Comments on: Wind Turbine Efficiency

By: Patrick

Patrick — Mon, 28 Nov 2011 21:36:02 +0000

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…

By: Martin

Martin — Mon, 08 Aug 2011 20:04:31 +0000

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 ?

By: Joshua Francis

Joshua Francis — Wed, 18 May 2011 01:31:44 +0000

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.

By: Vicky Portwain

Vicky Portwain — Thu, 21 Apr 2011 01:33:10 +0000

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.

By: Dodgy Geezer

Dodgy Geezer — Wed, 20 Apr 2011 14:11:58 +0000

“…. 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…

By: john f peacocke

john f peacocke — Sun, 17 Jan 2010 23:33:06 +0000

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.

By: Peter

Peter — Fri, 01 Jan 2010 22:38:06 +0000

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.

By: Jim

Jim — Tue, 22 Dec 2009 20:02:13 +0000

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.

By: David

David — Sat, 21 Nov 2009 12:15:27 +0000

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%.

By: David Johnson

David Johnson — Fri, 13 Nov 2009 11:20:24 +0000

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?