But I would welcome being corrected if I\’m wrong.
So, they\’ve taken the amount of electricity that is generated from wind.
And they\’ve looked at the amount being generated from gas.
And they\’ve seen that when wind goes up, gas goes down. This means that wind does indeed reduce CO2 emissions so Nyah, Nyah.
But that\’s not quite what I understand the case against wind reducing CO2 to be.
Rather, that you have to have the gas spinning away on standby, not producing electricity but still consuming fuel and thus producing CO2, while you\’re consuming the electricity from wind.
It\’s not the CO2 from the backup gas production that is the problem, it\’s the CO2 from the backup gas while not producing that is.
And that, of course, is something that you cannot divine from looking at the electricity production statistics.
It\’s entirely possible that I\’ve got the wrong end of the stick here so if I have please do correct me. Be gentle though….
Yup, I thought that too. In a way, a -ve correlation between wind and gas production undermines their argument, since it shows that when the wind drops, the gas turbines have to kick in.
But really, we need a completely different set of figures to address the issue
Alas, that’s not quite what the likes of the GWPF are talking about. Spinning reserve – gas plants running without generating – is used to handle large-scale instantaneous losses within seconds. This only really applies to single generators tripping offline suddenly, so the amount you need is proportional to the biggest generator on the system. It’s more relevant to nukes than wind, as individual wind generators are small. A large wind farm might have an impact if the grid connection associated with it went down, but the big offshore fatms will probably have multiple connections to avoid this issue.
Instead, the GWPF claim you need fast ramping gas plant to cover wind output drops over a period of half an hour to an hour, which is normally fulfiled by OCGT. This causes additional fuel burn due to these plants being less efficient. However, they’re simply wrong – as the article says, we actually use more efficirnt CCGT ramped over a longer period to balance wind. There are efficiency losses, but they’re neglible compared to the GWPF claims.
No mention of electricity generated by hot air in the Graun, either. Probably because there is just a bit of heat but never any light.
Last time we discussed this, the allegation was that wind has to be backed up with OCGT. The Guardian report seems to disprove that, at least at the current proportion of wind power:
Now you’re suggesting that the problem is not the need for OCGT but the energy cost of spinning reserve. But spinning reserve is needed to cover sudden load changes (ad breaks in popular TV programmes) or sudden power station failures. Because wind power is provided by a large number of small units, it has less need of spinning reserve than do conventional power stations.
John – with the Guardian’s dwindling readership the hot air is tending towards negligible microgeneration.
PaulB: but wind *does* have to be backed up with gas. Unless you assume the power generation capacity of wind, which is entirely random and unreliable, can be “done without” whenever the wind isn’t blowing
PaulB (#4) said ” spinning reserve is needed to cover … sudden power station failures. Because wind power is provided by a large number of small units, it has less need of spinning reserve than do conventional power stations”
But when the wind stops, the wind tubines in a wide area will all stop at once.
So the fact that it’s lots of little generators doesn’t help, since they are correlated across a broad area and will all go on or off together.
Once we have serious levels of wind power, the wind dropping will have the same big and sudden effect as a conventional power station failure.
Simple enough solution – Drop the ‘quick to produce’ OCGT stations and rely completely on wind with no back – up. Might have a few blackouts but we’re ‘saving the planet’ so all kudos to us….
“But when the wind stops, the wind tubines in a wide area will all stop at once.”
But the wind doesn’t stop everywhere at the same time. It’s a nicely distributed system.
Wind is actually quite predictable from one minute to the next. If it’s windy now it’s likely to be windy in a few minutes. Or, it’s 95% likely to be as windy in five minutes as it is now. In any case you won’t get a sudden (<30 minute notice) turning off of the energy supply unless the infrastructure fails. This is what requires the spinning generation reserve.
For longer term outages (high pressure areas mean there's no wind for a week) then you can ramp up the alternatives but there's no need to have them spinning away when you can refer to a weather forecast and see that it's predicting steady winds for the next week.
Or have I made too many simple assumptions?
You can follow the argument at Bishop Hill:
http://www.bishop-hill.net/blog/2012/9/26/missing-the-point.html
The Grauniad is carefully ignoring the energy consumed to build all the turbines. Since, despite Fishter’s claim periods with nil contribution from wind *do* periodically occur, the Grid needs as much fossil fuel capacity to supplement wind-power as it would if there were no turbines whatsoever. Smelting aluminium for turbine blades consumes vast amounts of electricity, so much so that most aluminium producers build their own generator instead of purchasing electricity from the grid or its local equivalent.
