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View Poll Results: Wind frams - good or bad for the countryside

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  • Yes - they look bad

    8 34.78%
  • No - They are a thing of beauty

    13 56.52%
  • I dont care either way

    2 8.70%
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  1. #51
    Intoxicated with the madness petertdavis's Avatar
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    Quote Originally Posted by mobyme View Post
    And I think anybody who thinks that people who are anti-wind farm are ignorant and in the pay of the oil industry; is arrogant and needs a reality check.
    And which of those pictures that I posted do you prefer to the windmills?
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  2. #52
    SitePoint Evangelist croatiankid's Avatar
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    Quote Originally Posted by petertdavis View Post
    And which of those pictures that I posted do you prefer to the windmills?
    How many pictures of windmills do you need to produce the power that 1 nuclear powerplant (or even only 1 nuclear reactor) makes?
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  3. #53
    Intoxicated with the madness petertdavis's Avatar
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    Quote Originally Posted by croatiankid View Post
    How many pictures of windmills do you need to produce the power that 1 nuclear powerplant (or even only 1 nuclear reactor) makes?
    Well, what kind of nuclear plant are you talking about? One like this maybe?

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  4. #54
    I hate Spammers mobyme's Avatar
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    A typical nuclear power plant produces 1,000 megwatts of electricity per hour.

    A 1500 acre wind farm of 60-70 turbines will produce approx 25 megawatts per hour. You would need 60'000 acres and between 2400-2800 wind turbines to equal 1000 megawatts. Unfortunately even then, they will only produce that amount of power if the wind is perfect for them. This is the case about 25% of the time, so in reality you need you need 240'000 acres and between 9'600 to 11'200 turbines to produce 1'000 megawatts per hour. 240'000 acres equals 375 square miles. That's the reality check

    The visual impact of nuclear power stations like the little beauty up above can be negligible while the Triffids are appearing on every available moor, hill and mountain in Britain. The sound pollution they cause is creating desolate wildernesses of the last few remaining refuges for wildlife.
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  5. #55
    SitePoint Wizard bbolte's Avatar
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    everyone keeps talking about noise from the wind farms. i've been right up next to one, massive ones and all i heard was a slight breezy sound. and i didn't feel any vibrations. i didn't see any dead birds but saw plently of wildlife around them.

    pictures here and here

    as i said before, they aren't the salvation of our energy problem, but they are part of a multifaceted solution.

    from one of the pages: "Compared to the emissions from 110 megawatts of coal-fired generation, the Gray County Wind Farm reduces carbon dioxide (CO2) emissions by 600,000 tons annually. This is the CO2 emission absorption equivalent of having a 120-square mile forest on the southwest Kansas plains."

  6. #56
    I hate Spammers mobyme's Avatar
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    Quote Originally Posted by bbolte View Post
    everyone keeps talking about noise from the wind farms. i've been right up next to one, massive ones and all i heard was a slight breezy sound. and i didn't feel any vibrations. i didn't see any dead birds but saw plently of wildlife around them.
    It's funny and something I can't explain but in actual fact my experience when up close to them is similar to yours, very little noise except for a slight whooshing noise; yet get about a mile away from them and there is a kind of a thrum that goes right through you. There is a wind farm about ten miles away from us and there are so many birds killed there that a local lad has been recruited whose sole responsibility is to clear up corpses. I think part of the problem is that the farm has been sited to take advantage of the wind which peels off two hillsides; birds naturally use this type of wind assistance and the "birdstrikes" are inevitable. There used to be Deer, Badgers and Hares up there but now there is very little except the odd Fox scavenging on carrion.
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  7. #57
    SitePoint Wizard bbolte's Avatar
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    Quote Originally Posted by mobyme View Post
    yet get about a mile away from them and there is a kind of a thrum that goes right through you.
    hmmm, interesting. haven't experienced that around these and i've been around them several time.

