This past March 12 the Center of the American Experiment (CAE) released a study of projected power costs for Minnesota on the basis of its new policy mandating 50% renewable energy by year 20301. This study was soon afterward reported on the blogs PowerLine and Manhattan Contrarian.

Among the assumptions CAE made to calculate levelized cost of energy (LCOE) was that capacity factor for wind plants supplying Minnesota in year 2030 would average 40% over the course of a year. While this is not as high as the 44% projected by the Energy Information Agency (EIA), or the 40-60% forecast by National Renewable Energy Laboratory (NREL) for year 20302, it still seemed high to me, and I began a short study of capacity factor to verify these assumptions. As sources of information I searched the various annual electricity profiles of EIA and technical documents of the EIA, Federal Energy Regulatory Commission (FERC), and NREL.

1. Capacity for Electric Generation

As explained in a technical document accompanying the various EIA State Electricity Profiles3, capacity factor is the ratio of actual electrical energy generated over a year to the maximum possible energy generation (plant capacity) adjusted by anticipated downtime. This adjustment, known as availability factor ranges from 0.97 for thermal plants to 0.99 for wind turbines, and is thus a small factor in most capacity calculations. In fact, it is not clear that it is even used at all for wind turbines.

Thus, capacity factor seems a very straight forward concept. Yet, the EIA State Electricity Profiles do not list capacity, but rather include a tab in their spreadsheet labeled Capability. Capability is defined nowhere among any glossaries or technical documents on the EIA site. However, a phone call to a staffer at EIA revealed that capability is most likely the Generating Summer Capacity or Net Summer Capacity5. It is, though, most undoubtedly the basis of capacity factor calculations.

Seasonal generating capacity is defined in many places, and always in the following way. A net summer capacity is the net power a generating station can deliver to a load during a multi-hour test operating at summer (May through October) conditions. Winter capacity would be similar except for being tested under conditions appropriate to the winter season of November through April. There is good reason for making such distinctions and tests for thermal plants. During a summer season the condenser side of a thermal plant might be unable to reach its low design temperature which inhibits its thermal efficiency. During winter, a different set of thermal parasitics comes into play; but these also reduce the net power delivered to load.

When it comes to wind turbines, however, all this sort of careful adjustment for power delivered to load under realistic conditions goes out the window. For wind turbines the net summer capacity is just the nameplate rating of the equipment. Yet, it is patently obvious that summer conditions would never produce net power from a wind turbine into a load at nameplate rating because the wind doesn’t blow.

Table 1 shows, as an example, the extreme (high and low) capacity factors for wind plants in selected states during the year 2017 and which winter or summer months this occurred in.

State Summer Capacity Factor Winter Capacity Factor
Colorado July 22.3% December 42.6%
Montana July 25.8% December 44.4%
New Mexico August 23.6% November 48.9%
Wyoming July 23.6% December 40.6%
Texas August 23.3% March 45.1%
North Dakota August 28.5% December 59.1%
South Dakota August 22.2% December 51.2%
Iowa August 16.0% February 47.4%
Minnesota August 15.8% December 49.2%

Table 1. Capacity factors for wind energy during summer and winter seasons in selected states. Statistics for year 2017. Data from EIA Annual Electricity Profile reports.

During the summer season, during August generally, capacity factors are always below 25%, and actually decline west to east across the country to values as low as 16% in Iowa and Minnesota. The actual numbers might change somewhat year to year, but the pattern is clear. Net summer capacity at wind plants is nowhere close to the capability published by the EIA. Compounding this is the typical pattern of electrical power usage which peaks nationwide during the late summer months of July and August–exactly during the times of lowest net capacity in wind plants.

2. A modest suggestion

LCOE may use projected average capacity factors ranging from 40% to 60%, but engineers do not design for average conditions. Instead, recognizing that the world presents uncertainties, they often design with particular uncertainties in mind. These may be worst case scenarios, or 99% certainty, or something similar, but never average conditions. We possess data regarding wind speeds at sufficiently fine time scale and measured over long enough periods to calculate an expected capacity from wind plants in any season or month, and could

calculate reasonable figures to any level of certainty required. In fact, even without plant specific data, a person can take weather station data at nearby sites and make a very reasonable calculation of net capacity in any month. Yet, we don’t bother. I suggest we should.

To add a realistic summer capacity to other measures of capability would have two positive effects on discussions of renewable energy.

First, with regard to discussions of power supply margins, one notices that government agencies treat the margin that new renewables add to the grid on the basis of nameplate rating6. This does not present much negative effect as long as wind and solar remain minor contributors to the seasonal net power landscape. However, as renewables attempt to reach the 40% to 50% of capacity envisioned in renewable portfolios, then people eventually will have to acknowledge that 1MW of nameplate wind power added to a system is actually only 160kW in the operation of that system in August.

Second, the so-called penetration of renewables into a system is often made on the basis of nameplate rating, or on actual generation with renewables being given priority to the grid. This has the pernicious effect of making renewables appear simple to integrate, and making renewable portfolios appear trouble free to mandate. To offer something like a worst summer month net capacity to augment other capability measures for renewable plants wouldn’t perfectly capture the complexity that uncertainties present, but it would inject more realism into any discussion. It would at minimum provide an explicit nod to the amount of overbuild required to make a reliable grid from renewables.

End notes:

1 Doubling Down on Failure: How a 50 Percent by 2030 Renewable Energy Standard Would Cost Minnesota $80.2 Billion, Isaac M. Orr, Mitch Rolling, and John Phelan. Find at: https://www.americanexperiment.org
2 Power Plant of the Future through Science-Based Innovation, Dykes, et al. National Renewable Energy Laboratory, Technical Report NREL/TP-5000-68123 August 2017.
3 These can be found online at, using Colorado as an example, https://www.eia.gov/electricity/state/colorado/.
4 For example, at the Duke Energy owned Top of the World wind turbine farm in Wyoming, the nameplate capacity of the various wind turbines adds to 200.2MW and the EIA lists this plant capacity as 200MW, which is well above an availability factor of 0.99.
5 This exercise of chasing down the true meaning of terms always reveals that definitions are slippery, sometimes difficult to locate; and, rarely does anyone exhibit complete confidence about how particular figures are calculated.
6 For instance, refer to the assessment the Offices of Electric Reliability and Enforcement at FERC made for summer 2017 found at: https://www.ferc.gov/market-oversight/reports-analyses/mkt-views/2017/2017-summer-assessment.pdf
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Howard Dewhirst
April 9, 2019 6:15 pm

how can wind power have 99% capacity factor?

