Capacity Factor – How People Misuse a Number
The concept of capacity factor for generators is one of the most misunderstood concepts in both the public, and in the electricity sector itself.
Capacity factor is really quite a simple concept. It is the percentage of maximum output that a generation facility produces on average. The key words there are “on average”. It does not mean the percentage of time that a facility produces.
For nuclear, the capacity factor would be very similar to the percentage of time that it operates. That is because nuclear basically has two states – on, and off. And this lack of intermediate states actually poses challenges for utility planners, because they have to figure out what to do with power when demand is low. Ontario’s nuclear plants have run about 60% of the time since they were built. Today, 12 out of 20 units are operating. Since they are only ever on, or off, their capacity factor is also about 60%. The nuclear industry argues that refurbishment time should be removed from the equation, and that units that are laid up should be removed. If that method is used, then 12 out of 16 of Ontario’s nuclear stations are operating today, or 75%.
There was a letter from an opponent to wind in the Sun Times that said that wind “only operates 27% of the time.” I have heard Murray Elston, the Chair of the Canadian Nuclear Assocition, and former provincial Liberal cabinet minister say the same thing from the podium at the APPRO conference. Fine. These folks have an agenda, and if using misleading information helps their cause, then so be it.
But in the introduction to the Supply Resources paper the Ontario Power Authority – Ontario’s system planners – perpetrated this error again. “Preliminary studies suggest that wind would be available, on average, 17 percent of the time in summer and 41 percent of the time in winter”.
It is simply untrue to state that wind would be available 17% of the time. Rather, it may produce an average of 17% of its maximum capacity. But achieving this average will be spead over time.
Wind turbines do not have two states – maximum and zero, like nuclear does. Rather, the output from a wind turbine increases as the wind increases. Sometimes it will produce nothing, when it is being serviced, or winds are light. Then it will produce at an increasing level as winds pick up. The average production divided by the maximum production possible is the capacity factor.
By way of example, the Ferndale wind farm has produced 543,000 kWh so far this month. It has been very windy. The maximum that could be produced in the first 9 days is 5100 KW X 24 hours X 9 days = 1,101,600 kWh. So we have produced at an average capacity factor of 49.3%.
But the wind farm has produced power 93% of the time. The power produced ranges between 0 and 5100 kW.
In July, the single V80 produced power 76% of the time. And it produced 297,000 kW, which is a capacity factor of 22%. 297,000/(1800 X 24 X 31) = 22%.
Wind industry people, in particular, need to understand that capacity factor is affected by equipment selection. I have heard many people in the industry talk about a “30% capacity factor site”. This doesn’t exist. All that exists is a 30% capacity factor site for specific equipment. I blogged on this in the past.
I can understand those opposed to wind farms, or nuclear proponents, confusing capacity factor with percentage of time a wind farm operates. But it is inexcusable for this to be confused by utility planners.
If a wind farm only produces 17% of the time in the summer, then backing up this power becomes much more costly, as the back up fossil plant will run 83% of the time, with considerable fuel expense. And that costs a lot. But since it produces 76% of the time, and a diversified wind resource would produce an even larger percentage, the cost of backing up wind drops dramatically, and the technology chosen to back up wind changes.
I hope that our utility planners understand this. It would be helpful if their reports would reflect that understanding.
December 12th, 2006 at 8:08 am
You’re right about people confusing capacity factor. I sometimes use “efficiency” and “capacity factor” the same but know it ain’t right.
I came across a term I never heared before: “capacity credit” in a report by E.ON Netz, the largest grid operator in Germany.
The Germans have 16,000 MW of wind power installed. They say the “capacity credit” is 8% and the more wind turbines they hook up to the grid the lower the capacity credit goes.
“As a result, the relative contribution of wind power to the guaranteed capacity of our supply system up to the year 2020 will fall continuously to around 4% (FIGURE 7). In concrete terms, this means that in 2020, with a forecast wind power capacity of over 48,000MW (Source: dena grid study), 2,000MW of traditional power production can be replaced by these wind farms.”
