Talk:Intermittent energy source/Archive 2

Archive 1

Archive 2

Costs of interconnection of systems

HVDC links are now relatively cheap and efficicnet - 3% losses over 1000 km, so the issue of intermittency becomes far less of an issue due to the increased diversity.

Quote from a UK power systems expert:

Cost of connecting UK to Europe

"Like most things it's dangerous to have back of the envelope numbers but the following are approximate PRIME EQUIPMENT costs for a 2000MW 500kV bipole conventional HVdc link. i.e. these costs exclude way-leaving, on-shore reinforcement works, consenting, engineering, insurance etc.

Converter stations ~£110M Subsea cable + installation ~£1M/km

So for an 8GW to the mainland in four links, you would not have much change from £750M for the installed works. you could probably add another £200-300M for the other works depending on how much additional on-shore works were required.

Regards, GB

Further info:

> > http://www.abb.com/cawp/gad02181/f665be70ddd7edb3c1256fe2002cdf0d.aspx

> > > > > > > > "The use of HVDC at 800 kV, has been found efficient, > > environmentally friendly and economically attractive for large > > point-to-point power transmissions of the order of 6400 MW and more, > > with distances of more > than > > 1,000 km. Worldwide there is an increasing interest in the > > application of HVDC at 800 kV. > > > > Paper presented at International Workshop for Ultra High Voltage > > (UHV) Transmission Systems 2006, Beijing, China, Nov. 28 - 29, 2006, > > organized by State Grid Corporation of China:"

HVdc

Roy Follow up to Dave's post. Re HVDC transmission. Planned Chinese HVDC is at http://search.abb.com/library/ABBLibrary.asp?DocumentID=9AKK101130D3877& LanguageCode=en&DocumentPartID=&Action=Launch and at http://www.abb.com/cawp/gad02181/c1256d71001e0037c12568940025fdbe.aspx Moving 6GW over ~1000+ Kilometre is well on the way.

The above link was sent to me originally by German Aerospace (Trieb) and passed to Colin Challen MP (all-party CC group Chair) at latter's request earlier this year. Trieb et al did the study for TRANS MED, which is the proposed regional EU / MENA scheme for balancing renewables electricity generation via HVDC (Gas is proposed for peak back-up and coal is to be phased out. See also TREC - Gerrry Wolfe this list - for links for info on the super-grid to include CSP Spain and then further CSP in N Africa etc).

The Norway hydro link to our huge wind reserves (a resource shared also with some of EU neighbours), is an obvious starter. Trieb et al study suggests nuclear can only get in the way of rational balanced grid-to-grid linkages of bulk power. Norway to NL bulk transfer cable is already underway as is NL to UK HVDC link, repsectively http://www.norwaypost.no/cgi-bin/norwaypost/imaker?id=75975 and http://www.nationalgrid.com/uk/Media+Centre/PressReleases/220507britned.htm. best PhilDC

More HVDC

From: energy-discussion-group@googlegroups.com [1] On Behalf Of Philip Harris Sent: 08 June 2007 14:04 To: energy-discussion-group@googlegroups.com Subject: future world HVDC re Compass AGM

Can't resist sharing. Snippet from Swedish company who will build the UK / NL HVDC link open in 2010. http://www.abb.com/cawp/seitp202/40b621aafd3db79cc1257225002fcd3d.aspx " ... China and India are set to be the main users of the new technology as [they] seek to secure reliable power supplies. India plans to build five ultra high-voltage DC lines over the next ten years, each with a capacity of 6,000 megawatts (MW); China is planning one line every year for the next decade, each with a capacity of 5,000 MW to 6,400 MW. ..."

Read these old engineers on a roll with ultra HVDC. Phil

effects of power station outages

To summarize part of what I have been trying to get over is that the unavailability of large power stations - coal or nuclear - has several effects for consideration:

1. No matter how short the periods of unavailability, the grid has to estimate the worst case simultaneous unavailability and keep that amount of reserve power stations ready - these can be started up in good time as needed. This includes cold stations, or stations on hot standby. I think that in the UK the max loss envisaged by National Grid is the sudden loss of 1.2 GW closely followed by 3 more - which is what appeared to have happened this month.

2. The fact that power stations can stop suddenly and without warning, even if infrequently, means that spinning reserve and frequency sheddable loads have to be instantly available to cover the maximum size likelihood. In the UK it happens to be 1.32 GW which happens to be Sizewell.

3. Fast response plant - OCGTs and diesels have to be available to back the Frequency Response sheddable loads.

4. Some grids eg France have special tariffs that can be invoked to cover sudden losses - eg EJP in France.

So, overall, grids always have to have quite large reserves to back up power stations, BECAUSE POWER STATIONS ARE INTERMITTENT THEMSELVES (Caps only added for emphasis, not rudeness)

And of course exactly the same, already existing mechanisms can be used for wind power at large penetrations.

A final point, is that if you were to have 50,000 wind turbines in the UK to run the whole grid...just imagine it, no fossil or nuclear plant on the grid, apart from spinning reserve, and some on warming, then they cannot all a) simultaneously fail, or b) nor can the wind simultaneously die away to nothing instantly over all turbines.

To that extent, the large the penetration of Windpower the less intermittent the mix of plant becomes, although of course it becomes more variable.

The rate at which the wind could, over a large area die away to nothing is quite within the ability of fossil plant, already in existence in the UK and on warming, to be started, particularly with current weather forecasting techniques.

Always remembering that 90% of the cost of running a power station is the fuel, so keeping already paid for plant idle is not particularly high.

This article is very poor, in my humble opinion and needs to be drastically pruned

In my humble opinion, this article is very long and confusing. Presumably the humble reader want to get a concise over view of the situation and a conclusion.

It is clear at least to me, having studied the issue in some detail, that the intermittency of renewables is an exaggerated problem, as all the methods to deal with it are already in existence to a greater or lesser degree. Why then does this article need to ramble on for so long about this, and that and maybe and on the other hand. Why is it quoting some guy from Green Peace who is mi-stating Greenpeace's and other renewables proponent's position? and in any case is factually wrong, and is as far as I know an astronomer?

Why are we quoting an unnamed official of Xcel who is clearly voicing an opinion - where are the references to back it up?

Here is a reference quote from a reliable source:

"a detailed study for the UK National Grid states "We have estimated that for the case with 8000MW of wind needed to meet the 10% renewables target for 2010, balancing costs can be expected to increase by around £2 per MWh of wind production. This would represent an additional £40million per Annam, just over 10% of existing annual balancing costs."

This is a paltry £0.11/MWh of if you divide total power produced in the UK into the extra balancing costs.

source: http://www.eurotrib.com/story/2007/1/28/183633/609

Ramping Rates Nanticoke power station

It can ramp up its output by 11,000 kilowatts a minute – almost 15 times the electricity generated by the CNE wind turbine. In four hours, it can go from idle to full throttle. http://www.thestar.com/SpecialSections/EarthHour/article/299725

Can wind give firm power?

Apparently yes:

"26 GW of wind provides 6 GW of firm power - Comes from a detailed statistical analysis by UK National Grid Transco - NGT - I think its 5 GW of gas plant, actually. A bit more background in: "A shift to wind is not unfeasible" by Dale, Mil borrow, Slark and Strbac, Power UK 109 "- Source - David Millborrow - ex CEGB (UK Central Electricity Generating Board)

Some authorities think it is misleading to call renewables intermittent, whereas conventional large plant clearly are

(What they mean is, that whereas large plant like Sizewell can and do fail suddenly, the equivalent sized wind farm simply cannot suddenly fail simultaneously whereas, its power might fade away over some hours.)

To: Dave T,

Well said. Which is why I have been arguing for some time that wind, wave, tidal and solar should be described as "variable", rather than "intermittent". Nuclear, coal and gas are intermittent: when Sizewell trips out, 1200 MW are lost rather quickly!

Best regards

David Mil (Ex UK Central Electricity Generating Board and co author of many of the papers listed in the main article under further reading)

David Toke <tokedy at adf.bham.ac.uk> wrote: Dear All, Some of you may have noticed yesterdays news story about how ‘hundreds of thousands’ suffered power blackouts after the sudden (unplanned) failure of over 3GWe of nuclear and coal power station failure (‘within a few minutes’). See http://news.bbc.co.uk/1/hi/uk/7422817.stm I do find it very irritating that this is turned around and put down as something to do with a lack of power stations.

What, at the end of May!

It was nothing of the sort. It is a clear case of how the traditional power station set-up is just as vulnerable to mass blackouts as intermittent sources (while we’re in a tizzy over the possible impact of large volumes of wind power). Now, granted, we do need research into how intermittent generation sources are going to affect things, and we need to build up the ability of the system to respond quickly to unplanned changes in supply side availability, but let’s pour cold water on this notion that wind systems are inherently more vulnerable to blackouts from unplanned outages than traditional power systems. We’ve seen the data on how storms in Denmark cause wind farms to go offline. But does it, or is it going to, happen with windfarms at the rate of 3GWe in ten minutes? The records of hurricanes in Denmark that I have at my disposal suggests that this rate of loss occurs over hours, not a few minutes. What I do find interesting is the lack of discussion by major power companies on the dangers posed by real unplanned outages by conventional power stations compared to the siren alarm calls over the problems that are going to be caused by windfarms.

Yes, we urgently need a lot more demand response methods (and also an increase in standby generation response rates using existing plant), but this is required just as much for the sake of the problems caused by the great lumbering conventional coal and nuclear dinosaurs as much as an anything else! Best Wishes, Dr Dave Toke

Intermittency exists in conventional power grids

From BBC UK power supply back to normal Wed - National Grid Wed May 28, 2008 5:07am EDT Email | Print | Share| Reprints | Single Page| Recommend (-) [-] Text [+] LONDON, May 28 (Reuters) - Britain's power supplies returned to normal on Wednesday after a series of unexpected plant shutdowns briefly cut off hundreds of thousands of people on Tuesday, network operator National Grid (NG.L: Quote, Profile, Research) said.

The almost simultaneous shutdowns of British Energy's (BGY.L: Quote, Profile, Research) Sizewell B nuclear power station and Scottish Power's (IBE.MC: Quote, Profile, Research) Longannet 1 coal-fired power plant caused local network trips, which left parts of the country without power.

Although the blackouts were resolved quickly, more unexpected plant shutdowns later in the day saw National Grid warn about possible volatage reductions and plead for more units to be made available.

But supplies were comfortable again by Wednesday morning, with Longannet restarting overnight and other generating units responding to the calls for more power.

"Some of the power stations that went off yesterday have come back and other generation has become available so it's back to business as usual," a spokesman for the grid operator said on Wednesday.

British Energy (BGY.L: Quote, Profile, Research) chief executive Bill Coley said on Wednesday that the company expected to restart the 1,180-megawatt Sizewell B power station within days.

"It appears to be an instrument problem. There is no issue with the plant and it should return (to operation) very quickly," he told reporters. (Reporting by Daniel Fineren)

French electricity networkoperator thinks that wind can replace capacity

If I may quote the 2007 RTE report (French electricity network operator, big PDF, in French), p.49

The second point is about wind's contribution to peak demand: despite wind's intermittency, wind farms reduce the need in thermal power plants to ensure the requisite level of supply security. One can speak of substituted capacity.

