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Alternative Energy Production - Tidal / Wave etc.


mgb2010
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Also, I am sure that somebody on Shetland knows just how much oil is consumed at Gremista year on year. They are hardly going to publish that kind of info!

 

The SIC publish an Annual (?) energy audit which details all forms of energy use in Shetland. They even used to include an estimate of peat in their calculations

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One of the main reasons, despite a falling population, that more electicity is being generated is to supply the wind turbines with good quality grid electricity to allow them to work in the first place - I will not get into technical details, but that is the only reason that the interconnector is required from the Scottish Mainland - to supply electricity to the wind turbines' windings!

 

Now this is something that I want to read about! Not being savvy about the internal workings of these huge proposed behemoths - that is something that just hasn't been covered.

 

The connector cable as I've been fed is there to "export" electricity to the mainland. Is there a laymans guide anywhere on the Net about such things?

 

I may not be a windmill expert, but I'd say with some confidence that this is simply not true. The mills don't need the connector cable to power them at all.

 

Here in Fair Isle our power is provided by two windmills (one 60kw, one 100kw) and, when there isn't enough wind, by a diesel generator.

When it is windy, and the windmills are producing power, the generator is off. There is no power being supplied to mills at all.

 

Obviously the mills we're speaking about are much bigger, but I fail to see why the technology now would be so much less efficient than it was 25 years ago when our first mill was erected.

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^^ Yes, that is my first impression too. Though I would hope/trust that should greenheatman wish for his invention to be taken seriously he would not be going around making untrue spurious claims and or remarks!?

 

Under that assumption I will give him the benefit of the doubt until I can find, or someone else points me in the direction of where these claims arise / can be refuted.

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^^ Yes, that is my first impression too. Though I would hope/trust that should greenheatman wish for his invention to be taken seriously he would not be going around making untrue spurious claims and or remarks!?

 

Under that assumption I will give him the benefit of the doubt until I can find, or someone else points me in the direction of where these claims arise / can be refuted.

 

I'm afraid I take the opposite view: when some bloke on the internet says that wind farms consume rather than create electricity and there's a big conspiracy to keep the truth from the general public, I won't believe him until he backs up his claims with evidence.

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^^^^^

 

that is the only reason that the interconnector is required from the Scottish Mainland - to supply electricity to the wind turbines' windings!

 

Read that sentence again. It simply doesn't make sense. Even if these mills do require some power to work, greenheatman is claiming that that is the "only" reason the interconnector is required. That is so outrageous a claim that I just can't accept that greenheatman is the only person in the world to have realised it.

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^^ Yes, that is my first impression too. Though I would hope/trust that should greenheatman wish for his invention to be taken seriously he would not be going around making untrue spurious claims and or remarks!?

 

Under that assumption I will give him the benefit of the doubt until I can find, or someone else points me in the direction of where these claims arise / can be refuted.

 

I'm afraid I take the opposite view: when some bloke on the internet says that wind farms consume rather than create electricity and there's a big conspiracy to keep the truth from the general public, I won't believe him until he backs up his claims with evidence.

 

:oops: That was the point I was trying to make.. though obviously not very clearly. If I can see evidence to back up the claims I will be happy. I err on the side of caution - though have my ears pricked as I would like to presume that this gentleman is a learned individual - though potentially with a vested interest in seeing the windfarm lobby fail!?

 

Anywho ... evidence .. evidence .. we need evidence!

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One of the main reasons, despite a falling population, that more electicity is being generated is to supply the wind turbines with good quality grid electricity to allow them to work in the first place - I will not get into technical details, but that is the only reason that the interconnector is required from the Scottish Mainland - to supply electricity to the wind turbines' windings!

 

Whilst most modern wind turbines need power for control systems such as the yaw-adjustment mechanism (to keep it pointing into the wind) and some designs of larger electromagnetic generators need an electrical 'bump start', you comment seems designed to mislead

 

IMHO, it may be worth posting links or evidence to back up your claims, as each of your posts is quickly followed by folk asking for more info, which doesn't seem to materialise

 

As has been stated earlier in the thread, you don't have to worry about sparing us technical details or facts & figures. We may not be as stupid as we are cabbage like. Spurious claims with no evidence aren't worth the storage space they take up on the server :wink:

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OK, you think that you can handle technical. There are two main types of generators, induction and synchronous - the ones on Fair Isle are sychronous and do require a bump start using pilot excitation circuitry connected to banks of batteries. These systems are not cheap to install and maintain and are used when there is no significant grid connection available.

 

The induction generator requires quite a lot of mains current at 50Hz to be applied to the the 'squirrel cage' particularly at start up. When the wind blows at say, gale force, the wind rotates the main low speed shaft at about 1% above the synchronous speed of the main generator. If the wind rotated the shaft at synchronous speed no electricity will be generated; 1% above means that lines of magnetic force are cut and electricity is generated.

 

The rating of a wind turbine of, say 2MW, does not mean that is generates 2MW of electricity. 1.8MW of electricity out is on the hopeful side and this is the gross output. The electricity used to feed the squirrel cage and the works power needs to be subtracted from this figure so that the best that a 2MW rated wind turbine can produce is around 1.65MW depending on the design.

 

As the wind reduces from gale force towards 12m/s the main generator output falls matching the mechanical power applied to the shaft to around 500kW(electrical)

 

At the 12m/s the main 6 pole generator drops out and the smaller eight pole generator, rated at 400kW cuts in to catch the loin's share of wind distribution ie below 12m/s - this smaller generator delivers around 360kW gross but by the time the power applied to the pitch and yaw mechanisms and its windings are subtracted it is not worthwhile switching the turbine on below 8m/s.

 

Evidence in support can be found at the following sites

 

http://www.windpower.org/en/tour/wtrb/stator.htm

 

http://www.esru.strath.ac.uk/EandE/Web_sites/98-9/offshore/wind/vestas.htm

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OK, you think that you can handle technical.

..[snip]

You are saying that a wind turbine produces most electricity when the wind is strong, less electricity when the wind isn't so strong, and no electricity at all below a certain wind-speed. This is not exactly controversial, and doesn't provide any support for your claim that wind turbines consume, rather than produce electricity.

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Thank you for the clarification there greenheatman - though could you also detail further

[...] but that is the only reason that the interconnector is required from the Scottish Mainland - to supply electricity to the wind turbines' windings!

 

- - - from it I understand you are pointing out that the power station at Gremista is not going to be able to produce enough power to "kick-start" these behemoths of windmills which are "synchronous"? That power will have to be fed up from the mainland on the interconnector just to get them to function to feed electricity back down, yes?

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[...] but that is the only reason that the interconnector is required from the Scottish Mainland - to supply electricity to the wind turbines' windings!

To echo Trout's point... how much power is needed to bump all the generators, and how much do you think that would exceed Shetland's present generating capacity (bearing in mind that neither Gremista nor Sullom power stations work at capacity)?

 

Surely the control systems will have basic facilities to stagger the turbine's power up times to avoid overloding capacity?

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Thank you for the clarification there greenheatman - though could you also detail further
[...] but that is the only reason that the interconnector is required from the Scottish Mainland - to supply electricity to the wind turbines' windings!

 

- - - from it I understand you are pointing out that the power station at Gremista is not going to be able to produce enough power to "kick-start" these behemoths of windmills which are "synchronous"? That power will have to be fed up from the mainland on the interconnector just to get them to function to feed electricity back down, yes?

 

greenheatman claims the only reason for the interconnector is to supply electricity to the wind turbines, implying that electricity won't be flowing the other way at all.

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