Wind Blowing Nowhere – Again

A central tenet of wind power advocates is that the wind is always blowing somewhere and thus on a regional scale intermittency becomes smoothed out. This is one of these half truths. If one is to have turbines at all, it is of course sensible to have them geographically dispersed as this most certainly helps to smooth out highs and lows in the wind. But it is not the day to day vagaries of the wind that matters but the extremes of wind blowing everywhere at once and worse still, wind blowing nowhere. It is when the wind is blowing nowhere that back up is needed and the physical low points reached defines the amount of backup that is required.

This is a theme we have covered often on Energy Matters. In January this year Roger Andrews had a post called Wind Blowing Nowhere that summarised a year of wind data for seven European countries and showed categorically that geographic dispersion does not smooth wind significantly on a pan-European scale. Hubert Flocard has shown similar. And yet the myth of wind being smoothed by geographic range just refuses to die.

Last week I had a post called Flat Calm Across the UK focussing on the spell of what seems to be uncommonly calm weather across the UK and Northern Europe. In this post I add wind data for Denmark and Germany for the months of September and October. On 19th October, for several hours, the combined output of 55 GW of wind turbines was less than 1.5 GW, that is below 3% average load. It was effectively flat calm across the whole of Northern Europe, not just on this occasion but on several other occasions in this two month period.

Figure 1 Atlantic pressure chart from the BBC / Met office for 4th November 2015. This has been a fairly typical configuration for several weeks with high pressure over Europe, the North Sea and the UK resulting in regional calm conditions. Weather fronts move through which are clearly visible from the wind generation data, but then the high re-establishes and calm conditions return. Atlantic depressions have been tracking to the north of the UK on a deeply meandering jet stream.


I need to thank Paul-Frederik Bach for helping me access recent wind data from Denmark and Germany.

Danish wind data was accessed at the Energinet.Dk site. German data was accessed from various sources as detailed on Paul-Frederik’s wind data base. UK data was accessed from BM reports via Gridwatch. All data have been recalculated to hourly averages and are presented on European time, with 1 hour added to UK time series. It would have been nice to include Ireland, but the data is no longer readily available from the Eirgrid web site.

It is not straightforward to find out the amount of wind turbines connected to the grid and metered by the various countries. The following are estimates garnered from various sources. Uncertainty over metered capacity means that inferences made about load factors are uncertain to the point where they may be totally wrong.

Total = 55386 MW

The raw wind data, at hourly resolution for September and October are plotted in Figure 2. The chart is dominated by the gigantic German wind fleet. The German data show clearly how the wind has come and gone between extremes of 331 MW @ 18:00 hrs on 29th October to 24127 MW @ 13:00 hrs on 6th September. That is a dynamic range factor of 73.

It is clear that there is a high degree of correlation between the countries with a tendency for the lows to be alined. See for example 17, 18, 19 and 20th October. When high pressure was in charge, the wind blows nowhere.

For geographic dispersion to act as a smoothing agent a negative correlation between regions is required. In fact Germany and Denmark are positively correlated (Figure 3) and the data for this period shows that Denmark and Germany cannot help balance each other’s wind output. The correlation coefficients with the UK are zero and nowhere near the negative correlation required to provide load balancing service. The zero correlation masks the periods when wind is blowing nowhere in Northern Europe.

Figure 2 Raw wind output, hourly data, for Denmark, UK and Germany, September-October 2015. Click on chart to get a very large version.

Figure 3 Denmark is adjacent to Germany and it is therefore not surprising that their wind data is strongly correlated. These two countries can do little to assist each other load balancing high against low wind production. But as we shall see, Germany finds Denmark to be a handy import / export conduit to Scandinavia.

