Wind Lulls

The installed capacity of  UK Wind farms is currently 25GW.  The business secretary Kwasi Kwarteng proposes to at least double that number, but there is a basic problem which seemingly everyone overlooks – Wind Lulls. Sometimes high pressure sits over northern Europe for many days on end bringing still air with no wind.  All UK, German and French wind turbines are becalmed producing little if any power. Life and essential services has to continue so old coal stations are fired up and CC Gas  stations run at maximum output to meet peak demand.

Here are two recent examples:

  1. The 7 day lull from 16-22 December 2021

Comparison of Gas and Wind output during the 7 day Wind Lull last December.

We also see below how coal is still needed to balance power on the grid.

2.The recent  10 day wind lull lasting 10 days. At least this time there was a bit of sunshine yet notice again how the remaining 2 coal power stations were also needed . The whole of March saw only two brief spells of good wind output.

10 day wind lull March 20 – March 30

Most of March saw light winds. Output reached a maximum of 15GW briefly or a maximum  load capacity of  60% . Note that I am also correcting the metered wind output to include embedded  small wind farms as well.

Gas output compared to wind output – almost perfect anti-correlation.

Don’t worry though we are told. We just need “energy storage”, but no-one ever calculates just how much energy we would need store in order to see us through a wind drought like we have just experienced or the one last December.

In December there was additionally no solar power generated. In fact solar energy is perversely anti-correlated to demand. Annual peak demand is around 6pm on winter evenings when solar energy output is zero. So let’s estimate how much energy would need to be stored to cover the December lull.

We need 7 days of continuous power delivery at an average load of  30GW. So we need to store:

7 x 24 x 30 = 5040 GWh  or  1.8 x 10**16 joules

This is a huge amount of energy which is approximately equivalent to

  • 1200 Hiroshima size bombs
  • 373 million fully charged Tesla Powerwalls
  • 67.2 million long range Tesla 3 car battery charges

So it is unlikely that any future fleet of electric cars can back up the grid, assuming their owners would agree to walk rather than drive during a wind lull.

The largest energy store in the UK is the Dinorwig pumped storage Power Station in Snowdonia. It took 10 years to construct but actually paid for itself within 2 years by balancing peak time loads.  It can store up to 9.1 GWh of energy which is a useful power source over short periods.  However it is still  500 times too small to balance a wind dominated energy grid for a week. Nor do we have enough mountains to dramatically increase such pumped storage systems.

The largest Tesla grid size battery storage is in Hornsdale Southern Australia. It can store 193 MWh which is useful to cover short outages but still way too small for a wind lull.

As David MacKay used to say “We need an Energy Policy which adds up”.


About Clive Best

PhD High Energy Physics Worked at CERN, Rutherford Lab, JET, JRC, OSVision
This entry was posted in Energy, renewables, wind farms. Bookmark the permalink.

78 Responses to Wind Lulls

  1. Paul says:

    Hello Clive

    Thanks for another great post . I’ve have been posting elsewhere the term ” Wind Drought” for the conditions we see, it resonates better with the public.



    • Clive Best says:

      maybe wind drought is better !

      • It doesn't add up... says:

        I think the German word Dunkelflaute has a nice resonance: it also highlights the fact that these spells are most troublesome in the winter when it’s dark and cold, and that this problem is international. I am starting to see it being used quite widely now.

  2. Ed says:

    1200 Hiroshimas for a week

    When will these guys learn to do sums we miss David Mackay

  3. TrevorC says:

    Don’t worry. All we need is maybe 20 or 30 times as many wind turbines to cover the lulls. We can also pay the providers to shut them down for the long periods when we don’t need the output. It shouldn’t cost more than a few hundred billions pounds. And once we have built them the earlier turbines will be worn out, so we can continue building them forever. I wonder which politicians have shares in the industry and how much the electricity will cost?

    • forbin says:

      may be worse than that – have you seen Denmarks load factors for wind ?

      due to maintenance they decline – age performance curves are a problem.

      ok newer turbine are expected to be better but this has yet to be seen.

      about 310Twh pa for the UK electricity alone, added in a figure for ground transport of 92Twh and nat gas of approx 100Twh and we have approx 500Twh for today’s population.

      Batteries ( iron/air ) in the 10’s Twh range ( 450 A-bombs per 10Twh storage according to one web site ) .

      I would be concerned if one such storage facility was near my home.


      • Clive Best says:

        Off shore degradation is even worse. The cost of and carbon emissions needed to replace off shore wind farms every 15 years is unsustainable.

        • MarkR says:

          What data are you using to decide there is major offshore degradation by year 15?

          Are they really replacing offshore wind farms after 15 years? What about the newer wind farms?

  4. entropicman says:

    Nobody mentioned the underlying purpose of wind farms, which is to reduce fossil fuel burn by replacing the output from gas power stations when the wind blows.

    Think how much less CO2 you release and how much less gas you need to buy from Russia.