Reply to  Howard Dewhirst
April 9, 2019 6:25 pm

It’s not the capacity factor. It’s the availability factor i.e. 99% of the time it’s available to operate (if there’s wind) and 1% of the time it’s unavailable due to maintenance etc. The 99% availability factor operates on the capacity factor so if capacity factor is 32% (what I’ve always read as being sort of reasonable) then the effective capacity is 32 x 99% = 31.68%.

Reply to  Scute
April 9, 2019 6:44 pm

The availability figure is irrespective of whether you use it, so if the wind blows doesn’t matter.

Lee L
Reply to  Bananabender56
April 9, 2019 9:13 pm

Maybe it ought to be ‘Availablity of electrical output factor’

No wind no availability of electrical output.

Johann Wundersamer
Reply to  Bananabender56
April 15, 2019 2:26 am


“No wind no availability” yields 100% capacity:

100% windforce 0 –> 100% of 0 energy.

Rich Davis
Reply to  Scute
April 10, 2019 3:25 am

Since the 32% figure is probably not even accurate to two significant digits, you should not show 4 significant digits on the calculation, but I understand that it’s just to illustrate the calculation.

old white guy
Reply to  Howard Dewhirst
April 10, 2019 5:23 am

availability, should always be 100%. no wind no availability, therefore no capacity.

April 9, 2019 6:32 pm

About once a month I check out google results for ammonia fuel in the past month. example

Ammonia has been produced using hydroelectricity to generate the necessary hydrogen for a long time. link Ammonia was used as fuel during WW2. The technology exists but the problem is efficiency.

Ammonia could be generated using wind power and then generate electricity when the wind doesn’t blow. For some reason, there is also interest in using ammonia as fuel for the giant two stroke diesel engines used in ocean going ships.

Anyway … ammonia looks more viable for storing energy than are grid scale batteries.

Crispin in Waterloo
Reply to  commieBob
April 9, 2019 7:56 pm


That is a good lead. If any chemical can be produced cheaply within a modest distance of a wind farm and it is a fuel that can be used, it is a good leap forward. What about hydrogen peroxide? Dimethyl Ether?

The ideal would be a precursor that has some embedded energy and to which can be added more energy to create a fuel that when used results in releasing the embedded energy. The electricity input would be used to access the embedded energy.

The concept is sensible. Are there any candidate technologies?

michael hart
Reply to  Crispin in Waterloo
April 10, 2019 12:45 am

Even if it is just electrolysis to produce hydrogen, I don’t see any reasonable way around the practical problems: A complete chemical manufacturing operation at each site of electricity generation requires raw materials (even just pure water is not as simple as imagined), synthetic machinery, and storage. All require maintainance as well as capital cost.

It surely makes more sense to transport the electricity to one or more central locations (probably the sites of current power sations) via the grid before doing whatever is going to be done.

All these operations envisage at attitude of a large excess electricity production where it is cheap and plentiful enough such that some losses in conversion and storage are affordable.
… But the basic “green” mentality is that energy should be rare and expensive, something quite antithetical towards human development and wellbeing.

Reply to  commieBob
April 10, 2019 5:23 am

Ammonia is a very good storage chemical for hydrogen, and it is widely available as a chemical feedstock for all sorts of chemical manufacturing, fertilizer, and such. The biggest challenge, in terms of using it as a fuel for fuel cell vehicles or aircraft is catalyzing the conversion to hydrogen gas at low temperatures. It is very easy to do at high temperatures, but of course heating the ammonia to high temperatures consumes quite a bit of the electrical power generated by the fuel cell and/or a battery. Consequently most of the R&D associated with ammonia as a fuel for FCVs has been concentrated on coming up with a low temperature catalytical process.

If a feasible low temp catalyst can be found and produced, then ammonia would be superior to high pressure hydrogen fuel storage systems, as the fuel tank would operate at very low pressures, typical of LP gas, so would greatly reduce the weight of the fuel system. In typical passenger FCVs, the weight of the actual fuel to travel a range of 300-400 miles is but a few kilograms … but the weight of the tanks necessary to contain 10,000 psi of hydrogen pressure is pretty significant, even with newer composite materials.

Kevin kilty
Reply to  commieBob
April 10, 2019 6:40 am

Ammonia produced by the Haber process requires high pressure and high temperature. This means there are all sorts of “irreversibilities” involved (I use irreversibility in the manner of mechanical engineers here). So the round trip efficiency of wind->electricity->ammonia->combustion->electricity is very low. It might be better to just use solar panels, which I do not advocate. You can substitute any number of other chemicals for ammonia in the round trip, hydrogen, diethyl ether, etc.

Reply to  Kevin kilty
April 10, 2019 8:20 am


Yes, most of the industrial scale ammonia production today is via the Haber process which is both high temperature and releases considerable CO2 to the atmosphere. There is considerable R&D ongoing to use lower temperature catalysis to convert hydrogen gas produced via renewables (primarily wind) or other electrical power sources, converting the ammonia to ammonia to make it easier, cheaper, and safer to transport and store than hydrogen gas.

I was referring to the other end of the cycle, within the FCV, taking liquid ammonia stored at low pressures and converting it via low temperature catalysis to hydrogen gas for use in the fuel cell.

There is also ongoing R&D, led by Japanese companies, to develop a fuel cell that directly operates from ammonia gas (“Direct Ammonia Fuel Cells” or DAFCs) rather than hydrogen gas .. again, via low temperature catalysis and using various membranes that operate at temperatures in the vicinity of 100 deg C.

Pat Frank
Reply to  commieBob
April 10, 2019 9:24 am

You can only “burn” the ammonia as far as dinitrogen — N2 — otherwise you produce oodles of NOx. How does your system assure the first and prevent the second?

Reply to  commieBob
April 11, 2019 9:32 am

The difficulty with all plans to use (unreliable) renewable power to produce storable chemical fuel is that they typically require large processing plants which can only be run with reliable power.

