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Thread: Green power

  1. #1
    Silver Member Graeme's Avatar
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    Green power

    Wind power is very topical at the moment, following the recent visit to South Africa of a Danish representative punting this means of electricity generation.

    Much is being written about wind and solar power, but it would seem to me that there is no coherent plan to put the two together. Wind power only produces electricity when the wind blows. This is about 15% of the time. Denmark has an arrangement with Norway and Germany to supply electricity during the 85% of the time when there is not enough wind to turn its turbines. Similarly, solar power is produced only when the sun shines.

    A new pump storage scheme is expected to come on stream in Tubatse in Mpumalanga in about 2014. These schemes operate by pumping water from one dam to another dam at a higher altitude and then letting the water run back down to the lower dam via turbines which generate electricity. Such a scheme has been running from the Spionkop dam for some time now. The advantage of these schemes is that the output is beautifully controllable, feeding electricity into the National Grid just when it is wanted during peak demand times.

    It would seem to make a lot of sense to erect wind power turbines and solar power installations very close to these pump storage facilities so that the stop/go power produced by them would not require incur expensive transmission costs, and could be used to pump water instead of being fed directly into the grid - or is that asking too much of inter-departmental cooperation?

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    just me duncan drennan's Avatar
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    The Palmiet pumped storage scheme has been going for some time, although it is much smaller than the two you mentioned (around 400MW). What they typically do is use excess energy to pump the water up (turning a coal fired generator on and off to regulate generating capacity is not particularly efficient). Another use of these facilities is to regulate power factor on the grid.

    One thing that I am not sure about with any of these facilities is how long they can run for, i.e. energy capacity.

    The most effective way to use these facilities is to store excess energy that is available on the grid (regardless of the source). The stored excess can then be used to supplement the grid when necessary. The source of the energy isn't really important, as you would rather use it directly if it is available.
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    Email problem Superscenic's Avatar
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    plenty of juice.

    I live in Cape town. What I can say with absolute certainty is that we have plenty of wind and much much more than 15 %. We also have plenty of sun. When the sun isnt shining, and the wind isn't blowing theres plenty of big wave action.

    I also heard that in Denmark they actually switch their wind turbines off sometimes because they generate too much power and the council makes a loss.

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    Quote Originally Posted by Superscenic View Post
    I live in Cape town. What I can say with absolute certainty is that we have plenty of wind and much much more than 15 %. We also have plenty of sun. When the sun isnt shining, and the wind isn't blowing theres plenty of big wave action.

    I also heard that in Denmark they actually switch their wind turbines off sometimes because they generate too much power and the council makes a loss.
    Hey Superscenic, Have you seen the wind turbines at darling? They are used (i think) to substitute some of cape towns power. See here: http://www.southafrica.info/about/su...rm-darling.htm

    I would like to see some wave power generation though, we have plenty of unused waves (From a surfers point of view ).
    once there was a man. the end.

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    Silver Member Graeme's Avatar
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    I got Denmark's figures from an article about Wind Power in last week's Engineering News. This publication does not usually get that sort of thing wrong. No mention there about having to switch the turbines off during high winds.

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    just me duncan drennan's Avatar
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    Graeme, you might enjoy this story about a new liquid battery which is in development.
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    Site Caretaker Dave A's Avatar
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    It's amazing how much progress there has been in battery technology of late.
    The trouble with opportunity is it normally comes dressed up as work.

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    Email problem Superscenic's Avatar
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    OMG nice!

    It's happening YAY!!
    here are some alternative designs in Digg: http://www.greenoptimistic.com/2009/...ible-to-build/

    And here is the link about Denmark producing TOO MUCH power with wind: http://got2begreen.com/green-infrast...ch-wind-power/

    "In western Denmark, the price of electricity can sometimes drop to 0 on a windy day which leaves utilities trying to find ways to offload the excess power. What a “good” problem to have!"

    http://www.metaefficient.com/cars/da...ind-power.html

    "In western Denmark, the price of electricity can drop to zero on a windy day, leaving utilities scrambling to offload excess power or take a financial hit."

    Love those wind turbine farms that are now being build in the sea to lessen impact on the countryside and their species. Check those big blue sea expanses with Dali-Like giant white flowers bobbing up and down, so Surreal.
    Last edited by Superscenic; 25-Feb-09 at 10:31 AM.

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    Gold Member twinscythe12332's Avatar
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    are there any notable impacts that happen due to these turbines? for example, would a 30 km/h wind hit the turbines, and slow down to a 28km/h wind?

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    Email problem Superscenic's Avatar
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    http://www.windpower.org/en/tour/wres/pwr.htm

    heres a wind speed / output graph from The Danish wind industry foundation.

    If thats any help

    I think there are many areas wich will still be improved upon. My personal issue is more the birds that get taken out by the blades. That is a huge problem apparently for Danes. They can spin at scary high speeds and birds can't always see them. That why I like the vertical stack design more, its not so pretty but it needs no maintanance or output dampers.

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