The capacity substitution rate (ratio of thermal capacity replaced to installed wind capacity) is close to the average capacity factor of wind farms in winter (around 30%) for a small proportion of wind in the system (a few GW). It goes down as that proportion increases, but remains above 20% with around 15GW of wind power.

RTE was really wary of wind, and has turned around quite spectacularly. Their report takes pain to explain how France benefits from some special factors (the total decorelation of wind regimes between the Mediteranean, Brittany and Northern regions, and the fact that most of its thermal capacity is already available for peak capacity), but the fact remains: a wind MWh fully replaces a thermal MWh, and creates no additional requirement for thermal reserves.

Jérôme

Danish Windpower experience and references

Dave,

Energinet.dk: Environmental Report 2008, table 1:

Key figures 2007

DK East
DK West
DK total

Wind share of net generation in the area

11,8 %
23,8 %
19,4 %

Wind share of consumption in the area

11,3 %
26,3 %
20,3 %

RE share of net generation in the area

22,2 %
31,5 %
28,1 %

Electricity accounts for the grid 2007

GWh
GWh
GWh

Electricity generation ex plant (gross incl. own consumption)

14.622
24.749
39.371

Electricity generation ex plant (net excl. own consumption)

13.653
23.371
37.024

Import, gross

4.053
6.266
10.319

Export, gross

3.233
8.041
11.274

Transmission grid losses

252
488
740

Sales to distribution

14.221
21.108
35.329

Specification of electricity generation

GWh
GWh
GWh

Electricity from wind

1.609
5.562
7.171

Electricity from hydro power and photovoltaic

0,09
30
30

Electricity from thermal production based on VE fuels

1.428
1.764
3.192

Electricity from thermal production based on non-VE fuels

10.616
16.016
26.631

So far the report is available in Danish only. Translations are from Environmental Report 2007,

http://www.energinet.dk/NR/rdonlyres/20F79A25-71A2-4B69-9F2E-125B6703F345/0/EnvironmentalReport2007.pdf

Reference to the 2025 target:

http://www.ens.dk/graphics/Publikationer/Energipolitik_UK/Engelsk_endelig_udgave_visionaer_energipolitikA4.pdf

I shall look for German figures.

Regards,

Paul-Frederik

............. Dave A,

According to the German Wind Energy Association............

19,460 wind turbines with a total capacity of 22,247 MW were installed in Germany altogether by the end of 2007. 39.5 TWh of wind electricity were generated during this year. These are over 7 % of Germany’s electricity consumption.

I defer to Paul for DK.

Best regards

David Mil

definitions of intermittent and reliable

I don;t know if people have looked, but there is a table of useful definitions to be used in this context, lower down in this article. There is a distinction between intermittent, reliability, and variability. It is the fact that wind is variable, sometimes down to zeros, which requires there to be an alternative source of power, which is of course the fossil or or otherwise stations already built. To keep these on standby does not cost a lot of money on the final bill to the consumer if you bother to work it out.

The fact that wind is highly reliable, in terms of the definitions, albeit slowly variable, and intermittent, means that less spinning reserve needs to be held available, and this avoids wasting fuel, and has been costed in the UK by modelling experts - eg Andrew Smith of London Analytics, as costing about max 0.5 p/kWh. Which is not a lot compared to end price of 10 p.Engineman (talk) 14:31, 8 April 2010 (UTC)

This isn't true. For nuclear plants in particular, capital costs are by far the largest factor. It costs nearly as much to run a nuclear plant 30 minutes a day as it does to run it 24x7. Coal plants also have a large capital component. As for costs, while some pro-wind proponents have tried to claim otherwise, the facts are against them. Denmark, the nation with the largest wind penetration (19.6%), has by virtue of that the most expensive electricity in the modern world. Further, they can only get that degree of penetration by selling a large portion of their wind energy to the EU grid at night, then buying back (much more expensive) dispatchable power during the day. FellGleaming (talk) 14:38, 8 April 2010 (UTC)

Err? No. Denmark doesn't have the most expensive electricity in the world because of wind. We have high electricity prices because of taxing. Taxing energy is thought to be an incentive to save energy (and it is). For instance if you compare prices with tax Copenhagen is the most expensive city in Europe, but if you remove taxes, it becomes the 3rd cheapest.[2]

Secondly the Danish wind capacity has two drawbacks that aren't considered: One of these is that state, education and industry together have made it very cheap and easy to put up turbines - to ensure that Denmark can be used as an exhibition ground for new turbines. Its one of Lomborgs points that our wind-capacity has been more expensive to put up, because a lot of these are new turbines, where the supply-demand hasn't set a price yet. --Kim D. Petersen (talk) 01:56, 9 April 2010 (UTC)

--I'll have to refute what FellGleaming has said as well. Iowa, in the U.S., now has reached nearly 20% penetration of wind power, comparable to Denmark. The price of electricity has not gone up any faster here than in the rest of the U.S., in fact it's gone up less. Wind generated electricity from Iowa is sold to utilities in other states. And I'm sure Iowa imports electricity at times from other states as well (S.Dak, for instance). 'Yes, wind power is not workable' said the Iowa farmer, laughing all the way to the bank.--71.214.221.153 (talk) 00:30, 30 April 2010 (UTC)

This isn't true at all. Even without the tax burden, Denmark still has the most expensive electricity in Europe. Compare it to Greece, for instance. Consumers in Greece pay less than 1/3 the cost for electricity as those in Denmark:

• http://www.cbs.nl/en-GB/menu/themas/prijzen/publicaties/artikelen/archief/2006/2006-1945-wm.htm

Subtract out the electricity tariff from both nations, and electricity in Denmark is still nearly twice as costly. And this is at only a 20% wind penetration level! Source:

• http://www.energy.eu/#industrial

In 1995, Denmark's price for electricity was 45% below the European average. But then the the radical plunge into windpower began to take its toll.

Almost half the wind energy Denmark generates, it can't use. Instead, it has to "dump" it into the EU grid, at fire sale prices. Denmark is then forced to buy back much more expensive energy on the spot market, when demand is high. This, combined with the naturally higher per-KWh cost of wind anyway, is the reason Danes are so heavily penalized for electricity prices.

Your final point makes no sense. Because the state subsidizes wind turbines, thus making them cheaper to put in production, that somehow makes the power from wind more expensive? That's entirely opposite basic economics. FellGleaming (talk) 04:31, 9 April 2010 (UTC)

I don't know what references you are actually using - because the ones that you actually link - doesn't show what you claim it to.

First link shows that Denmark has the highest taxes in Europe - but electricity prices (w/o tax) lower than all other western european countries except: Sweden, France, Spain, Finland, UK and Greece. Its 9th out of 15.

Second link (with taxes) show that we're below Italy and Cyprus (no matter how much energy you use). It also indicates that the Danish tax idea at least has some merits - since we are the country with the lowest Energy dependency.

As to your final point: Danish subsidizing of turbines doesn't work the way you think. Wrong assumption => wrong conclusion. --Kim D. Petersen (talk) 09:25, 9 April 2010 (UTC)

I missed Italy, my apologies. Cyprus can't be directly compared, for a number of reasons. In any case, I think you're missing the point here. Denmark has vast reserves of oil and natural gas. Most European nations have little to none. Denmark should have energy costs far below the EU average -- and in fact, it did, until it began investing heavily in windpower. Now its energy costs are second only to Italy....and with only a 20% reliance on wind.

But my second point is the one that's germane to this article. Denmark can't use half their wind-generated power; they're forced to sell it at a loss to the EU grid, then buy back dispatchable power at higher rates. They're also trying desperately to generate even larger "market signals" (e.g. higher prices) to force consumers to use less power when the wind isn't blowing. This speaks to the very heart of the problem with intermittent energy sources. FellGleaming (talk) 23:18, 10 April 2010 (UTC)

Ok. So here we have Denmark, with so much wind generating capacity, that when the wind is strong, it can use only half the electricity. It sells the other half to Norway. Now Norway normally get's its electricty from hydroelectric generators. So it just cuts back on hydro power and uses the wind generated power from Denmark. Now later on, the wind isn't blowing, and Norway, with excess hydro capacity opens up the gates and generates electricity for both Denmark and itself. Norway can charge a bit more for it's power because its not generated at the mercy of the wind. But let's suppose Denmark hadn't constructed all that wind capacity. It would be generated using the relatively more expensive coal, or petrolum (more expensive than either wind or hydro). So overall Denmark hasn't gained as much as it might have using wind power, but it is still ahead! Nothing I've said here contradicts the statements you made about the Danes selling windpower and buying it back. (P.S. they aren't selling it at a loss, as the marginal cost for wind generation is nearly zero.) --71.214.221.153 (talk) 01:07, 30 April 2010 (UTC)

They can and sometimes do sell it at a loss. As of last year, the minimum price on the spot market was lowered to −200€ per MW·h It seldom gets below zero, but it often gets below 30, while the price in Norway runs about 50 (see http://www.nordpoolspot.com/reports/areaprice/). So trading power is a good deal for Norway and Sweden, but less obviously so for Denmark.

—WWoods (talk) 18:53, 30 April 2010 (UTC)

Thanks for the info. It certainly is a good deal for Norway and Sweden. What I was trying to point out is that wind power might still make sense for Denmark even uder the situation described by FellGleaming. I'm not familiar with the economics of their system so I can't say for certain it does. --71.214.221.153 (talk) 20:18, 30 April 2010 (UTC)

Reliability of large wind penetrations

"Paradoxically, for very large penetrations of the most intermittent source, wind energy, such sources when taken together become highly reliable, and whilst the aggregate output can change as weather changes, this is highly predictable and relatively slow, and becomes much more reliable than say a single large power station which can (and do) fail suddenly and unpredictably. (This section in not accurate and should be corrected or removed) "

Why does this need a reference to modelling studies - surely it is a statement of the obvious, it is self evident with a little thought?

A large 2000 MW power station can fail instantaneoulsy. The wind over the whole of the UK cannot fail instantaneoulsy. Moreover any change in wind output can be readilly predicted at least hours or even minutes ahead, again self evidently. 400 x 5 MW wind turbines, cannot all suddently breakdown instaneously and simaltaneoulsy.Engineman (talk) 11:49, 3 April 2010 (UTC)

Your reasoning is fallacious. First of all, wind turbines are not distributed smoothly over an entire nation. They tend to be grouped in large farms, and wind speeds can and do fall over areas as large as the UK. Further, predicting a failing wind does not solve the problem -- your source is still intermittent, and you need an alternative. Finally, an entire wind farm can fail without warning, even though the original turbines may not, those turbines still rely upon upconversion and transmission. A failed transformer or broken line can take the entire farm offline instantly.