The Germans have decided to shutdown their nukes with wind. For every MW nuke power they want to shut down they are going to have to build ~20 MWs of wind. At $2 million /MW it will cost them $40 million to replace one megawatt of traditional power. But that’s what the German people have decided. Did they think this through or are they getting an expensive wasteful lesson?
Many out here are concerned that the Ontario Power Authority has similar hair brained plans. Didn’t they miscalculate the load demand by 4000 MWs? That’s like thinking you have only 15 fingers and toes. The DOUGS -DUMB OLD UTILITY GUYS got it wrong before. They’ll get it wrong again. They oppose innovations that would make us less dependent on the grid and be more effective in reducing green house gasses.
The plan for Ontario is to install 5000 MW wind. What’s the “capacity credit” for wind in Ontario? Will 5000 MW wind capacity displace 500 MW coal installed capacity? Will we have to install an extra 5000 MW in gas turbines to back up the wind and run them to produce 75% of the power?
We have 6000 MW coal installed. Looks like those coal plants will be around for a long time killing Ontarians. We won’t even be installing pollution controls. Where’s that Lambton plant anyway? Is that a better option than nuclear?
Somewhere on this blog I read that the plan is to use wind for peaking power? That means we are going to shut the machines down at non-peak times? That’s like letting the water go over Niagara falls and burn coal instead it putting the water through the generators!!! Unless were dreaming about installing enough wind to displace coal – that’s a pipe dream per above.
Are we going to back up wind with hydro power that’s normally used for peaking? How much stored hydro can we spare to back up wind? That’s an important question. If we use all the stored hydro for backing up wind at non peak times, what will we use for peaking power? Import dirty coal power at 10 times the going rate or build more green house gas emitting natural gas turbines?
The Ontario Power authority is now asking us what we think when they have already decided what they are going to do. We are being told that we can have our cake and eat it too. And that’s the piss-off. It’s the deception. It’s the contempt for the people. What’s sad about wind is that the proponents of wind don’t seem to have a problem with business being done this way.
December 12th, 2006 at 12:54 pm
Glenn you are playing with numbers. Using only 9 days in July for calculating and coming up with a capacity figure of 49.3 percent could be expected from you. The real capacity figure for a whole year you don’t dare to talk about because it will be so insignificant.
Wind turbines should never have been considered because of their lousy characteristics and dependents on the wind and the cost to the people , as the goverment subsidise them with our tax money.
When we need wind power it is not availble , remember the last July heat wave when we had to import coal generated power from the USA.
December 12th, 2006 at 3:40 pm
This article shows the problems they encounter in Germany.
A translation of an article from 03. 12. 2005 Sachsen Anhaltt News
“the Volksstimme” ( Voice of the People)
SWM business manager Johannes Kempmann about the risk of fast
wind power development.
“One short and whole of Germany is suddenly in the dark”
In a discussion of for and against wind power farms is a question frequently discussed. Does the power from wind turbines into the grid endanger the stability of the system?
Oliver Schlicht of the news paper “the voice of the people” had a interview with Johannes Kempmann technical manager of the city Magdeburg.
Q – As energy manager and a member of the green party you have
a model wind turbine on your desk are you positive in favour of
wind power?
A – Absolute without any doubt wind power provides a potential
opportunity. 3000 employees of wind turbine manufacturer Enercon in
Magdeburg is proof of that. The fast grow of this sector of
manufacturing and the amount of energy into the grid alarms me
greatly.
Q – Why can such a comparable small amount be alarming.
As per statistics in 2003, renewable energy was only 17.5% of which
90 % was from wind power.
A – With that amount we can live. The actual reality showed unfortunately
another picture. Our calculations and who other than we and
Eon Avacon as grid operator should know this better, was the part of
wind power in Norden Sachsen Anhalt in 2004 already 31%.
