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Capturing Wave Energy

08/24/2010 8:30 PM

The kinetic energy of waves can be converted into potential energy and then used to generate electricity by building reservoirs at sea.

When waves strike the walls of the reservoirs they will exert forces and hence pressure on them. If the walls have one way valves in them, water will enter but not exit the reservoir and continue to do so until the water pressure in the reservoir equals the pressure from the incoming wave. A head of water above sea level will thus be created in the reservoir which can be used to generate electricity with low head turbines.

The use of reservoirs which can be fixed to platforms or floating enables energy to be stored and smoother and more controlled electricity output.

If one way valves were incorporated in tidal barrages more water could be stored at high tides to enable more electricity to be generated over a longer period. of time.

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#1

Re: Capturing Wave Energy

08/24/2010 10:16 PM

Are there some sample calculations you could give that tell how much water can be impounded at how much head, at what cost for such a structure, and how much electricity can be gotten out of it?

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#2

Re: Capturing Wave Energy

08/25/2010 2:02 AM

It only raises a head if it's not a floating reservoir.
And I still can't se the point of the reservoir as an intermediate stage when you have moving water carrying energy in the first place the wave.
Maybe the head in the reservoir could be used to operate a wave machine?
Del

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#3
In reply to #2

Re: Capturing Wave Energy

08/25/2010 3:08 AM

Yeah, that too. The floating kinda does it in.

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#4
In reply to #2

Re: Capturing Wave Energy

08/25/2010 7:08 AM

Surf's up Dude!

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#5

Re: Capturing Wave Energy

08/25/2010 4:53 PM

Hello GEORGEB

There are all types of ideas for capturing wave energy. This site is a pretty good one for ideas already considered, or even tried.

I believe you idea (or something along the same line) is discussed in one of the white papers. Perhaps have a look at those.

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#6

Re: Capturing Wave Energy

08/25/2010 6:01 PM

The size of the head of water in the reservoir would vary with the square of the height of the incoming waves. Typical waves could produce a head of around 5m and larger waves a head of 10m or more.

Floating reservoirs are quite possible. If air tanks filled half the space of the reservoir the reservoir would sink by half its water level as it fills up and similarly rise as it empties.

The advantages of using reservoirs to capture wave energy over other non storage devices are:

1, They enable energy to be stored and used in a controlled way

2, They capture a greater proportion of the energy from passing waves than any other device

3, They produce a smoother electricity output

4, Large reservoirs can store enerrgy at high tides to produce greater output at low tides.

5, As the turbines are separated from waves maintenance is easier.

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#7

Re: Capturing Wave Energy

08/25/2010 11:07 PM

Have a look at this thread, started by Chrisg288 some time back:

http://cr4.globalspec.com/thread/32245

Also, visit the EPRI site (Electric Power Research Institute). They have available a large collection of studies (feasibility, technological, and economic) on various ocean energy conversion schemes- a good place to start for determining where the industry is right now.

Pelamis has a functional wave energy conversion system off the coast of Portugal that is probably a whole lot more practical than the reservoir concept...

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#8
In reply to #7

Re: Capturing Wave Energy

08/25/2010 11:35 PM

Thanks Charlie,

More specifically, there were a few posts within that thread that discussed using every available energy source available off shore. wind, wave, current/tidal, pressure, solar, etc. as well as storage concepts.

Chris

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#9

Re: Capturing Wave Energy

08/26/2010 9:26 AM

Natural fall into the reservoir can give free flowing in fluid.

If you are using pipe entries, naturally the higher fluid heads into reservoir should counteract entry of your tidal/ wave based fluid entry into reservoir under opened conditions

Saltire Prize Fevers?

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