I wanted to make a toy model of an electricity grid, to shed some light – at least in my own mind – on some of the issues that arise when a reliable generator is displaced by an intermittent one. Skip straight to the last section if you are allergic to maths.


The baseline is extremely simple. We live in a place called Utopia, where our energy needs are met by a generator called Mr. Reliable. Mr. R supplies a constant power R to the grid, fulfilling all its needs, so R is also the grid capacity. [By way of simplification, there is no hourly variation in demand.] Mr. R is owned by the public, and burns hydrocarbons. His costs, and ours, are


K is Mr. R’s operating costs, Barons per GW per year

R is Mr. R’s capacity (for simplicity he operates at a capacity factor of 1).

F is Mr. R’s fuel cost in Barons per GW year

So far so good. Now into Utopia comes the urgent need to wean our country off its fossil fuel addiction. The new generator is also publicly owned, and his name is Mr. Intermittent. (He isn’t intermittent yet, but still). Mr. I’s costs, and ours, are:


L is Mr. I’s operating costs, Barons per GW per year

I is Mr. I’s capacity

Mr. I has no fuel costs to pay. The fuel saved by adding Mr. I to the grid is:


c is the capacity factor of Mr. I.

So our new cost for the grid, having added Mr. I, is:

KR + FR + LI – cFI

If cFI > LI we have made a saving, or more simply if cF>L.

So if the operational costs of the new generator Mr I are less than his capacity factor times the per-unit cost of fuel he is displacing, we have saved both carbon emissions and money. Now let Mr. R’s actual generation, after Mr. I’s introduction, be A. His costs are now:


Where FA = FR – cFI. To displace all fuel, A must reach 0, which happens when R = cI. This is pretty obvious since for example if c = 0.4 [typical of an offshore windfarm], then R = 0.4I, so you need 2.5 times the capacity of Mr. I to replace Mr. R if Mr. I operates at 40% capacity factor.


The above holds true for the toy model if Mr. I is not intermittent at all, but goes flat out at capacity factor c. When R = cI, what happens in a slightly more realistic world is that half the time Mr. I produces too much power, and half the time he produces too little. Now, c represents not a constant capacity factor, but its average. So that at times when R > cI we have to ask Mr. R to turn back on, and when R < cI we are throwing energy away.

What happens at this stage depends entirely on the distribution of c. I’m taking an extreme example because it’s easy: c is a uniform random variable in the range [0…1] with mean 0.5.

Under this scenario, if Mr. I’s nominal capacity is twice Mr. R’s, I = 2R, and cI > R half the time; half the time Mr I generates more than R, half the time less than R. So half the time Mr. R has to turn on, anywhere from a little bit to full whack. The other half of the time Mr. R is turned off and power is being binned.

For the half of the time Mr. R is turned on, his output averages 0.5R, so that his overall output in the brave new world is 0.25R. For the half of the time power exceeds demand, we are throwing away an average of 0.5R, for an average wastage of 0.25R. Obviously these two things don’t happen at the same time, but all the time, one or other is happening: either Mr. R is turned on, or we’re throwing power away. And we can’t get rid of a watt of Mr. R’s generating capacity, for very occasionally he’s called upon to turn the wick up to full. Thus with twice the intermittent capacity added to the existing reliable capacity, we are still using a quarter of the amount of fuel we did before, and have all of Mr R’s generation still plugged in.

Our costs are now

KR + 0.25FR + 2LR

So we have made a saving if 0.75FR>2LR or if 3F>8L.


Determined as we are to get rid of fossil fuels entirely, running a grid of 3 times the previous capacity and still using a quarter as much fuel is unacceptable. The wisest minds of Utopia propose a new solution: storage.

Mr. R is retired, or as they say in Utopia, blown up by important people to the cheers of hoi polloi. Mr. I still has capacity 2R and produces as for the previous example, his capacity factor an unstructured random variable in the range [0…1], mean 0.5. Remember, half the time we are producing too much, and half the time too little. This implies that all we have to do is to draw on the big battery in times of need, and pay it back in times of plenty. It’s a nice little overdraft facility.

In terms of power, our backup has to be able to cover our needs, i.e. to produce power R. Now I’m going to put some fake numbers in for illustrative purposes. R, the grid power, is 100 GW flat out all the time. Our storage is going to be able to output that for 10 hours, so its capacity is 1000 GWh. For simplicity there is no energy lost in the process.

So the wise minds sit back and relax, knowing they are covered for power and have rid themselves of the dreaded fossil fuel addiction at last. Are they right?