    • And think how much tax payers money you have to pay them to switch off when there is too much wind. Think of the incredible amount of environmentally damaging batterie you’d have to have to cover a week long wind famine. ~No thanks

    • forbin says:

      no, the wind farms were to replace coal fired stations and always meant to have nat gas as backup .

      And it was never meant to be cheap as the consumer is finding out.

      And to what purpose if the fossile fuels get burnt anyway ? Which is what’s happening now.


    • Clive Best says:

      Yes, but even if true they can only ever reduce CO2 emissions by 50%

      The other 50% is backup from gas/ / dispatch-able energy

      It is a fundamental limit.

      The sooner we accept this basic physics the sooner we can solve “climate change”.

    • It doesn't add up... says:

      If that is the purpose then they have failed utterly. What wind farms have in fact done is eaten in to the earnings of baseload generation, forcing it to close and making new investment uneconomic. Because it has replaced continuous power with intermittent output it actually requires extra backup to balance, and that has come from gas and imports (the latter simply because we have insufficient gas and coal generation capacity, so we pay Europe to crank up theirs and pay for the interconnector to deliver it). When we still had coal capacity we could switch to coal when gas was expensive (as it was in the aftermath of Fukushima), or run additional coal in the winter time to free gas for domestic boilers and stoves.

      You can see all these features in this chart:

    • Phil Toler says:

      The best solution to this is not more wind turbines. We must reduce consumption by insulation and installing well designed modern heat pump systems – which are super effective. I have both and my heating energy consumption is around 20% of what it used to be with a gas boiler. This is a HUGE saving and a potential game changer in reducing energy market turmoil and reliance on unstable regimes like Russia and some middle East countries.

  5. Joe Public says:

    Hi Clive. A very informative post, thanks.

    1. “The installed capacity of UK Wind farms is currently 25GW.”

    Elexon informs that *GB* has 27.33GW of metered capacity, so the charted performances are actually worse than they appear.

    2. “Don’t worry though we are told. We just need “energy storage”, …… So we need to store:

    7 x 24 x 30 = 5040 GWh …”

    For context, Britain has >30,000GWh of natural gas storage (Plus ~4,000GWh in Linepack). Today’s stock level shown here:

    3. “The largest Tesla grid size battery storage is in Hornsdale Southern Australia. It can store 193 MWh which is useful to cover short outages but still way too small for a wind lull.”

    It can store 193 MWh, but its advocates conveniently forget to mention that a large chunk of its power is reserved for grid stabilisation.

    It’s Phase 1 was 100MW/129MWh, of which 70MW / 11.7MWh (10 mins @70MW) was:

    “contracted to the government to provide stability to the grid (grid services) and prevent load-shedding blackouts”, so unavailable for ‘storage’, its supposed raison d’être!

    The irony being that SA’s relatively large proportion of destabilising wind now needs grid stabilisation! 😉

    • Clive Best says:

      Of course you are right!

      How is it possible that dogma seems to have triumphed over logic ??

      Short term political gain by MP classics graduate without a clue may well be to blame .

    • It doesn't add up... says:

      The expanded HPR is no longer the world’s biggest grid battery Try this behemoth (and note that the UK is starting to head towards this league):

      I spent some time deciphering the operation of the HPR by looking at the data on its actual charging and discharging (at least at the 5 minute data resolution available to me: I had no access to the grid trader data at 4 second resolution). Whilst they conducted some early experiments with high continuous discharge, in practice it has only ever rarely been used in this mode, and that in windless heatwaves: its futility was soon shown up because it ran out quickly and they had to fire up the diesel generators. The main role is in second to second grid stabilisation, which is known in Australia as the FCAS market (Frequency Control Ancillary Service), with an overlay of charging up when power is cheaper overnight or during a solar peak, and discharging when prices are expected to be higher. The battery made a fortune out of the FCAS market a couple of years ago when other constraints left it as essentially the sole supplier charging monopoly rates – this financed its expansion. Here’s a fortnight of its operations alongside the output of the Hornsdale Wind farm. It flip-flops between charging and discharging at high frequency. Also shown is the cumulative net charge, which reflects changes in the level of battery charge and round trip losses and use for air conditioning, and the Regional Reference Price which is the system price that changes every 5 minutes.

      • Clive Best says:

        So basically battery storage is used mainly to stabilise the grid rather than provide any significant backup energy when the sun doesn’t shine or the wind doesn’t blow.

        • It doesn't add up... says:

          That’s basically correct. A 50MW/50MWh typical UK grid battery could earn £17/MW/h for providing the equivalent of FCAS (now known as Dynamic Containment in the UK) – about £7.5m per year. If it ran a daily round trip to store cheap overnight power for the morning rush and midday power for the evening rush it would need an average margin of over £200/MWh after allowing for ~20% round trip loss to make the same money. Prices rarely vary by that sort of amount, although recent volatility has produced some opportunities. Of course, they do manage to “stack” revenues by doing a bit of both.

  6. Dr Jonathan F Dean says:

    Have you read the ESO FES2021?