Elephant Room
A second cost they neatly overlook is the transmission losses between the windy hillsides and estuaries and the consumers who are mostly in cities in valleys onshore. Some estimates put it at one-third of the electricity produced.
Demand is rising. So we need to invest in more generation.
Which investment would be more economical? Wind and back-up gas (two investments) or gas (one investment)?
Don’t be shy now. Have a guess.
“Some estimates”? What’s the point in quoting a wild overestimate from an unidentified source?
Fishter @9, wind predicatble? Have you looked at the National Grid’s attempts at predicting the wind? They aren’t very good at all – and they are scientists. They can predict a general wind as in high or low, but wind can be gusty and when that happens all bets are off.
SBML: National wind power output forecasts look pretty accurate to me – within a few percent. What data are you looking at?
Dunno about the wrong figures but there does seem to be spectacular point missing.
As long as wind is c.10% or less of the energy mix, of course variability will be less of a problem as the system currently has a c. 10% spinning reserve.
What the hell happens when wind is 30 to 40% of the system is less clear.
Does anyone really think we are going to be able to carry a spinning (or other) reserve of 20GW or more?
Tim adds: That’s a very excellent point!
on the relevant bmreports.com page, there are considerable differences between what they term the initial forecast and the outturn. The later forecasts tend to be more accurate. I would paste a sample graph but this site will not let me.
The key fact in the debate is that wind power is lost in the noise of the totality of power generation – there is already capacity to handle short-term fluctuations, so wind power is wrapped up in that. Once it becomes more than 10% of the mix on a dependable basis, whatever dependable means in terms of wind-power (there were reasons for the demise of sailpower), then I suspect that load-balancing becomes very awkward.
@ PaulB
#13 Because I’m too busy to hunt down the reference. It was a quoted estimate of transmission losses from the planned offshore wind farm in the Hebrides to Glasgow.
#15 Have you seen the forecasts for turbine breakdowns? If so, how accurate are they?
It isn’t just the accuracy of short-term forecasts that matters – it is also the actual variability of wind from zero to useful to too high, have to switch the turbines off increase the blades break off. National Grid told Parliament that they would need to build twice as much capacity if they are to use Renewables as they would need to build if they don’t.
Certainly wind power gets more difficult to manage as it becomes a larger proportion of installed capacity.
Spinning reserve is not really an issue. Contrary to what jono says, National Grid runs about 1GW of spinning reserve, to allow the system to cope with the sudden loss of one large generating unit. Sudden variations in wind power generation are smaller than this.
And according to the data presented by the Guardian, the use of OCGT to substitute for wind power at short notice is insignificant, contrary to the arguments of some opponents of wind power.
What is an issue is the need for back-up generating capacity. You still need almost as much installed capacity of non-wind plant even after you’ve added the wind power.
Despite the fact that Lynas and co (honestly)say that they (and the NG) don’t know how the system will cope with more than 10% wind, this report will be used (and already is) by proponents of wind subsidy to make the following argument.
1. The current grid can cope with wind fluctuation without unnecessary CO2 creation.
2. We should therefore build more wind because the system can cope.
While the elephant in the corner of the room waves his trunk, trumpets and takes a large crap to try and get everyone’s attention.
Paul B
“Contrary to what jono says, National Grid runs about 1GW of spinning reserve,”
which, as I said, is circa 10% of capacity.
“Sudden variations in wind power generation are smaller than this.”
Yes – but only while wind remains at less than 10% of the mix. You are not addressing my point about to what extent the spinning or other reserve will need to increase as wind increases. The bigger the role of wind, the bigger the variability issue (yes – I know that scale increases the number of wind sites but the net effect will still be a bigger variability problem).
“the use of OCGT to substitute for wind power at short notice is insignificant”
More accurately the use of OCGT generally is very limited. OCGT capacity is only c. 1 GW. The question is, as we increase wind and retire coal, will we build OCGT or CCGT?
“What is an issue is the need for back-up generating capacity. You still need almost as much installed capacity of non-wind plant even after you’ve added the wind power”
Absolutely – and the bit I am still struggling with is why everyone thinks (a) this reserve will be met entirely by CCGT and (b) that CCGT will be running in (slightly inefficent) part-load mode rather than in (very inefficent) spinning reserve?