  8. #58
    Intoxicated with the madness petertdavis's Avatar
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    Quote Originally Posted by bbolte View Post
    hmmm, interesting. haven't experienced that around these and i've been around them several time.
    Well that's probably because he's just making stuff up. For example, the "between 2400-2800 wind turbines to equal 1000 megawatts" looks a bit off when you look at this project which is expected to have a 1 gigawatt capacity with 341 turbines.
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  9. #59
    I hate Spammers mobyme's Avatar
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    Quote Originally Posted by petertdavis View Post
    Well that's probably because he's just making stuff up. For example, the "between 2400-2800 wind turbines to equal 1000 megawatts" looks a bit off when you look at this project which is expected to have a 1 gigawatt capacity with 341 turbines.
    Oh, so I am not only ignorant but now a liar too. You really are a pleasant person aren't you.
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  10. #60
    Intoxicated with the madness petertdavis's Avatar
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    Quote Originally Posted by mobyme View Post
    Oh, so I am not only ignorant but now a liar too. You really are a pleasant person aren't you.
    So is "you're a big meanie" the only evidence you can present to prove the statements you made?
    Peter T Davis

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  11. #61
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    Quote Originally Posted by petertdavis View Post
    Well that's probably because he's just making stuff up. For example, the "between 2400-2800 wind turbines to equal 1000 megawatts" looks a bit off when you look at this project which is expected to have a 1 gigawatt capacity with 341 turbines.
    To be fair there are many different types of wind turbines that all produce different amounts of energy, and the location of the wind turbines also effects the energy produced because of the different winds you get. e.g. It takes many more small privately owned wind turbines that are designed to help power a house to produce the same amount of energy as far fewer but larger and more advanced commercial wind turbines.

    p.s. Can we please refrain from accusing fellow sitepointers of being liars and such, if you believe a statement is inaccurate then please debate your opinion respectfully to avoid unpleasant conflicts diluting an interesting and informative thread. Thank you.

    ro0bear

  12. #62
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    Quote Originally Posted by mobyme View Post


    A typical nuclear power plant produces 1,000 megwatts of electricity per hour.

    A 1500 acre wind farm of 60-70 turbines will produce approx 25 megawatts per hour. You would need 60'000 acres and between 2400-2800 wind turbines to equal 1000 megawatts. Unfortunately even then, they will only produce that amount of power if the wind is perfect for them. This is the case about 25% of the time, so in reality you need you need 240'000 acres and between 9'600 to 11'200 turbines to produce 1'000 megawatts per hour. 240'000 acres equals 375 square miles. That's the reality check

    The visual impact of nuclear power stations like the little beauty up above can be negligible while the Triffids are appearing on every available moor, hill and mountain in Britain. The sound pollution they cause is creating desolate wildernesses of the last few remaining refuges for wildlife.
    Most wind turbines range from 1.5 - 3.5 megawatts per hour so I am not sure if 60-70 can't produce more than 25 mw per hour. http://www.gepower.com/prod_serv/pro...36mw/index.htm
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  13. #63
    SitePoint Wizard silver trophybronze trophy mizwizzy's Avatar
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    lots of wind farms here

  14. #64
    I hate Spammers mobyme's Avatar
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    Quote Originally Posted by Hostpitable View Post
    Most wind turbines range from 1.5 - 3.5 megawatts per hour so I am not sure if 60-70 can't produce more than 25 mw per hour. http://www.gepower.com/prod_serv/pro...36mw/index.htm
    Thats about right. A typical wind turbine is the Danish manufactured Vestas V 80 with the following specification.

    Rotor Diameter: 80 m

    Swept area: 5,027 m2

    Speed revolution: 16.7 rpm

    Operational interval: 9 - 19 rpm

    Tower Hub height (optional approx.): 60 - 100 m

    Total height (blade vertical) 100 - 140 m (depending on tower) i.e. 305 to 427 feet

    Generator: Asynchronous

    Nominal output: 2.0 MW at 50 Hz 690 V

    Weight

    100 m Tower: 220 t

    Nacelle: 61 t

    Rotor: 34 t

    Total: 315 t

    Installed capacity and load factor (capacity factor)


    The nominal maximum output is referred to as the "installed capacity". If the machine generated at maximum rate, continuously for a year, it would yield, per installed MW: - 1.0 MW x (365 x 24) hours = 8760 MWh. The actual yield is much less, mainly because there is insufficient wind to maintain full generation.


    Onshore in the UK it is conventional to expect the achieved generation to be about quarter to one third of the maximum. The multiplication factor is called the "load factor" (synonym "capacity factor") - usually expressed as a percentage.

    In 2003, Lord Sainsbury told the House of Lords that load factor was about 30% onshore and 35% offshore (Hansard 18 November 2003: Column 1851)

    During the past two years of DTI records the average UK figures have been much less than this onshore: 24.1% in 2003 and 26.6% in 2004 (DUKES 2005).