    Don’t worry, it’s all in hand

      • Clive Best says:

        I found the report. It lacks numerical detail and does not give a unique solution. Instead it gives options of how to reach net zero based on choices that have to be made beforehand (i.e. now).
        1. Use Hydrogen for heating as well as electricity ?
        2. Use natural gas to generate hydrogen ?
        3. Dispatchable power is still needed.
        3. Negative emissions is needed in all scenarios

        • Dr Jonathan F Dean says:

          Who ever suggested dispatchable power was not required? Hydrogen CCGTs, biogas, gas/CCS etc

          Unless you’re eg of the anti meat camp, or anti concrete, then yes, negative emissions will be required

  7. Dr Jonathan F Dean says:

    Blogs like this are great fun, with folk thinking they have made a great discovery, but I’ve yet to read one (and there are so many) where the author has validated their “findings” with the ESO who have a statutory duty under the Electricity Act (1989) to plan for the most efficient and effective system. If the authors have genuine concern that the ESO is failing in its statutory duty, then that is the real story, and one of national concern. That would be a blog worth following, and one I would follow eagerly. Until then it’s just spreadsheet warriors who I doubt have performed anything like the analysis the ESO have

    • Joe Public says:

      ” …. have a statutory duty under the Electricity Act (1989) to plan for the most efficient and effective system.”

      If only warriors would discover that the obligation is for an efficient, effective and economical system.

    • Clive Best says:

      I have made no great discovery. I merely monitor the grid.
      I support Nuclear Energy to replace fossil fuels. Over reliance on wind and solar will lead to blackouts.

      • Dr Jonathan F Dean says:

        I assume from that comment then you haven’t even read FES2021 never mind validated anything with the ESO. So what your post is really doing is using a mass of data and graphs to give the impression you know what you’re talking about, in order to convince the less data literate that nuclear is THE answer

        Nuclear probably does have a role to play, but no one has ever been able to explain how nuclear could ever cope with the demand fluctuation we have. That would be an interesting blog. If nuclear did replace fossil fuels, and we had a peak winter demand of 90 GW against an average annual of 35 GW, what installed capacity would we need and what would be the delivered cost to consumer?

        • Clive Best says:

          Yes I have read it (see comment above) It gives a high level generalised overview offering 4 broad scenarios. Consumer driven (we all buy heat pumps and insulate houses). Steady Progress (we don’t meet net Zero in 2050). Leading the Way (Consumers are highly engaged in reducing and
          managing their own energy consumption). System Transformation (as now but replace gas with Hydrogen).

          It seems to put more of the responsibility for decarbonisation onto the consumer. It doesn’t explain how they will generate electricity i.e. mix between Nuclear and renewables. I would have thought this is their most important task.

          Regarding Nuclear. We need as much capacity as could be built in the next 20 years. If we can meet peak demand in winter (say 50GW) then we can use the excess energy during nights and weekends for electrolysis of water to hydrogen, Aluminium smelting, district heating, green methane production, synthetic aviation fuel, charging millions of EVs overnight etc.

          • Dr Jonathan F Dean says:

            You’ve not read the full report then if you can’t find the breakdown between all the different types of generation

            If you can’t give an answer with just a bit more detail we’ll have to assume it’s a non starter. The ESO could have included any amount of nuclear in their scenarios but they didn’t, as they optimised for minimum overall cost. So the all nuclear option would cost more than the bit of nuclear with lots if renewables option

            If you are sure that is wrong, and can prove it, then you have proof that they are failing in their statutory duty. That would be a great blog that I’ll look out for with interest

            Until then you’re just another of the paid and unpaid nuclear lobby

          • Dr Jonathan F Dean says:

            Next 20 years? Five for planning, ten to build, say 6 GW?

          • Clive Best says:

            If China can build 150 new nuclear stations then surely the UK could build 10 !

            link here

        • It doesn't add up... says:

          Nuclear flexibility is a matter of design and cost. Submarine reactors are designed to cope with very substantial variations in load, but of course cost is not the prime consideration. A first approximation is simply to divide cost at nominal full capacity by the average utilisation.. Some of the French nuclear fleet was built with flexible turndown of up to 80%, but it rarely gets used in that mode because flexibility is largely handled with hydro supplemented by gas as a cheaper option. SMR designs are said to be capable of handling a significant degree of turndown.

    • It doesn't add up... says:

      I have looked not only at its report, but also that of the CCC, and also at as many of the studies that were commissioned to feed into the scenarios in as much detail as is publicly available. It’s a shocking picture of utter complacency. Every single assumption is optimistic and much of the underlying work is amazingly simplistic. Nowhere does it properly evaluate storage needs or the trade off between over-investment in capacity and storage, which needs to recognise not merely wind lulls of a week or two, but seasonality and fundamental underperformance over many months or even years meaning that storage cannot be replenished, and also that the system gets forced into sharply rising curtailment volumes because capturing surpluses and storage are uneconomic at scale. These problems are all assumed away.

