According to David Rosser- director of CBI Wales the wind only blows strongly enough 10% of the time for a wind energy project to work. According to James May from Top Gear on his latest TV show, wind turbines only work 30% of the time . Why do people who are anti-wind energy keep using this against wind when they are so easily proven wrong? People with responsibility for disseminating information should check their facts.
To try and help stop the confusion, here are the facts:
1) A modern wind turbine has a maximum capacity of around 2000 kilowatts (kW) or 2 Megawatts (MW)
2) There are 8760 hours in a year (365 days x 24 hours)
3) A 2 MW wind turbine will generate around 30% of its maximum theoretical capacity resulting in 5256 Megawatt hours (MWh) generated per turbine per year
4) Taking all of the above into consideration a wind turbine will generate enough green electricity for the average annual needs of around 1100 homes, using an average demand of 4700 kWh per house based on electricity consumption figures from Digest of UK Energy Statistics
Wind turbines usually operate 75-90% of the time – but not at full capacity.
For further information this British Wind Energy Association web-page is helpful.
Picture above taken from www.science.nationalgeographic.com
David Johnson
November 13th, 2009
Why do wind turbines only produce, on average throught a year, 30% of their rated output if they “usually operate 75-90% of the time? Clearing, for a significant part of that 75-90% they are producing negligible power.
While I agree that generating power from wind is “greener” than burning coal (assuming material and maintenace costs are constrained), I am curious to understand how “green” energy may be generated to supply demand when wind generation is not effective?
David
November 21st, 2009
This is because it is more efficient to build turbines that generate 30% of their rated output than it is to build ones that would generate say 90% . The % of a turbine’s rated output that is generated depends on the amount of energy from the wind that is applied to the generator . This energy is collected from the wind by the blades. If turbine engineers wanted a higher % of rated output to be generated then they would simply place larger blades on the turbine relative to the capacity of the generator. However,its not efficent to do this because of the cost of larger blades relative to the cost of the generator. Therefore the optimal design is for turbines that generate at about 30% of the maximum capacity of the generator. The whole focus on this number as a measure of efficency is very misleading. The generator is only one part of the whole turbine and to focus on maximising the amount of utilsation of that one particular componenet would be sub optimal.
Another way to look at this is that we could take an existing 2 MW turbine , generating at 30% of capacity and replace it’s its generator with a 1 MW machine. The blades would still capture the same amount of energy so the generator might be expected to generate the same anount of electricity.. now 60% of its maximum output. Using the misleading measure of wind turbine efficency this turbine would now be twice as efficent. However, that isnt what happens, and it isnt because wind turbine engineers are stupid. There would be additional losses of energy and the overall design would be sub optimal.Its important to match the size of the generator with the size of the blades and the best design is one where the generator ( a relatively small cost of the whole turbine) works at a capacity of about 30%.
Jim
December 22nd, 2009
Just a quick comment ; this article is out of date anyway. I’ve proven that it’s possible to use the output of a generator prior to its dissipation in a load to compensate for the Lenz effect which is the reason for the requirement for high torque i.e. large blade swept area. No-one believes me but I have a prototype which demonstrates this beyond doubt. You have my email address.
Peter
January 1st, 2010
When the wind stops blowing the lights go out. you therefore need a gas fired power station on back up to maintain a continuous supply of electricity. This adds to the cost of wind turbines. A study carried out by the Royal Acedmy of engineering in 2004 showed that a kw hour of electricity produced by an onshore wind turbine, including the cost of standby generation, was 5.4p; more than double that of power from gas (2.2p), nuclear (2.3p) or coal fired plants (2.5p). Off shore wind platforms are even worse; at 7.2p per kw hour the cost is three times as much.
john f peacocke
January 17th, 2010
I am intrigued by PUMPED HYDRO ELECTRIC schemes, which seem to be an essential adjunct to the massive offshore wind installations currently considered.
