[Colin2B]

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?

[alancalverd]

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.

[alancalverd]

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!).   

[Petrochemicals (OP)]

,
- 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.

[alancalverd]

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.

[alancalverd]

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!

[wolfekeeper]

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.

[Petrochemicals (OP)]

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.

[evan_au]

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.