@ jono
“Absolutely – and the bit I am still struggling with is why everyone thinks (a) this reserve will be met entirely by CCGT and (b) that CCGT will be running in (slightly inefficent) part-load mode rather than in (very inefficent) spinning reserve?”
Because National Grid employs sane engineers not Guardian journalists.
I gather that the average load of windpower is in the teens of rated capacity so the back-up will be running most of the time. You need, in theory, to be able to shut down the whole of back-up in case all the windmills start working at once. To replace that much CCGT with OCGT would presumably lead to a net increase in CO2 emissions as well as costing a lot more.
FYI
” 102. As the amount of wind generation rises, the potential short-term change in wind output will also increase, and National Grid will have to hold more reserve to cope with this increase. The company told us that if renewables provided 40% of electricity generation—the share the company believes would be needed to meet the EU’s 2020 energy target—its total short-term reserve requirements would jump to between 7 and 10 GW. Most of this would be standing rather than spinning reserves. This would add £500 million to £1 billion to the annual cost of these reserves—known as balancing costs—which are now around £300 million a year (Q 293). This is equivalent to around 0.3 to 0.7 pence per kWh of renewable output.
103. Estimates of balancing costs vary widely. The government has commissioned research from the consultancy SKM,[36] which estimated that if renewables provided 34% of electricity by 2020, with 27.1% from wind power, the extra cost of short-term balancing would be about 1.4 p/kWh of wind output[37] (Q 481). This equates to a total cost of £1.4 billion, well above that assumed by National Grid. Several pieces of evidence cited a 2006 report by the UK Energy Research Centre (UKERC),[38] which had estimated the balancing costs with up to 20% of intermittent renewable output in Great Britain at 0.2-0.3 pence per kWh. Although the share of renewables in the SKM study was less than double that of UKERC, the balancing costs per unit were more than five times higher. In part, this may reflect higher fuel costs since the studies surveyed by UKERC were performed; but it will also reflect the greater challenges of dealing with larger shares of intermittent renewable generation.
104. Fluctuations in wind speed lead to short term changes in electricity output from wind farms. Greater use of wind power and other intermittent renewable sources therefore requires more backup generation capacity to respond very quickly to, for example, reductions in the output of wind turbines when the wind drops. But the technical challenges and costs of backup generation on a scale large enough to balance an electricity system with a high proportion of intermittent renewable generation are still uncertain. There is currently no experience elsewhere in Europe of the scale of dependency on intermittent renewables expected in the UK. Whereas the highest share of intermittent renewable electricity now being generated is 15% in Denmark, the UK is expected to reach a share of some 30%-40%. We recommend that the Government should ensure that further work is carried out to clarify the costs and encourage development of technical solutions to deal with intermittency.
105. Running a conventional plant at part load to provide spinning reserve reduces efficiency which leads to higher emissions per unit of electricity actually generated at that plant. Some commentators, such as Campbell Dunford of the Renewable Energy Foundation, argue that this might have offset the CO2 savings from renewable generation in Denmark.”
Source – House of Lords
The Lords seem to be comparing installed capacity in the UK with windpower generated in other countries. This report suggests that several countries are coping with a much higher proportion of wind power than is the UK.
jono: no, 1GW is not 10% of uk electricity capacity, which is about 80GW.
@ PaulB
Try re-reading – you don’t usually make that sort of error. The Lords are comparing planned share of power to be generated – implying a frightening nominal capacity – with the actual share in Denmark.
I have no idea what we should do if we had enough windmills to generate 40% of UK annual consumption of electricity and they all worked simultaneously. Provide everyone with poached herrings by boiling the North Sea?
So we are wanting to know what happens when we have lots of turbines, whether they require backup which produces carbon.
The guardian presents figures which are based on few turbines and claims this means the question asked is answered.
Fools
@ PaulB
I am annoyed because the report you highlight says that the highest contribution of wind power in any EU country is Denmark (which makes a lot of money by selling wind turbines) followed by Spain and Portugal 14%, Ireland 10% and Germany 9%. The House of Lords report states that to meet EU targets we need to have *40%* of electricity generated by renewables.
When I was young 40% was more than 24% or 14%.
Why are you wasting my time?
