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Topic Title: Wind Energy and the butterfly effect
Topic Summary: Has anyone researched the effect of removing large amounts of energy from the wind
Created On: 18 June 2009 06:00 PM
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 08 October 2009 07:15 PM
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sbdesign

Posts: 59
Joined: 08 November 2007

There have been a few newspaper articles reporting intermittent low frequency amplitude modulated noise near to wind farms. If the noise is real, then it would be good to find an engineering solution for it. Is it related to turbines being regularly spaced and turning at matched speeds? Maybe a reinforcement effect is happening at certain wind speeds, e.g. when the time for one rotation is the same as the time that the air takes to pass from one turbine to the next... Or, more generally, if one of those times mentioned is an integer multiple of the other.
 17 April 2011 06:06 PM
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ads114

Posts: 34
Joined: 10 July 2009

all complete nonsense, wind turbines generate electricity and affect absolutely nothing.
 18 April 2011 05:35 AM
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dvaidr

Posts: 519
Joined: 08 June 2003

And you're absolutely sure about this? We all know what transformers do, (don't we?), but there are 'hidden' forces to be considered which can and do affect the surrounding area......
 18 April 2011 08:47 AM
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rogerbryant

Posts: 866
Joined: 19 July 2002

This gentleman seems to think there is a problem in removing wind energy.

http://www.newscientist.com/ar...alance.html?full=true

It is obviously a highly controversial subject, but there seems to be an amount of sense in what he says.

Best regards

Roger
 19 April 2011 09:35 PM
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dougflorence

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Joined: 25 July 2008

Come on everybody. Try a bit of basic physics. You don't "remove" energy you just delay and relocate its ultimate conversion to low grade heat.

We are never going to be able to build enough wind turbines to come anywhere near the amount of energy extracted from the wind by trees. (If you find this concept hard, imagine the air was still and you were trying to push the tree through it.)

The New Scientist article quoted also suggested that soaking up solar energy in PV panels would add to global warming. What does the author think happens to the sunlight that falls onto a roof with no PV panel on it? Try standing on a slate roof on a sunny day. It is almost too hot to touch.
 20 April 2011 07:59 AM
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rogerbryant

Posts: 866
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As you say the trees extract the energy in the same ways as wind turbines do.
One wind turbine is not going to have a noticable effect, but the problem comes when you try to install a 'useful' number of wind turbines.
Doing a Nuffield physics type approximation (showing my age).

To replace one typical thermal or nuclear unit at 1 GWe:

Current peak output per turbine ~6 MW.
Good duty factor 25%
Average output per turbine ~1.5 MW.
Number of turbines 667
Laid out as 10 x 67 grid
Turbine spacing to avoid interference min 500m
Area required ~5km x 34km.

These turbines will also be taller than a typical European forest, 130m or more instead of 50m or less.

I can believe that a wind farm such as this will affect the local climate and if you start to significantly replace thermal stations with wind power it also seems reasonable that the climate over a wider area will be affected in some way.

Now as homework calculate the area required to replace the Fukushima nuclear complex, ~9GWe, with wind power and then predict the effect on this of a magnitude 9 earthquake and Tsunami along with the time taken to clean up afterwards. :-)

Best regards

Roger

Edited: 24 May 2011 at 10:05 AM by rogerbryant
 01 May 2011 07:51 PM
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jcm256

Posts: 1891
Joined: 01 April 2006

Now to much wind they can't handle it. What they badly need for the whole of the UK is a Chief Engineer (something like a chief medical officer) who job would be to coordinate and sort out this mess, be held to account, answer engineering questions in public.

http://www.bbc.co.uk/news/uk-scotland-13253876


The Royal Academy of Engineering, don't do much on wind, the extract below is from a lecture but that was in 1996. Would it still be true today?

UK wind resource matches loads well, increasing its dependability and value
It is also fascinating to look at how well the UK wind resource matches loads. If you look at going from zero to maximum demand - and these are percentile rank of the demand hour - here is the average which, for these years, was 28 per cent but, over the long-run, it averages 30. You will notice that, for the higher load periods, you are always above average on how much wind is available, which is a good thing. Wind power correlates well with electric loads and, during the highest demand hours, the wind machines are nearly three times more productive than during the lowest demand hours. In the highest 10 per cent demand hours, 82 per cent of the sites are actually working. Low wind speed correlates well with low load, conversely. Thus, if you are using annual average metrics to look at a wind site, you will very much understate windpower's capacity value for meeting peak loads. You have to do this probabilistically with a real analysis.

http://www.raeng.org.uk/events/pdf/future_lecture.pdf
 02 May 2011 12:37 PM
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rogerbryant

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A "chief engineer" would have just the same problem sorting out this mess as those currently involved do. All the same factions would fight their own, often political, corners and progress would come to a halt in a long series of public enquiries and tribunals.