      Of course, this is exactly what we have seen over the past year in Europe: underperforming renewables led to extra gas generation, preventing gas storage from being refilled ahead of winter, and leaving the market extremely vulnerable to any disruption. Market prices were reflecting these risks last summer and went ballistic in the autumn.

      Unfortunately Ministers and Civil Servants and most MPs prefer to be told that their net zero utopia is feasible, and lack the ability to question it. They don’t worry about 2050, by which time they will no longer be working. It’s also clear that vested interests are both pushing net zero propaganda and stifling debate if they can, just as has been the case over climate itself.

      • Clive Best says:

        Exactly right. You can keep your well paid job now by telling politicians exactly what they want to hear to placate the green lobby. Perhaps you can even get a knighthood or be ennobled like Lord Deben.

        You’ll be long retired on a fat pension well before the Renewable Energy dream collapses.

  8. Dr Jonathan F Dean says:

    Could the U.K. build 10 nuclear stations in the next 20 years?

    There are 8 sites where nuclear is allowed by NPS EN-6. One is taken by Hinckley, Sizewell will get another. Bradwell is in limbo. Wylfa and Oldbury are owned by Hitachi with no sign of a sale. Not many places left. Plus the “historic” nuclear sites are bad choices … long way from major demand centres with no chance of district or industrial heating

    Two projects would not happen concurrently at the same location

    Typically it takes 5 years in planning and a minimum of 10 to build

    EN-6 is out of date with no scheduled update from BEIS

    Wylfa was rejected at planning before Hitachi cancelled for multiple reasons

    The Nuclear Financing Bill is not passed

    So 10 in 20 would be a real stretch

    Meanwhile we are on target for 40 GW offshore wind by 2030. Scotland has just licensed 25 GW!

      • Dr Jonathan F Dean says:

        I thought this was old news! Not a surprise, and France has, for years, had an established export market for all their excess power. Their entire system is geared up to supply neighbouring countries. It would be an entirely new venture for the U.K., as our interconnectors are primarily for two way trading, not bulk export. It also helps that the French state has such a large stake in EDF, their main generator and grid operator. We could do the same, but a similar suggestion didn’t win many votes at the last GE, and it would mean unpicking over 30 years of our current ways of working

        If you’re so convinced all nuclear is the answer, make your case to the ESO, not me

        • It doesn't add up... says:

          You haven’t read the reports. Otherwise you would know that there is a plan for a massive expansion of interconnectors, with the aim of becoming a major exporter of wind power. Of course, this hasn’t been thought through at even the most cursory level, since even now when we generate surplus wind we are exporting at very low or even negative prices, with the wind farms being subsidised by consumers via CFDs and ROCs to do so. Adding more export surplus just when other grids are well supplied with their own renewables is a money losing proposition.

          I have made these points forcefully to OFGEM and in their mealy mouthed way they have taken on board a few of them at least.

          • Dr Jonathan F Dean says:

            I’m well aware of the plans for more interconnectors but we don’t have much capacity at the moment. Well done for challenging Ofgem

        • It doesn't add up... says:

          European power flows in 2021

          Data from PF Bach.

          The UK uses imports as a substitiute for dispatchable capacity investment. Incidentally, France has been a net importer for some months with all its nuclear shutdowns. With the threat of closures in Germany reducing its export surplus there is risk of severe power shortages in Europe. Fortunately it seems that policies are urgently being reversed: Belgium has just agreed to extend its nuclear by 10 years, and Germany is considering cancelling nuclear and coal closures. Whether it will prove sufficient remains to be seen. Germany is already talking about closing down chunks of industry.

          • It doesn't add up... says:

            Click on the chart to display if it isn’t showing: or take a look at PF Bach’s informative commentaries and analysis with particular reference to the Scandinavian countries,but also the wider European picture.


  9. Dr Jonathan F Dean says:


    I was lucky enough to go inside Dinorwig when they were building it, when I was a teenager. It was still just a huge cavern in the bare rock and we walked through muddy puddles up the access tunnel. It was like a cathedral inside, My dad ran Wylfa so they were only too happy to show us round. Dinorwig was built to provide the flexibility Wylfa didn’t have, and Wylfa was the biggest nuclear station (at 1 GW, LOL!) at the time. The two went hand in hand. The rest of the grid was pretty inflexible too back then (but loads of inertia)

    Now the nuclear stations don’t really need flexibility, as the grid gets it from gas and wind. They can just be left to run flat out

    If we don’t have wind, for both power and cheap hydrogen, and we don’t have hydrogen replace gas in CCGTs, and we just use nuclear, where will we get the flexibility from?

    • Clive Best says:

      Of course there is a difference between relying on Dinorwig and Gas for flexibility compared to Wind, assuming a core nuclear base load. The balancing mechanism of the grid is much easier for the former.

      Now imagine a scenario of just nuclear, wind and solar. You cannot ‘balance’ the grid in real time. All you can do is disconnect wind when there is too much wind and burn “green” methane when there is no wind. Perhaps excess wind power could be used to make “green” methane.