    Calculation of load factor –



    Example for a 1.0 MW turbine: -

    (Achieved generation/(Maximum possible generation)/ x 100 = Load factor

    Maximum possible is 1.0 MW x 8760 h/y = 8760 MWh

    Achieved generation is (say) 2190 MWh

    Load factor thus = 2190 MWh / 8760 MWh = 0.25 i.e. 25%

    The calculation should be based on yield over a stated time (the Ofgem period is January to December.)



    Windspeed

    A wind turbine cannot generate until there is sufficient wind, usually about 4 m/s, called the 'cut-in' speed. The machine does not reach peak generation until about 15 m/s. It then maintains a constant output with increasing speed (see Physics of windpower, below) up to a safety 'cut-out' speed of 25 m/s.

    A rotor can be allowed to idle (generator declutched) at wind speeds well below cut-in speed to take instant advantage of periods of stronger wind (a 30 tonne rotor otherwise takes time to come to speed).

    Above cut-out wind speed the turbine is shut down for safety, with blades 'furled' (feathered), i.e. edge-on to the wind and with generator de-clutched and the wind-shaft locking brake on.

    Some examples are given below, from manufacturers' specifications.

    Vestas V 66 1.75 MW turbine. Rotor d. 66 m cut-in 4 peak 16 cut-out 25 (metres/second)

    Vestas V 80 2.0 MW turbine. Rotor d. 80 m cut-in 4 peak 15 cut-out 25 (m/s)

    General Electric 3.6 turbine. 3.6 MW Rotor d.104 m cut-in 3.5 peak 14 cut-out 25 (m/s)

    Conversion of speed units: 4 m/s = 8 knots = 14 km/h = 9 mph = B3 : 15 m/s = 29 kt = 54 km/h = 34-mph = B7 : 25 m/s = 49 kt = 90 = km/h = 56 mph = B10.

    Beaufort wind scale (B): 3 = Gentle Breeze; 7 = Moderate or Near Gale; 10 = Whole Gale or Storm

    Prediction of the performance of a wind turbine may be obtained by previous anemometric recording of wind speed on the site but an approximate prediction of generating output may be made from maps of the distribution of wind speed in the UK. For example: - http://www.esru.strath.ac.uk/EandE/W...dspeedmap.html

    This map shows that average wind speeds in lowland Britain are 5-6 m/s, coastal and upland areas 6-7 m/s and exposed uplands 7-8 m/s. Only a few extreme sites in the uplands, west and north lie between 8-10 m/s average speeds. Note that the average wind speed, even in the windiest sites is below peak generating speed, suggesting that a wind turbine anywhere in the UK, exposed to a variable wind regime will spend much of its time well below maximum generation thus explaining the low load factor of about 26% (average for 2003 and 2004)

    It is also this distribution of windspeed which makes high ground and coast the preferred target for wind developers.

    Physics of wind power

    i) Theoretical output is proportional to the square of the blade-length (radius).

    A wind turbine converts the kinetic energy of moving air into mechanical work. The theoretical electrical output is thus related to the mass of air passing through the rotor. Doubling the area of the rotor doubles the amount of power available and, because the area of the swept circle is pi x radius squared, the output is proportional to the blade-length squared.

    ii) Theoretical output is proportional to wind speed cubed so even a small increase in average wind speed should give substantially more electricity over the course of time.

    Real wind turbines follow the first rule closely hence any increase in height allowing increase in rotor radius gives substantially more power. The practical consequence is that machines originally designed for offshore installation (both V80 and GE 3.6) have quickly migrated onshore.

    The second rule is not followed closely by real wind turbines. At first as wind rises above cut-in speed the power output increases dramatically with speed (because of the cubic relationship a doubling gives 2 x 2 x 2 increase in power). However the output then becomes more or less proportional to wind speed up to peak generation (i.e. x 2 increment doubles power) and then between peak and cut-out wind speed the output remains almost constant (because the generator is running at maximum output).

    This lack of conformity to the cubic relationship is a result of aerodynamic (stall) regulation, or pitch regulation of power conversion by the blades, of 'electrical-braking' and of the alternator reaching its peak capacity. In the first case the shape of the blades allows wind-flow to become turbulent over an increasing part of the blade as the speed rises, reducing theoretical power conversion. In the second case the whole blade pitch is varied, or control surfaces (ailerons) are moved to 'spill' wind with the same effect. The load imposed by the generator also controls rotor speed (just as an idling car engine slows if the headlights are switched on) - this loading, like pitch regulation, is under operator or computer control. Such modification of the aerodynamic and electrical-braking characteristics allows a modern wind turbine to harvest maximum power from fairly low wind speeds but also safely to continue operation in high winds up to gusts of almost 60 mph.

