Naked Science Forum
Non Life Sciences => Technology => Topic started by: Petrochemicals on 11/04/2021 07:44:07
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As in the big white things that are becoming quite common, why do they shut down? If its maintenance that is not very good.
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As in the big white things that are becoming quite common, why do they shut down? If its maintenance that is not very good.
Many of the inland ones were badly placed, not enough wind to keep them going all the time.
They will also shut down if wind speed is too high to prevent damage. Otherwise, I assume maintenance.
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Some windmills (or farms) may not yet have been commissioned.
There are also instances where there is "too much" electricity, outside peak hours.
- Sometimes this is because the transmission lines are already overloaded
- Sometimes regulators guarantee a certain amount of capacity to nuclear or coal, which can't shut down or start up quickly
- Sometimes electricity markets allocate wholesale electricity generating capacity based on price bids to deliver the demanded capacity. Electricity from wind is almost free (there is some wear and tear on an operating windmill). But sometimes, the wholesale price can go even lower than this....
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Wind farming is mostly about drawing subsidies from the users of reliable sources of electricity. In summer, it is common for wind farmers to receive subsidies for not generating electricity: if demand drops below 20% of peak (surprisingly common!) it is preferable to subsidise windmills than to run down nuclear plant, which takes a long time to switch on again.
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As in the big white things that are becoming quite common, why do they shut down? If its maintenance that is not very good.
Why isn't it? Maintenance of the gearbox is one cause. Obviously if there's not enough wind then they will all shut down locally. If they're undergoing maintenance some small proportion of the time, that's no big deal. ALL power plants need some maintenance sometimes.
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As in the big white things that are becoming quite common, why do they shut down? If its maintenance that is not very good.
Many of the inland ones were badly placed, not enough wind to keep them going all the time.
They will also shut down if wind speed is too high to prevent damage. Otherwise, I assume maintenance.
That sounds like bad design, either in the structure or the generator, if they shut down in strong winds it is not really in keeping with the conditions of the UK.Some windmills (or farms) may not yet have been commissioned.
There are also instances where there is "too much" electricity, outside peak hours.
- Sometimes this is because the transmission lines are already overloaded
- Sometimes regulators guarantee a certain amount of capacity to nuclear or coal, which can't shut down or start up quickly
- Sometimes electricity markets allocate wholesale electricity generating capacity based on price bids to deliver the demanded capacity. Electricity from wind is almost free (there is some wear and tear on an operating windmill). But sometimes, the wholesale price can go even lower than this....
That rings of amtuerism, there is no pont installing more if energy cannot be relied on and no way to store it Wind farming is mostly about drawing subsidies from the users of reliable sources of electricity. In summer, it is common for wind farmers to receive subsidies for not generating electricity: if demand drops below 20% of peak (surprisingly common!) it is preferable to subsidise windmills than to run down nuclear plant, which takes a long time to switch on again.
So existing generation types are still a necessity. I wonder how much waste there is among the generation types, the sort of information that is an open secret in industry.As in the big white things that are becoming quite common, why do they shut down? If its maintenance that is not very good.
Why isn't it? Maintenance of the gearbox is one cause. Obviously if there's not enough wind then they will all shut down locally. If they're undergoing maintenance some small proportion of the time, that's no big deal. ALL power plants need some maintenance sometimes.
The ones I have seen in the seas off the North Wales coast about 50 percent where not working. A bit of maintenance is ok but 50 percent sounds like a poor design. I am sure that having a generator at 100 m in every windmill cannot be the cheapest or most clever design.
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there is no point installing more (windmills) if energy cannot be relied on and no way to store it
The fact that wind is unreliable is a good reason to install more windmills in more diverse locations. where the output is not correlated...
- While one wind farm is becalmed in the middle of a high-pressure system
- Another wind farm 500km away is very active working off a cold front
...and more diverse sources which are also not correlated with the wind
- For example, while wind is reduced in the middle of a high-pressure system, a solar power station could continue to produce daytime power
Provided you have a long-distance electrical transmission network, one or the other can supply the power to a wide area,
- Countries like Norway can store electricity with extensive hydropower storage
- More vertically-challenged and/or desiccated countries have to content themselves with more moderate short-term electricity storage like lithium batteries or flow batteries (or hydrogen storage?) - enough to keep the network running for a few minutes until gas turbines can warm up.
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So existing generation types are still a necessity.
And always will be until someone devises the means to store 5 days' worth of electricity at winter consumption levels, because 5 days with no wind is pretty common. And of course you need to install four times the anticipated peak load capacity so that you can recharge the store at the same time as supplying actual demand, during the next 5 days.
Why four times? Because wind generators rarely deliver more than 50% of rated output. There's a very narrow band of windspeeds between rated output and shutdown to prevent blade damage.