But the most compelling reason it needs to be sources is basic WP policy. All content must be verifiable. The above statement is original research and reflects the opinion of one or more editors. It also doesn't align with real world data, which has yet to see wind turbines achieve more than a 35% capacity factor over a national area. FellGleaming (talk) 05:09, 5 April 2010 (UTC)

There is a useful distinction between reliability and intermittency. Whilst a power station can fail instantaneously, ie we can lose 2GW in the time it takes for the breakers to open - this simply cannot happen under any conceivable circumstances with the number of turbines that would be needed to generate the equivalent 2 GW. They cannot individually suffer a simultaneously breakdown, and the wind cannot instantaneously suddenly go to zero all over the country. And if there were 2 GW of wind, they would be distributed. Therefore it is quite clear that wind turbines in large penetrations are highly reliable compared to power stations, but intermittent.Engineman (talk) 16:27, 5 April 2010 (UTC)

The widely agreed fact that turbines need another source of power when there is no wind is irrelevant to the argument. As indeed is the low load factor. Wind turbines are essentially fuel savers not capacity savers.Engineman (talk) 16:27, 5 April 2010 (UTC)

There are several fallacies in the above, and a good indication of hy WP has the wise policy of not allowing origiinal research. The first is a basic error in statistics. While the chance of simultaneous failure of a group of units is less than that of any single unit, the chance of individual failures is much higher. Comparing 10 nuclear reactors to 10,000 turbines, you will often have all 10 reactors online at once, but you are very unlikely to have all 10,000 turbines working simultaneously. Further, since grid capacity are always designed to handle the loss of (at least) a single unit, even a large 2GW nuclear plant, calculating based on a single failure is irrelevant. What matters is the availability factor, the percentage of time an aggregate of the respective units is expected to be functional.

Ahh - you undermine your own argument with 'availability factor'. Nuclear units go off line for a month at a time for refuelling and maintenance. This happens about each 18 months. Availability factor: 17/18 (94%). I just read a reference on wind power - availability factor 95% and increasing. --71.214.221.153 (talk) 23:34, 29 April 2010 (UTC)

Refueling can be scheduled years in advance for periods when demand is low. A wind turbine may be in perfect working order, but if there's no wind, it's just a fancy lawn ornament.

—WWoods (talk) 19:03, 30 April 2010 (UTC)

Further, as I've already pointed out, while 1,000 turbines will not fail simultaneously, a transformer they are feeding can, which would take out the entire farm at once. There are single points of failure in wind farms.

Still further, winds can and do fail over large areas simultaneously. Would they fail over an area the size of the entire USA? No, but since you don't service the entire USA with a single nuclear reactor either, the point is moot. Failing wind can take out an entire wind farm, 10,000+ turbines, an amount of power equal to that of a single nuclear reactor. QED FellGleaming (talk) 15:21, 5 April 2010 (UTC)

Typical power of reactor: 600 MW. Typical power of wind turbine: 1.67 MW. 600/1.67 = 360. Typical size of a wind farm 150 MW, (that could be 60x2.5MW or 75x2.0MW or 90x1.67MW or 100x1.5Mw). My point? - Get your numbers right, at least in the right ballpark.--71.214.221.153 (talk) 16:48, 30 April 2010 (UTC)

Yes winds do fail, but the point is, from the reliability definition point of view, they do not and cannot fail in the time it takes for a breaker to open on a large power station. Hence GW for GW on that basis, wind energy is more reliable, and this means that less spinning reserve is likely to be needed at any one time.

Regarding the transformer issues, at worst this puts them on the same footing reliability wise as power stations. If transfromers is an issue than clearly you might have several transformers per 1000 wind turbines and multiple points of connections.

It remains the case then, that a countgry with a high proportion of wind energy is as reliable in the sense of leading little spinning reserve as conventional stations. It would of course need conventional back up, but this is already exisiting ie the power stations we already have.Engineman (talk) 16:27, 5 April 2010 (UTC)

Again, this is fallacious thinking, as any power engineer will tell you. Wind turbines generally have a CF of around 30%, meaning you need 3 times the reserve to continually generate the rated output. For nuclear, the CF is generally 90%, meaning you need only a 10% reserve.

Finally, I have to remind you that what you are attempting to do is a violation of WP:SYNTH and WP:NOR. All WP content must be verifiable with reliable, external sources...not your own theories and conclusions. FellGleaming (talk) 16:41, 5 April 2010 (UTC)

Capacity factor (CF) is not what you want here, you're talking about capacity credit. There has been a study that has determined that it's possible to integrate up to 30% wind power on the U.S. eastern grid without too much problem (except for the problem of limited Transmission Grid capacities.) The report stated that dealing with variability of wind generated sources (due to changing wind conditions) was not a problem, dealing with sudden load increases/decreases is a much harder problem. Widely distributed wind farms would allow more of wind generated power to be treated as baseload power. (This was also stated in the report.) --71.214.221.153 (talk) 00:05, 30 April 2010 (UTC)

Wind may be 'reliable' in the sense that you can forecast what you're going to get ... more or less, in the near future .... See Ireland's wind production. However, it utterly fails to be reliable in the sense of being there whenever you might want power. See the Pacific NW, Germany, Ireland. Even in theory it fails — see the Jacobson paper referenced in the article, which says that at best 20% of wind capacity can be counted on, for a weak definition of counted on. And Jacobson is a big, big fan of wind.

Yes - we know that - wind power does need back up, and now one is trying to argue the contrary, but that is the power stations we already have and these can be started in the predictabel times scales within which wind can vary, becasue wind is relialbe in that sense. This means less wasteful spinning reserve. Engineman (talk) 23:39, 7 April 2010 (UTC)

"The widely agreed fact that turbines need another source of power when there is no wind" is a nice way of saying that wind is not reliable. "Wind turbines are essentially fuel savers not capacity savers." This is true.
—WWoods (talk) 20:57, 5 April 2010 (UTC)

The point is everyone accepts that wind will need a certain amount of back up for when there is no wind. That is because it is intermittent. But it is highly reliable in the sense that it cant disappear as quickly as say a 2 Gw power station can. That means it is highly reliable - its rate of change can be calcualted with much greater certainty than can a conventional power station. This means that less spinning reserve is needed. No one is saying that no back up is needed.

I quote a power engineer, who used to work for the UK CEGB and has written many learned papers on this subject

"Chris,

You take me to task for saying:-

it is extremely unlikely that 1000 MW of dispersed wind will disappear instantaneously',

but do not refute it. On a number of rare occasions the DK-W wind power excursions have registered a 20% change of the rated capacity in an hour. (I think that includes the example you quote, but have not had time to check). Assuming the same would apply in UK, we might very occasionally experience a 6 GW hourly change from 30 GW of wind. That's a bit more than the UK system has to cope with at the moment during the evening peak from consumer demands.

But what matters is the combined change, and in Proc Inst C.E. Issue EN3, and using real DK-W data, I showed that the maximum hourly excursion (with 26% wind) in 2007 went up from 675 MW to 900 MW. Not, I would suggest, unmanageable.

As Energinet have looked at (and quantified) the implications of operating the western system with 100% wind (without the external links, or storage), and NGT have suggested the issues are technical, not economic, I do not consider there is cause for concern. The wind penetration will build up gradually, so there will be time to identify problems and evolve remedial measures.

Best regards

David MEngineman (talk) 23:39, 7 April 2010 (UTC)

See BPA Balancing Authority Load and Total Wind Generation, Near-Real-Time (power operators in the US Pacific North-West). This is real wind production data in a area over 30,000 square miles with 27 separate sites well distributed (if you're skeptical, here is a map). Wind capacity has been rapidly increasing and they've posted records since 2007 when capacity was about 1/2 what it is now. See this page of documents for some various things they compile. Now, most important, see the Excel book that covers major wind ramps for the exact answer to what you're asking about. It has a list of the largest swings in power.

Total capacity ranges 1496 MW to 2780 MW

Time frame	Largest increase	Largest decrease
in 1 hour	1385 MW	-1097 MW
in 30 min	919 MW	-739 MW
in 5 min	421 MW	-724 MW

That was the worst. But is this a common occurrence? I'm posting this reply on April 29, 2010. On 4/27/2010 at 3:20pm, wind generation was 722 MW. On 4/27/2010 at 4:25pm wind generation was 1721 MW (first link). That's an increase of 1 GW (around 1/3rd wind capacity) in 65 minutes, on Tuesday of this week. Let me revisit the claims. I'll consider the first point covered aside from individual's definition of instantaneously.

• "it is extremely unlikely that 1000 MW of dispersed wind will disappear instantaneously."
• "I showed that the maximum hourly excursion (with 26% wind) in 2007 went up from 675 MW to 900 MW."

Please show me the source from which you calculated this (2nd bullet) in a manner like what I've done here. You should be unsurprised to hear that I don't believe it. -Theanphibian ^{(talk • contribs)} 02:07, 30 April 2010 (UTC)

The BPA is in an enviable position with respect to being able to add wind power capacity to it's grid. That's because most of it's other power is generated using hydro, which can quickly respond to load changes. I could see BPA being able to add wind capability to its grid to the point where it's equal to the capacity of its hydro dams (and that's a boatload of capacity). So when the wind blows - it uses wind power. When it doesn't - it uses hydro. --71.214.221.153 (talk) 18:08, 30 April 2010 (UTC)

I completely agree. There are issues with dam management and effects of fish populations with the quick ramps, but ideally they won't happen many times in a day and can be well prepared for. Whether or not wind power providers should pay an integration fee for this inconvenience, which is what BPA argues, is another story. -Theanphibian ^{(talk • contribs)} 23:24, 30 April 2010 (UTC)

Someone made a statement above saying the windfarms are 'well distributed'. This is grossly incorrect. The windfarms are mostly all located in a small region of Washington. About half of them are located within a radius of 20 miles from a point 40 miles east of the Dalles. (See the map). It's easy to see why the wind power output can vary 50% over the course of a half hour. Grid operators say wind power is highly predictable over the course of 15 minutes. That doesn't mean it can't change a lot in 15 minutes. It means that they generally have 15 minutes 'notice' in which to respond to the change. Nuc plants can't respond this fast. Coal fired plants might have difficulty. No problem for gas or hydro. --71.214.221.153 (talk) 18:08, 30 April 2010 (UTC)

The map covers 30,000 square miles. Small region of Washington? On what planet is 30,000 square miles is small area of anything? Washington state is 71,000 square miles. Don't believe me? Look at the scale, divide the image, multiply, you obtain close to 30,000 square miles. Are large swaths of the map lacking wind turbines? No. There is 108 MW farm 5 miles from the top and a 110 MW farm 5 miles from the bottom boundary. The majority are distributed (mostly) linearly along the river going east-west. Your qualitative observation that "half" are within some boundary (that is also very large) is not very helpful. In addition to this point - do you think they SHOULD have spaced them out better? The reality is the there is a spatial intermittentency of "good" and "excellent" wind locations. The area they cover is monstrously large (even though you seem to think it's small) and benefits from being fairly flat, rural, and having high wind. Because of this the wind farms are well distributed (even though you think they aren't) and most other areas on Earth will dictate that they be clumped much tighter. See Cape Wind, packing 454 MW into 24 square miles. Do you care to continue to demonstrate the propensity of wind advocates to hyperbole?