What is needed is large sets of small processing units that can be started and stopped more or less instantaneously, as sun and wind dictates, and which despite this, and inevitable low usage, can produce ammonia/hydrogen etc at costs comparable or better than conventional plants.

Good luck with that fellows!

Bro. Steve
April 9, 2019 6:36 pm

The fact that so many of these things are induction machines, as opposed to synchronous, also needs to be cranked into the discussion. As more green gadgets are brought onto the grid due to enviro-virtue signaling by politicians, it’s no longer sufficient just to talk about capacity, as though nothing is needed but a place to plug in and use the megawatts. The discussion has to include other vital grid functions such as voltage, frequency, and reactive power.

Rich Davis
Reply to  Bro. Steve
April 10, 2019 3:54 am

I’m not an electrical engineer so this is probably nonsense, but I have often wondered if they could just connect the wind farms or pv farms to an isolated DC power grid, and allow it to fluctuate from 0V to whatever it reaches under gale-force winds/bright noontime sun. Then at a central location, produce a fuel like ammonia as quickly or slowly as the voltage allows. You don’t need to invert to AC, or synchronize to a grid frequency, or waste any power when there is low demand. It also seems like the wind turbines could be mechanically simpler, more reliable and thus cheaper. Either build a distribution pipeline or periodically have tank trucks/rail cars carrying the fuel to market.

I’d be curious to hear where this idea breaks down.

I assume it’s because the fuel that could be produced still costs more than gasoline or cng? Might still be a future technology for a distant future where economically-extractible fossil fuels have been depleted?

Carbon Bigfoot
Reply to  Rich Davis
April 10, 2019 4:48 am

Rich Davis:
With 3,000,000,000,000 BOE identified and more being produced by natural forces, these ideological wet dreams are a waste of time and money. However why don’t find enough enviro-signaling investors to pursue this while you project manage your idea. Then if your theory pans out try to implement the plant & equipment Nationwide.

Dave Yaussy
Reply to  Carbon Bigfoot
April 10, 2019 8:24 am

Wow. Rich asks an interesting question, and what he gets in response is an angry, dismissive diatribe that doesn’t provide any thought or consideration of what he has proposed.

Rich Davis
Reply to  Dave Yaussy
April 10, 2019 5:45 pm

Dave, you ignoramus! With 6,000,000,000,0000 other blog posts to comment on and more being produced, your response is a waste of time and money!


Reply to  Rich Davis
April 11, 2019 9:42 am

“I’d be curious to hear where this idea breaks down”

Very few things will work with variable DC. By the way it would be vastly simpler to use a fixed voltage and vary the current. I think electrolysis could be made to work this way, but efficiency would necessarily be very low and costs very high. The usage factor for the plant would necessarily be quite low (unless you would be willing to close down most of the wind fars when there is a strong wind, in which case their usage factor would be very low).

Incidentally DC generators and DC motors are not simpler than AC ones.

Rich Davis
Reply to  tty
April 12, 2019 4:15 pm

tty, I didn’t necessarily mean that you should run the electrolysis cells at variable voltage, only that the DC grid would be allowed to vary and presumably you’d have to do something with a variable transformer to stay in a usable range at your centralized production facility. (But only one place needs to adapt rather than all of the units generating). The main point was no need for every wind turbine to synchronize phase. Although you’d be right that you couldn’t maintain a constant production rate if you depend on the unreliables for a consistent supply of energy, that was actually my thought. Design a system that accumulates a chemical fuel at a variable rate matching the unreliable power output of the wind and PV units. Much like windmills used to be used to pump water on a farm. You’ll produce a lot for an hour and then none for a day and then a little and then a ton, but most weeks you’ll have a relatively predictable amount if you consider seasonal effects. You do not need to predict it or control it to be delivered at a rigidly fixed rate. It’s got to be cheaper not to need to worry about controlling things tightly.

You necessarily can’t worry about how much you are utilizing the electrolysis cells. In fact you can pretty much expect that you need to have about 4x the capacity on electrolysis cells compared to the average amount of power available, if you want to make use of all the power that is generated when you hit peak. When power is low, you would operate fewer cells, when power is extremely high, you would operate them all. You could also have other schemes such as to run water pumps that fill municipal water towers or preheat boiler water with resistance heaters, and do other work that doesn’t necessarily need to be done “synchronously” whenever there is unusually high power that exceeds your ability to use the power for electrolysis. That would allow you to reduce the amount of overcapacity needed on the electrolysis cells.

It was already totally clear to me that this is not economically competitive with fossil fuels today, just as the current use of wind and PV is not competitive when viewed on a total system basis. I was more thinking in terms of how you could possibly make a dog of a technology work a little better. If you ended up depleting all the economically-extractable fossil fuels, you better have a lot of nuclear power available. Then you would be able to produce all the liquid transportation fuels you need from synthesis gas and biomass, using cheap and reliable nuclear power instead of expensive and unreliable wind and solar. So there will never be a time in the future when this idea makes economic sense.

Tractor Gent
Reply to  Bro. Steve
April 10, 2019 8:57 am

This is a general issue with high percentages of wind/solar power feeding a grid from many points. Essentially it becomes almost impossible to stabilise, as the power inputs fluctuate from ‘floppy’ generators , the power flows everywhere stuff up synchronisation. The network needs significant ‘stiff’ power sources, i.e. big synchronous spinning rotor generators in the Gigawatt range to give it a frequency reference. There is some good stuff on this here (UK-centric):


Actually a more localised conversion of wind/solar to fuel which is then conveyed to a big spinning rotor would largely obviate the stability problems, but introduce all the problems associated with the fuel system & its transportation.

Reply to  Tractor Gent
April 11, 2019 8:02 am

Exactly because of these problems I have always wondered how it could even be possible to use “distributed generation.” Frequency and frequency stability is extremely important. As an operator on a nuclear submarine I had to bring on a generator as we were losing the main generator during an event. It was the most stressful thing I did. Watching the frequency of one generator going down, the other going up and the phase meter spinning like a propeller. If you do not close the breaker at the right time both breakers could explode. With distributed generation each generator will need a reference frequency that is in phase with the grid. Just a few degrees of phase difference will cause the breaker to immediately trip. Several degrees of phase difference will destroy the breaker and the inverters they are using on PV panels and even on wind turbines today. So the problem I see is how do you get all of this information to the “Distributed generators’ ?? The communications problem will be enormous. How do you maintain frequency with the remote objects? Lag time over wires are bad enough and wireless/satellites will be even worse.

