Bishop Hill Big wind just got smaller
Feb 26, 2013 Energy: wind A new paper by Amanda Adams and David Keith reports that once deployed on a large scale wind farms may generate even less power than previously thought.
Estimates of the global wind power resource over land range from 56 to 400 TW. Most estimates have implicitly assumed that extraction of wind energy does not alter large-scale winds enough to significantly limit wind power production. Estimates that ignore the effect of wind turbine drag on local winds have assumed that wind power production of 2–4 W/m2 can be sustained over large areas. New results from a mesoscale model suggest that wind power production is limited to about 1 W/m2 at wind farm scales larger than about 100 km2.
David Mackay, the chief scientist at DECC, has this to say about the UK's onshore wind resource:
...if we covered the windiest 10% of the country with windmills (delivering 2 W/m2), we would be able to generate 20 kWh/d per person, which is half of the power used by driving an average fossil-fuel car 50 km per day.
If the true figure is 1 W/m2, we could cover half the country with windmills and still not get enough energy for the average daily commute.
Wind power isn't looking any more sensible is it?
Reader Comments (38)
The wind, the water, and the sun are Nature's way of regulating climate. We interfere with them at our peril.
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A sunny day delivers up to 1000W/m2, which can be quite efficiently extracted with thermal solar panels. Hell, even photovoltaics can deliver more than 2W/m2 with 10% insolation and in the UK!
wind turbine shading
O/T: anyone else in Leeds (UK) next week? I'm going to this lecture at the University ‘Is natural gas the answer to the UK’s energy challenges'
It's not just other windmills that are affected...
Link
As I said in a posting on a slightly different subject on the "Watts Up With That?" blog, the power output from wind turbines could be increased if in periods when there was no wind everyone feeling cold due to power cuts could go out and blow hard on the blades!
That would kill two birds with one stone. It would solve the problem of wind power being unreliable and it would help to keep people fit at the same time!
Why did it take the scientific and engineering communities decades to discover that there is something called "wind shadow?" I could have explained "wind shadow" when I was ten years old. But I had the huge advantage of growing up on a working farm.
@Roy
Isn't killing birds especially two at a time one of the other problems with windmills?
The green solution would then be to cut down all those irksome trees, I suppose.
You could then use the trees as biofuel I suppose.
"You could then use the trees as biofuel I suppose."
Only if you obtained a prior waiver from your local authority, to allow you to pollute the air with visible smoke.
@James P
"A sunny day delivers up to 1000W/m2, which can be quite efficiently extracted with thermal solar panels."
Right. But most of that extracted energy will be needed to unfreeze the ground below which is now permanently in the shade. Why were these things ever called 'renewable'?
In the Jenga tower that is renewables, you have to wonder how many supports have to be removed before the damn thing falls over. I'm beginning to believe in magic because it's now defying gravity.
"A sunny day delivers up to 1000W/m2, which can be quite efficiently extracted with thermal solar panels."
I do not understand how someone who lives in England could believe that solar panels have something to contribute in the area of energy conservation. At DisneyWorld, my solar panels managed to heat my bath water for eight months of the year. Yes, they were inspected and working properly.
Well, blow me down with a feather!
:-/
"we would be able to generate 20 kWh/d per person, which is half of the power used by driving an average fossil-fuel car 50 km per day."
Just not on cold days, when wind power barely works.
This may be a sign some are catching on to the problems with wind power. (Or at least here "across the pond" some are.) Small coastal cities in New England are wondering what the heck to do with their malfunctioning wind turbines, and in some cases just take the darn things down.
http://sunriseswansong.wordpress.com/2013/02/26/what-can-you-do-with-a-drunken-sailor-i-mean-broken-wind-turbine/
Feb 26, 2013 at 10:38 PM | Theo Goodwin
Was that in the Magic Kingdom?
The effect of wind shadowing is taken into account somwehat in the design and layout of turbines in the UK. There are two main effects of putting turbines too close together. Firsty, downwind turbines see a lower wind speed and produce less electricity. Secondly, downwind turbines see the turbulence and vortices produced by upwind turbines. This also reduces the electrical output, but also leads to increased loads and extra wear and tear on the turbines. However, the subsidies are so huge that it pays developers to cram in as many turbines as they can regardless. Sometimes a developer will get planning permission for a wind farm and then sell on the planning permission to some other unsuspecting greedy developer.
Here in mid-western France, in an area of high sunshine (2000 hours/year); I can heat my water for about eight months of the year with a 4m² panel. The problem is that this is during the summer months when I use less hot water than in the winter.
