Using river flow to generate electricity

[factseeker88]

All it takes is flexible paddle wheels attached to generators biting into the flowing river surface.

[Externet]

Why flexible ?

The generator should run at its suggested rpm. Use gearing. You need speed.

 

----> http://www.scienceforums.net/topic/65768-paddle-wheel-calculations-please/

 

----> https://groups.google.com/forum/?hl=en#!searchin/sci.physics/%22how$20to$20calculate$20the$20force%22/sci.physics/iM108GzW6tI/KbDIS008fCgJ

Edited July 20, 2014 by Externet

[studiot]

 

All it takes is flexible paddle wheels attached to generators biting into the flowing river surface.

 

 

There is considerable recorded knowledge and wisdom about the use of river flow to provide energy. This came from the times when watermills were used to provide mechanical energy.

 

Externet is correct, gearing is essential to provide correct rotational speeds.

 

Further considerations are that most river levels are not constant, but some by several meteres, some by a few tens of metres.

This makes 'dipping a paddle in' more difficult.

Conventional technology also has that overshot wheels are significantly better than the undershot (dipped in) variety.

 

Like most technology there is the capital investment to consider and the available return. This is what led to watermill technology dying out originally, it was much less cost effective than later (steam) technology.

 

If this is a (school) project, re-evaluating the economics in today's world may be a good subject.

Edited July 20, 2014 by studiot

[factseeker88]

Why flexible ?

The generator should run at its suggested rpm. Use gearing. You need speed.

 

----> http://www.scienceforums.net/topic/65768-paddle-wheel-calculations-please/

 

----> https://groups.google.com/forum/?hl=en#!searchin/sci.physics/%22how$20to$20calculate$20the$20force%22/sci.physics/iM108GzW6tI/KbDIS008fCgJ

 

True, but that could part of the

 

 

There is considerable recorded knowledge and wisdom about the use of river flow to provide energy. This came from the times when watermills were used to provide mechanical energy.

 

Further considerations are that most river levels are not constant, but some by several meteres, some by a few tens of metres.

This makes 'dipping a paddle in' more difficult.

Water level is no problem because the paddle wheel unit floats on top, and all the other design problems can be worked out by trial and error, of course this only works when the water flow isn't impeded by snow or ice , but winter doesnt need as much electicity as summer.

 

“What we think, or what we know, or what we believe is, in the end, of little consequence. The only consequence is WHAT WE DO.” John Ruskin (1819 - 1900)

 

installation

[studiot]

Have you been on holiday?

I hope it was somewhere nice.

 

Whilst you were away your question was also developed in another thread.

 

http://www.scienceforums.net/topic/65768-paddle-wheel-calculations-please/

[Airbrush]

This is an interesting question. The only hydroelectric power generation seems to take place in huge megastructures, dams. Why not distribute the generators along rivers for miles, along one side so as not to interfere with the river flow?

[swansont]

This is an interesting question. The only hydroelectric power generation seems to take place in huge megastructures, dams. Why not distribute the generators along rivers for miles, along one side so as not to interfere with the river flow?

 

Probably because, as studiot pointed out, river levels can vary dramatically. Dams don't have, and are often meant to solve, this problem.

[studiot]

 

factseeker

Water level is no problem because the paddle wheel unit floats on top

 

Of course it's a problem.

 

Near where I live the river Severn goes up and down 30mtres, twice a day.

 

How do you connect the electrical output from floating paddles to appaatus that has this magnitude of movement?

 

Note I did not say it was impossible, I just said it was a difficulty to overcome.

 

 

Airbrush

The only hydroelectric power generation seems to take place in huge megastructures, dams. Why not distribute the generators along rivers for miles, along one side so as not to interfere with the river flow?

 

 

Did you look at the other thread I linked to? There is a deal more information about small installations on rivers there.

 

In the old days watermills were indeed dotted along many rivers, but most had dedicated channels to improve efficiency.

 

Other considerations against simpky 'dipping in are':

 

What about damage to river wildife from the paddles?

 

What about damage from the river in spate including free floating logs etc to the paddle wheels?

 

This is where dedicated side channels score, they can be closed off against flood conditions and netted against fish or debris ingress.

[Airbrush]

Then build turbines that are on the bottom of small rivers so that as long as there is any water flowing, the turbines will spin. When the channel dries up, it goes inactive until the rains return. There can be turbines generating electricity anywhere inside a city's sewer system, or anywhere water flows after a rain.

Edited August 4, 2014 by Airbrush

[studiot]

 

Then build turbines that are on the bottom of small rivers so that as long as there is any water flowing, the turbines will spin

 

An excellent suggestion for sevral reasons.

 

Since our last posting here Externet has posted some video references in his thread on this subject, and I replied selecting an axial flow turbine to achieve exactly this.

 

http://www.scienceforums.net/topic/65768-paddle-wheel-calculations-please/

 

Incidentally one of the advantages of many small installations using horizontal flow is financial.

 

In order to use water head you have to impound water and expend the capital sums to do this (ie build expensive dams or whatever) before there is a penny piece of £return.

 

A small, low cost, installation, placed into an existing flow tidal or river, will immediately start generating and thus providing a £return to help fund a second installation and so on.