      • Dr Jonathan F Dean says:

        Just wind and nuclear would be disaster, which is why no one is suggesting it. Majority from wind, due to cheapness, balance wind with hydrogen, biogas and gasCCS and a bit of nuclear as long as you can ensure it all gets used at full capacity without impacting the cheaper sources of power. Not much is required, but there has to be some to subsidise the Navy supply chain. Nuclear is too expensive to make hydrogen so that will be made from constrained wind. It’s all in FES2021. You should have a call with them. They are very approachable and like engaging

        • Clive Best says:

          Sounds like wishful thinking to me. Explain to me how we get through a 10 day wind lull after we have electrified all transport and heating and winter demand has doubled to 90GW ?

          • Dr Jonathan F Dean says:

            Read FES2021! The section on flexibility. A combination of some generation from far offshore, stored hydrogen in CCGTs, interconnectors, nuclear, biogas, gasCCS etc

            As I’ve said before, if you think, after all their extensive modelling, they are wrong, then that is genuinely a good story and worthy of investigation. But you need to be prepared to put your high level numbers up against their detailed analysis

            They have no axe to grind. They can use any mix of generation to produce least cost. They do not choose lots of nuclear. They do choose lots of renewables

          • Clive Best says:

            They are making a huge bet on Hydrogen production by electrolysis of water. By 2050 it is the main (only) dispatchable power source since renewables are intermittent and weather dependent.

            So when there is lots of wind the excess power especially at night is supposed to produce enough Hydrogen to see us through wind lulls. I think though it may be wiser to also produce green methane as well.

            Storing and delivering hydrogen is much harder than methane because it is so light. That’s why there is none in the atmosphere. It tends to escape to space and needs near perfect containment.

            and of course consumers will bribed to reduce demand when energy is in short supply.

            “Appropriate price signals and incentives will be needed from the energy market and from policy to encourage the types of flexible demand-side response behaviour that a net zero world requires from consumers.”

            We really need to start testing hydrogen electrolysis and small scale hydrogen turbines to see if this is really feasible,

          • It doesn't add up... says:

            Hydrogen has only started to feature in these energy scenarios precisely because earlier versions made no proper provision for storage at all beyond simple things like storing a solar peak for use in the evening. The present incarnation is a farce, because it has only been modelled on the most simplistic level. Here’s the toy model from FES 2020:


            So all the time they are making hydrogen they are using it, in effect simply destroying much of the hydrogen they make uselessly. It only makes sense to feed an electrolyser when there is a genuine surplus as input: if there is not, you are using methane or hydrogen to make electricity to make hydrogen. When you look at the real world hour by hour you get surpluses that vary because demand varies as well as wind production. You end up with surplus duration curves whose scale depends on the level of capacity. However, when you come to work out how much electrolyser capacity to install it soon becomes apparent that the duration curves imply very low utilisation rates if you wish to try to use most of the surplus: the rates aren’t all that fantastic even for using the fist part of the surplus. It’s uneconomic to attempt to use much of the surplus, which therefore ends up being curtailed. I have yet to see this fundamental economic evaluation addressed by the FES work (although the Shell REFHYNE project appears to have looked at the economics of low electrolyser utilisation – see ). See this chart:


            The reality is that it is much cheaper to try to reduce the requirement for storage by massive over-investment in renewables capacity, sufficient to result in curtailed surpluses that are massive and mean that the cost is a multiple of the number you first thought of.

        • John Brown says:

          Dr. Dean,

          I have read your posts and your argument is basically dependent upon wind being ultimately cheaper than nuclear, which I doubt will be the case.

          Perhaps you are basing your nuclear costs on Hinkley Point C where Sir Dieter Helm, Professor of Enery Policy at Oxford University, said that the price of electricity from this plant would have been at half the price if EDF did not have to use China for financing at 9% interest?

          The last round of wind CfD for the Dogger Bank project brought bids of around £40/MWhr but these contracts have yet to be built and the contracts are non-binding. The Norwegian Wealth Fund, Equinor, has “invested” in the latest Dogger Bank windmill project. The Norwegian Government undertook a study of this “investment” and came to the conclusion it was “unprofitable”.

          I think the way forward is definitely nuclear but not using the large one-off Hinkley Point C type builds but rather SMRs or SNRs where small nuclear plants can roll off a production line. Or even a series of production lines if necessary and nuclear capacity can therefore be increased far more quickly than large one-off Hinkley Point builds.

          Rolls Royce are claiming they supply electricity at £40/MWhr using their 470MW SMRs if they have RAB funding which matches the latest wind CfD prices (probably on purpose) and I would expect costs to become lower as production gets going and even competition between suppliers occurs.

          Nuclear can not only provide base load but also industrial heat and of course green hydrogen for grid stability and backup purposes.