There is good prediction in the 15 minute time frame, and this is well documented on the BPA site. And you are correct to say that steam plants don't respond well either way. I would only add that gas plants only respond well if they're not combined cycle (and thus less efficient). So be careful what you wish for. -Theanphibian ^{(talk • contribs)} 23:24, 30 April 2010 (UTC)

Are large swaths of the map lacking wind turbines?Yes. And,even though the map may cover 30,000 square miles, half of the wind farms could be shown on a map of just 1500 square miles. That's a very small area in compared to the size of weather systems, which is why the power output from the various farms are highly correlated. --71.214.221.153 (talk) 03:32, 11 June 2010 (UTC)

Copyedit needed

A list of bullet points is not an encyclopedia article; this needs a rewrite into prose form. The article is now a forest of see-also links, which disturbs the flow and seems redundant. There are too many one-paragraph sections and there seems to be some redundancy in descriptions of forms of power plants. --Wtshymanski (talk) 13:36, 4 July 2010 (UTC)

Denmark numbers

This article seems to contradict the 20% figure quoted for Denmark's wind production.

http://www.cepos.dk/fileadmin/user_upload/Arkiv/PDF/Wind_energy_-_the_case_of_Denmark.pdf

The article argues that over half of the electricity generated in Denmark from wind is exported (at very low, or even negative prices) and so the figure should be more like 9.5%. It seems that Denmark is actually being charged for the service of evening out its volatile electric grid, i.e. negative spot prices for energy imports in neighboring countries. http://www.pfbach.dk/firma_pfb/statistics_2009.htm

While Denmark pays full price to import energy when the wind has stopped of course...

See the Wind power in Denmark article.

The problem is how to credit intermittent electricity when supply is large and demand is low. We are getting to the point where they will be building stations that simply dissipate electricity to get rid of it when the wind is blowing too hard. IDK112 (talk) 09:23, 30 May 2011 (UTC)

The CEPOS paper got refuted within weeks of publication, though, didn't it, by Henrik Lund et al at CEESA http://www.energyplanning.aau.dk/Publications/DanishWindPower.pdf ? So the Sharman CEPOS report is not a usable reliable source Ernestfax^Talk 16:07, 30 May 2011 (UTC)

I'm not sure that I agree with the logic in the CEESA report. They show that both wind turbines and large power plants have a positive correlation between generation and export, and say that this proves that wind power doesn't lead to higher exports and that wind generated power is mostly consumed locally. I'm still not seeing that.

I think the basic point that variable wind generation sometimes produces a useless excess of electricity is still valid, and that the article shouldn't say that 'Denmark produces 20% of its power with wind' if a lot of that power is being exported and can't be used to meet local demand.

I do know that Norway reduced the minimum spot price they can pay for imported Danish power, apparently due to increasing variability in Denmark's supply and increased exports from them. This seems like pretty strong evidence that wind power has been creating large surpluses that have to be exported.

I can't claim to be an expert though. Go ahead and delete this entire section if you're convinced the CEPOS report is bogus.... IDK112 (talk) 01:31, 5 June 2011 (UTC)

Looking at the CEESA report more closely, I completely disagree with their logic. It's true that the wind turbines have the lowest merit order, but that completely doesn't matter. Coal, nuclear and other large thermal power plants are limited in their ability to load follow, and end up transmitting electricity to Norway for pennies on the dollar whenever wind is peaking. Arguing that these conventional powerplants already export some does not in any way prove that wind isn't making things much worse. The true calculation for how much wind contributes to Denmark's power production should be:

Wind Production / Total Production ** NOT** Wind Production / Total Demand

And obviously that is going to be lower than 20% IDK112 (talk) 01:51, 5 June 2011 (UTC)

if you accept the merit-order argument (and it is written in law, as well as the laws of economics), then the CEESA argument about exports must hold, pretty much by definition, as it's what's last in the merit order that gets exported, because that's the economically marginal plant. By the way (not that it's relevant), different thermal plants have different responses: nuclear is indeed relatively poor, but coal, gas and biomass are good. Storage hydro is superior to all of them, sure. I don't think any of Denmark's thermal plants are nuclear, are they? Do bear in mind that minute-by-minute balancing and exports are two very distinct things: that is to say, it's possible to export variations in power, without exporting power itself. As I understand the figures and reports, It's (some of) wind's variations that get exported, not its power. We agree that the calculation for how much wind contributes to Denmark's power production is Wind Production / Total Production. But the questions here was (if I understand this correctly), the contribution of wind to Denmark's power *demand*, which is (wind production - wind exports + wind imports) / total demand Ernestfax^Talk 06:59, 5 June 2011 (UTC)

I apologize, you're right that Denmark has no nuclear power, I was thinking of Sweden... :/

I don't really buy the merit order argument. All merit order says is that wind plants are less likely to be shut down that other energy sources when demand is low. The correlation between high wind penetration and low export prices seems pretty conclusive to me that the exports should be considered wind power.

Natural gas and oil plants tend to be ok for load following, but not so much with biomass and definitely not with coal. Since half of Denmark's electricity comes from coal, there is clearly some inflexibility in their power supply. Which is why they use all that lovely Norway hydro power to balance it out. But even if its coal power that is being exported, it is wind power variations that are leading to the increased export. It seems that this should be accounted for in the formula, like maybe: (wind production - exports due to wind variability + imports due to wind variability in other countries) / total demand

But of course how do you quantify that? I guess I should delete this section of the talk page, since we are not going to achieve consensus. The Wind power in Denmark page does a good job of describing the debate, so I should just be happy with that I guess. IDK112 (talk) 16:52, 6 June 2011 (UTC)

I'm a little surprised that you consider coal to be poor for load-following - what's your source for that? And remember - correlation is not causation. Danish coal plants are more efficient than their neighbours', (see e.g. Platts database of power stations) so when grid prices are low, Danish coal can afford to run and German plants can't, hence Denmark exports energy. Ernestfax^Talk 20:36, 7 June 2011 (UTC)

Correlation is not absolute proof, but I think the rise in wind penetration and the correlated rise in regional spot price volatility is pretty strong evidence that wind power causes increased imports and exports. I don't think anyone is really claiming that Denmark could operate right now (for long) without grid access to the rest of Europe. Coal power can be used for limited load following, but the economic losses for the owners are much higher then when using more expensive fuel sources. You say that Danish coal plants are more efficient than others in Europe; I believe you. That probably means they are newer and use injected coal dust and combined cycle technology. If that's true, then they are probably worse at load following than older, less expensive and more robust plants. This: http://www.wecc.biz/committees/BOD/TEPPC/TAS/DWG/Shared%20Documents/Generation%20Cycling%20Documentation/The%20Cost%20of%20Cycling%20Coal%20Fired%20Power%20Plants.pdf comes up on the first page of google hits for "coal power load following" Also, the wikipedia page for Load following power plant does not mention coal. Partly this is just semantics, but I really don't consider coal power plants to be flexible enough to handle the variability issues associated with wind power. IDK112 (talk) 16:13, 14 June 2011 (UTC)

Intermittency of conventional plant

There seems to be a number of articles in which conventional generators are deemed to be "intermittent", which is a novel and unorthodox use of the term, and appears to be original research. In normal use the UK National Grid's definition provides a guide to the usual use of the term:

"For the purposes of this report National Grid has interpreted ‘intermittent’generation as renewable plant that does not have full control over its primary fuel source to the extent that it cannot plan in the longer term to run at maximum output at times of system peak." http://www.nationalgrid.com/NR/rdonlyres/459CB43B-5098-4F4E-9240-E969B713EE7B/9239/Condition3reportfinal.pdf (page 3) Given this, the section needs should be adjusted accordingly.GrahamP (talk) 07:22, 24 July 2011 (UTC)

With regards to the "UK National Grid's definition", it is not a definition at all, but an "interpretation ... for the purposes of this report ... [which] is not necessarily a common view", as this quote says:

"For the purposes of this report National Grid has interpreted ‘intermittent’ generation as renewable plant that does not have full control over its primary fuel source to the extent that it cannot plan in the longer term to run at maximum output at times of system peak. As highlighted in the summary of responses, this is not necessarily a common view across the whole industry".

With reference to your suggestion about a "novel and unorthodox use of the term" with regard to nuclear power, what source do you have that makes this claim about being "novel and unorthodox"? I know of several notable scientists who are using the term intermittency to apply to nuclear power. Johnfos (talk) 02:07, 20 February 2012 (UTC)

They may be notable, but they are pushing a tendentious argument. The graphs here show what an intermittent source looks like. Hence all the talk about the need to mitigate the problem with large-scale storage, smart grids, and continental-scale transmission. By contrast, US nuclear power has a capacity factor over 90%, even including scheduled downtime for maintenance and refueling. That's about as far from intermittent as is humanly possible.

—WWoods (talk) 01:23, 21 February 2012 (UTC)

Yes, thankfully there are some positives with US nuclear. But it is when I think of the situation in Japan, the Kashiwazaki-Kariwa Nuclear Power Plant and the Fukushima nuclear disaster, that I think of intermittent nuclear. As physicist Amory Lovins says: Nuclear power plants are intermittent in that they will sometimes fail unexpectedly, often for long periods of time. Scientists who talk of nuclear intermittency are not presenting a tendentious argument, they are presenting a significant minority view. It doesn't need to be mentioned in the lead of the article, but should be covered in the body of the article in the usual way. Johnfos (talk) 05:32, 21 February 2012 (UTC)

In over 20+ years professional experience, I have never seen an electricity supply authority or electrical generation publication refer to any baseload source as "intermittent" (including nuclear, coal, CCGT). I provided the UK reference as a starting point. I have no objection to further discussion if you can provide a reference from an authoritative electrical supply authority, publication, or another authoritative electrical engineering source that describes nuclear as "intermittent". GrahamP (talk) 02:41, 21 February 2012 (UTC)

If you are moving in narrow electrical engineering circles, I'm not surprised that you haven't heard of nuclear intermittency. Thankfully, other disciplines have a contribution to make too. Some of the views of physicist Amory Lovins are discussed in this article, at Intermittent energy source#Nuclear power, and so don't need to be repeated here. Mark Diesendorf trained as an applied mathematician, and some of his ideas on the intermittency of conventional sources are at Greenhouse Solutions with Sustainable Energy#Wind power variability. Tom Burke (environmentalist) has said: “It is true that the sun does not always shine or the wind blow. What is less obvious is that nuclear electricity is also intermittent though for different reasons. Sometimes this is planned, over 10% of the time, on other occasions it is not. In both cases it means a lot of power is lost all at once”. [3]

You may also be interested in an article by Mark Z. Jacobson (environmental engineer) in Scientific American: "A Path to Sustainable Energy by 2030. Johnfos (talk) 05:32, 21 February 2012 (UTC)

Johnfos, thanks for your comments.