If we replace oil-burning transport and gas heating, we will need to increase wind energy production by a factor of about 1200%, and vastly overhaul the distribution grid.
In the interim, the electricity supply cannot be considered secure if more than 20% comes from wind and solar.
It's all very sad, but inevitable. If you want to run the country entirely on renewable electricity, you need to install an awful lot of hardware, some of which will hardly ever be used. Coal, gas and liquid fuels are very easy to store with negligible hardware cost. It is a serious question whether the UK, one of the windiest populated areas of the planet, could be powered by renewables at an economic cost.
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The fact that wind is unreliable is a good reason to install more windmills in more diverse locations.
The people who built he grid knew this (and it applied to coal fires power stations too- they still need to close for maintenance sometimes).
It's a pity that people seem to have forgotten in the mean time.
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It is a serious question whether the UK, one of the windiest populated areas of the planet, could be powered by renewables at an economic cost.
It is a serious question whether the UK can be powered by coal if you consider the full economic cost.
That's the point.
At the moment we aren't paying for the floods in Bangladesh.
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Wind farming is mostly about drawing subsidies from the users of reliable sources of electricity. In summer, it is common for wind farmers to receive subsidies for not generating electricity: if demand drops below 20% of peak (surprisingly common!) it is preferable to subsidise windmills than to run down nuclear plant, which takes a long time to switch on again.
You see, you're taking things out of context. To my way of thinking that's a form of lying.
No, wind power is about making electricity without generating huge amounts of pollution- and it is, overall, one of the cheapest ways to make electricity there is. It's cheaper than nuclear, coal etc. and continuing to plummet in cost.
If you're talking about constraint payments, they're something of order 0.1% of your electricity bill; and they're paid to all forms of generation- natural gas power stations get them also, and get bigger payments than wind does. Why are you not complaining about that?
So existing generation types are still a necessity.
And always will be until someone devises the means to store 5 days' worth of electricity at winter consumption levels, because 5 days with no wind is pretty common. And of course you need to install four times the anticipated peak load capacity so that you can recharge the store at the same time as supplying actual demand, during the next 5 days.
Why four times? Because wind generators rarely deliver more than 50% of rated output. There's a very narrow band of windspeeds between rated output and shutdown to prevent blade damage.
Nope.
The power output of any particular wind farm has a very asymmetric power curve. It produces far more power at high wind speeds than at low. So you would think that the grid's output power would be equally asymmetric.
But that's untrue! Because of STATISTICS, specifically the central limit theorem:
https://en.wikipedia.org/wiki/Central_limit_theorem
Basically as weather systems move over the UK, the UK's grid averages out the different wind speeds, and you end up with a highly Gaussian distribution of overall power output.
So, no, you don't need five times the number of wind turbines(!) You need around 1/capacityFactor where capacity factor is about 0.4.
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Does anyone share my visceral dislike of the idea, that in the 21st century, we should be building windmills?
Doesn't it strike any scientifically-minded person, as a deplorable throw-back to the medieval ages. When "windmills" were one of the best of the only energy-sources available. In those pre-scientific times.
But now we have modern science. Surely this can enable us to devise better, more efficient and reliable sources of energy than anachronistic windmills. The deficiencies of which have been well pointed out by previous posters.
I live in Brighton, on the south coast of England. Just off the coast, out to sea, there seems to be a whole collection of windmills.
In a "windmill farm", as the term is. I've glimpsed them with my naked eye, but have never cared to look at them with binoculars or a telescope, to verify whether they're really there, or just a mirage.
That's because I don't like the sight or even the thought of them. They are repellent.
Whereas if a modern 21st-century nuclear power-station were built off the coast. I could look at that all day with admiration and delight!
Am I the only one to be thinking this way?
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But now we have modern science. Surely this can enable us to devise better, more efficient and reliable sources of energy than anachronistic windmills.
It has.
The ones that we are building are a vast improvement on the old ones.
On the other hand, the internal combustion engine hasn't changed much in 160 years and the steam engine is pretty much the same idea as it was 2000 years ago.
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But now we have modern science. Surely this can enable us to devise better, more efficient and reliable sources of energy than anachronistic windmills.
It has.
The ones that we are building are a vast improvement on the old ones.
On the other hand, the internal combustion engine hasn't changed much in 160 years and the steam engine is pretty much the same idea as it was 2000 years ago.
Yes, that's why should take a step forwards from steam and combustion engines. Not a step backwards to ruddy windmills!
Even if these windmills were improved, by modern engineering and blade technology, they are still a retrogressive. step. They don't present a real advance in energy source.
Whereas nuclear power does. It derives power from utilising the fundamental structure of the Universe.
Not from local terrestrial effects such as winds blowing, in the case of windmills, or chemical effects in a terrestrial oxygen-laden atmosphere, in the case of combustion engines.
