable in flow rate and direction and most electrical devices require stable and continuous power this may prove more reliable and practical.

Depending on how much power you need your alternator and battery system will vary of course. Typical automotive and heavy truck alternators are non directional in rotation as are most belt drive AC generator types as well. The cooling fans are typically all that dictate what direction they run and many are bidirectional so which way they spin is of no concerns.

With out knowing how much power you need it impossible to recommend a system and components. If its a low power application you may only need a small automotive alternator. If its high powered you may need a larger belt driven multi KW generator head unit and a large battery system as well.

thanks pw slack and guest,

a bridge rectifier would probaly be best, i did'nt know what they were called. i would have to get a bi-directional dynamo though would'nt i, or would a standard on do?

but it would be better than losing effeciency from the mechanical systems i suppose, as the undershot and no head water wheels are the least efficient types of water wheels and i want to get the most out of it.

thanks for the advice, i realy appriciate it. cheers.

thanks tmtech,

much needed information there, it has helped me alot.

right, this project is now starting to look a lot better than this morning.that's great.

thanks and cheers.

alex.

I'd guess that you might only have 4 periods of 2-3 hours of useful electricity generation per day and then that will be subject to the monthly fluctuations with the cycle of the moon. The outflow of the tide will produce more because it will have the benefit of the river flow. Any idea of a typical tidal flow for the location of the barge?

I don't have experience of these kind of tidal waterwheel systems and I'm inclined to think that the output could disappoint. It might be cheaper and simpler to put up a wind turbine, particularly if a renewable energy company would sponsor it...? Keep us informed and best of luck with the project.

Riverkeepr,

you need to speak to a reliable marine electrician and/or a renewable energy specialist. Try alanw@energy-solutions.co.uk. I don't know if they can find a solution that will fit your pocket but I can warrant their abilities. They are just down river from you on the Medway. Alternatively send me a private message from this site. (just click on my name and it will take you to a page with the option to send a PM)

Your flow rates are low I believe (6knots peak?) so you won't be able to harvest very much energy from a small turbine. Thus bigger is better.

You will need, as already mentioned, batteries and an inverter. I would suggest that you will probably need a generator as well unless your power requirements are very low. One serious problem you will have is getting the people aboard to switch lights and other equipment off when not in use.

Keep us informed with the solution you end up with.

good luck & Regards

Chas

If both the flow and the velocity of the river water are variable you may need some sort of a switching power supply to get the voltage to something that you can work with. Battery chargers are not going to be of much use when the input voltage is lower than the battery voltage. If both voltage and frequency are important to you then things could get complicated. An alternator to generate AC current, a switching supply to get the right voltage for the batter charger, battery charger, batteries, and a UPS to give you useable power on the barge. Even using an alternator there will times when the voltage is zero and as the speed of the current changes so will the frequency produced by the alternator.

An underwater cable is starting to look attractive.

Thoughts :- Use a permanent magnet machine as an alternator and rectify the output. Exciting wound field machines mean big loss at low speed and car generators are particularly inefficient. Fisher and Paykel (NZ) washing machine motors are very suitable, see Silicon Chip magazine. Switchmode techniques allow efficient charging of the batteries. Appliances should be direct battery load not mains via inverter. J section polyvee belts, (ex washing machines) allow 20:1 ratios at high efficiency. I hope to see the project in the next couple of years.

Did you try looking on line for similar projects. One that comes to mind on this side of the ocean is a project in the Hudson River. I am not sure of the particular details but do remember that it is working reasonably well. Do you guys have a website? I think people would be interested in learning about your project.

Riverkeeper

Also do a search on "water turbines" , "Small water turbines" etc. as these are not the only manufacturers of these systems. You might also consider wind power, especially if you are truly in the middle of the river, and solar panels.

You might also use the water equivalent of a VAWT but you will need to make sure it is tough enough to withstand the collision with the debris that floats down Old Father Thames. Any kind of rigid structure, presumably off the side of the barge, needs to be mounted so that it can swing out of harms way if it encounters an unusual force caused by debris.

When you buy batteries make sure you buy true deep cycle batteries. the extra cost is worth it in extra life time. Also, do not cut corners on the ampere-hours as the fewer Ahs will mean deeper discharge cycles and this shortens the life regardless of what type you use.

Welcome to the "Off-Grid" world!

Where are you moored on the Thames? (It's nearly 30yrs since I lived in London)

regards Chas

been talking to some guys down here they call there selfs energy for nothing.i was talking to them about wind turbines they make out of junk and scrap.ask them about your problem.they think a waterwheel would not be efficient for you.they have made only one water power turbine using a 12 blade 1mtr duct fan with a large funnel inlet.being belt driven they were able to extend the generator drive above water.it works well and would be easy to rotate with current.theres is in the over flow current of the Ebro dam and is making a constant 20kva.

Hi, I also live on a tidal river in Yorkshire, and am trying to do much the same thing. I have a small steel fabrication business also, if I can be of any help. Any ideas on waterwheels, turbines greatly appreciated. I have looked at the ampair u/w turbine, but its output is very low. Thanks, Schoolouse.