On the basis of wind farms in planning state for 2006 will it be 60%.
Compared with the whole of Germany will dat be the same as in
Norden.
Q- What does that means for the grid?
A- Much wind, much power of which we don’t know what to do with it.
We have not many power users in Sachsen Anhalt . The power must
be distributed with a constant same voltage. A drop in voltage
endangered the grid. Storage is impossible . For the future it means
that the grid from a distribution net in a surplus net must be build.
The rural grid is not designed to transport great amount of wind
power to the main grid.
Q- What is the problem? You extend the grid so it does not trip.
Financial data shows that your most important share holder profits
are greater than before..
A- That’s right. The question of power transport from the rural area is
ultimately not a political ideological but plain and simple a question of
money is. One thing is sure that at the end the customer pays.
We plan, because the wind energy development force us, together with
our partner Eom Avacon and others the construction of transformer
stations and a new 30 Km. Long 110 Volt power line in Altmark.
But planning and building takes many years.
Q- Wind farm constructions is going on for more then 10 years.
Why have the grid operators not extended the electricity net work.
A- The wind energy proponents applauded us because we were part of a
study which accounted for 7% wind energy in the whole of Germany.
It seems that we have under estimated the fast grow of the wind
energy. But that is of no help. The grid is as big as it is. It are the
physical limits that cause me sleepless nights.
Q- Critics say that the energy group exaggerated the grid problem because
they of the wind energy business expect annoying competition.
How bad should we take your sleepless nights?
A- Very serious. You can not blame me because your computer doesn’t
work and I didn’t warn you directly of an imminent blackout.
Also for the energy conservation and export plans it is not advantages
for a country know for it stable electricity grid,
.
Q- Are you serious that a blackout in Germany is possible caused by the
many wind farms in Sachsen Anhalt ?
A- Sure, and the danger is much greater then men think. It has to do with
politics and not with physics.
Q- How can the wind turbines in Altmark cause a trip of the whole
German electricity grid ?
A- That is the scenario of my sleepless nights. Its not my idea but from a
investigation in the Dena Electricity net study of February last year.
In this study the grid operator, the wind business and the ministry of
economics have worked together and concluded that an incident close to
the transformer station Wolmirstedt could happen a short in a 380 KV.
line
Q- That’s the most powerful line , the high way of the European electricity
Grid. Is a short of a 380KV line not a exaggerated horror scenario ?
A- No, this happens 4 to 5 times a year in Germany. I mean not a break
of a line but a short, eg a big branch that falls across a line , also a big
bird like a swan can cause problems. Manual switching errors can
cause shorts too. Those shorts cause voltage drops which the grid could
easily handle before .
In a generation station the voltage drop is detected and in a short
moment adjusted until the cause is gone and the voltage is returned to
normal.
Q- What about the wind turbines.?
A- This manner of adjustment is not possible with wind turbines.
The old ones not at all, the newer ones not on a sufficient scale.
They are simple switch off by a voltage drop.
Q- When the technical standards were developed for wind farm connection
to the grid the energy companies were too sitting around the table..
A- That’s right. But who had thought that the wind farms today supply
such a great amount of power to the grid. In the meantime new
compatible connections are being considered. Most of the turbines who
are operating in the rural areas are designed to handle and
compensate for a voltage drop on the grid.
Q- But why caused specific Wolmirstedt in the Dena Study you sleepless
nights ?
A- That location is not chosen without reason . Wolmirstedt is a
transformer station and is one if the most important junction in the
German electricity grid. Imagine the following. It is Friday afternoon.
People are barbequing. The power demand is low. Begin of the
weekend. Most of the factories in Sachsen Anhalt are shutting down.
There is a strong wind. All turbines supplying power to the grid.
So much power forcing the generation station to throttle their output.
while the percentage of wind power increase on the grid of Sachsen
Anhalt. So much that in the evening the country is almost completely
supplied by wind power …….