What we want to see is the combined wind output from all three countries and that is shown in Figure 4. Figure 4 is a stacked area chart where the data are added to the stack to provide a picture of the combined outputs. Nine spells where the combined outputs fell below 5000 MW are numbered. Let me focus on the period 17th to 20th October (number 8). For most of this four day period, the combined output fell below 2500 MW, that is below 5% load. Lulls such as this CANNOT be and NEVER will be met from storage. Nor can they be met by importing wind power from somewhere else. Let us imagine that somewhere else was Spain. Spain would have to reliably produce a 10 GW wind surplus for 4 days that would have to be transmitted to northern Europe requiring 10 GW of HVDC power lines.  And since the wind in Spain can never be relied upon to fulfil this role, as shown by Roger Andrews, it is plainly madness to contemplate such scenarios.

Figure 4 This stacked area chart adds the wind production from the UK on top of Denmark and Germany on top of the UK. The profile of the green shaded area gives the aggregate production of all three countries. In this two month spell, the wind was blowing nowhere in northern Europe on 9 separate occasions. Click on charts to get very large versions.

How has Denmark Coped?

Denmark has the advantage of being small and attached to Norway, Sweden and Germany  via inter connectors. Figure 5 shows that Denmark simply overcame the problem by importing electricity from its neighbours when the wind stopped blowing. Denmark imports hydro power from Norway and nuclear + hydro power from Sweden. Denmark has in fact become an electricity parasite feasting off its Scandinavian neighbours. Note how in this two month period net exports were almost non-existent. And Denmark is buying high and selling low, and we all know that is the dumbest way possible to play any market. The parasite is not getting a free lunch.

Figure 5 When the wind drops in Denmark it simply imports more electricity from Norway and Sweden. Peak load in Denmark is of the order 5 GW. Hence, at times of low wind about 50% of Danish electricity supply is from imports.

Figure 6 This chart is not stacked, all data originate from the zero datum. The lines show wind production and net imports. The negative correlation is plain to see. The main features are near constant imports from Scandinavia throughout the period and near constant exports to Germany. This may seem odd, but what in fact is happening is that Germany is importing from Norway and Sweden via the Danish inter connectors.

The import / export picture is in fact rather complex. The details are shown in Figure 6. Note that this is not a stacked area chart since XL does not manage negative numbers in a stacked chart in a rational way. What we see is Denmark exporting electricity to Germany throughout most of this period. Whilst at the same time importing electricity from Norway and Sweden. What in fact is happening is that Germany is importing electricity from Norway and Sweden through Denmark. The sixth of September is the only day when significant electricity was exported to Norway and Sweden and we see that most of that came from Germany via Denmark. I calculate that Norway and Sweden exported 1.23 TWh of electricity to Denmark during September. I don’t know what impact that has on their magazines, but it has also been quite dry with high pressure in charge.

Concluding Thoughts

Has September / October 2015 been unusually calm over northern Europe? That is a complex question to answer. The wind data is there is to answer it, but it is a huge amount of work to go back over years of production data and match it to installed capacity.

I have compared UK wind data for 2015 with 2014. Results below:

Installed capacity 13169 MW
Sep + Oct wind generation 3.08 TWh

Installed capacity 13445 MW
Sep + Oct wind generation 2.68 TWh

Grossing up the 2014 generation for the marginal increase in capacity yields 3.15 TWh for 2014. 2015 is 15% below 2014 wind generation for September and October. So my perceptions of flat calm are not misjudged but nor are they highly significant. Scotland has had a dismal summer and this spell of very fine weather has heightened my sense of quiescence.

The bigger questions here revolve around the wisdom of this whole energy strategy. For example, there seems to be a commitment to build the North Sea Grid. Its one of these ideas that has taken root and simply will not die. Had the North Sea grid existed today it would not have made any difference to the performance of N European wind apart from extending the financial losses that are picked up by the consumer. It might have helped in shunting a few GW of French nuclear power around Europe to countries left short.

