From The Telegraph
Britain’s wind farms are wearing out far more rapidly than previously thought, making them more expensive as a result, according to an authoritative new study.
By Robert Mendick, Chief Reporter
8:40AM GMT 30 Dec 2012
The analysis of almost 3,000 onshore wind turbines — the biggest study of its kind —warns that they will continue to generate electricity effectively for just 12 to 15 years.
The wind energy industry and the Government base all their calculations on turbines enjoying a lifespan of 20 to 25 years.
The study estimates that routine wear and tear will more than double the cost of electricity being produced by wind farms in the next decade.
Older turbines will need to be replaced more quickly than the industry estimates while many more will need to be built onshore if the Government is to meet renewable energy targets by 2020.
The extra cost is likely to be passed on to households, which already pay about £1 billion a year in a consumer subsidy that is added to electricity bills.
The report concludes that a wind turbine will typically generate more than twice as much electricity in its first year than when it is 15 years old.
The report’s author, Prof Gordon Hughes, an economist at Edinburgh University and a former energy adviser to the World Bank, discovered that the “load factor” — the efficiency rating of a turbine based on the percentage of electricity it actually produces compared with its theoretical maximum — is reduced from 24 per cent in the first 12 months of operation to just 11 per cent after 15 years.
The decline in the output of offshore wind farms, based on a study of Danish wind farms, appears even more dramatic. The load factor for turbines built on platforms in the sea is reduced from 39 per cent to 15 per cent after 10 years.
Prof Hughes said in his conclusion: “Adjusted for age and wind availability, the overall performance of wind farms in the UK has deteriorated markedly since the beginning of the century.
“In addition, larger wind farms have systematically worse performance than smaller wind farms.”
The study also looked at onshore turbines in Denmark and discovered that their decline was much less dramatic even though its wind farms tended to be older.
Prof Hughes said that may be due to Danish turbines being smaller than British ones and possibly better maintained.
He said: “I strongly believe the bigger turbines are proving more difficult to manage and more likely to interfere with one another.
“British turbines have got bigger and wind farms have got bigger and they are creating turbulence which puts more stress on them.
“It is this stress that causes the breakdowns and maintenance requirements that is underlying the problem in performance that I have been seeing.”
Prof Hughes examined the output of 282 wind farms —about 3,000 turbines in total — in the UK and a further 823 onshore wind farms and 30 offshore wind farms in Denmark.
The report, published last week by the Renewable Energy Foundation (REF), a think tank that has campaigned against wind farms, will give ammunition to sceptics, especially within the Conservative Party, who believe the cost of subsidies to the wind industry is far too high and that the growing number of turbines are blighting the countryside.
Dr John Constable, the director of REF, said: “This study confirms suspicions that decades of generous subsidies to the wind industry have failed to encourage the innovation needed to make the sector competitive.
“Bluntly, wind turbines onshore and offshore still cost too much and wear out far too quickly to offer the developing world a realistic alternative to coal.”
HT/Alan Tomalty
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If the bias is so obvious, it shouldn’t be hard for you to detail it. Come on, just one example.
Disagreeing with a liberal is not evidence that you are wrong.
PS: Using a biased media source to prove bias. Really?
I just loved the quote:
Juliet Davenport, chief executive of green energy provider Good Energy, is highly critical of the group’s [REF] choice of name.
Wear out sooner than “expected”. Expected? How willfully ignorant would anyone need to be to expect this spinning junk to last 30 years. Wear out sooner than “claimed”? imagined? hoped? lied about? dreamed?
Wind advocates love to claim that this junk “creates jobs”. The only worthwhile jobs will be those for tearing down each and everyone of these worthless ugly monsters; the sooner the better.
In 2009, 15 percent of turbines were made with direct drive. In 2012, that number is expected to double.
The 10’s of 1,000’s of gearbox equipped turbines should be “removed from view” as they fail. Realistically, how many turbines <1MW peak capacity installed prior to 2009 are worth the $100,000 more or less to replace the gearbox? I'm sure there isn't any data available, too negative, but it would really be interesting.
Idle question: What is the internal air pressure at the tip-end of a large blade? Does it vary and will it change the shape of the blade?
What do you mean by “internal”?