And now it happens, A big branch falls on the 380KV line at
transformer station Wolmirstedt.
Q- OK, the wind farms keep operating, can the generation stations quickly
compensate for the voltage drop ?
A- Not at all. Not one not even two but are taken out of service. The Dena
study indicates that thousands of wind turbines in a 150Km corridor
between the Baltic sea and Helmstedt are taken off the grid. Causing a
shortage of 2900 MW..
No generator station can compensate for that. The grid frequency
becomes unstable and in seconds the grid in Sachsen Anhalt after that
the grid in the new Bundes States (former East Germany) and possible
of whole of Germany breaks down. Black out !!!
Q- Are their any other reserves to compensate for the voltage drop ?
A- Not enough . We in Sachsen Anhalt have 2 X 60 MW hydro power
available to supply to the grid. In the whole of Europe is between
Norway and Greece, Portugal and the Ural Mountains only about
3000MW reserve available. Never will this solves the problem.
Q- A branch on a power line in Wolmirsdedt is able to darken the whole of
Germany? Are you serious ?
A- That is what the Dena study says.
A great part of Germany was 2 days without power, but the politicians
are not interested. Wind power is a holy cow, nobody want to talk
about it. I am convinced that in the end the grid operator will be held
responsible.
Q- What do you think should be done ?
A- Not withstanding the problems I’m still in favour of wind power, but we
must stop. It must not go on so fast. We , the wind energy business
and the politicians must keep the ideology and politics out of it and
only talk about physics.and that very quick. Otherwise for real the
proverbial lights go out.
To quote Murphy’s law: At the end it will be much worse then men
expected
December 14th, 2006 at 9:22 pm
A few comments. First, “Glenn you are playing with numbers. Using only 9 days in July for calculating and coming up with a capacity figure of 49.3 percent could be expected from you.”
This was the production for the first 9 days of this month, not July, and this was clearly stated in the entry. As of the first 13 days of this month (December), the capacity factor has increased to 52.6%. And the wind farm has produced at least some power 93% of the time. I apologize if the substantial production from the wind farm results in me playing with numbers. I just report what has happened. I guess my experience comes from an operating wind farm, and others comes from reports written with a certain bias.
Second, regarding the concerns about wind farms causing blackouts, as mentioned in the interview with Johannes Kempmann. The final report on this summer’s blackout in Germany has specifically ruled out wind as the cause. The trigger was the shutdown of two transmission lines to allow passage of a newly built cruise ship from a shipyard.
http://www.washingtonpost.com/wp-dyn/content/article/2006/11/06/AR2006110600883.html
The concern about turbines in Germany is related to older models that do not have Low Voltage ride through. All transmission connected wind farms in Ontario require Low Voltage ride through. This allows the wind farm to continue producing during temporary voltage drops. This eliminates the fear that was expressed by Johannes Kempmann, that a voltage disruption would shut down all the wind turbines, causing a shortage of power when the voltage disruption ended. In particular, there is absolutely no concern today, or in the next few years, as the percentage of power supplied by wind is far less than Germany has today. I would suggest these issues would be best left with utility planners. Believe me, they are an extremely conservative lot. They will not allow our electricity supply to be in peril.
Finally, if we are going to get personal on this blog, by accusing others of intenionally providing misleading facts, I would suggest we fully disclose our interests. My interests, as the author of the Blog, are pretty clear. I have a commercial interest in wind, yes. But it should be clear from this Blog that my real interest is sustainability, and wind is a part of the solution. Nowhere do I state that wind is the whole solution. I have many entries about conservation, policy, solar, biodiesel, even hybrid cars.
Before accusing others of providing misleading information, let us know your interests, so readers can assess the source. Is a wind farm proposed next door to you that you don’t like? Do you or your family depend on competing sources of power for a livelihood? If you don’t like wind, do you have an alternative that is better? With my information, I think the interests are transparent, and readers can judge for themselves.