YANBURU Okinawa is a pioneering project using sea water and a man (made,modified?) header lake on the cliff top. Dinorwic is one of five UK sites using two lakes.
Ireland has TURLOUGH Hill whose egg shaped upper lake is plain to see on aerial view of Wicklow Mountains.
This provides 240MW for 6 hours within 60 seconds at 78pc efficiency.
N.Ireland has Camlough similar sized system, mothballed but likly to be revived.
The seawater PSE schemes might be seen to avoid the massive rockboring of the mountain lake options. However a massive upscaling of storage volumes nay be required. Any comments welcome.
Dodgy Geezer
April 20th, 2011
“…. wind turbines only work 30% of the time . Why do people who are anti-wind energy keep using this against wind when they are so easily proven wrong?”
Perhaps because reality is even worse? The figures are now down to 25%. http://www.jmt.org/assets/pdf/wind-report.pdf refers…
Vicky Portwain
April 21st, 2011
If you had read the post and the thread you would understand that most turbines do not only work only 30% of the time. Many turbines operate at 30 % of their maximum theoretical output and this is not the same as only working 30% of the time.
Joshua Francis
May 18th, 2011
I know the cost to build these wind turbines is high;however,after they are built it would seem the cost would be little to maintain.
Martin
August 8th, 2011
If these turbines operate at 30% efficiency for 100% of the time they are running.Then what is the overall efficiency when you factor in the time they are not running ?
Patrick
November 28th, 2011
It sounds to me that people are getting lost in the efficiency of the individual components of the turbine. We’re losing site of the main objective of a wind turbine which is to take wind energy and create electricity. Therefor the efficiency we need to discuss is the conversion from potential wind energy to electrical energy output. Then see how wind energy stacks up to coal, nuclear and hydro. Lets start comparing apples to apples…
Daniel Reaman
March 9th, 2012
you all know nothing it is used in the frmer feilds witch is pointless because when you use solar panels you can put it on roofs of homes and not in the farmers feilds, did you know that a bird dies every 2 min because thry fly into the blades of the wind tubines.
Ray
April 22nd, 2012
The 5256 MWH is measured at the turbine. It does not measure line loss, which for a wind turbine is considerable due to the wide range of power output which has to be transformed to usable levels.
slim shady
April 24th, 2012
birds are stupid
tom
May 1st, 2012
Daniel Raeman – No I didn’t. And in fact nor do you.
Did you know that every time a man throws an apple out of his car window a cat dies? .. and every time a cat dies a little peruvian child eats an ice cream? There’s your evidence. I AM THE EVIDENCE!
Alex Simpson
May 14th, 2012
I think Wind Turbines can be efficiently used if they are put in less populated areas. They would be an easy way to power a small town.
Who cares about stupid birds. Did you know every 2 minutes every other bird in the world DOESN’T die!
Also, in Denmark, pigs outnumbe humans 4:1. How many pigs don’t die from wind turbines? all of them?! I thought so.
Anddog
May 29th, 2012
Wind Turbines are pretty efficient as they stand now, apart from birds hitting them and stuff.
And you are true, of course, pigs dont die from Wind Turbines, and they also dont fly, and I for one, Alex Simpson do care about birds.
When they hit the Turbine they slow it down, reducing energy efficiency, and if a bird dies every 2 minutes, among other things like hunting and predators, we might soon run out of birds? What will you do then?
Remember Alex Simpson, I’m Bird. You are too. Do you want to die in 2mins? I didn’t think so.
Joseph
July 7th, 2012
Here is what I don’t understand. Why are we not using Wind power in correlation with let’s say hydroelectric. There is a hydroelectric facility named Raccoon Mountain in Tennessee. It consists of two parts, a holding facility at the top of the mountain “Lake” and a holding facility at the bottom of the dam another “lake.” During the day the water drops down through the dam and then at night when peak power consumption is down. They pump the water back to the top. Instead of having to use the dam to pump the water back to the top use the wind turbines.
b
July 19th, 2012
careful joseph, you’ll end up ‘committing suicide’ with forward thinking ideas like that..