The central question lies in the wisdom of distributed power generation. Generating your own wind power down on the farm or solar power on your two bedroom semi’s roof may sound like a great back to nature green solution to electricity production. That is until the wind doesn’t blow and the sun doesn’t shine and your dependency is shifted to the owner of the 3000 mile long, 200 GW HVDC power line to Saudi Arabia. Is it not better to be dependent upon the 100 mile long, 1 GW power line to your local nuclear or gas fired power station?


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37 Responses to Wind Blowing Nowhere – Again

  1. Nial says:

    “Generating your own wind power down on the farm or solar power on your two bedroom semi’s roof may sound like a great back to nature green solution to electricity production”

    Euan, I’ve always thought there’s a big difference between consumer side generation where anything generated reduces your bill, if it doesn’t blow you rely on the grid, and ‘source’ side generation where you’re supposed to be providing the grid everyone relies upon.

    Wind for providing grid power is patently madness.

  2. GeoffM says:

    Interesting calculations Euan. I too have been pondering over how UK wind generation has performed for the period early June to early Nov of this year compared to the same period of 2014 (31 Aug to 23 Sep 2014 was especially poor). In Aug and Oct last year Renewable UK put out press releases about how “good” wind production had been; but there’s been nothing from them during the same period this year. Your report suggests that it’s been even more wind-less this time around. On 24 Dec DECC will publish it’s quarterly figs for Jul-Sep, and the pro-Wind people won’t be able to say “That data has been discredited”.
    To do a calculation on how useful a Euro super-grid would be for wind energy, in my opinion, one doesn’t necessarily need to know metered totals for each country (the main use for this is to calculate load factor). If a country’s historic Wind data shows production for that year of, say, 15TWh, and the country consumes, say, 150 TWh annually, I’d extrapolate the Wind data up by a factor of 10. In fact I’d factor it up even more to account for worst-case which is mid winter. By doing this, the scenario would be close to an all-renewable system. I would calculate various main results from this including:
    1. During problem periods (ie when a major country has either too little or too much Wind energy), what percentage of these times would the other countries have exactly the same problem?.
    2. When some countries have a shortage and others have a surplus, what percentage of that shortage could be supplied?
    3. How much surplus Wind energy would there be annually which would need to be disposed of?
    4. What length/capacity/estimated cost of transmission lines would be required?
    5. If these new transmission lines have, say, a total annual capacity of 876 TWh, what percentage of that capacity would be utilised?
    And I would prefer to only include November to February so that solar could be ignored. Hydro could quite easily be factored in. I would ignore biomass and similar technologies as these increase carbon emissions.

    • Euan Mearns says:

      I had a quick look at Sep – Oct 2014 and was surprised to see that beginning of Sep last year was also very calm across the UK, but over the two months this year was even calmer as the post indicates.

      As for the Super Grid, I’ve only just come to appreciate that to have any security value at all the connection to the UK would have to be of the order 10 GW and that 10 GW connection would have to stretch as far as secure supplies can be procured and since we don’t know where that is, lines would have to go to Scandinavia, Ukraine, Turkey and Spain. And given that we are dealing with weather systems, everyone may want to tap into the cyclone over Spain or Turkey at the same time, and each of these regions would have to maintain gigantic surplus capacity that would stand idle most of the time.

      And of course, if Europe wanted to tap into cyclones over the UK the link would have to be way over 10 GW if we were to export meaningful capacity.

      Does anyone know what the North Sea grid is supposed to be rated? Same question for Desertek.

      The whole thing is so insane, its not really worth spending time contemplating it.

  3. Lars says:

    Euan, very fascinating again thank you!

    Just one comment, you said: “I calculate that Norway and Sweden exported 1.23 TWh of electricity to Denmark during September. I don’t know what impact that has on their magazines, but it has also been quite dry with high pressure in charge”

    The reservoir levels for both Sweden and Norway have been record high this autumn at over 90% full in October, and still almost 90% full at the beginning of November. Both countries have had incentives to export power to prevent “water losses” and get a higher price in this period. It will be a mistake to assume that Denmark`s and Germany`s imports of power have been out of pure necessity, they have just taken advantage of very low wholesale power prices instead of relying on all of their own (more expensive) spare capacities.