April 9, 2019 6:40 pm

Let’s face it folks, our energy grid is now a Prius. There is the nasty, filthy, disgusting, dirty fossil fuel baseload, topped off with a heaping helping of very expensive , intermittent, feel-good, Green Smug.

Reply to  Wharfplank
April 9, 2019 7:39 pm

+1 Excellent analogy.

Reply to  Wharfplank
April 9, 2019 8:15 pm

It’s interesting that the latest Prius, besides being ugly as sin, is just about as efficient as the best automotive diesel. Somewhere south of 60%. That is a max for any viable power plant, determined by thermodynamics.
η=T1−T2T1/T1, in Kelvin. T1 is input temperature, T2 is the exit temperature.
For example: 1300K-450K/1300K=.65, or 65% efficiency.

That fact is why fuel cell electricity production seems very attractive. Battery efficiency is not limited by temperatures, but the various electric potentials and losses. Batteries can be as efficient as 95% in returning electricity used in charging.

edi malinaric
Reply to  Philo
April 10, 2019 12:14 am

Hi Philo – ancient engineer here – you wrote…

“η=T1−T2T1/T1, in Kelvin. T1 is input temperature, T2 is the exit temperature.”

Sixty years ago I was taught that eff = Tmax – Tmin/Tmax.

when did that extra T1 creep into the equation?

cheers edi

Randle Dewees
Reply to  edi malinaric
April 10, 2019 5:02 am



Reply to  Philo
April 11, 2019 9:55 am

“Batteries can be as efficient as 95% in returning electricity used in charging.”

Provided you charge and discharge them very slowly. There is no way to get around the internal resistance. And as a matter of fact battery efficiency (and life) is strongly affected by temperature. Which is why Tesla has battery cooling. Which in turn consumes power….

Johann Wundersamer
Reply to  Philo
April 15, 2019 3:52 am

η=T1−T2T1/T1 –> η=T1−T2/T1

Reply to  Wharfplank
April 9, 2019 8:50 pm

As the Romans used to say: “Quem deus vult perdere, prius dementat.” [The Prius drives nuts whom the gods would destroy.]

Rod Evans
Reply to  jorgekafkazar
April 10, 2019 12:32 am

There are far too many COGS in the Prius…

old white guy
Reply to  Wharfplank
April 10, 2019 5:25 am

green smug, reminds me of an episode of South Park.

Reply to  Wharfplank
April 11, 2019 8:09 am

My neighbor who has owned a Prius for 10+ years now has just replace the battery a second time.
Which begs the question, “How many miles can you go on $6,000 worth of gas? [She did not tell me how much each cost, and I did not ask.]

April 9, 2019 6:53 pm

Unless renewables can produce electricity at or below the costs of fossil fueled power plants all households will suffer .
Of course households with little or no surplus income will be hardest hit .
Renewable’ s except hydro are not competitive and wind and solar need expensive back up to generate when the wind stops and the sun sets .
I saw a post recently in that researchers had come to the conclusion that poorer households were hardest hit with soaring power prices due to renewable generation .
Any one with more than a modicum of common sense would not have to do an extensive study to come to that ground breaking news.

nw sage
April 9, 2019 6:54 pm

Good article about ‘real’ capacity factor. Clearly 40% (of nameplate rating) will NEVER be achievable in the real world on a year-round basis. To assume otherwise is to assure that the power will go out just when your wife’s favorite TV show come on -or worse, in the middle of it – during a summer hot spell.
Note to self – DON”T make the wife mad!

Reply to  nw sage
April 10, 2019 4:02 am

Better during a TV show, than your open heart surgery.

Gary Pearse
April 9, 2019 7:01 pm

Haven’t they discovered in Europe that the life of these turbines is turning out to be something like 25-30% lower than anticipated and their output declines over this lifetime? What would that do to “capacity” and “capability”? Re cost, the backup power plants would have to be higher design capacity to fill in the W mill decline, or redundancy mills would have to be a greater number. Deployment of renubles is virtually stalled in Europe and the fleet doesnt look like its going to be replaced given the arrival of the Russian Nordstream gas line and with the dismal failure in reducing CO2. This beast is dead.

I’m not a power engineer, but I can’t believe that the failure of this whole scheme is a surprise to engineers.

Dave Fair
Reply to  Gary Pearse
April 9, 2019 8:04 pm

I was a power engineer, Gary. Responsible engineers have pointed out the problems with renewables from the beginning. But powerful green political players and vested interest profiteers have pushed the schemes on unsuspecting consumers.

The only effective response will be: “Wife, where did you put my yellow vest?”

Kevin kilty
Reply to  Dave Fair
April 10, 2019 4:58 am

Good comment. It doesn’t really matter how many experienced people weigh in on a topic, or are asked for advice. Money moves projects, and if the moneyed people and politicians see how to enhance their wealth or power–then bar the door.

A good analogy from history is the Scottish project at Darien in Panama. Had the Scottish elite listened to people who knew the conditions in Panama, or had had to fight the Spanish. Then this idiotic project which ended up bankrupting Scotland would never have happened.

Jay Salhi
Reply to  Gary Pearse
April 9, 2019 9:44 pm

Yes, in the UK, for example.

“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 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.”


old construction worker
April 9, 2019 7:15 pm

Wasn’t there a study done using real data in Spain. I can’t remember if it was using solar panels or wind generator data. I do remember the results were not impressive.

Roger Knights
Reply to  old construction worker
April 9, 2019 11:56 pm

“Wasn’t there a study done using real data in Spain.”

Here, is a commentary by a Spanish expert who formerly believed renewables were the solution http://thetyee.ca/News/2013/05/01/Solar-Dreams/

André Friedli | April 9, 2017 at 7:36 am | Reply
I thoroughly recommend Euan Mearns blog “Energy Matters”, which frequently debunks the claims made by the sponsors/operators/promoters of real-life flagship RE schemes (the “100% Renewables” El Hierro island project in the Spanish Canaries being a prime example). Energy Matters link: http://euanmearns.com/

Reply to  Roger Knights
April 10, 2019 3:38 am

Roger that site is a great read.