1) I am already well acquainted with 3 of the authors you provided. Can I recommend a reference which discusses intermittency by Vaclav Smil, who famously said about Lovins “Inexplicably, Lovins retains his guru aura no matter how wrong he is.” [4]

Personal attacks on Lovins are not appropriate here. If you want to challenge something he has said, you need a sourced counter-argument, not personal criticism. See WP:BLP. The vaclavsmil.com paper is a 2006 publication. A lot has happened since 2006 and we really need citations that are more up to date. Johnfos (talk) 20:30, 24 February 2012 (UTC)

2) All power sources are subject to unscheduled outages - in the case of baseload plant, this might be say, a single incident a year. The network accomodates this through the use of reserve margins to maintain frequency stability. In the Australian NEM, the rules define less than 0.002% unserved energy averaged over a ten year period. The likelihood of any generator failing is independant of others, therefore only a few generators can provide very high reliability.

The risk of unscheduled outages plant is quite different to the stochastic profile of wind. In the Australian NEM, total wind generation is frequently less than 3% of capacity. On 20/21 June 2010, the entire NEM wind capacity was below 5% for 33 hours continously, then rapidly ramped up and down to 60% by the 24th. Similar events occurred between the 1st and 5th, and 12th and 16th due to slow moving, large, high pressure systems across the continent - under these conditions, geographic spread provides little "smoothing". This needs to be actively accomodated and is defined as intermittency. Baseload plant performs a role within a grid, along with intermediate and peaking plant and does not need to be accomodated or require "additional" backup or firming for network security. [5]

Some very old-fashioned, pre-Fukushima thinking here. Johnfos (talk) 20:30, 24 February 2012 (UTC)

3) When you drive your car, you apply the accelerator or brake to control the speed of the vehicle. The fact that there is always a risk that your car might break down does not mean that your car is "intermittent". Perhaps if your car broke down hourly, you might begin to call your car "intermittent" (among other things). If your car sped up and slowed down by itself, out of your control, this would also be intermittent.

Anecdotes are of limited interest on WP. We need relevant, reliably sourced, up-to-date, encyclopedic information, see WP:RS.

4) Interesting, even Mark Diesendorf does not claim that coal or nuclear are not intermittent in this article, but rather argues that renewables can substitute for baseload. See for example; [6]

Diesendorf's main point of relevance here is that every conventional power station breaks down unexpectedly from time to time, causing an immediate loss of all its power. That is true intermittency, according to Diesendorf, and it is a particular type of variability that switches between full power and no power. Once a conventional power station has broken down, it may be offline for weeks, much longer than windless periods. Johnfos (talk) 20:30, 24 February 2012 (UTC)

5) Mark Diesendorf and Amory Lovins are well known environmental activists who have sought to confuse the usual meaning of the term "intermittency" in electricity supply because they support renewables. There is nothing wrong with academic activists promoting a particular view - we are fortunate enough to live in a pluralistic society. However, as far as I'm aware, neither has qualifications in running electricity systems, and or is considered authoritative outside of the environmental field.

You are resorting to personal attacks again, questioning the motives and credentials of Lovins and Diesendorf, and calling them “environmental activists”. As I’ve already said above, Lovins trained in physics, and has been writing about power supply systems since 1982 when he published Brittle Power. Seldom have I seen someone who has won so many prestigious awards, see Amory Lovins#Awards. Diesendorf trained in applied mathematics and was a Principal Research Scientist with the CSIRO. Johnfos (talk) 20:30, 24 February 2012 (UTC)

5) The Jacobson article does not define baseload or nuclear as intermittent.

The Jacobson article is good general background reading, and I thought this was quite an interesting point:

"Because the wind blows during stormy conditions when the sun does not shine and the sun often shines on calm days with little wind, combining wind and solar can go a long way toward meeting demand, especially when geothermal provides a steady base and hydroelectric can be called on to fill in the gaps". – Mark Z. Jacobson and Mark A. Delucchi. Scientific American, November 2009, p. 43. Johnfos (talk) 20:30, 24 February 2012 (UTC)

6) I agree with you that perhaps the inclusion of a paragraph that says something like "Amory Lovins claims that ..." outside of the main body may be appropiate, but I'm not sure whether it would add anything of substance to the article, other than promoting an activist viewpoint. Power sources are what they are, regardless of whether people have favourites.GrahamP (talk) 02:32, 22 February 2012 (UTC) (restored text accidentally deleted previously Ernestfax^Talk 09:00, 24 February 2012 (UTC))

We do not use "claims that" as it immediately casts doubt on what is being said, see WP:Claim. Johnfos (talk) 20:30, 24 February 2012 (UTC)

Johnfos, thanks for the comments. I'll simply re-iterate my response to Ernestfax which is that the purpose of this discussion, as far as I can see, is to establish the correct technical use of the term "intermittent". For a more complete discussion of "intermittent", MIT's report available from (large file):
http://web.mit.edu/mitei/research/reports/intermittent-renewables-full.pdf
which states
"Intermittency refers to the limited-controllable variability and partial predictability of a generation resource. For example, solar generation is intermittent because it both varies throughout the day and is not perfectly predictable." GrahamP (talk) 09:18, 18 March 2012 (UTC)

I think Ernest has put it quite eloquently in his comment below. As Ernest says, you are claiming "just one very narrow definition of intermittency. You've now been pointed at technical documents that use it in a broader sense. You seem to be using technical words as they were used in the 1970s and 1980s, from what I've seen of old technical documents. The electricity system, and the language used to describe it, has moved on a lot since then. This article has a golden opportunity to give contemporary knowledge in contemporary language". Johnfos (talk) 16:11, 19 March 2012 (UTC)

There would seem to be something of a language problem here. Maybe it's an issue of different dialects of English; and maybe that's compounded by an ordinary English word which also has a specific technical usage too. Intermittent means it switches on and off, with an implication of abruptness and that applies to pretty much any one generator: one (wind/gas/coal/nuclear) turbine, or one solar panel. However, a wind farm or solar farm as a whole does not exhibit intermittency: it exhibits exogenous variability; it will have times of not generating, but ramps down, rather than trips off, to that state. Thermal plant, such as nuclear, coal and gas, does indeed trip off, and so does exhibit intermittency. That's in the meaning of "intermittent" that I'd take from lay British English. I note, from the authoritative UKERC TPA study of intermittency, that: "Terminology is controversial, many lean towards the term ‘variable’ others toward ‘intermittent’. Neither term is perfect; the outputs of thermal plant are variable too, and can be intermittent, e.g. during faults. There are no unambiguous terms to capture the difference between renewable and conventional plants, except perhaps exogenously variable (e.g. wind) and controlled-variable (e.g. gas), which would be ungainly". For that study, they ended up using "intermittency" to mean exogenous variability of some renewables, but that's because the report's context was renewables anyway. As this article we are discussing here is just on intermittent energy sources, it would seem that we've got the opportunity to set out the intermittent nature of all generating plant, and to explicitly separate out the issue of intermittency from exogenous variability. Ernestfax^Talk 11:45, 21 February 2012 (UTC)

Ernestfax, thanks for your contribution
1) Words have specific meanings in specific contexts. In the context of the electricity supply industry worldwide, "intermittency" has a clear meaning that is well understood. There is no ambiguity at all.
2) The use of terms including "exogenous variability", "tripping versus ramping", "abruptness", and the claims that "the outputs of thermal plant are variable too" and there are "no unambiguous terms to capture the difference between renewable and conventional plants" is merely serving to confuse rather than clarify. There is no ambiguity, no confusion, no language problem: intermittency refers to renewables that are highly variable and substantally uncontrollable. Baseload plant is controllable, dispatchable, can operate 24 hours a day, but like all machines, is subject to breakdowns.
3)One can argue that linguistically "intermittency" is not the best term for renewables. Perhaps stochastic, variable, uncontrollable, undispatchable, whatever. That isn't the purpose of this discussion. The purpose of my WC:NOR was because a section that misleadingly describes nuclear as "intermittent" was being inserted.
4) If this discussion was about, say, medical terminology, we would accept the terminology normally employed by medicos and taught to undergraduate medical students, and accepted by every mainstream medical publication. Take the term "strain", which in medical usage refers to injuries that affect muscles or tendons. Now, a non-medico could get into this long linguistic debate about what the English for "strain" really means, where it comes from, what other things it might mean, maybe stresses and strains are similar, and apply it in different ways. Medical professionals would laugh. — Preceding unsigned comment added by GrahamP (talk • contribs) 02:26, 22 February 2012 (UTC)

GrahamP - it's great that there's no confusion in your mind, and that you're absolutely rigid in your own personal definition. However, you are not the whole energy industry, as my quote from the authoritative UKERC study shows. You'll also find that across the English-speaking electricity industry, "baseload" is used in a variety of different ways. Typically it refers to the plant which comes first in the merit order, ie that with the cheapest short-run marginal cost. By historical accident, that was typically must-run thermal plant. However, that's no longer true: wind and PV are first in the merit order (having zero short-run marginal cost), and are, in technical publications, referred to as baseload for that very reason. To a degree, that just shows that jargon has not kept up with technology (after all, they're not mid-merit, nor peaking plant, so baseload it is). In this article, we have space to clarify all the confusions around intermittency and exogenous variability (both within and outside the industry), some of which are elegantly exemplified on this very talk page and the history of the main page. I'm a little surprised that despite the long industrial experience you tell us of, you've never come across common-mode failure in thermal plants (in your words: "The likelihood of any generator failing is independant of others"), because there have been quite a few, and it's always been known that it was possible: no generation source is immune. This article would be improved with a discussion of common-mode failures for each of the industrial-scale generation technologies. Ernestfax^Talk 12:03, 22 February 2012 (UTC)

Ernestfax, thanks again for your further comments. The purpose of this discussion, as far as I can see, is to establish the correct technical use of the term "intermittent" rather than elaborate on "base load", "merit order" etc. For a more complete discussion of "intermittent", MIT's report available from (large file):
http://web.mit.edu/mitei/research/reports/intermittent-renewables-full.pdf
which states
"Intermittency refers to the limited-controllable variability and partial predictability of a generation resource. For example, solar generation is intermittent because it both varies throughout the day and is not perfectly predictable."GrahamP (talk) 09:15, 18 March 2012 (UTC)

<---------------------

GrahamP - I mention baseload because you raised it first: you claimed that you'd seen no technical documents that "refer to any baseload source as intermittent". But wind and solar are baseload by a standard industry definition: they have zero short-run marginal cost, and so come first in the merit order. The point remains: you claimed just one very narrow definition of intermittency. You've now been pointed at technical documents that use it in a broader sense. So claims for special treatment of exogenously variable renewables fail. You seem to be using technical words as they were used in the 1970s and 1980s, from what I've seen of old technical documents. The electricity system, and the language used to describe it, has moved on a lot since then. This article has a golden opportunity to give contemporary knowledge in contemporary language: we can discuss the different types of intermittency and common-cause failure that affects different types of generator. I can't see why we might want to squander that opportunity. Ernestfax^Talk 06:53, 19 March 2012 (UTC)