          Just as there are in fact two 1.6GW reactors being built at Hinkley Point C, I see no reason why several SMRs cannot be built at each suitable location and I don’t see why all of the old nuclear sites cannot be used. If they are not near “demand centres” any excess energy can be used to produce green hydrogen or industrial “demand” can be brought to the sites.

          I believe wind has far too low an energy density and not only is its output intermittent it is also of poor quality.

          I have watched the HoL Industry & Regulators Committee meetings on the subject of “Ogem & Net Zero” and in many meetings it was discussed that wind powered Net Zero would mean that demand had to match supply rather than, as we have at present, supply matching demand.

          In fact at the meeting of 02/11/2021, Clare Dykta, the Head of trategy, National Grid admitted (reluctantly) that Net Zero requires smart meters and said :

          “As you rightly say, as we move forward, prices are likely to become more volatile and in a low-carbon system, I completely agree that some volatility of pricing is important for that system to work well.

          So it appears to me that the National Grid are planning for “volatile” pricing and energy rationing through the use of smart meters.

          This is definitely not a scenario to which I look forward.

          Note also that nuclear can be used to match demand, the French do it with their nuclear fleet, but it does come at a cost through additional maintenance.

          You may be correct, however, in thinking wind and other intermittent renewables are the answer.

          But I do not.

          We shall see.

          • Dr Jonathan F Dean says:

            I read that Norwegian study and it actually says it doesn’t meet their investment criteria, but this was reported as unprofitable, which is quite different

            I’m not anti nuclear, and you might be right about SMRs (if RR ever finish their design), but the place to put them is major cities where the demand is, and the waste heat can be usefully used. The CHP study for Wylfa Newydd concluded no scale of CHP was feasible as the local population was too small. Meanwhile one of the reasons PINS gave for rejecting the project was the impact on local communities too great

            If RAB is the real game changer for nuclear, it should be made available to all forms if generation for a level playing field, but at least tidal lagoons and pumped storage which are similar to nuclear in cost/benefit profiles

            Moving industry to the power station works when the location is fixed by other constraints eg coal field or windy sea, but SMRs can go virtually anywhere, so we should put them where they’re needed

            Variable pricing is something we have in almost every aspect of our lives, so there is no reason why we shouldn’t embrace it for electricity. People love a bargain! Flat tariffs will always be available for those who choose not to engage

          • It doesn't add up... says:

            Tidal lagoons? More extremely intermittent, high cost electricity that would be an utter pain to integrate into the grid at any scale. Evidently you’ve never really looked at these things. I have. Here’s what the variation in output from a possible Severn barrage looks like:


            You will find a lot of discussion about the (im)practicalities of tidal power in this PhD thesis (which includes the data behind the chart), including the need to handle rapid ramping of other power to accommodate spikes from tidal, backup for the lengthy periods of zero generation, etc.


            A nice round up of discussion with lots of references to studies of multiple lagoons around the coast etc.:


            Debunking the idea that converting some of the facilities to storage is helpful:


            You lose 70% of the output, more than trebling costs in the process.

        • It doesn't add up... says:

          Is wind cheap? Capital spending per GW on the latest wind farms doesn’t seem to be falling much, and turbine manufacturers are saying they need to raise prices. Plus we are only at the start of much higher grid integration costs, with storage for anything beyond intra day turnover being uneconomic, sharply rising levels of curtailment, need for very fast ramping “spinning reserve” (in practice, massive battery capacity is planned) to handle sudden changes in wind output that can otherwise lead to massive grid instability and blackout. You end up with two complete backup systems: the batteries to handle the rapid ramping, and dispatchable generation to take over because long duration batteries are too expensive and have to be recharged.

          Unless you look at system costs of wind you get a very false picture. There are very good reasons why systems that were designed to maximise wind and solar renewables use stop at about 65% renewables penetration as delivered (actual generation is rather higher, because it is curtailed e.g. at King Island Tasmania it is dumped into a massive resistor that just heats the atmosphere).

  10. MarkR says:

    I think this is one of Europe’s most important energy problems. The US’ problems going renewable are a piece of piss by comparison.

    I don’t think your post is completely fair though;
    “We just need “energy storage”, but no-one ever calculates just how much energy we would need store in order to see us through a wind drought like we have just experienced or the one last December.”

    As in, it’s a bit unfair on the authors of the studies who calculate this to call them no one!

    About the most extreme I saw claims 25 TWh storage requirements:
    but that’ll be an overestimate compared to reality because of their assumptions.

    • Dr Jonathan F Dean says:

      It’s certainly unfair to call National Grid ESO “no one” who calculate the amount of storage we’ll need for a range of scenarios, and update those calculations each year with the best available data

      • It doesn't add up... says:

        It is fair to recognise that National Grid is a business that makes its money from maximising its transmission assets and securing unfair advantage for its interconnector investments. Once you understand that perspective its approach to future energy scenarios becomes entirely transparent. They certainly don’t calculate the storage needs properly or use the best available information.

        NG has been busy promoting this work as demonstrating that a net zero grid is feasible by 2035.