    Rotor speed

    Wind turbines are so gigantic that the rotor appears to be travelling quite slowly but this is illusory. A big turbine like a Vestas V 80 2.0 MW machine rotates at 16 rpm and so, with a blade radius of 40 m, the blade tip velocity is 241 km/h (149 mph), over twice the motorway speed limit. The GE 3.6 turbine at its maximum 15.3 rpm has a blade tip velocity of 300 km/h (186mph), approaching the average speed of a Formula 1 racing car and its blade-swept area is substantially larger than that of the V80, at 8,495 m˛ [larger than a football pitch which is 7392 m˛]

    A bird which just avoids a GE 3.6 blade tip has only 1.3 seconds to dodge the next blade, approaching from about 93 yards away on a strongly curved path!

    Spacing of turbine: area of land needed

    To avoid “taking the wind out of each others sails”, wind turbines require spacing at 8 to 10 rotor diameters (downwind) and across-wind at c. 5 diameters (Manwell et al; 2002). Some authors suggest even greater spacing.

    An example is Horns Rev off the Danish coast where 80 turbines (2.0 MW) are in a square array of 20 km2, thus 0.25 km2 per 2 MW turbine (or 0.125 km2 per MW installed). This is rather more closely packed than the counsel of perfection above.

    The biggest onshore windfarm (2005) in the UK has 39 turbines (1.5 MW) on a land area of 7.5 km2 giving 0.2 km square per turbine (or 0.13 km2 per MW installed).

    For comparison a 1500 MW fossil fuel station with a load factor of 80% would occupy no more than about 2 km2 and generates 1500 x 0.8 = 1200 MW. With wind load factor of 25% a 2MW turbine yields 0.5 MW - so we need 2400 turbines to equal this electricity and occupying 2400 x 0.25 = 600 km2 of land.

    None of this incidentally is my work and has been cribbed from the work of a much respected professional environmental scientist Dr John Ethrington, formerly Reader in Ecology at the University of Wales.
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  15. #65
    SitePoint Wizard bbolte's Avatar
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    sorry to dig this back up, but thought this was interesting enough to add. I've been hearing about Texas and plans to build wind farms in that state,

    http://www.itwire.com/content/view/19580/1066/

  16. #66
    Now available in Orange Tijmen's Avatar
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    Quote Originally Posted by bbolte View Post
    sorry to dig this back up, but thought this was interesting enough to add. I've been hearing about Texas and plans to build wind farms in that state,

    http://www.itwire.com/content/view/19580/1066/
    Sounds like a good plan to me
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  17. #67
    got beer? jabo's Avatar
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    well, whatever other source of energy anyone comes up with, there would always be environmentalists out there who would be against it. it is really difficult to decide on this sort of stuff I guess as people will always have opinions. other source of energy could be cheap and all but it could be harmful.

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    Smile

    Quote Originally Posted by Tailslide View Post
    The problem for me isn't actually their looks - it's that they take more energy to manufacture and maintain than they'll produce.

    Plus the wind is an unreliable source of energy, plus if the wind gets too high they turn them off!!
    That's News to me! Thanks for the info! Regards, Dave.

  19. #69
    One website at a time mmj's Avatar
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    Well put petertdavis (on post #49). I was going to make the same point.

    Also, they do not endanger birds or bats. In Australia there was a well publicised issue where a politician opposed a wind farm because it might be a danger to the critically endangered bird species the orange-bellied parrot, despite that there was a similar concern on a previous wind farm and that no birds were known to have been harmed in the six years of its operation. The wind farm went ahead when studies found it would not pose a significant problem. To date no bird is known to have collided with a turbine, and being critically endangered, the birds are tracked very closely.
    http://en.wikipedia.org/wiki/Orange-bellied_Parrot
    The power of the orange bellied parrot to have so much influence in politics became a bit of a running joke, mostly because it was a red herring argument - the turbines have no effect on the birds, it was just an act of desperation on the part of the politician to oppose the construction a wind farm in his electorate.

    They look quite beautiful, really. I don't understand the opposition. They're clean and green. They are quiet and generate no significant pollution. And they can provide power 24/7, because there is always a suitable wind blowing somewhere in the country!

    Note also that there is no such thing as "megawatts per hour". Megawatts is a measure of power, not energy. It is a rate, not accumulative.
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