Neither windmills nor combustion engines would work outside the Earth. Except perhaps on planets such as Mars and Jupiter. But atomic-power can supply energy throughout the Universe, anywhere. Even in the furthest depths of Space, far from any planet or star.
The atoms will never let you down! Therefore isn't atomic-power much better than windmills?
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How about nuclear fusion?
Is that futuristic enough?
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How about nuclear fusion?
Is that futuristic enough?
Didn't someone say that nuclear fusion is the power-source of the future - and always will be?
I deplore such pessimism. It's just a matter of making very small fusion bombs, which detonate in succession inside the power-station without blowing it apart.
Why can't such "micro-fusion" technology be developed? Are our engineers not equal to the challenge?
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It's just a matter of making very small fusion bombs,
The only way we kno of to make a fusion bomb is to use a fission bomb as a trigger.
And there's a minimum size for a fission bomb- they call it the critical mass.
However, I still like the idea of a fusion reactor.
In particular, I like the idea of using the one we are in orbit round.
It's really cheap.
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Does anyone share my visceral dislike of the idea, that in the 21st century, we should be building windmills?
Doesn't it strike any scientifically-minded person, as a deplorable throw-back to the medieval ages. When "windmills" were one of the best of the only energy-sources available. In those pre-scientific times.
But now we have modern science. Surely this can enable us to devise better, more efficient and reliable sources of energy than anachronistic windmills. The deficiencies of which have been well pointed out by previous posters.
I live in Brighton, on the south coast of England. Just off the coast, out to sea, there seems to be a whole collection of windmills.
In a "windmill farm", as the term is. I've glimpsed them with my naked eye, but have never cared to look at them with binoculars or a telescope, to verify whether they're really there, or just a mirage.
That's because I don't like the sight or even the thought of them. They are repellent.
Whereas if a modern 21st-century nuclear power-station were built off the coast. I could look at that all day with admiration and delight!
Am I the only one to be thinking this way?
Polls have been done on that, the overwhelming majority of people disagree with you. They either really like them as I do, I think they're really elegant and cool looking, majestic and inspiring, or they think it doesn't matter how they look. Only a very small minority hate wind turbines like you do. And that INCLUDES people that live near them.
Where I am now, there's several less than a mile away, and numerous wind farms about 5 miles away. If I look in the right direction from the living room, there's one I can just see one through the trees. They're absolutely no trouble to us at all. They did turn one down for planning permission because it was on a ridge and might have caused TV interference for the village, but that's all. And they don't kill huge numbers of birds either, they kill about as many birds as a single house per year, and far less than the cats from inside the house.
Very few people think nuclear power plants are cool-looking. They're just squat buildings most of the time.
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Thanks Wolf
I take in the reasonable points that you make in your post.
But still, I don't like seeing windmills! There's something about them that smacks of defeatism and retrogression into the past.
Perhaps this is an unwarranted and unduly emotional reaction. But whatever the justifications for windmills that you very plausibly put forward in your post, I just can't stand them. I want to see thermonuclear fusion stations. Not windmills.
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But still, I don't like seeing windmills! There's something about them that smacks of defeatism and retrogression into the past.
Don't look in the mirror. You will be astounded by the 200,000 year old design.
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But still, I don't like seeing windmills! There's something about them that smacks of defeatism and retrogression into the past.
Well, they aren’t grinding wheat are they.
There is nothing wrong in reusing technology and ideas; even nuclear power stations create steam to drive turbines - how retro is that?
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The power output of any particular wind farm has a very asymmetric power curve. It produces far more power at high wind speeds than at low. So you would think that the grid's output power would be equally asymmetric.
But that's untrue! Because of STATISTICS, specifically the central limit theorem:
https://en.wikipedia.org/wiki/Central_limit_theorem
Basically as weather systems move over the UK, the UK's grid averages out the different wind speeds, and you end up with a highly Gaussian distribution of overall power output.
Today, as yesterday and forecast for tomorrow, the surface wind speed all over the UK was less than 5 kt, current average about 3 kt.
The power output of a wind turbine varies with the cube of the wind speed but there are upper limits. The rotor tip must not exceed Mach 1 so you have to feather the blade at high wind speeds to reduce the lift and thus the conversion efficiency. But that increases the drag force which increases with the square of wind speed so at some point you need to turn the blade to zero alpha and stop it rotating, to prevent the blade bending. So the distribution is something of a skewed curve rather than a symmetrical gaussian.
Like you, I think windmills are magnificent structures and a great idea, but they are a long way from realistically fuelling the United Kingdom at present levels of energy consumption.
I remain to be convinced about the downwind noise of land-based wind farms: the last time I attended a meeting to discuss the noise in a house a mile downwind, the meeting was abandoned because we couldn't hear each other speak. However that problem will not get any worse as all the viable land sites have now been occupied and nobody worries too much about the noise offshore.