The wind pressure on any object is related to the density of air, the square of the wind velocity, and the ‘shape factor’ of the object = Cd.1/2.[rho].v^2. This gives the lateral pressure on the blade – assuming the turbine is spinning in a plane that is perpendicular to the wind direction. Simplistically, if the blade was a straight cantilever beam then the tip deflection could be estimated from the wind pressure, the fourth power of the blade length, and a stiffness factor (k/ [8.E.I] ) retaliated to the cross-sectional shape of the blade and the elastic stiffness properties of the blade material.
It then becomes necessary to account for the effect of the speed of the blade on the relative wind speed and direction (or ‘apparent wind’ to sailors and airmen). This introduces a velocity vector component in the direction the blade is moving (as opposed to the actual wind velocity which is perpendicular to the blade’s movement). It is the main cause of drag on the blade. But the deflection caused by drag would be relatively small because the blades (like a plastic ruler) are much stiffer and resistant to bending in that direction. (Apologies if you knew all this already.)
Sorry,”related” – not “retaliated”.
Thanks for your response. I am asking about ‘internal air pressure at the tip-end ‘ … given that the blades are hollow.
TonyN, I’ll assume that you are asking what air pressure is developed internal to a hollow core wind turbine blade due to centrifugal forces at maximum design rpm, assuming the blade cavity is sealed along its radial length but vented to atmosphere near its hub.
Let’s consider the limit case condition of one of the largest commercially-available industrial wind turbines, the Siemens 6-MW turbine:
“The B75 turbine blade itself is 75 meters long, while the entire rotor assembly measures 154 meters in diameter. As it spins, the blades cover an area of 18,600 square meters—that’s roughly two and a half soccer fields—at a brisk 80 meters per second, or 180 MPH at the tips.” — source: https://gizmodo.com/5930272/the-worlds-biggest-wind-turbine-blades-are-so-long-their-tips-spin-at-180-mph
The centrifugal acceleration at the blade tips is easily calculated from the 77 m radius and 80 m/s tip velocity to be about 8.5 g’s. Since sea-level air in a 1-g acceleration field (i.e., one earth gravity) has a pressure of 14.7 psia (equivalent to a density of 1.225 kg/m³, or .0765 lbm/ft^3), at 8.5 g the outermost foot of radial length would be at an average density of about 8.5 * .0765 lbm/ft^3 and an equivalent pressure of about 125 psia, assuming the blade’s internal cavity stopped just short of the very tip.
Apologies for using the mixed metric/English units . . . you can convert to mega-pascals of pressure if you wish.
Also, I should have mentioned that such a calculated relatively high internal pressure, given the physical size of the blades, would create some added high absolute structural loads on the outermost portions of each blade, so I suspect (but could not confirm) that such large blades are most likely vented to atmosphere near their tips.
The resulting continuous centrifugal “pumping” of air along the blades during operation is therefore likely to be one of the negative factors contributing to the overall rated aerodynamic efficiency of the turbine during operation.
Gordon, thanks for the response. I.m posting here because ther was no reply button on your two emails.
Now 8.5g and 125 psi is pretty impressive, and the variation between the twelve o’clock and six o’clock positions would cause quite a problem for the bearings, I’d have thought.
As an aside, in the late fifties I remember seeing some experimental windmills in Denmark, using wooden blades from, I think, Sycamore helicopters. The energy was extracted by a small air turbine mounted at the bottom of the column, which was evacuated via internal ducting connected to ports at the tips of the blades. I wonder what the performance was like?
Are we seeing the start of “Peak-Wind”. 🙂
Doubling the cost of electricity is meaningless for the Elite Rulers, and is only important for middle class and the poor. And if there’s one thing the Elite Rulers care nothing about, it’s people who are not part of the ruling Elite.
May we have a link to the actual study, or at lest be told what the study is called to make it easy to google search for it?
[I would suggest you forward your complaint about lack of a link, to The Telegraph. Mod]
I just hoped that as a science site, that you might provide a reference to the study you have published this article about, regardless of who actually wrote the article or where it came from.
If true for the U.S., that would double the unfairness of “Levelized” Cost of Energy comparisons for decision making. Conventional sources are well understood. Renewables rely on pro-renewable what ifs.
WUWT had an article before about internal Siemens documents that indicated that the bearings of their windmills were going to wear out faster than advertised. Does anyone remember this.
Producers of windelecs always denied stress to people in neighboring houses.
No it seems they even stress neighboring windelecs.
What news.