        See if you can spot the gaping chasms of holes in the analysis and why it offers no reassurance at all. A starter is that they assume that 20% of wind capacity represents a challenging day, and another is that they only look at one day, not several in succession: there are many others. Yet Ministers will point to it and pretend that everything in the garden is lovely.

        • Dr Jonathan F Dean says:

          National Grid make money by their transmission assets existing, not necessarily by how much they’re used

          • It doesn't add up... says:

            Well, quite. So doubling electricity demand is good for business, and even better when peak transmission requirements become 3 times average instead of 1.5 times average. Renewables are ideal for that.

    • It doesn't add up... says:

      That’s far from the most extreme calculations. The paper is more easily accessed here:

      It does make a number of good points: V2G is virtually useless for the longer term storage required to balance a renewables dominated grid, for instance. Studies that promote V2G assume that if the vehicle fleet batteries are depleted today they can be recharged tomorrow (i.e. there will be a surplus over and above average daily charging to make good the depletion for grid support) – which doesn’t happen in a week long Dunkelflaute.

      But in levelising the annual demand it actually reduces the storage estimates that might be required: it also uses high efficiency storage, which might be OK if we had sites for 2,750 Dinorwigs to provide 25TWh – but we don’t. Hydrogen storage round trip efficiencies are much lower: around 60% for PEM to hydrogen, and probably no better than 50% for intermittent CCGT use for generation, for a round trip of 30%, less energy used in compression and pumping in and out of storage. You might do a bit better, but not radically so. That actually favours higher levels of surplus generation, but the implications on the volumes of hydrogen storage required are considerable, given that hydrogen storage density is a third of methane’s. I ran a simple comparison using just last year’s wind and demand on hourly data – which clearly could be improved on through over generation and through adding some solar – which gives the following comparative picture:

      N.B. this assumes that all surplus can be stored, which is not an economic solution.

      By the time you start adding in extra seasonality because of the electrification of heat demand the storage requirements will rise again. Last year an even flow of gas would have required storage of 127TWh to meet demand. Even if you halve
      that on the assumption that heat pumps allow an average COP of 2 against straight gas use, that’s another 60TWh of seasonality you need to provide for – then try a cold winter.

      The storage requirements aren’t getting lower.

      • MarkR says:

        Yeah heating is an enormous issue.

        For electricity alone though we’ll have Hinkley (~2 TWh/30 days) and other sources, we can build wind and solar in other places*, and we’ll link to other countries too. Wind lulls are a big problem but I bet this paper’s estimate is way too high for electricity alone.

        *other than sticking wind in the south and most of the solar in the north, as the paper assumes

  11. Dr Jonathan F Dean says:

    Electrolysis is established technology and Siemens have hydrogen turbines

    Green methane? You mean biogas from AD plants or synthetic from direct air captured carbon and green hydrogen? Very energy intensive to make. I’d see any synthetic green hydrocarbons reserved for air fuel

    “Bribed to reduce demand” … you mean shift demand to cheaper times, like Economy 7 but more dynamic. Sounds great to me. Octopus Agile was before the recent price increases. Given the number of batteries on wheels we’ll have parked up, demand shifting should be a doddle

    • It doesn't add up... says:

      I think a comment you made about using floating offshore wind for hydrogen production has been edited out. It’s certainly a feature of FES 2021, and worthy of comment. There can be no question that the input to offshore electrolysis is free: it would come at the full levelised cost of floating offshore wind. That is not a pretty number: Hywind gets 3.5ROCs/MWh worth almost £200/MWh in subsidy on top of market price, and its accounts show it has struggled to make a profit (though clearly getting the subsidy on top of current market prices will make it very profitable right now). Equinor acknowledge that floating wind will always be expensive: for them it is a green vanity project that allows offshore oil and gas platforms to be part powered by wind, paid for by the oil and gas. Then you have to invest in an offshore electrolysis farm and water purification, and a lengthy pipeline to shore with a high risk fuel. If we think of the Piper Alpha accident, it caused a production interruption measured in years, and even the Cormorant Alpha gas leak led to suspension of production for 6 weeks. Such outage risks are real on any longer timescale. So we end up with hydrogen being piped to storage at ~£400/MWh producing electricity at ~£800/MWh. That is meant to be economic?

      • MarkR says:

        Is there no hope of tech improvement bringing down costs of floating wind? What’s the reason?

        I’d assumed it would drop, although maybe not as quickly as normal offshore wind.

        2015: Round 1 offshore wind cheapest strike price: £114.39/MWh
        2019: Round 3: £39.65/MWh

        • It doesn't add up... says:

          That Round 3 price is proving to be a fiction. Please bear in mind that there is no requirement to actually start the CFD when the wind farm is completed: investors in later wind farms are relying on other interventions that support market prices, like carbon tax which effectively already puts a floor under prices of CCGT cost +£30+/MWh, and almost certainly will not exercise the CFD – notwithstanding that today it would actually pay £51.06/MWh with the indexation added in. In fact, we are already seeing CFDs not being commenced because the market price is way above the CFD price. The risk is that in periods of wind surplus there is no protection against low or negative prices, and the wind farm may end up curtailing without compensation.