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the steam engine is pretty much the same idea as it was 2000 years ago.
Really? The (failed) tip-jet helicopter was the closest thing I've seen to Heron's reaction spinner. Piston engines are about 300 years old and steam turbines 140 or so (both proudly British inventions!).
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- Countries like Norway can store electricity with extensive hydropower storage
- More vertically-challenged and/or desiccated countries have to content themselves with more moderate short-term electricity storage like lithium batteries or flow batteries (or hydrogen storage?) - enough to keep the network running for a few minutes until gas turbines can warm up.
This sounds like a victim of Brexit. Britian has the wind and others have the storage. The power output of any particular wind farm has a very asymmetric power curve. It produces far more power at high wind speeds than at low. So you would think that the grid's output power would be equally asymmetric.
But that's untrue! Because of STATISTICS, specifically the central limit theorem:
https://en.wikipedia.org/wiki/Central_limit_theorem
Basically as weather systems move over the UK, the UK's grid averages out the different wind speeds, and you end up with a highly Gaussian distribution of overall power output.
The power output of a wind turbine varies with the cube of the wind speed but there are upper limits. The rotor tip must not exceed Mach 1 so you have to feather the blade at high wind speeds to reduce the lift and thus the conversion efficiency. But that increases the drag force which increases with the square of wind speed so at some point you need to turn the blade to zero alpha and stop it rotating, to prevent the blade bending. So the distribution is something of a skewed curve rather than a symmetrical gaussian.
It must be something more than blade speed, surely they have gearing of some sort. It must be the structural integrity of the apparatus.
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If the blade tip will exceed Mach 1 you need to completely redesign the blade, from "glider" to "interceptor" aerofoil, and add a lot of expensive strength. Problem is that interceptors don't generate much lift at low speeds! So you try to get the blade to rotate at constant speed over a wide range of wind speeds, by varying the pitch or adjusting the load. When the wind speed is very high the drag on a rotating blade is higher than that on a stationary one, so you shut down to prevent structural damage.
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This sounds like a victim of Brexit. Britian has the wind and others have the storage.
No, 'Twas ever thus. The only nearby countries with substantial unexploited hydropower are Norway and Switzerland, which are not EU members!
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I remain to be convinced about the downwind noise of land-based wind farms: the last time I attended a meeting to discuss the noise in a house a mile downwind, the meeting was abandoned because we couldn't hear each other speak. However that problem will not get any worse as all the viable land sites have now been occupied and nobody worries too much about the noise offshore.
I checked into this, I've never heard any objectionable sound from any wind turbine.
That's not a general problem that wind turbines have at that range, but apparently 3% of wind turbines may make a lot of noise. That may have been an old model wind turbine that had some sort of aerodynamic issue, but one theory is that turbulence of wind through the blades causes the blades to stall. But that will depend on where it is, and perhaps weather conditions and the model. The suggestion I read was that reprogramming the controller to change the blade pitch when the problem occurs might ameliorate or solve the issue.
More vertically-challenged and/or desiccated countries have to content themselves with more moderate short-term electricity storage like lithium batteries or flow batteries (or hydrogen storage?) - enough to keep the network running for a few minutes until gas turbines can warm up.
At the moment the UK National Grid has a gigawatt of batteries attached to it. That's not for wind power, some of it may be for peak shaving for solar power, but most of it is for 'fast frequency response'. In other words, sometimes things fail, and when it does, they need instant power, and for the next hour, until they can jump-start some gas turbines.
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If the blade tip will exceed Mach 1 you need to completely redesign the blade, from "glider" to "interceptor" aerofoil, and add a lot of expensive strength. Problem is that interceptors don't generate much lift at low speeds! So you try to get the blade to rotate at constant speed over a wide range of wind speeds, by varying the pitch or adjusting the load. When the wind speed is very high the drag on a rotating blade is higher than that on a stationary one, so you shut down to prevent structural damage.
Well if the blades are 100m long that is 300m cir umference. Basically 1 rpm. That would be very fast, ii have never seen a turbine approach that speed., more like 1/5rpm max. It must be the strength of wind loading. If it is the case that is leaving a great deal up to chance.
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I've never heard any objectionable sound from any wind turbine.
It has certainly caused a lot of public debate in Australia, with people complaining that noise from wind turbines gives them headaches and nausea.
https://www.abc.net.au/news/2017-03-24/victorian-town-divided-over-wind-turbines/8373760
It appears that to a large extent, these symptoms were triggered by rumors generated by a petrochemicals-funded lobby group:
https://en.wikipedia.org/wiki/Wind_turbine_syndrome
I understand that in some Scandinavian countries, they require something like 10% of the investment in a windfarm to come from local residents.
- If the locals are invested in it, these problems don't occur.
- If the locals think it is something imposed on them, they may feel victimized, and that would make them feel ill.