Tim Worstall: “Rather, that you have to have the gas spinning away on standby, not producing electricity but still consuming fuel and thus producing CO2…”
Starting from the pedant position, natural gas powered turbines continue to generate electricity when they are on standby. There is no practical way to disseminate their energy other than to feed electricity into the grid. With time we could convert that natural gas burning into stored energy, but we have to measure the efficiency of storage versus usage of immediate energy.
If the target is an energy supply that does not depend on carbon fuels, we have to create a non-carbon backup supply for environmentally sourced supplies. Nuclear?
I used the expression “environmentally sourced supplies”* deliberately; I’m unconvinced by the “sustainable energy” label attached to wind, tide and solar sources. To many people, the label suggests that no carbon fuel was used for their construction.
We are going through a transition stage, from 95% reliance on carbon fuel to a lot less. Even the carbon burners in China and India recognise that this is a short term phenomenon and that carbon burning is detrimental (eg by diminished air quality in towns) in the long run. Londoners learned and taught that lesson 50 years ago.
* Nuclear is not an “environmentally sourced supply”; wind and sun are unavoidable on this planet, but you have to try hard to uranium or even coal.
‘Demand management’ solves all of these problems. Just don’t build any backup generators. When the wind stops the lights won’t turn on. Inconvenient perhaps, but so much better for Gaia!
john77: thanks. Yes, you’re right, the Lords did mean what they said. However, the actual windpower share in Denmark is now about 34%, and it’s planned to reach 50% by 2020.
(Denmark is in an unusually favourable position because it can use Swedish hydroelectricity to smooth supply)
and I’m sorry to have annoyed you. My point, which I think was not ambiguous, was that the UK is currently well down the European league for wind power generation, so we are not beating the path. 30-40% is the range of estimates for electricity generation from renewals to meet the EU Renewables Directive target of 15% of all energy. As I said just now, Denmark is already in that range.
@ PaulB
Thanks
Actually, being a pendant, Denmark uses Swedish nuclear power and Norwegian hydroelectricity but I have no difficulty this time in understanding.
I have long lost count of the number of times that I have stated something unambiguously and it has been misinterpreted by people who actually know the answer.
Starting from the pedant position, natural gas powered turbines continue to generate electricity when they are on standby.
“Pendant” around here Charlieman 🙂
This is not an area where I know much – I deal with electricity after it’s produced, and mostly after it’s been stepped down to low voltage DC for electronics – but I would have thought that spinning reserve would be mechanically disconnected from the generator, hence no electricity production?
Or I could just say “doesn’t it have a clutch?”
There is no practical way to disseminate their energy other than to feed electricity into the grid.
Yes, if you don’t match supply to the load the system will do it all by itself in ways you *really* don’t want to hear about. Loud noises will be involved.
Spinning reserve is reserve that comes from generators that are part loaded, eg not producing their max MW. It is not machines synchronised but producing zero (except for hydro stations which can be turned on and off like a tap). All CCGTs have a min stable level which is usually about 50% of their max.
Thanks Alan. The question then is, do they run at equal efficiency at 50%? If not, then Tim is correct and there is additional fuel being burnt per megawatt while they run that way, and that should be taken into account.
In the hypothetical case, that is, that you go past the current situation of using existing spinning reserve (there anyway, and necessary) to address wind variability, to having to build additional spinning reserve to cover 40% of the load.
CCGT runs a bit less efficiently at half load. Improved designs have reduced the difference; for the latest plant thermal efficiency might fall from 61% at full load to 60% at half load.
But the spinning reserve isn’t there because of wind power. It’s there to guard against sudden failure of large plant. With present levels of wind-power production, the Guardian is quite right to ignore the energy costs of spinning reserve.
However, at some level – estimates vary, but certainly well above where we are now but well below 30% of electricity consumption – spinning reserve would need to be increased. Spinning reserve costs should then be taken into account in emission calculations.
It makes sense to combine spinning reserve with demand management – ‘smart grid’ technology. We don’t have to run the grid in 2020 the same way we did in 1970.
@LTW
Of course they are less efficient at 50% – its like driving down a motorway in 2nd gear! The spinning reserve requirement doesn’t change as more wind is added – it is used to cover the loss of the largest infeed (the largest conventional generator on the system). But more ramping capability will be required to balance wind variability – and this will eventually mean more OCGTs, or CCGTs with fast(er)ramping capability.
Does anyone have figures for economic cost of energy transmission over distance?
The Greens, ‘the wind is always blowing somewhere’, argument seem to depend on dynamic transfers around a Europe-wide energy grid (not just a National grid).