Ernestfax and Johnfos, just to re-iterate, the primary purpose of this discussion is to establish the correct technical definition for “intermittent” which I believe I have done, including authoritative references. If you disagree, please provide authoritative references supporting your specific claims - otherwise I encourage you to rewrite the relevant section or remove the offending WOP. Your suggestion that a Wikipedia article provides a “golden opportunity to give contemporary knowledge in contemporary language” seems to explicitly endorse the use of original research - is this your intent or have I misunderstood??
Ernestfax, to address your other comments. According to your definition of 'baseload' as being generators with zero short-run marginal cost, nearly every renewable source would be baseload, but coal and baseload gas, including CCGT would not be baseload - clearly that definition is absurd and incomplete - merit order is quite different to baseload - where are you getting these definitions from? Can you provide any references to support them?
In relation to the suggestion that the electricity system has ‘moved on’, it’s worth noting that around 90% of global electricity is produced in thermal plants using Parson’s steam turbine developed in the 1880s, with nearly all the rest from hydro using the Francis turbine developed in the 1840s, gas turbines using Whittle’s Brayton cycle from the 1930s, and Diesel’s reciprocating engine from the 1890s. Power systems are not subject to a type of Moore’s Law in the way that data systems such as telecommunications and IT are - the thermodynamic principles underpinning these machines is well established and unchanging and cannot be miniaturised or worked-around. Indeed, much of the fundamental design for equipment, such as transformers, dates from the 19th century. The advances in power electronics, such as IGBT’s, and computing in recent decades has completely revolutionised control systems, switching, motor drives etc but global electricity supply still completely relies on the basic thermodynamics, science and engineering that would be still familiar to the 19th century pioneers if they were alive today. Finally, your suggestion that I'm using archaic language is odd, and not very helpful in a context in which you're suggesting that a person that is both professionally qualified and has significant experience in the the topic is somehow "backward".  :) GrahamP (talk) 12:46, 13 April 2012 (UTC)

Sorry if what I wrote was unclear GrahamP. As you'll see above, I've already provided an authoritative source on intermittency. And you've misunderstood the baseload issue. Please allow me to clarify: one definition of baseload is that it's the generators with the lowest short-run marginal cost; in a market, that's the first bid to be accepted. A zero short-run marginal cost is lower than an above-zero short-run marginal cost. So, for example, a fuel-less plant such as a wind turbine or PV has lower short-run marginal cost than a fuel-burning plant. And is, therefore, baseload - it comes earlier in the merit order. Oh, by the way, there has been innovation in thermal plants: Brayton cycles were superseded by combined Brayton/Rankine cycle CCGT, and have become quite common over the last 20 years or so.

Ernestfax^Talk 19:55, 15 April 2012 (UTC)

Only on Wikipedia...surely our proverbial bright 12-year-old reader could tell us the difference between something that can run as long as it's not broken, vs. something that can't run even if it's not broken, because the wind has died down/sun has set/tide is out, etc? --Wtshymanski (talk) 14:33, 13 April 2012 (UTC)

As this is a discussion that cuts across generations within the energy industries, and relates to evolution of terminology over several decades, it's not surprising that there are different views expressed. There may also, for all I know, be differences between different English-speaking countries. Anyway, it seems to me that there is a problem with the concept of an article on "intermittent energy sources": there are at least two very different issues that are buried within "intermittent energy sources". One is the balancing of a grid with non-trivial penetrations of exogenously-variable supplies; the other is the balancing of a grid with sudden and unexpected losses of non-trivial amounts of generation. Perhaps splitting into two separate articles is the answer? Or at least making those two aspects explicit, and dealt with separately, within this current article?

Ernestfax^Talk 19:55, 15 April 2012 (UTC)

I'll copy some of my previous discussion here. There is labelling of nuclear power as an "intermittant" energy source, which appears to be founded on a common, lay definition of intermittant, backed up by a single source outside of the electricity industry.

My points against:

(1) The terms "baseload," "intermittant," "peak," "reliable," and the like have specific meaning when applied to power generation. They may or may not be mutually exclusive - it is possible to be baseload & intermittant, or peak & reliable. Using a more common definition stinks of the "evolution is just a theory" argument.

(2) It's an overall negative argument. If nuclear power plants, with CF >=90%, are "intermittant," is there such thing as a "reliable" generator? The section also becomes self-contradicting with "Sovacool says that previously intermittent sources such as wind and solar..." (emphasis mine), when the Intermittent_power_sources page has wind CF of 20-40%.

(3) Some of the points raised don't seem to apply to reliability or to nuclear power in general. There's a mention of geographic smoothing with regards to wind and solar... which have little to do with a discussion on the reliability of nuclear power plants. A comparison of capacity factors, downtime, and the like are needed, but this isn't a wind or solar power page.

(4) The argument is explained in a generally poor fashion. Again, see the Intermittent_power_sources page. The sections on solar and wind are easy to read, explain how each term applies to that method of generation, and then explains possible solutions. They both have multiple sources. The nuclear section reads as a short blurb without any substance, and cites one source. That same blurb is used verbatim in this article. If nuclear power is going to be considered intermittant, it ought to be presented in the same fashion as the others.

(5) The aformented source is not from the electric/power generation industry. A discussion on the reliability of nuclear power plants uses language from that industry, the same as any other specialized topic. This goes back to point #1 above.

From http://needtoknow.nas.edu/energy/glossary/ , an intermittent source is "...characterized by output that is dependent on the natural variability of the source..."

At a bare minimum, the section on this page needs expanding - right now it is a bare quote with no substance. However, I feel that it should simply be removed. Inqrorken (talk) 18:13, 8 June 2012 (UTC)

Merge proposal

Propose to merge Variable Renewable Energy into this article as duplication and potential WP:POVFORK. This page was moved on 2 February 2012 to Variable renewable energy and was moved back on the same day. Creating a new article just with different capitalization is not the way to solve the issue about the article title. If necessary, the title could be discussed by using WP:RM procedure, but it should be done only after merging the articles. Beagel (talk) 10:09, 28 May 2012 (UTC)

As was pointed out above there are two separate topics - sources that are inherently variable because of their source being variable, and sources that drop out due to sudden failure. This article was created for the former, before the industry had adopted a standard terminology to describe the issue, and was co-opted by the later, which is why the second article was created, in order to keep the two topics separate. I would suggest moving much of the VRE items to that article and keeping this article for the general topic of intermittency. Delphi234 (talk) 13:22, 3 June 2012 (UTC)

Well, from the above discussion, I don't see that there is consensus. However, I don't have at the moment final opinion if these issues should be in one or in two articles. The important thing is that Variable Renewable Energy is not correct title per WP:TITLEFORMAT. Correct should be Variable renewable energy, but this is a redirect to this article here. I see that on 2 February 2012 you moved this article into the Variable renewable energy and it was immediately moved back at the same day. That shows that the issue is potentially controversial and that kind unilateral actions are not the best way to solve the issue. At the moment, it seems to be potential WP:POVFORK issue. If you say that much of the VRE items should be moved into new article, lets have a proper split process and move it to the proper title. Beagel (talk) 14:16, 3 June 2012 (UTC)

Is Delphi234 saying that variable renewable energy is a more modern, or more widely accepted, industry term than intermittent energy source for real-world renewable energy sources? if so, I can understand that, but we need to see some documentary evidence (i.e. WP:CITEs) to back the assertion. I would understand if, under this newer terminology regime, the term intermittent energy source is relegated to describe only those sources that are prone to 'drop out due to sudden failure', but I'd expect to see refs that actually say precisely that. The other point, that this article 'was created for' energy sources that are prone to sudden failure (and was 'co-opted by' discussions of variable renewable energy sources) is not supported by the facts. This article was created on 17 November 2006, and its very first version opened by defining intermittent "sources [... as ...] either variable or intermittent [... and ...] not dispatchable", and included a long section on wind energy. The current version discusses solar, wind and hydroelectric, as well as having sections on nuclear, gas, and diesel power. Variable Renewable Energy has sections on wind, wave, solar, and tidal. I would understand a referenced suggestion to create two articles, one on the variability of renewable energy sources, and the other on failures and intermittency in power generation in general. This would leave the question as to which is the best place for discussion of 'Compensating for variability' - currently a section in this article that is partially duplicated at Variable Renewable Energy#Matching demand. I agree that the nonsense over title capitalisation should be quickly brought in line with WP:MoS. --Nigelj (talk) 14:53, 3 June 2012 (UTC)

Keep the Variable Renewable Energy article as a separate article. Do not merge. First of all the current article (Intermittent energy source) was originally a split from Wind Power to deal with addressing with what at the time was called 'intermittent energy sources'. And as was pointed out the article was later co-opted by others to discuss other issues to the extent that the current article is now a hopeless piece of garbage. --Aflafla1 (talk) 20:12, 3 June 2012 (UTC)

Some of the US power companies seem to use "variable energy resource", while the rest of the world seems to use "Variable Renewable Energy", or VRE: [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] (note the footnote on page 78: "Variable energy resource is the term used by FERC to describe renewable energy resources that have variable or intermittent production characteristics.") Variable energy resource: [18] [19] [20] [21] [22] It would be interesting to see when each term was first used. My guess is that it was after this article was created. I know that at the time, or soon after, I did a search for industry standard terms to use and came up blank. I do agree that this article came from the wind power article.[23] Delphi234 (talk) 21:24, 3 June 2012 (UTC)

If you do a google search for each term you find slightly more for VER, but if you limit the search to the last year it is overwhelmingly VRE:[24] - 1160 vs 200. Delphi234 (talk) 21:47, 3 June 2012 (UTC)

WP:LOWERCASE applies here, so it is irrelevant which companies spells it VRE and which not. Beagel (talk) 04:51, 4 June 2012 (UTC)

Upper case has nothing to do with the merge request. It is, however, a term like RPS or FIT that is occasionally abbreviated as an acronym. The question is should the article use the name that FERC uses or the name that the rest of the world uses? Delphi234 (talk) 21:07, 4 June 2012 (UTC)

I just replied to your argument, and answering to you–in similar cases WP:LOWERCASE has been used. However, the article title is relevant as there was previous attempt to move this article to Variable renewable energy; however, there was no consensus. I am sorry to say but Variable Renewable Energy seems like classical WP:POVFORK. Beagel (talk) 04:27, 5 June 2012 (UTC)

Support merging the two as the issue of intermittency is essentially related to variable renewables, while the issue of reliability of conventional plant is never described as "intermittency" and is dealt with a quite different manner. A good starting point is from MIT : [25]. My concern from my prior discussion (above) is that the article has been used as to promote a POV outside of widely agreed industry terminology, and therefore serves to confuse terminology rather than clarify. GrahamP (talk) 01:26, 5 June 2012 (UTC)

Oppose - both "Variable renewable energy" and "Intermittent energy source" are unhelpfully undescriptive titles; and the two articles are trying to pick out different aspects of electricity grid balancing. I think a broader discussion is needed about how we structure a group of pages on balancing, thought out from the engineering realities as reflected in the literature, rather than all the POV stuff: a merge of the two articles would just brush over much deeper problems with the way that wikipedia articles on this topic are structured. So that's why I oppose the merger proposal: not because I think that they should be two separate articles, but because I think the merger proposal is the wrong question to be asking. So, what is the right question to ask? Well, there are several challenges to balancing a grid, including but not limited to:

• large changes on the supply or demand side, over seconds to hours;
• annual peak demands;
• exogenous variability at the scale of seconds to days; and
• rapid unforeseen loss of generation from large plants: the sort of incident that is sometimes dealt with by N+1 redundancy (aka N-1 redundancy).

