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…