January 5th, 2007 at 11:06 am
In the frenzy to provide the world with zero emission electricity production, governments around the world are starting to recognize that their headlong rush to wind power generation has been a huge mistake.
Due to its inefficiency (not one wind turbine project has lived up to the output claims made by the corporations who own them), grid fluctuation due to the unreliability of the wind and exorbitant power costs (contracts guarantee the corporations a profit by paying them 2-3 times the current cost per kw hour produced) new wind projects have been cancelled or put on hold in many countries recently. So why is the Ontario government still handing over billions (yes Billions – $2.5 Billion to date — $30 Billion more in future commitments) of dollars to private wind power corporations?
Not one country in the world has been able to shut down a fossil fuel or nuclear power station because of wind power displacement.
Before our rural landscape is covered with 315’ high structures (tower + rotors) that produce absolutely no electricity on those hot, muggy, windless summer days when we really need it, we should ask ourselves — who really benefits?
With no viable way to store large amounts of electricity, guaranteed profits from our tax dollars going to wind corporations and no commitment to dismantle their towers when present technology becomes obsolete in 5-10 years or less, we will be left literally blowing in the wind by wind power corporations, their lobbyists and our Provincial government.
We must find green sources of energy, but let’s think before blindly buying into what may become the biggest corporate fraud of the new century.
January 7th, 2007 at 10:03 pm
Some facts:
Installation of wind turbines were up worldwide by 30% last year. Seems like governments around the world are embracing wind technology.
Wind turbines sometimes do produce on hot muggy days. Take a look a July 17 blog entry, “A day in the Life”, when the turbine produced at a 91% capacity factor, on a day that was over 30 degrees C. Ontario’s hot muggy days seem to sometimes blow in from the south.
Confusing capacity factor with efficiency is just silly. What is the capacity factor of a methane molecule? It is drilled in Alberta, transported (with energy consumed along the way) to Ontario, then burned at as low as a 40% efficiency. Net efficiency is probably less than 30%. And methane is more efficient than coal. There is no argument here.
Yes, I founded a big bad corporation to build wind farms. It has 16 shareholders, a lender, and one employee. The accusations of corporate fraud and use of big lobbyists, when compared to those working for status quo, is truly laughable.
It is interesting that we “must find green sources of energy.” But if not wind, then what? I can tell you what. Coal and nuclear. Evidently we don’t really want green sources, do we.
January 7th, 2007 at 10:41 pm
W,
Where has wind been recognized as a big mistake?
In Texas, where the powers that be reluctantly accepted a renewable portfolio standard, they found it to be a better investment than their fossil alternatives and they have outpaced the “mandated” rate of investment.
Also true in Iowa. And the Dakotas. And Germany.
I haven’t seen a single jurisdiction backpedal on wind. Any chance you could substantiate your argument?
Failure to shut down fossil sources is not a very good yardstick in the context of our current energy consumption growth. Could it be that specious arguments (like yours) against wind energy are what inhibits it progress?
January 11th, 2007 at 7:03 pm
Glen,
You are way too polite. The authors of that OPA report should be fired. To so error in a public planning document is a dismissable offense. There’s zero excuse for that. I certainly wouldn’t want people of that competetence insuring the safety of your nuclear power plants.
I see that the anti-wind forces attacking you are not much better informed than OPA. I hope they are not in any position requiring technical sophistication.
February 5th, 2007 at 3:16 pm
Coenraad,
In response to your earlier post I pull the quote:
“When we need wind power it is not available , remember the last July heat wave when we had to import coal generated power from the USA. ” And I have to reverse it and ask where were your coal and nuclear power plants? They didn’t seem to provide enough power did they.
Another point is wind is not the silver bullet for all our energy needs. It is part of a portfolio that needs to be joined with hydro, solar, and other green sources.