Many farmers in this area are rebuilding their barns and putting PV panels on the whole of the roof. They have a huge subsidy for this and for the electricity produced. Utter madness.
Lewis Page at el Reg provides his take on this paper from Keith and Adams:
Page also has a piece on the results of a long-term survey on the relative importance of climate change:
Seems to me that sooner or later (although one certainly hopes the former) our political leaders (and political leader wannabes) are going to have to come to grips with such inconvenient realities.
@John de Melle
I don't which part of France you're in but here in the Limousin they're building new barns covered in PV.
I still have trouble with:-
1. Using a source which only works 50% of the year and best on cloudless days and is unpredictable
2. Using a source which is unpredictable and doesn't work at low or high speed.
3. Using a source which has a 12.33 hr on off cycle (predictable I suppose)
4 Using a source which is unusable during droughts and lowrainfall periods.
5 Using a source which puts up the price of food and fuel for the poorest in the world
However it seems they will save us from the catastrophe ahead
Onshore, why is it always 'onshore'?
There is a deflection strategy going on here - it is; good wind = sea, bad wind = land.
When all the time, the strategy and mindset of sensible people and engineers all around the world is wind power went out of 'fashion' before the Victorians booted it back to the antiquity where they reasoned it belonged.
The drag effect, is not simply restricted to land based birdchompers - the drag effect works just the same at sea.
Out of sight out of mind - HMG GREEN Seagull-mincers policy and ££££billions of YES = YOUR MONEY!!! - sent down to Davy Jones's locker.
Off shore have another problem.
http://www.ukoffshorewind.com/news/foundation-fault-found-at-uk-wind-farms.aspx
oh dear!
E=MxVxV. Reducing Velocity has a large effect on Energy. This is a well known relationship to engineers and should not need pointing out by scientists. The fact that it has been only serves to highlight the corrupting effect of subsidies.
I oftne look at "Electricity Generation by Fuel Type" on the bmreports.com website.
Interesting to see Wind is at 2.3% today but was down to 0.1% last week and has been at 0% before now.
Is it just me or is Solar PV not anywhere in sight on here? You don't have to travel far in the UK to see a PV installation on the roof of a house but are they really not making any significant amount of electricity?
Jack Hughes: What you see on bmreports is only the generators that the grid sees. So for wind it is only the big wind farms, mainly in Scotland. The actual installed capacity is much greater than reported. The grid does not see embedded generators such as small wind farms, individual wind turbines, solar panels etc, so it has no idea how much electricity is actually being generated by thousands of these schemes. It just makes the work of the grid, trying to balance supply with demand, that much harder.
Theo
"I do not understand how someone who lives in England could believe that solar panels have something to contribute in the area of energy conservation."
I was just reinforcing the idea that the power density claimed for windmills was pretty pathetic, not trying to make a case for solar, although the relatively simple heat absorption panels used for pre-heating water work tolerably well. They were popular in the 70's for a while, after the fuel crisis, and I have some friends whose 35-year old installation is still working.
I can't see many solar PV systems lasting that long, and of course they wouldn't have been installed in the first place without the subsidies.
Strange that the figure for wind is a couple of watts per square metre. That is the same amount as the increase in warming due to delta CO2. Yes, I know they are different things which happen to be measured in the same units, but when I asked for an observation of delta CO2 effects I was told you can't find two watts per sqm, it is 'lost in the noise'. Perhaps that is where the windmill contribution is, lost in the noise.
Just imagine. Walking the footpaths of the UK, you top a ridge and see the natives gathered in a circle beside the local wind farm, frozen harder than rock, dust gathering over them as they become fossils at the alter of green lunacy. You flip in your travel guide and see that your next stop is Stonehenge. As you slowly make your way toward the circle, you wonder if that was how Stonehenge really came about. History repeating and all that.
Interesting to see the article on "large wind farms". As I know of the Laws of Conservation of Energy, I have always wondered why this thinking was not used against wind farms. If you take energy out of the wind, you cannot then get the same amount out next time. I was looking for some wild ideas of how to reconcile the two. But the Laws of physics still work thank goodness. It was a long time ago since I was at school but I do remember some things.
@ JamesP "A sunny day delivers up to 1000W/m2, which can be quite efficiently extracted with thermal solar panels."