          Perhaps the best guide to what investors expect revenues to be can be had from Oersted’s recent sale of interest in the Hornsea 2 wind farm: £3bn for 50% of 1.3GW, or £4.6m/MW. I suggest that is not compatible with ~£50/MWh or even ~£73/MWh for the Hornsea 2 CFD – it’s well above the actual cost of earlier windfarms at about £3m/MW (e.g. Hornsea 1) which have been struggling to make much of a profit at £164/MWh.

          Floating wind technology is largely taking long established deep offshore oil and gas technology and sticking a turbine tower on the top. It can be done, but whereas an offshore oil platform will be producing perhaps 300MW of oil (approx 5,000b/d), a wind turbine producing 5MW on average is not going to have the same economics. Moreover, in reality the oil platform will link to a number of wells scattered across the seabed improving the economics still further, whereas the turbines must themselves be spaced out.

          • MarkR says:

            I thought all of the CfDs were baselined to 2012 prices so in that case isn’t the comparison of round 1 vs round 3 fair?

            I didn’t realise they could opt out of CfDs. Have you got links for that?

            Also, the highest price stated I can find for Hornsea 2 is just under £2.80/MW – I only found 3 bn referring to the implied evaluation of the whole thing. And the numbers for Hornsea 1 seemed way above £3/MW, but I don’t think you can get a full comparison from the press release numbers.


          • It doesn't add up... says:

            The point is that these low CFD prices are never going to be honoured, and they are not an indication of the cost of wind. These windfarms will live off “market ” prices that happen to be heavily boosted by other factors, including carbon tax and a general capacity shortage. The only contractual penalties for failure to commence the CFD (which requires submission of a formal notice) are that it can be cancelled – which is no penalty at all when it is way out of the money, and that the CFD counterparty can be wallied from the next round of CFD allocations, which again is no penalty, because they use special purpose vehicles for each segment of each wind farm so it will never be bidding in the next round anyway. I’ve actually read through the CFD agreement terms for the various allocation rounds and have the benefit of having dealt with drafting of complex energy contracts with a special eye to unearthing holes in the terms. You can find the agreements on pages at BEIS.

            If you want indications of real costs, look at the work of Prof Gordon Hughes who has actually ploughed through the accounts of these wind farms to extract real data. Do not confuse the actual capital cost with a sale price, which reflects the discounted value of expected revenues less maintenance and financing costs and any decommissioning cost, adjusted for tax. The cost of building the wind farm doesn’t enter into that except in so far as it impacts the tax bill and the financing cost.

            I avoid using 2012 prices that are getting rapidly out of date, and bear no relation to current prices: use tends to be an attempt to pretend that CFDs are much cheaper than they really are. The indexed current values are readily available from the CFD register – and have just been uprated for inflation as of 1 April.

          • MarkR says:

            Thanks for sharing your insights. It’s a tricky topic and I’m no financier so I didn’t understand a few things. Could you clarify on these points?

            1. No offshore wind farms have skipped a CfD.

            2. If one skips activation then they would get wholesale market price or do some PPA. Would we see if that happened?

            3. The sale price of Hornsea 2 mattered when you thought it was £4.6m/MW but given that it’s £1.5-2.7m/MW it doesn’t matter now?

          • It doesn't add up... says:

            Sale was £3bn


            Triton Knoll 3 has yet to commence its CFD despite commissioning in January – at least up to 23 March, the latest data on CFD payments from Low Carbon Contracts Company I looked at.

          • MarkR says:

            Thanks for the link, that does seem expensive! I can’t understand what that means for current construction costs but it implies those investors believe more mainstream projections about O&M costs etc.

            What happens if a wind farm doesn’t activate the CfD immediately? Can it sell into the market and then start the CfD later, or does it have to give up the CfD forever?

            Moray Firth website says they’ll finalise the first part in June 2022, so we can expect new information then.

  12. It doesn't add up... says:

    Helm has a good understanding of energy market drivers. I always feel he needs to do the Lomborg mile and query the balance between emissions targets and cost of adaptation. He is taking the entirely arbitrary target as gospel, and is consequently willing to impose high cost, inefficient solutions like CCS.

    • Clive Best says:

      He probably has to agree with Government policy since he has worked directly for them and been knighted for it. However he is pointing out that they have no realistic plan of how to get to Net Zero. Nor does it make sense for the UK to destroy its economy in the attempt, since it anyway has just a 1% effect on global CO2 emissions.

      What the world needs is some breakthrough in providing cheap Nuclear Fusion energy. Otherwise we will always continue to burn things for energy. It would have been nice if Cold Fusion had been real !

  13. MarkR says:

    From “It doesn’t add up…” regarding Hornsea and claiming “these low CFD prices are never going to be honoured”, it appears like Hornsea recently commissioned and began honouring its CFD prices.

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