Ignoring the political naivety of this for a second, I know there are practical/cost implications to long-distance transfers of electricity.
Does anyone know the costs/technical limits to the movement of generation, with todays powerline technology?
Can you move excess wind farm electricity from Thurso to Cornwall, or even Naples?
Tim adds: Using AC, as we do, no, you cannot move power all that far. You lose too much for it to be economic.
Which is why the Greenies are advocating a DC long distance transmission network. Which could even work just that no one’s ever done it as yet.
This table seems to say that transmission losses from Thurso are of the order of 20%. They could be reduced if it became important enough – the Western HVDC link will improve matters.
Thanks very much.
This is quite interesting. (From 2008)
http://www.nationalgrid.com/NR/rdonlyres/4D65944B-DE42-4FF4-88DF-BC6A81EFA09B/26920/ElectricityTransmissionLossesReport1.pdf
Here’s their own estimate for UK losses (2%), so imagine it would be much greater for a pan-European grid.
“A small percentage of the energy transferred over the GB electricity transmission system is lost
every year, due to physical processes such as resistive heating of transmission lines and
magnetic and resistive losses in transformers. This loss is typically of the order of 2% of the
energy transferred across the network.”
Interestingly, their explanation for the main driver of losses is variation in generation, not demand. The very issue we’ve been talking about here.
“The analysis described in the sections above shows that the calculation of losses is robust and
that the primary driver of variations in losses over the period studied is variations in the
disposition of generation output. Movements of the same magnitude in the disposition of
demand on the system would lead to similar variations in losses but changes in demand do not
occur as readily, or with the same scale during the period studied, as variations in generation. “
As wind increases this will surely become more problematic.
@Tim, the losses on HVDC networks can be quite substantial, particularly in the conversion process from AC to DC and DC back to AC. Losses of 6% or more can occur in the conversion process, but it is improving a bit.
The Wind lobbyists talk about 24% capacity utilisation in a “normal wind year” Let’s be generous and say that’s 10%-38% instead of the known 0% to something higher. So to get 40% of power from wind we need wind nameplate capacity of 167% of average electricity consumption. What happens if wind-power generation exceeds 60% of nameplate capacity for half-an-hour? The grid literally melts down.
john77: “The grid literally melts down”? A couple of weeks ago wind-power generation ran at 80% of capacity for several hours. And the grid didn’t melt down.
24% utilisation is very pessimistic. See this paper
Stuck-Record: read that carefully. It says that the main driver of variations of losses is variation of generation. That is, if you generate the electricity in different places, you get different losses.
PaulB
Reading skills?
My query was what happened if wind-power generated more than 100% of electricity consumption and the grid could not turn it off. You appear to say that this is refuted because wind-power generated less than 10% of electricity consumption and there was no melt-down then.
NO NO NO
You are also claiming that the claim by EWEA, the wind-power industry lobbying group is very pessimistic. You will just have to put up with my tasking that with a Siberian salt mine
john77: ah, ok, that’s what you meant, I dare say I should have understood. No, the grid wouldn’t melt down, there would be control systems to take some windmills off-line.
I don’t know where you got 24% from, because you were too busy to provide a link, but if it came from the EWEA it will be a number for the whole of Europe, and an out-of-date one at that. I don’t understand your point about salt mining, but you are mistaken on this one.
Paul B re 44.
I think I see what you mean regarding the variation issue. But it also seems clear that the system is sensitive not only to demand, but to location and type of generation. This is pretty crucial in a widely distributed wind-based network.
Going back to a point made by many others, and yourself, the issue is scalability. There doesn’t seem to be any acknowledgement in green circles that upscaling wind power generation requires massive permanent backup. This is not possible with nuclear or coal (Greens won’t tolerate them), oil (too expensive and dependent on lunatics or mediaevalists), hydro (we’re not Norway), or shale gas (still unacceptable to huge sections of the green movement).
For those of us who want to keep the lights on it seems that the large part of the current green movement is living in a fantasy world.
I think Greens would prefer wind power with gas backup to gas alone. Quite rightly they’d like to see supply variability compensated for with demand management in so far as practicable.
And ‘demand management’ is a polite euphemism.
No it isn’t. We already have a crude form of it – FCDM – in which heavy users agree to have their supply cut off at two seconds’ notice, in exchange for money.