April 9, 2019 7:33 pm

What a bunch of BS…

U.S. Energy Information Administration (EIA) actually has baseline capacity factor numbers for all US windmill plants, which average ……wait for it… wait for it…… just 34% of nameplate (2013~2018 average)…. Oh, goody… (Similar to Germany’s wind capacity factor)


Nuclear Power by far has the best capacity factor at around 92%….

Why the HELL do we waste $trillions on insane wind/solar boondoggles when Thorium MSRs will, by far, be the most sustainable, cheapest and safest form of energy, with an energy density that will be 2,000,000 TIMES that of fossil fuels, and will have a capacity factors exceeding 92% (no downtime required to change out fuel rods because they’re not used)…

China will have commercial Thorium MSRs in about 10 years, and will eat Western Civilization’s lunch, while we joust with windmills…


Western Leftists have gone insane…

Ron Long
Reply to  SAMURAI
April 10, 2019 3:20 am

Go get them, SAMURAI, and remember to take your sword with you! Thorium nuclear reactors are in favor because they don’t function as breeder reactors, ie, you can’t get fissile bomb-grade material from reprocessing spent fuel rods. That’s right, no plutonium to spice things up.

What the hell are these crazy Minnesotans thinking? Wind turbines destroy many bats, and bats eat mosquitos, which is a plague in Minnesota.

Malcolm Carter
Reply to  Ron Long
April 10, 2019 12:18 pm

Other MSRs use enriched uranium or mixed uranium plutonium oxide fuels that do breed plutonium as do light water reactors. Thorium reactors usually need an initial load of enriched uranium or plutonium to produce the neutrons needed to transmute the thorium to fissile U-233. The difference is that the solid fuel rods in light water reactors have to be replaced every 18-24 months and at this point the ratio of fissile Pu-239 to nonfissile Pu-238 is high and chemical processes can separate plutonium for bomb cores. In MSRs molten salt fuel remains for several years in the reactor vessel and the Pu-239 becomes increasingly denatured with Pu-238. Separating Pu-239 from Pu-238 requires expensive isotope separation.
The long fuel cycle in MSRs means that they are much more energy efficient and also burn up many of the long half-life actinides that make spent waste problematic.

Mark Luhman
Reply to  SAMURAI
April 10, 2019 10:37 am

SAMURAI said “Western Leftists have gone insane” no the have not you cannot go insane when you are already insane. To be a leftist is to be insane. If anyone does not believe that I can only say how can anyone support a political philosophy that murdered 200,000,000 people in the twenty century. If you think the left has reformed look at what they are proposing today and demand today. There are a number of leftist that believe humans can destroy earth and for that reason we need to eliminate six billion people. Yet these loons are not condemned by their comrades instead they are help up as enlighten thinkers. All I can say if they get control of power in the US good help us all!

Tom Abbott
April 9, 2019 7:35 pm

Trump said recently that if they put up a windmill within sight of your house, your property value declines by 65 percent!

Trump is a real estate guy, you know. 🙂

April 9, 2019 8:13 pm

The answers my friends, are blowin’ in the wind
The answers are blowin’ in the wind.

william Johnston
Reply to  Mr.
April 10, 2019 7:18 am

Why did you invert the “M”??

Reply to  william Johnston
April 10, 2019 12:41 pm


Angus McFarlane
April 9, 2019 8:20 pm

I concur with Gary Pearse’s comments, other factors that are used to improve the cost performance of wind turbines are:

a. Degradation in output of wind turbines is ignored. This is typically 1.6 % ± 0.2% per annum and this unrecoverable loss is attributed to gradual deterioration, such as fouling of the blades (which impedes the aerodynamic performance) and a gradual reduction in component efficiencies (gearbox, bearings and generator). These may not be recoverable by maintenance procedures but only by component replacement.

b. Design life is usually assumed to be 25 years but wind turbines rarely exceed a 20-year lifespan and can be as low as 15 years.

Nick Schroeder
April 9, 2019 9:25 pm

“…adjusted by anticipated downtime.”


Capacity Factor is the ratio between the actual MWh produced over a period of time and the possible nameplate capacity MWh over the same period – period. There are no “adjustments.”

Availability is the amount of time the unit was capable of generating the nameplate whether or not it was dispatched.

A unit with a month of downtime for scheduled maintenance has an unavailability of 8.3%.

If it was dispatched at nameplate the rest of the year its CF cannot be more than 11/12 = 91.7%.

For the proper definitions and applications see NERC-GADS not EIA.

Nick Schroeder
April 9, 2019 9:33 pm

A turbine generator, any turbine generator, with a nameplate of 100 MW could produce 876,000 MWh per year (+ 2400 for leap year.)

If during the year it produced 219,000 MWh that would give a capacity factor of 25%.

If it were broken and 100% unavailable three months of the year its CF could not exceed 75%.

If during the remaining nine months it produced 219,000 MWh it’s CF would still be 25%.

Geoff Sherrington
April 9, 2019 9:57 pm

Here in Oz there seems to be 2 types of economic analysis for the viability of the main renewables.
Type 1 does not factor in the need for backup electricity sources.
Type 2 does attempt to cost backup, but it is seldom seen

IIRC, every government-based costing I have seen in the past 5 years assumes that the effect of the Paris Climate Agreement is that fossil fossil fuels will become insignificant; so they do not need to be part of the cost modelling. Every one of these ‘official’ analyses is silent on what happens when sun don’t shine and wind don’t blow; though a few of them mention the exciting future prospect for large batteries, CO2 capture and storage, using leccy cars as a battery base and ‘look over here, there are pretty coloured flowers that will line our path to the new power enlightenment.’

In my humble view, this is criminally misleading. Has anyone found references to other countries where legal challenged was made to these misleading, incomplete financial analyses?

Patrick MJD
Reply to  Geoff Sherrington
April 10, 2019 1:25 am

You are not wrong. Unfortunately the average voter in Aus is not equipped with such reasoned opinions. I really fear for the future of Australia. Continuous bleating in the media about “renewables” and “electric vehicles” on and on.

BTW, I can’t vote federally. So vote well.