Begin simulation…

Whoops, no they’re not. Beginning fully brimmed with 1000 GWh in the bank, in the first 500 hours we have hit zero storage and power cuts on ten occasions. But before we ran out of energy altogether we did manage to cap out the storage 6 times. Of course we had nowhere to put the excess at these times so the energy was thrown away. The top figure shows the power Mr I produced each hour (GW). The bottom one shows the energy stored in the big battery (GWh).

This is just one run, but it is as they say in the literature a “representative” example. The average capacity of the series was 0.491. 915 GWh was thrown away when storage was capped out. Actually, of ten runs with this scenario, 8 had power cuts.

Remember if Mr. I was a constant friend and ran at a continuous capacity factor of 0.5 (=100 GW) we would never need Mr. Storage at all.

But perhaps unstructured noise is an unfair test. What about if there is some persistence in Mr. I’s power output? In this example, half of Mr. I’s output depends on the previous value. As before the top figure shows Mr. I’s power output, and the bottom figure shows the energy we have in storage. In this run, storage maxed out 18 times and we had 5 power cuts. Average capacity factor was 0.514. Energy wasted when the storage was brimmed was 1898 GWh.

Power cuts also occur with different scenarios like a bounded random walk with 0.75 of the power dependent on the previous value. Below this situation is illustrated, and here we had 8 power cuts and we threw away 14323 GWh of energy.

So things look bleak for a storage solution, at least in Utopia. Note: The big battery in Hornsdale Australia offers 150 MW/ 193 MWh, and cost A$ 172,000,000. [That’s about a hundred million quid. The cost of the Utopian battery would therefore be about half a trillion quid – that’s 7.1 Barons in Utopian currency.]


Let’s rewind a bit. A minute ago Mr. R was still with us and he was reduced to running at an average of 0.25 of his capacity, thanks to the addition of Mr. I’s generation. Remember, in this scenario Mr. R cannot be got rid of, but has to stand dutifully by for whenever Mr. I is in the doldrums. At the moment this is all fine, although probably quite expensive.

Our costs are

KR + 0.25FR + 2LR

In Utopia where everything is cross-subsidised, we can afford to prop up Mr. R. What about if we inject a little capitalism?

At the beginning, Mr. R’s costs were


And he would be able to cover those costs with sales of R.

But now his costs are

KR+FA, (A being the actual power delivered) which in this case equals KR + 0.25FR

And he can only pay his way with sales of A = 0.25R. The price per unit of power needed to cover costs is (KR + FA)/A, or (KR/A) +F.

You’ll note that if the unit price depends on dividing by the quantity supplied, then as A goes down, the unit price goes up. And as A–> 0, the unit price approaches infinity. This is not surprising as at this stage Mr. R has to cover his costs on an infinitesimal quantity of sales.


What, you may ask, does all this mean? The model is necessarily overly simplistic, but it illustrates the problems of introducing an intermittent generator to a stable grid. In particular what it appears to show to me is that, the more power you get from the intermittent generator, the worse things get. In my first example, with a large amount of random generation and reliable backup, all of the reliable backup had to remain online, and it was still supplying a quarter of the grid’s power.

The storage model showed that even ten hours of flat-out power as stored energy was insufficient to buffer the new intermittent grid once all the reliable generation had been blown up. (That’s an implausible quantity of backup, I think.)

The last bit of maths made the point that, if you have to retain the reliable generator’s capacity, but it is increasingly under-utilised thanks to overcapacity of the intermittent generator, then in a capitalist world the reliable generator has to charge more and more for the power that it is called upon to deliver if it is to break even. In a reverse auction where the last generator to enter sets the price for all, this would be a recipe for very expensive electricity.


  1. The featured image shows an important person blowing up Longannet to the cheers of hoi polloi.

    Longannet was capable of a steady couple of jiggawatts, and it had about four months of energy stored in a large black heap next to it. A behemoth, it was too dirty, and had to be brought down.