  4. Willem Post says:

    “And yet the myth of wind being smoothed by geographic range just refuses to die.”

    That RE myth has been carefully nurtured by many “reports”, etc., paid for by RE moneyed interests. The public has been suitably brainwashed.

    During the Middle Ages, bigger and bigger monuments, called cathedrals, were built to keep the salvation myth going. It was big business, just as the defense and RE businesses today.

    Then Martin Luther came a long, and all hell broke lose. It look a long time and many wars for that myth to finally die.

    • climanrecon says:

      Cathedrals eventually paid off for the towns and cities hosting them, just think of the tourist revenue, I doubt that the giant wind turbine cathedrals of today will be held in such esteem by future generations.

  5. Günter Weber says:

    More interconnectors will help. But not so much for transporting wind power from Turkey to Ireland. Instead interconnectors will allow to reduce the necessary backup capacity from maybe 105% to 90% of peak demand for each country. Because unexpected unavailability of backup capacitiy together with minimum renewables production together with peak demand is very unlikely to occur in several neighbhouring countries exactly at the same time.

    And for the (relatively minor) question if backup capacity can savely be reduced from let’s say 92% to 88% of peak demand, the analysis to what extend wind/solar production are smoothened in larger and larger areas will be of importance. On the European scale, even the slightest smoothening still might save a few billions of investments in backup capacity.

    • Willem Post says:


      A lot of ifs.

      With windy conditions around the North Sea, all will have high wind energy production. This will cause voltages to increase on grids, if the energy is not “exported” to areas with lower voltages, i.e., “under-generation”, assuming local demand/balancing is not lowering the voltages enough.

      To create under-generation, Norway merely reduces flow through it turbines (reservoirs remain fuller) and satisfies ITS under-voltage with VERY LOW/NEGATIVE COST energy coming from Denmark, Germany (via Denmark), etc.

      Germany would have a subsidized COST/kWh of that ENERGIEWENDE energy of about 15 – 20 eurocent.

      With sufficient interconnection capacity, more countries can get in on the game, until Norway and Sweden run out of balancing capacity, such as when reservoirs are full (as in spring), spilling is occurring, too little water flowing through the turbines to modulate massive VARIABLE energy quantities entering Norway.

      Wind energy curtailment in higher voltage areas likely would be required.

  6. Jack Ponton says:

    The proposed UK-Norway link is 1.4GW, less than the French interconnector.

    It is worth looking at Gridwatch’s French grid report. They have interconnectors to six countries including Spain and Germany. These regularly work both ways and France benefits from excess wind and solar from them and exports nuclear, presumably very profitably. France has significant hydro which is of course very flexible. Their nuclear is also mor flexible than the UK’s. Because of the larger capacity they have more reactors with fresh fuel rods which I understand means they can be ramped up and down more easily.

    In principle wind or solar generation from Spain could reach the UK via France. However the isobars on the chart suggest that the wind there was not a great deal stronger than in northern Europe. And at 6pm UTC in the winter even Mediteranean won’t be doing much.

  7. Jack Ponton says:

    Sorry, last sentence should read:

    And at 6pm UTC in the winter even Mediteranean solar won’t be doing much.

  8. Tim says:

    Many thanks to Euan for the time and effort he spends educating the rest of us. Most likely, only those of us inclined to agree with Euan’s work read his messages. But Euan, you arm the rest of us with the facts to confront those that perpetuate destructive myths.

    Thanks for your hard work.

    • Knut says:

      Not quite. I am inclined to disagree with Euan and Roger’s overall perspective, in particular their basic decision to judge the prospects of renewable energy based on historical data. The main premise of any sensible case for renewable energy is that technology will improve and cost decline, in particular for storage. I don’t see them investigating this question, which the argument really hangs upon.

      But I keep coming back, because there really is a lot to learn here, such as in this post. Thanks Euan and Roger!