James Fosser
Reply to  Patrick MJD
April 10, 2019 2:07 pm

Here in Australia we have just been told that a general election is in the middle of May and everyone with a brain cell knows that a Socialist government will walk it (I like this warning because it gives me time to move my money out of Australia and into South Malacca Shekels). The following general election result is completely predictable when even those without a brain cell will help to vote the Socialists out after the horrendous damage inflicted on the country.

William Astley
Reply to  James Fosser
April 10, 2019 6:25 pm

It is a cycle. Same cycle everywhere there is democracies.

The left promise to spend money that we do not have, to get elected.

The left spend the money.

We run out of money and the scams do not accomplish anything lasting.

Conservatives come in and balance books.

The danger now is the press is no longer critical, thoughtful.

dodgy geezer
April 9, 2019 10:57 pm

I can’t see what the issue is.

It should be obvious that the poster is mixing up two different figures. These are ACTUAL Capacity and POLITICAL Capacity.

The first figure is used for electricity generation prediction. The second is used for Green Subsidy Justification…

April 9, 2019 11:32 pm

….. I have a modest suggestion for Green Energy schemes…. But it would end up in the sin bin. 😉

Reply to  J.H.
April 10, 2019 1:51 am

Let me help. Virtue signalling always looks good and feels terrific, especially if you have no idea of the consequences. Beware of ignorant do gooders.

Rod Evans
April 10, 2019 12:54 am

Maybe the time has arrived to demand the COGS dis-invest their pensions from fossil fuel driven industries.
No more big oil returns for the Obama’s the Kerry’s the Sanders’ or AOC’s (does she even have a pension fund) just tell them, from now on, their money will need to be invested in Green schemes only.
That will boost the wicker basket makers, the daisy chain necklace industries, and let us forget the sack cloth and ashes manufacturers.
Let the COGS put their money where their enthusiasm lies.
I would go one step further. Just as we have to sign up to cookies coming onto our computers if we decide to visit a use a site these days. I would send all energy users a contract to sign or not, saying they agree to the supply of their energy coming from predominantly fossil fuel and nuclear sourced generation. Anyone not happy to sign, should be informed they will be removed from the supply security side of the contract, and advised to seek another supplier.

April 10, 2019 1:05 am

As soon as you see the acronym LCOE relating intermittent electric power sources to grid power you know the authors are in need of a clue.

There is a very clear admission of the acronyms misuse in a document produced by ARENA, which is Australia’s wind and solar generation advocacy group. This paper talking up the economics of dispatchable RE gives details:
From page X of the summary:

In much of the previous published analysis that informs electricity policy, single LCOEs per technology have traditionally been used in a rather misleading manner to compare generation technologies that are variously continuous, peaking or variable.

Also starting with an assumed capacity factor means any modelling is naive and useless. The only valid modelling for intermittent generators is to use time run data collected from the actual planned sites. That will yield the potential native CF and also the achieved CF given all the interactions with the load, storage and other generators. The CF of wind turbines in South Australia are steadily declining as curtailment becomes more common due to the dwindling demand and increasing wind and solar capacity. The native CF for wind turbines also falls due to interference on the air stream from nearby towers. In Queensland it is becoming more common for grid scale solar to shut down production at lunch time because all the small scale rooftops are cranking near their rating and the wholesale prices goes negative (more than 30% of residential properties now have solar being sent out at a fixed price irrespective of time). The solar subsidy farms have to pay to send out power and the subsidies are not high enough to cover that cost.

Reply to  RickWill
April 10, 2019 1:22 am

Actually you know a paper that uses the term “renewable” in conjunction with wind and solar energy production in its current form is mythical. Wind and solar generators are unrenewable in their current form. They cannot produce enough energy over their life to produce their replacement and support the industry needed to build the replacements.

These forms of generation do have some economic value. For example in a low energy intensity application beyond an existing grid. When combined with current batteries, they are competitive with diesel generators where wind or solar is abundant.

James Bull
April 10, 2019 2:22 am

I have on several occasions tried to get actual against nameplate outputs for various subsidy farms in the UK both windmills and solar this information is either very well hidden or I’ve not hit on the right place to look.
If all these power sources were so great and everything you’d think they would be proclaiming it from the hill tops shouting how it’s performing but all the media give you is the usual “we weren’t getting any power from coal today” (no mention about yesterday when the wind wasn’t blowing).
If anybody knows where I should look it would be very useful.

James Bull

Reply to  James Bull
April 10, 2019 3:38 am

You’re right, James. I have spent some time trying to find this information, but have had to resort to assuming parity with the figures readily available for the USA, a poor assumption for many reasons, I know. I think this disclosure will require action within the freedom of information framework, although this would only include public bodies. Companies would still be able to hide behind the “commercially sensitive information” barrier.

Heaven forfend that the British taxpayer should ever discover what their hard-earned is being squandered on.

Reply to  James Bull
April 10, 2019 9:54 am


May help – overall figures going back on eyear

Reply to  griff
April 11, 2019 10:05 am

Unfortunately the data asked for is not available at that link.

You are not very good at those techy thingies are you griff?

Dave Ward
April 10, 2019 3:08 am

“One notices that government agencies treat the margin that new renewables add to the grid on the basis of nameplate rating”

That’s because government agencies (and the government themselves) are stupid. Just look at the UK…

April 10, 2019 4:02 am

I’m guessing that to achieve this goal the entire state will need to be covered with wind turbines including all 10,000 lakes. Not sure where the storage batteries or people will go.

Reply to  bluecat57
April 10, 2019 1:03 pm

Like many others, to warm states — Texas, Arizona, Florida, etc. Unfortunately, they takes their communism w/them.

Dudley Horscroft
April 10, 2019 4:02 am

What a pity. I thought this would be about eating windmills.

Reply to  Dudley Horscroft
April 10, 2019 9:19 am

It was a modest suggestion, not a modest proposal.

Ben Vorlich
April 10, 2019 4:37 am

The data here is a little bit out of date but the conclusion is still the same.

None of these capacity / load factor comparisons account for the inevitable intermittency and non-dispatchability inherent in the performance of Weather Dependent Renewables.

If the objectives of using Renewables were not confused with possibly “saving the planet” from the output of Man-made CO2, the actual cost in-effectiveness and inherent unreliability of Weather Dependent Renewables would have always ruled them out of any consideration as means of electricity generation for a developed economy.