For further info, see for example the ENTSO-E Operation Handbook

A good encyclopaedic documentation of these should either have all those on the same page, or maybe a set of linked pages, with helpful titles for each. Neither "variable renewable energy" nor "intermittent energy sources" are helpful titles in that context: as discussed above, intermittency is used in technical & industry papers to describe both of the latter two bullet points, so "intermittent energy sources" is bound to create exactly the sort of discussions we see further up on this talk page. And pretty much all plant is "variable" at one timescale or another, so "variable renewable energy" is indistinguishable as a title from "renewable energy".

Hence I oppose this merger proposal, and instead propose that we find a consensus for a better structure for one or more pages on the topic of balancing electricity grids, which will cover the bullet-points I've given above, and maybe others too. Ernestfax^Talk 20:35, 6 June 2012 (UTC)

I can see the benefits of having a grid operation article. Most of that is technical and behind the scenes - all we know is that most of the time when we turn the lights on they come on and most of the time they stay on (except for those regions where daily power outages are ubiquitous) - and when they go out it is usually storm related, at least around here. But making that happen does require a huge amount of planning. There is also an element of feigned secrecy (maps of powerlines are often not published "for security", but thinking you can hide the existence of a powerline is idiotic). Seabrook nuclear station took down the signs at the entrance in a totally idiotic attempt to hide the power plant. The distinction between a variable renewable energy and the rest of the renewable energy sources, the rest being hydro, biomass, biofuel, osmotic power, and geothermal, is that all of those are either available on demand, in the case of biomass and biofuel, controllable, in the case of hydro, or are relatively constant, in the case of osmotic power and geothermal. Wave power is relatively less constant, but tidal power and solar power inherently come and go every day, and wind comes and goes whenever it feels like it, hence the word variable for those resources. Note that you can control any resource, but if you turn it down it is lost forever in the case of wind and solar, but in the case of hydro (other than run of the river hydro), it just backs up in the reservoir if you turn it down - and is available for whenever needed. If you shut down a wind farm because you do not need the output, the lost output is gone forever. Texas lost a substantial amount of wind power that could have been generated because insufficient powerlines were built in time. It also takes longer to build a powerline than a wind farm, but that is no excuse - Texas had plenty of time to plan ahead if they had looked ahead. It is pretty interesting to see how the "free market" does planning - a billionaire sees an opportunity and steps in, vs. central planning that sets up a series of five year plans. In the case we are facing now, we need a trillionaire to see the opportunity and step in - otherwise we are going to spend $8 trillion extra for gas over the next 25 years instead of switching to renewable energy and electric cars, and essentially pay nothing for gas. Delphi234 (talk) 08:03, 8 June 2012 (UTC)

I like Ernestfax's suggestions here. Very often when no one can see the best answer to a question, the reason is that we're asking the wrong question. It sounds like an article called something like Electricity grid balancing could be created, with sections about balancing given supply from various types of source - renewables, fossil fuels, nuclear, storage. This would be beyond my capability to plan, let alone write, even with some references as I have no overview mental picture to work from. can I ask, is there anyone here who feels that they could make any kind of start on this, perhaps in user-space? If we all tried to lend a hand too, once we all have something to look at? Ernestfax, are you up for this? --Nigelj (talk) 20:45, 8 June 2012 (UTC)

We already have an article called Control of the National Grid which explains how one typical grid operates. Engineman (talk) 21:48, 8 June 2012 (UTC)

Edits to "Solving Intermittency" section

The "Solving Intermittency" section of Intermittent energy source was lacking in clear and detailed explanation on some subsections.

The first paragraph, which lists all of the approaches detailed below, was missing energy storage, and had the potential to be improved grammatically.

The summary of Delucchi and Jacobson’s paper, which describes seven ways to accommodate a high penetration of renewable generation, did not adequately describe several of the listed approaches. Some items only needed minimal rewording, others needed additional description, and the storage and electric vehicle items needed to be completely rewritten.

Ryanm24 (talk) 05:44, 3 December 2015 (UTC)

External links modified

Hello fellow Wikipedians,

I have just added archive links to 3 external links on Intermittent energy source. Please take a moment to review my edit. If necessary, add {{cbignore}} after the link to keep me from modifying it. Alternatively, you can add {{nobots|deny=InternetArchiveBot}} to keep me off the page altogether. I made the following changes:

• Added archive https://web.archive.org/20081208120416/http://www.claverton-energy.com:80/download/42/ to http://www.claverton-energy.com/download/42/
• Added archive https://web.archive.org/20080910115928/http://www.parliament.uk/documents/upload/EA273%20National%20Grid%20Response%20on%20Economics%20of%20Renewable%20Energy.pdf to http://www.parliament.uk/documents/upload/EA273%20National%20Grid%20Response%20on%20Economics%20of%20Renewable%20Energy.pdf
• Added archive https://web.archive.org/20070706221755/http://www.ukerc.ac.uk/component/option,com_docman/task,doc_download/gid,550/ to http://www.ukerc.ac.uk/component/option,com_docman/task,doc_download/gid,550/

When you have finished reviewing my changes, please set the checked parameter below to true to let others know.

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 18 January 2022).

• If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
• If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—^{cyberbot II}_{Talk to my owner:Online} 09:45, 18 January 2016 (UTC)

External links modified

Hello fellow Wikipedians,

I have just added archive links to one external link on Intermittent energy source. Please take a moment to review my edit. If necessary, add {{cbignore}} after the link to keep me from modifying it. Alternatively, you can add {{nobots|deny=InternetArchiveBot}} to keep me off the page altogether. I made the following changes:

• Added archive http://web.archive.org/web/20120321220558/http://www.dcenr.gov.ie/Press+Releases/2008/Study+shows+Ireland+can+be+world+leader+in+renewable+energy.htm to http://www.dcenr.gov.ie/Press+Releases/2008/Study+shows+Ireland+can+be+world+leader+in+renewable+energy.htm

When you have finished reviewing my changes, please set the checked parameter below to true or failed to let others know (documentation at {{Sourcecheck}}).

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 18 January 2022).

• If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
• If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—^{cyberbot II}_{Talk to my owner:Online} 08:01, 1 March 2016 (UTC)

100% Wind and Solar

In the interest of presenting a simple scenario of current technologies, I'm suggesting this addition to the section - Intermittent_energy_source#Solving_intermittency

Using established technology is possible to provide the electricity needs of an entire county using only Wind power and Solar power.

For solar to provide half of all electricity and using a solar power capacity factor of 20%, the total capacity for solar would be 250% of the grids average daily load.

For wind to provide half of all electricity and using a wind power capacity factor of 30% the total capacity for wind would be 160% of the grids average daily load.

A pumped storage facility would need to store enough water for the grids average weekly load, with a capacity that matches peak demand ie:200% of the grid average. This would allow for one week of overcast and windless conditions. The 20% loss when using pumped storage intermittently is included in the grid average.

Total generating capacity is six times the grid average.

And yes I am aware that there are many possible alternatives to pumped storage ie:biofuels, hydrogen, supergrids etc. I'm using this scenario to keep it simple. I would appreciate any comments. Dougmcdonell (talk) 17:02, 3 November 2016 (UTC)

External links modified

Hello fellow Wikipedians,

I have just modified 14 external links on Intermittent energy source. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

• Added archive https://web.archive.org/web/20090115212122/http://www.memagazine.org/backissues/membersonly/oct05/features/rerere/rerere.html to http://www.memagazine.org/backissues/membersonly/oct05/features/rerere/rerere.html
• Added archive https://web.archive.org/web/20081001205145/http://www.ceere.org/rerl/about_wind/RERL_Fact_Sheet_2a_Capacity_Factor.pdf to http://www.ceere.org/rerl/about_wind/RERL_Fact_Sheet_2a_Capacity_Factor.pdf
• Added archive https://web.archive.org/web/20070710024744/http://www.bwea.com/pdf/ref_three.pdf to http://www.bwea.com/pdf/ref_three.pdf
• Added archive https://web.archive.org/web/20110927101054/http://www.rmi.org/rmi/Library/E09-01_NuclearPowerClimateFixOrFolly to http://www.rmi.org/rmi/Library/E09-01_NuclearPowerClimateFixOrFolly
• Added archive https://web.archive.org/web/20081001205145/http://www.ceere.org/rerl/about_wind/RERL_Fact_Sheet_2a_Capacity_Factor.pdf to http://www.ceere.org/rerl/about_wind/RERL_Fact_Sheet_2a_Capacity_Factor.pdf
• Added archive https://web.archive.org/web/20140701230913/http://www.risoe.dk/rispubl/reports/ris-r-1608_186-195.pdf to http://www.risoe.dk/rispubl/reports/ris-r-1608_186-195.pdf
• Added archive https://web.archive.org/web/20090318231423/http://www.ukerc.ac.uk/Downloads/PDF/06/0604Intermittency/0604IntermittencyReport.pdf to http://www.ukerc.ac.uk/Downloads/PDF/06/0604Intermittency/0604IntermittencyReport.pdf
• Corrected formatting/usage for http://www.dcenr.gov.ie/Press%20Releases/2008/Study%20shows%20Ireland%20can%20be%20world%20leader%20in%20renewable%20energy.htm
• Added archive https://web.archive.org/web/20070706221755/http://www.ukerc.ac.uk/component/option%2Ccom_docman/task%2Cdoc_download/gid%2C550/ to http://www.ukerc.ac.uk/component/option%2Ccom_docman/task%2Cdoc_download/gid%2C550/
• Corrected formatting/usage for http://www.ukerc.ac.uk/component/option%2Ccom_docman/task%2Cdoc_download/gid%2C550/
• Added archive https://web.archive.org/web/20080216073251/http://www.ukerc.ac.uk/Downloads/PDF/06/0604Intermittency/0604IntermittencyReport.pdf to http://www.ukerc.ac.uk/Downloads/PDF/06/0604Intermittency/0604IntermittencyReport.pdf
• Added archive https://web.archive.org/web/20070706221755/http://www.ukerc.ac.uk/component/option%2Ccom_docman/task%2Cdoc_download/gid%2C550/ to http://www.ukerc.ac.uk/component/option%2Ccom_docman/task%2Cdoc_download/gid%2C550/
• Added archive https://web.archive.org/web/20090318231419/http://195.200.115.136/g8/2008/Empowering_Variable_Renewables.pdf to http://195.200.115.136/g8/2008/Empowering_Variable_Renewables.pdf
• Added archive https://web.archive.org/web/20080914023245/http://www.rmi.org/sitepages/pid518.php to http://www.rmi.org/sitepages/pid518.php

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 18 January 2022).