At our latitudes, averaging peak insolation over the year results in 10%, so your 1 kW/m2 comes down to 100 W/m2 average. Again here the problem is how to store the peak energy to make use of this average 100 W/m2 insolation (which, through Si band gap efficiency results in an absolute maximum of 14W/m2 electrical energy).
The reason that the average is so much lower than the peak is the fact that, for example during winter with extended high pressure spells, there are long periods, sometimes a week long, when there is almost zero output.
An example: in a medium size house, standing on its own ground, average electric power use is about 1kW continuous. For this about 65 m2 solar panels are required, with optimum sighting. This value is obtained from practice at a large site close to where I live. They have 650 m2 top quality panels yielding 100kW peak with a yearly average of 10kW. One week of electrical energy storage for a house would be 1kW x 24 x 7= 168 kWh, which would mean 168 fairly large lead-acid batteries with associated equipment. These batteries can stand about 500 charge/discharge cycles before they would have to be replaced. This means they would last from 2 - 5 years.
The conclusion is that at our latitudes solar energy is even more useless for general electric power without fossil fuel backup than wind energy. It may be a little bit useful for pre-heating your hot water, but in winter even that is useless, especially when there is a lot of frost.
@ Feb 27, 2013 at 10:38 AM | jamesp
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Due to the low incidence of sunlight in relatively high northern climes, the particular cloudiness of the UK, and the fact that in the UK peak energy demand is in winter at night, solar PV is obviously inefficient and is unlikely ever to provide a worthwhile source of energy.
Low grade solar thermal on the other hand is an economically viable option. Again, one has the problem of low angles of solar irradiance and short daylight hours in winter, but for much of the year, it is capable of producing sufficient hot water or at any rate contributing significantly to hot water requirements to be a viable provider for those with a south facing aspect.
Where I live in Spain, low grade solar thermal works far better. It is sufficient to adequately heat swimming pools between May and September/perhaps even to mid October, and with the right tank storage can produce almost year round domestic hot water suitable for a small household. Of course, one important difference between Spain and the UK is clear skies. Usually, there is not a cloud in the sky - with probably close to 330 sunny days a year.
The combination of slightly less polution (certainly aroud the Med coastline), slightly higher angle of incidence of sunlight and substantially greater numbers of clear sky days, means that even in winter (when it is rare for there to be more than 3 consecutive cloudy days), solar thermal for domestic hot water is very worthwhile. Systems can be had for less than €1,000 plus fitting. In fact it is possible to make a DIY system (which probably has about 95% of the efficiency of latest glass tube designs) for a few hundred pounds.
The upshot is that the breakeven costs can be achieved within two or three years, whereas solar pv will probably never pay for itself and could make a house difficult to sell. There is much to recommend about low grade solar thermal even for those who live in the UK.
@ Richard Verney, Feb 27, 2013 at 11:28 AM
During week-long spells without sun you would be out of hot water soon, unless you lay on very large hot water storage tanks, say 1500 litres, with much thicker insulation than normally used. I notice that my 250 litre boiler has to use the heat pump about six times a day to keep temperature at the right level.
I don't have much confidence in solar heat at our latitudes.
The Matt cartoon in the Telegraph today is worth a look. http://www.telegraph.co.uk/news/matt/
I have been saying for years: if the greens precious "precautionary principle" means that fossil fuel extraction and generation is risky because of possible indirect effects on the climate, surely directly extracting energy from the wind is far more risky? Ask them and they start talking about "insignificant levels", an argument which never seems to apply to other forms of energy. I think part of it is because they think windmills are simple devices which they understand, fossil fuels involve chemistry and engineering at levels which are akin to witchcraft for them.
It is also interesting to look at the evolution of traditional wind and water power; with the development of steam and later IC power, wind and water mills were adapted to use them for backup power when sufficient wind or water wasn't available when it was needed. As the backups became more reliable and efficient, the cost of maintaining the wind or water machinery meant it was uneconomical and in many cases it was decommissioned.
Where is Josh when you need him?
Average electricity production for February was:- coal 19 GW/hr(43%), Nuclear 8.1GW/hr (18%), gas 1.6 GW/hr (27%), wind 2GW/hr (2%). for 7 hours in Feb wind production was less than 0.1GW/hr, another 133 hrs was between 0.1 and 1 GW/hr, 377 hours between 1 and 3 GW/hr and 145 hours between 3 and 5 GW/hr. Only 3.5 hours for the whole of February was wind producing more than 5 GW/hr. What is the point of wasting billions of pounds building something so unreliable and inefficient as wind turbines?