Pete
October 2nd, 2012
This has not answered the question. The usual gobldygook. Efficeiency is measured in Engineering terms as energy out over energy in and ususally expressed as a percentage. What is being discussed here is the Utlisation of the plant which is a totally different thing. And an even bigger question is value of energy produced over capital and maintainance outlay with no subsidies to skew the answer.
Mr Sir
December 27th, 2012
I don’t see why anyone would think that 30% effeciency is a valid reason wind power should not be harnessed. The average efficiency of a fossil-fuel plant is……………. 28% to 32%. And coal must be burned to produce it.
Jones
February 21st, 2013
Firstly
1) If the wind doesn’t blow there is no electricity.
2) It doesn’t blow at the right sort of speed for more than 30% of the year.
3) Ergo for 30% of the year there’s no electricity!
4) In winter when the power is most domestically needed the wind hardly blows at all.
Answer; build a more traditional power station to plug the gap knowing that such power station can’t practically be turned on or off that easily.
Secondly, how green is green?
1) Making a wind turbine involves processing a good deal of rather nasty materials that consume vast amounts of land to find the ores, vast amounts of energy to process and refine the hydrocarbons and the concrete and after a short 15 to 20 years we’re left with a load of stuff and junk that’s exceedingly difficult to recycle
2) For the fifteen or twenty year we destroy the beauty of the countryside, wreak havoc with the local ecology and erect thousands of pylons to get the product to the consumer.
When are we going to wake up to the fact that wind turbines are not the answer and accept that the low carbon argument is based on bad science and hogwash put about by people whose only interest is make lots of money!
Sunlight, tidal power, wave power, geothermal power, adopting a step changes in building insulation, district heating systems from burning waste instead of chucking it into a hole in the ground and poisoning the water table, anything but stop making me pay an energy levy for something that doesn’t work forced on me by a government that’s bereft of any meaningful idea’s
Wally Waba
March 3rd, 2013
With so many wind turbines already operating when are we ready to decommission just one dirty coal fired power station anywhere on earth.
Nick C
March 3rd, 2013
This article was titled “Wind Turbine Efficiency” but the discussion is almost entirely about how much of the rated capacity WT’s deliver, problems of intermittency etc. this discussion is primarily about utilisation factor which is completely different from efficiency. Efficiency is about how much of the energy in the wind is converted to electrical energy. One could argue that on a windless day turbines are 100% efficient; zero wind energy and zero output, output = input = 100% efficiency. The reality is that the maximum efficiency of a wind turbine is about 60%, large turbines achieve a somewhat less than this at optimum speed but still much better than rooftop solar.
The real issues are:
1. Wind turbines are ENERGY collectors; they can supply/generate a large amount of clean but intermittent ENERGY, but only when the wind is blowing.
2. The energy available in the wind is proportional to the cube of the wind speed, e.g. wind at 10mph has 1000 times more energy than at 1mph, hence the large variability in WT output.
3. The grid requires a large amount of reliable POWER (non-intermittent energy)
4. To turn large amounts of intermittent energy into large amounts of power requires large amounts of energy storage.
5. If wind, or other intermittent RE sources, are supplemented with backing (fossil) generation this only makes sense where peak intermittent generation is less than minimum demand minus base load (nuclear) otherwise during periods high RE availability and low demand there will be excess RE generation that can’t be used, this reduces the economic viability of RE generation and creates the problem of energy dumping to maintain grid stability.
6. The solution to large amounts of energy storage is ‘Green Coal!’ and I don’t mean biomass/biofuels, but that’s another topic.
Nick C
March 3rd, 2013
PS
If you actually are interested in Wind Turbine Efficiency try this link http://www.ftexploring.com/energy/wind-enrgy.html.