• If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
• If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 15:59, 11 April 2017 (UTC)

intermittency / variability vs. (non) dispachablility

I found two definitions in the Oxford Online Dictionary:

a) variable
- Not consistent or having a fixed pattern; liable to change.
- Able to be changed or adapted.
b) intermittent
- occurring at irregular intervals
- not continuous or steady

The Merriman-Webster says:

a) variable
- able or apt to vary: subject to variation or changes
- fickle, inconstant
- characterized by variations
b) intermittent
- coming or going at intervals
- not continous

Yes, wind and solar parks are variable and intermittent, but other generators have the same property, e.g. daily cycling peaker plants and medium load plants which are also not continously operating. Their output is liable to change and show an on-off pattern coming and going at intervals.

If we want to describe the term "bicycle", we can't define it as a two-wheeled vehicle, as scooters, motorbikes and segways are two-wheeled vehicles as well.

The main feature is that you can't store wind and solar as primary energy. Therefore the conversion unit from wind and solar into electricity is not controllable. You may switch a wind or solar park off, but you can't ramp it up to do some load following or let it react price elasticly on market needs if the wheather condition is not given. A guy from UK recommended to use "dispatchable" (DE: disponible) instead of controllable. So please start calling wind and solar non-dispatchable, as medium load coal-fired plants with their daily on-off cycle are also intermittent and variable. The future discussion will focus on market integration: this is possible with intermittent coal fired plants, but not with intermittent wind parks, as wind and pv are not price elastic: the higher the price, the lower the output (and not vice versa). Gunnar (talk) 13:55, 7 October 2017 (UTC)

"The intermittent source may be quite predictable, for example, tidal power, but cannot be dispatched to meet the demand of a power system." This sentence is simply not true, as natural gas fired CCGTs with a daily production cycle are an intermittent source of electricity, but can be dispatched. The qualifier "intermittent" does not fit and is wrong. Gunnar (talk) 13:59, 7 October 2017 (UTC)

The characteristics of a particular energy source, in a particular location are quite unique and are poorly described by generalizations. For instance solar thermal can be stored as primary energy and dispatched later (it's solar PV that doesn't store as primary energy), solar can be dispatched for air conditioning loads every day (it's in a cold peak demand that solar doesn't load follow), tidal power is 100% predictable and dispatchable (on certain calendar days) and market price means nothing in a state run utility. So let's avoid the temptation to use narrow definitions for terms and simple models for the wide variety of circumstances around the world. Dougmcdonell (talk) 18:06, 7 October 2017 (UTC)

The predictability is another issue, you can predict the output of wind farms very vell as the energy forecast methods have been improved greately in the last two decades. The same applies to solar energy (PV) on a regional scale - of course you don't know when a cloud will cast some shadows on a specific PV system, but the output of a whole area can be estimated in advance. Yes, thermal solar plants are dispatchable if they use a heat storage. Thermal solar energy is storable and therefore dispatchable. Hydropower with a reservoir is also dispatchable, as the mechnical energy of water at a higher height is easy to store. Even run-of-river plants are sometimes dispatchable if the operation in swell mode is allowed. Du to environmental considerations the up and down of water levels in streams is often forbidden, so many run-of-river plants are not dispatchable. Tidal power is not dispatchable as well. You can forecast the energy yield according to the movements of the moon around the earth, as you can forcast falling tide and rising tide. But if the tides have a pause, a tidal power plant will have to wait until the output power can increased to nominal power.

"So let's avoid the temptation to use narrow definitions for terms and simple models for the wide variety of circumstances around the world." I don't get it. The confusion is there if you call it "intermittent energy source", but you want to say *non-dispatchable renewable energy source*. Intermittency is not a synonym for non-dispatchability. If you don't offer a correction for the sentence "The intermittent source may be quite predictable, for example, tidal power, but cannot be dispatched to meet the demand of a power system." I will do it, as the message "inntermittent source cannot be dispatched" is wrong. If you/we want to focus the article on non-dispatchalbe energy sources such as PV, wind, hydro without reservoir, etc. then we should use proper adjectives. Gunnar (talk) 01:28, 8 October 2017 (UTC)

"Effective use of intermittent sources in an electric power system usually relies on using the intermittent sources to displace fuel that would otherwise be consumed by non-renewable power stations" - This sentence wants to say that RES generators displace fossil fuels. According to the Oxford Dictionary effective means "Successful in producing a desired or intended result." It has an effect, that means it works. This is not the point here: displace fuel in non-renewable power plants is a matter of saving fossil fuel an this is an effect which saves greenhouse gas emissions and we reduce our dependency on exhaustible primary energy. Any intermittent source e.g. a peaker natural-gas fired plant displaces fuel that would be consumed e.g. by coal fired medium or base load plants. Thus, the sentence is incorrect and not very precise using the term "effective use": it saves GHG emissions and we reduce our dependency on exhaustible fuels - this is the effect and we should name it that way. --Gunnar (talk) 08:56, 29 October 2017 (UTC)

@Gunnar.Kaestle Hi, thanks for the note on my talk page, the issue I had with your recent edit was changing "fuel" to "fossil fuel" - The word fuel includes hydrogen used in fuel cells and biofuels used to generate power. If you would like to mention fossil fuel specifically then I would expect to see some others, "fossil fuel, synthetic fuels, biofuels". When you changed all fuel to fossil fuel only, you left out the non-fossil fuels that are also displaced by renewables. It is not just "every bit of renewable power is a drop of diesel oil displaced" as you've suggested. It is also that "every bit of renewable power is a drop of bio-diesel fuel displaced which then in turn can be dispatched to displace a drop of diesel oil". So I remain opposed to your wording "displace fossil fuel that would otherwise be consumed"

re:effective use, your edit mentioned one effect "Environmentally friendly" There are more intended results in the generation of power than just the environment, there is also making the grid function, avoiding brownout and failures, there is also the cost of these sources to recover, there is also the consumer effects of peak pricing - The phrase is "not very precise" because there are a great many things under "effective use", the power system wasn't built to help the environment, it was built for people. There is a page primarily about GHG emissions, but on this page the word "emission" occurs twice, this page is about electric power distribution.

What does "we should name it that way" mean, name it what way? Please refrain from instructing me on what is, and is not the point here, there is room on the page for more than one point regarding an incredibly complex situation. Dougmcdonell (talk) 22:46, 30 October 2017 (UTC)

Yes indeed, non-dispatchable energy sources (such as wind & solar) substitute dispatchable energy sources (mostly fossil fuels but also other chemical fuels such as biomass and other renewable PE sources, such as hydropower with a pondage or reservoir). The motivation to invest in wind and solar is first the climate change, but I do also worry about the peak fossil fuel szenario - remember, we have seen triple digit oil prices in 2008 which triggered the financial crisis, as sub-prime mortgages couldn't be paid back when the inflation basket (in fact only the energy sub-basket) made variable interest rates more expensive. And I also believe that the gas & oil glut is a kind of rather flash in the pan, as oil & gas companies may find enough income to cover the marginal cost of drilling and fracking, but not the full costs including the sunk costs. ("We are all losing our shirts today. You know, we're making no money. It's all in the red." Rex Tillerson as Exxon's CEO in 2012)

"we should name it that way" means: if the main purpose for wind and solar as intermittent and non-dispatchable energy source is 1. the reduction of greenhouse gas emmissions and 2. the sparing use of our fossile stockpile of fuels made by past sunlight, then we should say exactly that. BTW: I don't like the idea of expanding the introduction too much. Here, the scope and definition of the lemma should be precisely given in a short manner. All details should follow later in the main body. --Gunnar (talk) 12:20, 12 November 2017 (UTC)

External links modified

Hello fellow Wikipedians,

I have just modified 12 external links on Intermittent energy source. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

• Added archive https://web.archive.org/web/20090318231439/http://www.ukerc.ac.uk/Downloads/PDF/05/050705TPASindenpres.pdf to http://www.ukerc.ac.uk/Downloads/PDF/05/050705TPASindenpres.pdf
• Added {{dead link}} tag to http://www.iset.uni-kassel.de/abt/FB-I/publication/2006-02-09Reliability.pdf
• Added archive https://web.archive.org/web/20160125083857/http://energinet.dk/EN/El/Nyheder/Sider/Dansk-vindstroem-slaar-igen-rekord-42-procent.aspx to http://energinet.dk/EN/El/Nyheder/Sider/Dansk-vindstroem-slaar-igen-rekord-42-procent.aspx
• Added archive https://archive.is/20120802081858/http://www.ens.dk/graphics/Publikationer/Statistik_UK/Energy_statics_2006/html/chapter03.htm to http://www.ens.dk/graphics/Publikationer/Statistik_UK/Energy_statics_2006/html/chapter03.htm
• Added {{dead link}} tag to http://www.ens.dk/graphics/Publikationer/Energipolitik_UK/Engelsk_endelig_udgave_visionaer_energipolitikA4.pdf
• Added {{dead link}} tag to http://www.energypulse.net/centers/article/article_display.cfm?a_id=1528
• Added archive https://web.archive.org/web/20110720003111/http://www.ieawind.org/AnnualReports_PDF/2008/2008%20AR_small.pdf to http://www.ieawind.org/AnnualReports_PDF/2008/2008%20AR_small.pdf
• Added archive https://web.archive.org/web/20110324033215/http://www.wind-energie.de/en/wind-energy-in-germany/ to http://www.wind-energie.de/en/wind-energy-in-germany/
• Added archive https://web.archive.org/web/20150106223105/http://energinet.dk/DA/El/Nyheder/Sider/Vindmoeller-slog-rekord-i-2014.aspx to http://energinet.dk/DA/El/Nyheder/Sider/Vindmoeller-slog-rekord-i-2014.aspx
• Added {{dead link}} tag to http://repa.econ.uvic.ca/publications/Working%20Paper%202006-02.pdf
• Added archive https://web.archive.org/web/20071231141101/http://www.risoe.dk/rispubl/SYS/ris-r-1405.htm to http://www.risoe.dk/rispubl/SYS/ris-r-1405.htm
• Added archive https://web.archive.org/web/20090506162616/https://www.ferc.gov/news/videos/wellinghoff/2009/04-22-09-wellinghoff-transcript.pdf to http://www.ferc.gov/news/videos/wellinghoff/2009/04-22-09-wellinghoff-transcript.pdf
• Added archive https://web.archive.org/web/20070829114854/http://www.sustainabilitycentre.com.au/DissentMD2006.pdf to http://www.sustainabilitycentre.com.au/DissentMD2006.pdf
• Added archive https://web.archive.org/web/20090318231420/http://www.berr.gov.uk/files/file21352.pdf to http://www.berr.gov.uk/files/file21352.pdf
• Added archive https://web.archive.org/web/20070101204618/http://www.ieso.ca/imoweb/marketdata/genEnergy.asp to http://www.ieso.ca/imoweb/marketData/genEnergy.asp
• Added archive https://web.archive.org/web/20090325014258/http://www.eirgrid.com/EirGridPortal/uploads/Publications/Wind%20Impact%20Study%20-%20main%20report.pdf to http://www.eirgrid.com/EirGridPortal/uploads/Publications/Wind%20Impact%20Study%20-%20main%20report.pdf

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 18 January 2022).

• If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
• If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 20:43, 14 November 2017 (UTC)