It is always so easy to tear down and attack an idea but tough to actually take action yourself. I don’t see you offering any other alternative which in my opinion severely cripples your credibility. Post again when you have started a company producing reliable green power that rivals all the work Glenn has done.
April 16th, 2007 at 8:09 pm
In the original entry to this particular blog subject, the writer (assumed to be Glen) criticizes others for stating that wind operates only 27% of the time, or 17% of the time in summer and 41% of the time in winter. In Germany the experience with extensive windfarm implementations is about 17% averaged over a year. In opposition to this, Glen claims that windfarms produce electricity 70-90% of the time.
The difference between these two positions is in the use and meaning of the words “working” and “producing”, which can be used interchangeably in this context. Each side is assigning different meanings to the terms. Who is right? Both sides are. Both are measuring something over time, but what?
Taking Glen’s position first, he appears to be quite correct in saying that windfarms “produce” (“work”) 70-90% of the time. I cannot vouch for the actual numbers but it sounds reasonable. What Glen is saying is that windfarms are “producing/working” as long as there is output, whether it is 1% or something approaching 100% of their capacity. He acknowledges that the other side is expressing an average over time.
What the other side is saying that unless windfarms are producing at something approaching 100% capacity they are not really “working”, and you have to factor the total time they are “working” by the reduced level of performance. Another way to say this is that windfarms are actually “working” the equivalent of a lesser amount of time.
Remember that the two sides are using different meanings for the terms “working” and “producing”.
Putting this in a more familiar way, consider an employee who “works” an 8 hour day. Assume that there are sufficient things to do (or “work” to be done) to more than fill the day. If employee A works the 8 hours at something close to 100% of a reasonable expectation of capacity (a reasonable day’s work) an employer should be satisfied. We must of course allow for the usual break and lunch periods. It could be said that that employee has “worked” something approaching 100% of the time.
On the other hand, if employee B puts in a full 8 hours, but only achieves 17% of the output of employee A, because employee B produces at this level “on average” over the 8 hour period (assuming periods of lower and higher performance throughout the day), we would not be satisfied as an employer. It could be said that employee B “works” only 17% of the time. The statement is logically correct, but it has the disadvantage of the possibility of being misinterpreted to mean that employee B put in only 17% of the hours.
In any event, to achieve the same output as employee A, the employer of B would have to hire another part-time employee to make up the difference, and this would have to be 83% of a full-time employee. The total amount paid would be the equivalent of 1.83 full-time employees assuming the rate of pay for the part-time employee was the same as full-time.
Let us not be distracted by the 100% number, because that is not the point. The issue of nuclear capacity factor has been discussed in another blog. The point is that both positions are correct. In other words neither is wrong, and this goes to the heart of this blog subject.
I note that Glen has suggested that those commenting disclose their interest in these matters.
Here is mine. I am interested in reality, good public policy, and proper use of facts, logic and statistics. I am retired, have a bachelors degree in electrical engineering, am not or never have been in the employ of an oil company, do not take money from them, have no relatives or friends (that I can think of ) who depend upon competing sources of power for livelihood and there are no windfarms planned for my neighbourhood. I try to keep emotion and ad hominem arguments out of my comments, and I am disappointed when anyone oversteps this line. I have been studying Ontario’s electricity issues for almost 5 years and have looked at a wide range of sources in the process. I have done this because, being retired, I have the time and because of the importance of getting this right.
April 18th, 2007 at 8:38 am
The analogy to work days is interesting. So lets expand on it. But first a comment on availability.
Along with capacity factor, and “working”, or “producing” at least some power, is the the concept of availability.
This is the percentage of time that a turbine is available to produce, if there was wind. Turbine manufacturers often quote European availabilities, which are in the 98% range. It is important to note, though, that turbine vendors use their own definition of availability, and it is higher than what a developer would use. Turbine suppliers refer specifically to availability of their equipment. They ignore other outages, such as problems with the grid, the collection system, the transfer trip system etc. This will usually reduce true wind farm availabilities to somewhat lower than 98%. Wind overall availabilities, however, are among the highest of any technology, and would exceed both fossil and nuclear availabilities by a wide margin.
