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Timoja
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# Posted: 7 Jan 2018 09:29am
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I recently had the idea for a new small-scale hydro power concept which doesn't require any head, therefore just using the kinetic energy of a stream and which potentially could be implemented with minimal material cost. I just wanted to share the concept with you, please let me know if you have a cabin where such a system could be useful. Currently, no prototype of this system is available. Skip to "Requirements" to see if the concept could work at your location.
Concept
In the attached image the basic concept is depicted.
A generator is joined to a wheel that is driven by two umbrellas. In the depicted state, the lower is umbrella is open, and it is pulled by the water stream in the direction of water flow while the upper one is closed. At the end of the length of the rope, the lower umbrella is closed ( by a mechanism that is not depicted) while the upper umbrella is opened. The cycle starts again, with the umbrellas and thus the wheel moving in the reverse direction.
I can share the mechanism of the closing and the opening mechanism in a further mail, but just assume that this problem is solved and doesn't require any other energy or any form of active control.
To me, the concept has the following strengths:
* Use for both electric power generation or water pumping
* Adaptable to many possible sites by changing umbrella size and adding several umbrellas behind each other
* lightweight system, easy transportation, mobile solution possible
* use of existing low cost technology (usual hydro power generator or pump mechanics, use some form of plastic fabric for the umbrellas), can be fabricated locally
* only small batteries/capacitors needed to bridge dead time between two cycles, otherwise available 24/7
Possible downsides
* low efficiency
* possible issues with debris --> maybe need for grating
Requirements
* High water flow speeds of minimal 0.5 m/s
* At least an unobstructed flow cross section of 2 x 0.5 x 10 m, more is better.
* With those minimal numbers, power output is expected to be in the low kW (0.5 kW -5 kW) range. For larger power output, only bigger umbrellas or larger operation lengths are needed.
Concept of power generating system
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creeky
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# Posted: 7 Jan 2018 10:54am
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You need to build a working model. I know lots of folks who would like this. Myself included.
How do you keep your umbrellas from rubbing against rocks? Being damaged by flotsam? Opening and closing reliably for years?
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Timoja
Member
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# Posted: 13 Jan 2018 08:12am
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Can you maybe tell me about the locations that you have in mind? How much water flow and what water levels can be typically expected? How much power should be generated?
The umbrellas shouldn't rub against rocks as the upper side will be floating. At locations with low water levels it could be possible to reinforce the lower side of the umbrellas (e.g with steel plates) in order to minimze wear.
Proving reliable operation will be difficult for me as I'm living in Germany. Getting a permit for a hydro power station is very difficult here.
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Cowracer
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# Posted: 13 Jan 2018 08:45am
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Only potential drawback that the electrical engineer in me sees is that your power production would be cyclical. Of course charging a battery bank would smooth that out, but there would be a zero power moments in each cycle as the direction changes, and then a ramp-up of indeterminate time back full power output. Make sure your system can deal with that.
tim
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FishHog
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# Posted: 13 Jan 2018 01:08pm
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if you have moving water, why not just go with a wheel that catches water and gives you movement in one direction 100% of the time and other than surface debris won't have the issue with debris.
While its neat idea, I'm not seeing that its an improvement on existing ideas, but perhaps I'm missing something.
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Timoja
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# Posted: 15 Jan 2018 01:47pm
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@Cowracer: It is true that there is a dead point between two cycles. However, those zero power moments could already be smoothed out by a capacitor instead of a battery if one assumes a dead time in the range of 1-3 seconds leading to a much better longevity than a battery buffered system.
@FishHog: While it is true that there are other concepts that use the kinetic energy of water, I think this concept could shine in cost per active area. I think it could be possible to have the active area of a rather big water wheel by using just one pair of umbrellas.
Another advantage of this concept is that you can further add additional umbrellas in a row to achieve the power output that is actually needed.
Installation costs is another factor: With this design, one just needs one fixed point within the river (or two fixed points at the river banks and a rope) and the electrical connection to the target location.
A water wheel needs an axis over the whole river, or some form of mount in the middle of the stream. I would furthermore assume that the whole construction is rather heavy, making transport difficult.
To summarize the potential advantages:
* small, lightweight set
* potentially low cost per active area
* easy installation
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