Ben Vorlich
April 10, 2019 4:42 am

For anyone interested in UK data there’s a treasure trove here


Reply to  Ben Vorlich
April 10, 2019 5:13 am

Thanks, Ben, very useful (and not easy to discover!)

Reply to  Ben Vorlich
April 10, 2019 9:53 am

Thanks! Really useful…

I expect most people have already seen:


April 10, 2019 5:10 am

This discussion is right on target…the predictable, available, reliable capacity is the issue that set the value of generated energy from any source. BUT, capacity to serve load (customer demand) at any moment, at every point in the distribution, transmission, and pool system may be significantly different than summer pool peak. It would be very helpful for discussion if operating and planning engineers with real data at each level in the electric system describe examples of needed generation capacity on each major circuit.
Summer or winter peaks met by predictable capacity to serve the load may still dominate pool planning, but distribution and transmission costs to adapt to intermittent wind/solar may have higher unit capacity costs.

April 10, 2019 5:33 am

The author writes as if he discovered something new. He didn’t.

The variability of winds by time of year at any specific wind farm location was always well understood and factored into wind turbine power production models from the very beginning. Indeed, that knowledge was essential going back hundreds of years in places like northern Europe where windmills were used to power early industrial age machines, or in arid locations where farmers or ranchers used windmills to power water well pumps. This kind of knowledge has always been “baked into the cake” for siting windmills.

Indeed, in siting any modern wind turbine “farm”, among the first tasks performed by the engineers is to set up temporary weather stations to collect wind speed and direction data continuously for a minimum of one year, or preferably more than one year, in order to construct a probabilistic wind rose database. That location specific database is then used in conjunction with other available area weather and climate data to predict the average annual power production capacity for the proposed turbine site.

Regardless of any subsidies that might be available, the investor or owner of the wind farm still needs to produce a profit, and having a very good understanding of the revenue potential of any wind turbine site is essential to making a business case for locating a wind turbine farm at a particular location.

william Johnston
Reply to  Duane
April 10, 2019 7:28 am

“Regardless of any subsidies…..the investor or owner needs to make a profit”. Which is why Warren Buffet
said without subsidies, wind turbines make no sense. No subsidies, no profit, no turbines.

Reply to  william Johnston
April 10, 2019 9:28 am

Doesn’t matter. The Federal subsidy for wind power is a “Production Tax Credit” – it varies with the actual number of kw-hours of energy produced, so the more energy produced the greater the credit.

So my point is, all wind turbine generator investors/owners/operators despend upon actual annual production of energy in kw-hours per year, regardless of whether they get a PTC or not.

PTCs only apply to the first 10 years of operation of any wind turbines. and the actual PTCs have been ramped down for each of the last three years, and ends altogether the end of this year. Wind energy has become so cheap and efficient that PTCs effectively are no longer needed for wind turbines to compete effectively with combined cycle gas plants – currently the cheapest form of non-renewable energy in the US. The PTCs should remain expired from here on out.

Johann Wundersamer
Reply to  william Johnston
April 15, 2019 6:14 am

““Regardless of any subsidies…..the investor or owner needs to make a profit”. Which is why Warren Buffet
said without subsidies, wind turbines make no sense. No subsidies, no profit, no turbines.” –>

Regardless of any subsidies – the investor will seek profits

at the expense of the owner. At least.

Coach Springer
April 10, 2019 6:22 am

Points could have been presented more straightforwardly. The modest suggestion was so modestly stated that I had to make the effort of going back to sift it out and then evaluate its bases.

April 10, 2019 7:29 am

“Renewables” is green-sounding. “Weather dependant” is more sceptical-sounding. Would those projects proceed with that terminology?

April 10, 2019 7:42 am

And when you thought it couldn’t get any sillier, this is what the EU commissioner for energy (Miguel Arias Cañete) has to say on the subject:
“We are giving €5 billion of subsidies a year to fossil fuels. And there’s no system of taxation that incentivises renewables”.
I’m so glad I don’t live on his planet.


April 10, 2019 8:11 am

In Australia it’s accepted that diverse geographic wind turbines can produce on average 30% of their installed capacity over a year which marries with Table 1 but that hides a multitude of marginal sins-

You’re overthinking it with fancy measures when all it needs is a level playing field mandate that no tenderer of electrons to the communal grid can supply anymore than they can reasonably guarantee 24/7/365 or they can keep them. Their State sponsored dumping game would be over at the stroke of a pen as they either invested in storage to lift their tender or partnered with thermal and paid them their just insurance premia or some combination of the two. That’s the great cost lie at present with so called renewables.

April 10, 2019 8:39 am

A physicist put the impossible monumental task any rational intelligence could understand into a simple analogy-
but it falls on deaf ears with people who believe national electricity grids run on emotion rather than STEM and concomitant economics. Now they reckon lithium battery production should go into cars to boot so what can you say?
So we have to have exorbitant power bills and rolling blackouts before they finally get it in enough numbers to cast the shucksters and dreamers out for good. Meanwhile in South Australia we rationalists have a backup genny and wait for the inevitable as you can’t argue with feelings.

April 10, 2019 8:39 am

Add MA to the list. The poster child is in Scituate MA, right on the Coast, so similar output to what would be expected by ‘off shore’ also. Barely averaging 15% for the Year. Many months well below 10% of NamePlate. 1.5MW nameplate. Best output ever is 31% and that was 1 month in the entire lifespan.


April 10, 2019 9:26 am

Doesn’t matter. The Federal subsidy for wind power is a “Production Tax Credit” – it varies with the actual number of kw-hours of energy produced, so the more energy produced the greater the credit.

So my point is, all wind turbine generator investors/owners/operators despend upon actual annual production of energy in kw-hours per year, regardless of whether they get a PTC or not.

PTCs only apply to the first 10 years of operation of any wind turbines. and the actual PTCs have been ramped down for each of the last three years, and ends altogether the end of this year. Wind energy has become so cheap and efficient that PTCs effectively are no longer needed for wind turbines to compete effectively with combined cycle gas plants – currently the cheapest form of non-renewable energy in the US. The PTCs should remain expired from here on out.