Wind power generates very variable amounts of enegy, generally a long way from where it is required.
To effectively utilise this energy requires a very good distribution infrastructure and a means of storage.
Attempting to build new overhead powerlines and pumped storage systems brings immediate protest from the environmentalists and NIMBYs. Who pays for these infrastructure improvements? Is it the same people who are getting the FIT for puting the turbines in in the first place?

Would I get a double FIT (in and out) if I built a small pumped storage unit?

Best regards

Roger
 02 May 2011 07:31 PM
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TomThomson

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Maybe the crucial statement in that 16 year old lecture was "You have to do this probabilistically with a real analysis".
Looking at averages, poining out a correlation between demand and capacity, is not really useful without that probabilistic analysis. What we need to know is what is the probability that capacity will at some time in a period of 50 years be sufficiently below demand for sufficiently long to be harmful. Obviously we can maybe have mothballed rapid start-up coal-burning (or whatever) capacity to reduce that probability, but I for one regard such capacity as being highly unreliable if it isn't fired up and used sufficiently frequently that we can be sure it will fire up without problems when it is needed; so the cost equation is affected in two ways: the build costs go down rather less than they would if we didn't need that capacity; and the operational costs go down less too - we will need teams of engineers to carry out the regular tests and evaluate the results, and we will need people on standby to fire the things up when needed (anyone who thinks this can be done by throwing a remote switch without warm bodies on site probably has a screw loose). Whether such capacity is needed, and how much, will depend on that thorough probablistic analysis, and there politics (party politics, inter-company politics, inter-pressure-group politics, and all the rest of the ideology-based evidence-disregarding "reasoning" that fouls up so much of our activity) will come into play: what is an acceptable risk? How much can we get away with massaging the figures to get the result we (as opposed to they) want? How much are we prepared to disregard evidence to maintain our current beliefs (that happens more than enough even without the politics). What evidence/information should we conceal in order to further our side of the "game"? How much are we prepared to disregard evidence in order to be able to retain (or obtain) research funding?
I would dealy like to see proper analysis of solar pools (some water, a cover to reduce evaporation but allow useful radiation, a removable cover to keep down heat loss when the sun is down, and a handful of salts to produce a brew which is denser at usefully high temperatures than at ambient, some thermocouples, and maybe some fluid piped through for direct heat exchange; why is is so long since last we heard of those?), wind power, wave power, tidal power, and conventional hydroelectric power with large scale storage capacity. But it's like som many things today: vested interests (pressure groups with close to no understanding of the issues or the consequences of what they advocate, and no desire to gain any understanding) will ensure that proper discussion and analysis are extremely unlikely to take place.
I suspect that if proper discussion and analysis had been done a couple of decades ago we would now be burning very little coal and oil to generate electricity, new UK houses would not require expensive central heating plant, efficient and effective low energy lighting would be available (instead of the abysmal ineffective rubbish labelled with thoroughly misleading claims about light levels currently found in our supermarkets and DIY stores) and we would not be using anything like as much steel in automobiles. But the "politics" has held us back.

-------------------------
Eur Ing Tom Thomson MA MSc MBCS CITP CMath FIMA CEng FIET
 02 May 2011 08:08 PM
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jcm256

Posts: 1891
Joined: 01 April 2006

Tom, I enjoyed reading that post.
Thanks
J Moore I Eng MIET
 23 May 2011 05:11 PM
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Willshearer

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Joined: 11 March 2011

There was a rather poorly executed article on the New Scientist website a few weeks ago where someone had claimed to calculate the wind energy lost if a certain percentage (I think 30%) of energy was created via wind turbines, I think it got slated, however the arguments people put up against it were an interesting read... I will try and find the link.
 24 May 2011 10:02 AM
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rogerbryant

Posts: 866
Joined: 19 July 2002

Do you mean the article I linked to further up the page?

http://www.newscientist.com/ar...alance.html?full=true

Best regards

Roger
IET » Energy » Wind Energy and the butterfly effect

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