      • JerryC says:

        The main premise of any sensible case for renewable energy is that technology will improve and cost decline, in particular for storage.

        The snag is that while wind turbines, solar panels and metal oxide batteries are often thought of as new, disruptive technologies that have the potential for sudden, massive efficiency gains, in reality, they’re old, mature technologies that can reasonably be expected to improve slowly and incrementally. Much like internal combustion engines or coal-fired power plants.

        • Willem Post says:


          Many non-technical people are exposed to knowledge, but it does not sufficiently penetrate to affect their notions, usually fed to them by RE hypers and wishful RE dreamers.

          I have yet to see any hype from Euan and Andrew, both high-level technologists, who are reality-based.

          They think on a higher level about energy matters, and see the picture more clearly than almost all commentators on this site.

          We are lucky to have them spend so much of their time, effort and money to squash lies and get out the truth.


          Exactly correct, and the same goes for battery-based energy storage, despite occasional TESLA-like hypes.

          Here are some calculations that basically blow the TESLA hype out of the water.

          Chevy-Volt and TESLA: The Chevy-Volt has a 16.5 kWh battery, but it uses a maximum of about 10.8 kWh (about 65% 0f its capacity), because the battery controls are set to charge to about 90% of capacity and discharge to about 25% of capacity. GM does this to minimize costs of its 8-yr/100,000 mile manufacturer’s warrantee. That warrantee is for manufacturing DEFECTS, does NOT cover performance. According to GM, the battery is expected to have a performance loss of 20% over its 8-yr WARRANTEE life, and more beyond that 8-yr life. The 10.8 kWh gives the Chevy-Volt an ELECTRIC range of about 38 miles on a normal day, say about 70 F, less on very cold and on very warm days, less as the battery ages.

          TESLA has a 10 kWh, Li-Ion, wall-hung, battery unit. I assume TESLA is as capable as GM, i.e., no magic, no hype. There are battery charging losses and discharging losses, and AC to DC and DC to AC conversion losses. The TESLA 10-year warrantee is for manufacturing defects, does NOT cover performance!! The INSTALLED cost of the 10 kWh unit = $3,500 + S & H + Contractor markup of about 10 percent + $2,000 for an AC to DC inverter + Misc. hardware + Installation by 2 electricians, say 16 hours @ $60/hr = $7,100, or $7,140 per this URL.

          Assuming a 65% charge/discharge, and a 90% AC to DC inverter efficiency, and allocating half of the 8% DC-to-DC loss to the charging side (the unit has a round-trip DC-to-DC efficiency of 92%, per spec sheet), it would take 0.65 x 10/(0.9 x 0.96) = 7.523 AC kWh of off-peak grid energy to charge up the unit. During on-peak hours, one would get back 0.65 x 10 x 0.96 x 0.90 = 5.616 AC kWh to use in the house, for a minimum energy loss per cycle of (1 – 5.616/7.523) x 100% = 25.4%!!

          If we GENEROUSLY assume the battery would have NO performance loss over its 10-yr WARRANTEE life, and one cycle per day, i.e., 3,650 cycles, and night-time cost of charging at 10 c/kWh and day-time avoided cost at 18 c/kWh, then 3,650 x (5.616 x 18 – 7.723 x 10) = $943.76 would be the gain over 10 years. The cost of financing, PLUS any costs for O&M, PLUS any capacity degradation due to cycling, PLUS efficiency reductions of part-load operation of AC/DC or DC/AC inverters, PLUS the cost of depreciation are ignored.

          The above is a best-case analysis. Actual results are much worse, i.e., terrible.

        • gweberbv says:


          I agree that ‘sudden, massive’ efficiency gains are unlikely. To be honest, I have no idea if such a thing ever happened for any technology. To me it seems a much better description that sudden, massive efficiency gains were to harvest, once new technologies were spread throughout industry and society (while the technology itself still developed more or less slowly).