Jay Salhi
Reply to  Duane
April 11, 2019 5:31 am

A person investing in a wind project doesn’t have to worry about the cost of backup because wind farms are built in places where the backup is already in place. The cost of backup is not born by the investor. The stated policy goal is to eliminate fossil fuel plants which would eliminate most of the backup. And backup is just one of many issues.

Wind is not remotely competitive with gas when you look at the full picture.

“With today’s technology, $1 million worth of utility-scale solar panels will produce about 40 million kilowatt-hours (kWh) over a 30-year operating period. A similar metric is true for wind: $1 million worth of a modern wind turbine produces 55 million kWh over the same 30 years. Meanwhile, $1 million worth of hardware for a shale rig will produce enough natural gas over 30 years to generate over 300 million kWh. That constitutes about 600% more electricity for the same capital spent on primary energy-producing hardware.”


April 10, 2019 9:57 am

Hmmm… we need also the demand figures for the state over the year…

I can’t find a chart, but I would expect that like the UK, Minnesota has much higher demand in winter, when wind capacity is higher and lower in summer. And of course Minnesota also has solar power, which you’d expect to deliver in summer…

(Peak UK winter demand 50GW, summer 35 GW)

Reply to  griff
April 10, 2019 2:15 pm

The horse named “Griff” just ran a hard fought 2nd at Keeneland, it paid $6.00 to place, made me $2.00 on my bet.
It always runs hard.

Dennis Sandberg
April 10, 2019 11:15 am

Correct me if I’m wrong, but isn’t most of Minnesota’s wind and coal power generated in North Dakota? (I’m pretty sure it is). Seems Minnesota is well positioned to get stuck with most of the big power bills for junk off spec interruptible, non-dispatchable wind power while giving North Dakota contractors and landowner’s the economic benefit. Note: I’m pretty sure most of Minnesota’s hydropower comes from Canada. Greatly increasing Canadian hydro would be an alternative. Sounds like an economic plus for Minnesota’s neighbors, but bad policy for the Minnesota voters who want this insanity. Karma?

April 10, 2019 12:45 pm

All power plants use energy from outside sources during their life span. This downwards adjustment needed to get the net output is expressed as the Site Factor (SF). It is a ratio akin to the capacity factor (CF), but whereas CF is the ratio of the plant’s actual output averaged over the life of the plant vs. the name plate power rating, SF is the ratio of the plant input energy from all external source to the net output of the site in its life. The external sources of energies are the grid electricity, gas, gasoline, diesel fuel, aviation fuel (helicopters), propane, … Adjusted for the SF, the actual output over the life of a site is some 10, 20 percent lower, the former for excellent sites, the latter the poor ones and measured towards the end of their life. With thermal plants such adjustment is minuscule on the scale of the huge output.

April 10, 2019 2:44 pm

In Australia the Anero.id website reports hourly capacity factors for each wind farm connected to the AEMO grid. In total wind has a reported nameplate capacity of 6.1 GW in a grid with average demand of 24 GW.
Tony from Oz https://papundits.wordpress.com/2019/04/10/australian-daily-electrical-power-generation-data-tuesday-9th-april-2019/ takes that data and provides a daily report. Averaging that data over the last 9 months shows an average generation of 1.7 GW equal to 27.6% of nameplate capacity. And on a hourly basis those wind generators in total have delivered a minimum of 0.2 GW and a maximum of 4.0 GW. On a weekly basis the lowest minimum has been 0.8 GW and the highest 2.8 GW.
This data demonstrates the intermittency of wind, and therefore any calculation of the cost of wind generation must include the cost of a reliable backup supply so that demand can be met on reliable basis.
So in Australia, if wind were to be required to supply 25% of demand on average, or 6 GW, that would require a nameplate capacity of 22 GW, but with delivery ranging from 1-14 GW, standby generators, presumably gas, must be costed into the supply cost. So, massive over-investment is required.

Bruce of Newcastle
April 10, 2019 6:53 pm

My modest suggestion regarding renewable energy involves dynamite. Especially for wind turbines. But, then, I like birds.

April 11, 2019 6:34 am

Australia is in Federal election mode so naturally the virtue signallers are coming out of the woodwork as EVs have become a bit of an election topic-
Going down the Google road like a loose cannon-

‘That includes improving the energy efficiency of its buildings and staff areas and working with energy providers to ensure power comes from renewable sources. In the rare case it can’t be guaranteed, Atlassian will buy Environment Attribute Certificates to offset its emissions.
“Effectively, what that means is you’re paying someone to do some form of carbon removal to balance your consumption,”’

Ever heard of the fallacy of composition? What is it with these software lightweights that believe putting in a few LED lights and turning the aircon down and buying some thin air derivatives is all it takes. What about all the sunk fossil fuels in your buildings, furniture, furnishings and hardware not to mention the roads your workers are driving on in their ICEs to get there and all their sunk fossil fuels proportional to their working time at the office dude? Are they all to become vegans and you’re giving them Environment Attribute Certificated bicycles to get to and from work for starters? Where’s your accounting brainfade at dude?

April 11, 2019 7:04 am

“The Tesla-driving Cannon-Brookes has a thing for the homes of car dealers, having bought the Palm Beach retreat of Neville Crichton in early 2013 for $8.7 million.”

Perhaps Mike the bike could give them all a Tesla to get to and from work and create some more Environment Attribute Certificates for other firms to buy?

William Astley
April 11, 2019 10:33 am

The first wind farms are located in the best wind locations where land is available. Windy locations are often a long distance from the cities.

The wind capacity number drops as more wind farms are installed as there is a limited amount of land available in the ideal windy locations which explains why German wind and sun gathering efficiency is less than 20% of nameplate.

Large wind farms require high voltage power lines, complete with transformers and protection breakers.
The high voltage power lines require the purchase of rightway which is a big deal and requires energy to construct and maintain.

Wind power varies as the cube of wind speed. A large wind farm power output can change as much as 30% in an hour.

The constantly changing power output for the wind farms must be matched by turning on/off/on/off/on single pass natural gas turbines. Single pass gas turbines take roughly an hour to reach optimum temperature and efficiency. Cycling wears them out and increases the amount of natural gas required to produce power.

In Germany there is 17% surcharge on the electrical bill to cover the increased cost for variable power.

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