For consumers we can be more subtle. For example, we could programme fridges and freezers to run slightly warmer than normal when the mains frequency drops. Do you know what temperature your freezer is set to? Why would it make a difference to you if it let the temperature drift up from -18 to -15 for a few minutes from time to time?
Sorry. Difference of opinion on that.
It’s perfectly possible for ‘x’ budget to build a power generation system that will supply ‘y’ power (all the consumer’s needs.)
Our politicians have made the choice to build a system that will NOT supply ‘y’ for 2-5 times the cost of ‘x’ (min).
Their solution is to tell us to use less power.
A system that, at best, costs 2-5 times as much to provide rolling micro black-outs is not ‘demand management’. It’s ‘failure’. And when said system doesn’t even reduce CO2 we’re talking very big failure.
And that is being kind.
@ PaulB #46
Sorry – done a little more than an average week’s work in three-and-a-half days. The link is
http://ewea.org/fileadmin/ewea_documents/documents/statistics/EWEA_Annual_Statistics_2010.pdf
Yes that was published last but unless you think that EWEA, as lobbying organisation, is deliberately understating capacity utilisation in a “normal wind year” or you think that they are so stupid that they’ve erected windmills in areas where wind is less frequent before putting them up where wind is more frequent or output per hour divided by capacity is not a measure of utilisation, then we get 24% as an estimate of capacity utilisation.
PS There is a phrase (or, at least there was when I was young) “take it with a pinch of salt” to denote polite scepticism.
john77: yes, the numbers there imply a capacity factor of 24.5%. But as I said, that’s a European average for existing plant. Capacity factors are higher in the UK than in Europe as a whole, because we’re on a windy offshore island, and higher for new plant than old. The EWEA itself projects that European capacity factors will increase from 24% in 2007 to 30.3% in 2020. UK capacity factors will be higher than that.
Stuck Record: adjusting the control system in your freezer in a way you’re unlikely ever to notice is not a “black-out” or any sort, it’s a sensible use of technology.
You should say “if”, not ” when. Let’s try some numbers. Assume a capacity factor of 30%, and peak wind generation of 80% of capacity (you’re not going to get perfect conditions everywhere in the country at once). Cover the variation with CCGT with this sort of specification.
For a number to compare with, assume the whole 80% comes from CCGT at 61% efficiency. So for each MW of electricity, gas power input is 1.64MW
With our gas and wind mix, the CCGT plant that are being subject to part loading and turning on and off will run at 58% efficiency. The CCGT plant that are being handled more gently (because wind is quite predictable) will run at 61% efficiency. Let’s assume, conservatively, that the average is 59%. For each MW of electricity, 5/8 on average comes from CCGT, so gas power input is 1.06 MW.
The conclusion is that wind power with CCGT back-up, using the sort of plant that would be installed now, reduces CO2 a lot.
@ PaulB
Thanks, but that report is older than the one I had read and its forecast of 30% capacity utilisation by 2020 is looking pretty unlikely given that it had forecast an improvement to 25.3% by 2010 and the actual figure (on its own claim) was 24.5%, less than half the improvement forecast by then. There is a lot of bullshit in it (if there is a genuine commercial case for windpower why do they demand such vast subsidies?). I see no reason why capacity factors should be higher for new plant than old unless their minimum windspeed for generation is lower and, if that *is* the case, the addition capacity utilisation will be trivial. (Yes, a lower mechanical failure rate would significantly improve utilisation factor but they don’t admit to a non-trivial failure rate despite the evidence).
I am prepared to give EWEA more credence than Exxon, but not unlimited credibility when I can see that some of their claims are blatantly incorrect.
“The conclusion is that wind power with CCGT back-up, using the sort of plant that would be installed now, reduces CO2 a lot.”
Only if you ignore the energy consumed in building the windmills.
john77: the 24.5% in the 2010 report is not what was actually generated, it’s just a slightly different estimate – “…would in a normal year produce…”. I can’t see why you would doubt that the UK is windier than Germany, or that wind power plant technology has improved somewhat, just as CCGT technology has.
Of course I agree that the energy cost of building the windmills has to be taken into consideration. But Tim’s question was whether the energy cost of spinning reserve changes the calculation, and the answer to that is no, not much. Similarly, the answer to the claim he quoted last month that the need for OCGT back-up makes wind-power ineffective is no, that’s just wrong. This thread is getting old, so let’s leave the construction cost for next time.