But back to our work analogy.
With wind farms, a single turbine is an employee. And like all employees in the electricity sector, she works 24 hours per day. It is true, the wind turbine is less productive in low winds. And the employee doesn’t work at all when there is no wind. Overall, the employee produces something about 70-80% of the time, but sometimes is very productive (high winds), and at other times less so. The wind turbine also has a few absences, when down for maintenance. But the wind employees have less absences (ie. the turbine is not available) than other employees. And when they are absent, typically it is only one employee at a time. That is except when there is no wind. Then they go into work, but don’t do anything. Fortunately, it is very unusual for all of the wind workers to do this across the province at the same time.
The nuclear units are bargaining units. There is a team of 600 employees, and boy do they work hard. 24 hours per day, 7 days per week, they work at their maxiumum output, whether there is demand for power or not. Except when their union declares a strike. Then all 600 stop working, and no electricity is produced. Sometimes this is planned, and sometimes it is not planned – a wildcat. So the the employer has to be sure to accomodate an unexpected work stoppage, by employing another 600 employees as back up. This is called spinning reserve. The employer is smart, though, and shares this back up with neighbouring jurisdictions, so that the back up covers many bargaining units. The nuclear guys have been on strike 40% of the time since they were hired. But some of them have been locked out for years, so if you exclude them, the rest of them have only been on strike 20 or 25% of the time. Sometimes the strike can last for months, or even years. Older workers seem to strike more.
The fossil units are the casual labour. They can be called into work when you need them. They too, are bargaining units, and 500 of them will leave work suddenly from time to time. Some of the fossil units take awhile to get into work. It can take 3-4 hours to ramp up the coal workers – they need lots of coffee. The natural gas workers take less time to start, but you have to pay them more. The coal and gas workers have very bad digestion – and pollute the air.
Waterpower is a mixed bag. Like wind, they almost never take time off (good availability). Some of the waterpower is like casual labour – you can call in additional workers as you need them. Some of them just keep working (baseload). The workers at Niagara Falls work all the time, although they call a few extra in from time to time. Of course, sometimes the waterpower crews take holidays. During drought years, they produce quite a bit less, putting more stress on everyone else. Overall, waterpower produces about 60% of what they theoretically could.
We don’t have very many solar workers today. And they are lifestyle people. They insist on spending their evenings and nights with their families, and do no work at all then. Still, they do all of their work when demand is highest.
A good company needs all types of workers. A diversified workforce keeps the lights on. Over-reliance on any type of worker would reduce system stability.
April 19th, 2007 at 9:59 am
A lot of words that neither proves your original point nor disproves mine. Your point was that others are incorrect in saying that wind power operates or produces only (insert capcacity factor) amount of time. I did inadvertently introduce a new word “working”, but this does not change the argument. My point is that both positions are correct, yours and theirs. It depends upon your definition of the above terms, and my “working employee” analogy was intended to illustrate this.
July 14th, 2008 at 5:19 pm
How can I get capacity factor for wind power at the Tehachapi area in Kern County, California?
October 18th, 2008 at 7:20 pm
In one line: Capacity Factor (CF) is the percentage of time that a wind farm (or single wind turbine) would have to run at maximum output (as defined in manufacturers specifications i.e., 1.5 MW machine producing 1.5MW 24 hours a day 7 days a week) in order to produce predicted MWh/yr values.
For machine durability i.e., minimal down time for maintenance, this value is typically capped to be between 20 – 40 %.
Capacity factor is not an indication of amount of time spent producing energy as Kent H’s comments suggest. It is solely an indication of percent of time that would have to be spent producing energy at wind turbine’s maximum rated capacity in order to produce the predicted amount.
Hope this clears things up.
Cheers,
Ruth