          On the other hand, your statement is really ridiculous when you compare the last ten years of massive photovoltaic cost degression to the very minor gains of combustion engines in the same period of time.

          • robertok06 says:

            “last ten years of massive photovoltaic cost degression to the very minor gains of combustion engines in the same period of time.”

            Reality check: the efficiency of the average PV module is marginally better now compared to what it was 10 years ago.
            You are comparing the COST of PVwith the thermodynamic efficiency of combustion engines. Nobody ever told you that apples and oranges are not the same fruit?

          • Günter Weber says:


            I bet you know pretty well that improving the physical efficiency of PV is not a major concern for the PV industry. As ‘fuel’ is for free and space necessary for the installation also (more or less).

            While the values of ‘record cells’ produced in research institutes did no improve so much during the last years, the perfomane of the cells in the market improved a lot:
            But this improvement only happens as part of a general effort to bring down to price per produced kWh. And as I explained above, this price depends not so much on the physical efficency of the modules.

  9. Graeme No.3 says:

    Australian experience is that 1500km. is too short a distance to ensure supply from wind turbines.
    I am not sure how far you would have to go eastwards – wind farms in the Urals?
    You also have the problem of icing up in the Arctic areas.

    Nothing will discourage the advocates of wind and solar, you will have to wait for the inevitable blackouts to restore sense.

    • GeoffM says:

      Even when there are blackouts these people will blame fossil fuel power stations for having the audacity to break down. DECC will no doubt try and sort the disaster out by bringing in yet more contradictory subsides. Maybe they’ll do something ridiculous like pay huge sums per unit of energy generated during a crisis, or for hundreds of large diesel generators that don’t need planning permission and have very high emissions per unit of energy.

  10. John Harrison says:

    The correct way to deal with this question is to study the correlation of the output between wind farms. This was done for the Ontario system back in 2008. The correlation length was 400 km. There have been similar determinations elsewhere with similar results.. See the following link for the Ontario study.

  11. David McCrindle says:

    It is also interesting to note that out of an installed capacity of 41GW, the maximum generation was 24 GW over the period (german data). As you have stated the uncertainty in knowledge of capacity means that load factors are difficult to estimate. However, without actually doing the integration, it looks like the peak to mean ratio over the period was quite high – indicating a lowish load factor – even relative to the 24GW peak.

    I wonder if this actual performance is typical.

    Thanks for your informative website

    • gweberbv says:


      wind generators are usually paid for producing kWh not for achieving a certain load factor. You can optimize wind generators for high load factors, but this translates to higher production costs per kWh as you introduce something similar to curtailment.

  12. It is the same in Sweden, I have the data for Sep. and Oct. if would like to have it.

  13. Euan

    Can you put the German and wind output on different graphs with their own scales?

    Some of the German data looks strange to me. For example the data from say the 10th to 23rd of October, this seems to show that Germany gets a greater magnitude increase than Denmark when wind spikes.

    To further add to my confusion, I checked the Irish data for this data and from the 12th to 19th of October, it is flat calm (peak about 400MW).

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  15. Flocard says:

    To access French data, you might find the following site (monitored by the French grid RTE) convenient :

    The only problem is that one has to wait about 15 days after the end of each month to have access to “consolidated data” whose accuracy is much better than that of those published on a daily basis (those daily data remain available as long as no consolidated data has been published, after that, they are destroyed. In the same way consolidated data are erased once “final data” are published – generally sixt months after the end of a calendar year).

    As a matter of fact, as most French wind turbines are installed in the great plain north of the Loire and as this is going to stay like that just because it is mostly empty space without much tourism economy (as opposed to the Thone valley to Provence and Languedoc Roussillon) wind- production France also just as Belgium belongs to the North Europe you are discussing.

    You are right to say that in winte time at least, Spain wind production departs from that of the rest of Europe. But as often it means that the correlation coefficient is close to 0 and not to -1 as would be necessary to compensate excess or lack of wind in northern Europe.

    On the other hand, until recently connexion of France to Spain was limited to 1GW. After more than 10 years of discussion and work it was pushed up to 2 GW. The main obstacles came from the ecologists which refused the building of an aerial high voltage line. An underground crossing of the Pyrénnées was necessay with a total cost exceeding by a factor 5 to 10 (there are various estimates) what the aerial line would have cost. At this point people and budgets are so exhausted that no serious project for an increase in HV connexion. People have been mentionning an undersea connexion across the gulf of Biscaye..


    • Euan Mearns says:

      Hi Hubert, I actually just grabbed French wind off Gridwatch and want to look at pattern of French exports in this 2 month period. I also have data for Sweden, so quite a large geographic spread.

  16. David MacKay says:

    One detail: you said that “For geographic dispersion to act as a smoothing agent a negative correlation between regions is required.” I don’t think this is true. Yes, a negative correlation would be wonderful, but you could get a useful smoothing effect too if there is zero correlation. It’s a “law of large numbers” thing. I’m not saying that such a smoothing effect exists. All the evidence I have seen (especially on this website!) shows that people who believe in smoothing effects in Europe are indulging in wishful thinking. I’m just saying don’t overstate the case the other way.

    • Euan Mearns says:

      David, you are correct and I agree. But this has prompted me to think a little about what is a complex issue. There are two end member states of high correlation. 1) wind blowing nowhere and 2) wind blowing everywhere. In between there is a spectrum of smoothing which has given me the idea to look at the power spectrum as a means of characterising the smoothing effect.

      The extremes (1 & 2) are important. The former defines the amount of storage / back up / interconnection. The latter defines the scale of losses made by the swing producers that are required to keep the system alive and / or curtailment payments.

      I think there is sufficient data to show that wind intermittency in Europe cannot be solved by interconnection or storage at a sensible level of investment. And spending large sums on weak partial solutions does not seem sensible to me.

    • Euan Mearns says:

      I should have another post on this Monday since I now have data from France and Sweden too. Below is the power spectrum for the 5 countries:

      At either end is maximum correlation with wind everywhere and wind nowhere. All other points arguably show varying degrees of smoothing. Might have expected to see a plateau in the middle of the spectrum that would represent a most-likely smoothing scenario. But it doesn’t exist in these data that show continuous variance.

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  18. David MacKay says:

    Yes, it is a good idea to show the histogram of wind output (or the cumulative distribution, which is what your “spectrum” graph is showing, rotated 90 degrees). I’d suggest showing a histogram or cdf using load factor as the vertical axis (in your spectrum plot); this makes comparison easy between regions and lumped regions. You can also easily compute what would happen to the histogram if two or more added regions were perfectly uncorrelated (by just randomly permuting all the hours in each of the data sets before combining). I think such a set of cdf plots would be instructive; it would certainly show how much more frequent “everywhere” and “nowhere” are than would be the case if sub regions really were uncorrelated.

  19. Euan Mearns says:

    Hubert Flocard posted this link in another thread.

    I agree that plotting load is a good idea. Not sure what cdf plots might add (I had to Google cdf ;-). I don’t think the frequency of “everywhere” and “nowhere” is of great interest, unless one is still thinking about storage. The fact that “nowhere” exists creates the need for back up (or storage) that cannot be run economically.

    I’ve grown to realise that so called distributed generation creates the need for gigantic grid up-grading. Either hundreds of GW coming into Europe or hundreds of GW leading to and away from mega pumped storage schemes. National Grid provides vocal support because its great for their business. National Grid is strategic and should be nationalised IMO.

    An argument can be made that nuclear is more distributed that renewables. I don’t know, but I bet that inter connections within the UK never exceed 2 GW (I imagine you know the answer to that) and that is because we distribute power stations evenly among the population centres. We then don’t need 100 GW of cables leaving Strath Dearn nor the Beauly Denny link.

    In case you haven’t seen it:

    Its the cheapest solution I’ve seen.

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