    The present >10 GW of offshore wind in the UK at times outputs as little as 90 MW. This is a graph of the last month’s output (thanks to quentinmichael for the link to the Crown Estate): https://www.thecrownestate.co.uk/en-gb/what-we-do/asset-map/#tab-2

    Liked by 1 person

  2. Jit, thanks for the maths lesson.

    This might also be vaguely relevant:

    “Addressing the high real cost of renewable generation”


    “…There are just over a million small-scale domestic solar systems in the UK. They are low-output, intermittent and tend to be distributed across power grids in large numbers. The power they supply to the grid in export mode is unpredictable with generators going on and off-line intermittently – households adopt the role of consumers or producers, as usage and weather conditions vary both throughout the day and across the year. The Nottingham analysis shows that microgrids spend most of their time operating in the least favourable conditions for grid resilience, across all ranges of PV uptake due to a supply-demand discrepancy. This means microgrids are alternately dominated by either consumption or generation and are therefore unable to exploit the robustness advantages that increased distribution would be expected to provide….”.


  3. Jit, your conclusions are consistent with others like Gail Tverberg, who concluded: “The apparent “lid” on intermittent electricity at 10% to 15% of total electricity consumption is caused by limits on operating reserves.” The economics force the baseload operators into bankruptcy, unless they are also subsidized, driving consumer costs ever higher. All this without the additional costs of long transmission lines, backup generation etc.

    “Few people have stopped to realize that intermittent electricity isn’t worth very much. It may even have negative value, when the cost of all of the adjustments needed to make it useful are considered.

    Energy products are very different in “quality.” Intermittent electricity is of exceptionally low quality. The costs that intermittent electricity impose on the system need to be paid by someone else. This is a huge problem, especially as penetration levels start exceeding the 10% to 15% level that can be handled by operating reserves, and much more costly adjustments must be made to accommodate this energy. Even if wind turbines and solar panels could be produced for $0, it seems likely that the costs of working around the problems caused by intermittent electricity would be greater than the compensation that can be obtained to fix those problems.”

    Climateers Tilting at Windmills Updated

    Liked by 1 person

  4. The big thing about stable grid operational management is the power balance, not energy storage. The generation has to be in near perfect balance with the load. If it isn’t, then neither the voltage or frequency is stable or at the correct value. A lot of critical equipment (think water pumps) rely on this stability.
    As well as keeping it in balance, there needs to be provision for changing load or generation. The big one here is generators tripping off. Transmission line issues like lightning strikes or lines clashing in high winds on heavily loaded lines can also have big effects.
    The grid has to cope with this and stay stable. If we take generation or line shortfalls, It does this several ways. There is interruptable load, where things like non-critical pumps or smelters shut off for a short period (they get their power cheaper to compensate. There are partly loaded machines that can ramp up on either dispatch or frequency governor control. There are places like Dinorwic that have plant spinning at synchronous speed but not generating (tail race depression lowers the friction losses). That is how things are kept in balance. But it need the grid to have inertia so the rate of change is manageable. This is because equipment like circuitbreakers take real time to operate. They have to sense there is a problem, then trigger the protection and the arc has to subside. Often the fastest ones can be hundreds of milli-seconds, depending on the fault type.
    Large thermal plant with spinning turbines and generators locked onto the grid provide inertia. Asynchrous generator like the unreliables don’t. They can sort of compensate by fast acting batteries (if they are charged up) and synchronous condensers but these are not that successful at large events. Think trip of Sizewell B
    If you don’t have enough inertia, grid will go from OK to blackout in less than 1 second. That was South Australia’s problem. Not enough inertia.

    Liked by 2 people

  5. This may also be indirectly relevant:


    “The power market is facing its biggest overhaul in decades after National Grid said that wholesale electricity should be traded at local prices that vary from town to town.

    The company responsible for keeping the lights on said that the radical change was needed because Britain’s national electricity market was “not designed for net zero and if left unchanged will impose excessive costs to consumers”.
    At present, power plant owners can sell their electricity on the national market, even if there are not enough cables to take that power to where there is consumer demand.

    That is forcing National Grid’s control room to pay wind and solar farms in remote locations to switch off at times when the network cannot cope and to pay expensive gas plants closer to consumers to switch on and replace them. These “constraint” costs, which are passed on to consumers via their energy bills, have risen sevenfold since 2010 as more renewables have been built, hitting £1.2 billion in 2021.

    The National Grid ESO, or Electricity System Operator, warned industry last week that keeping supply and demand in balance nationwide was “becoming more challenging” and was resulting in “dramatic and rising costs for consumers”, even with plans to build lots of expensive new transmission cables. Constraint costs could hit £2.3 billion a year by 2026 without market reform, it said in a presentation seen by The Times.”

    Further on it says:

    “National Grid will publish formal recommendations this spring, but it told industry that local pricing was the only effective solution and could be implemented within five years.

    Jake Rigg, director of corporate affairs at the National Grid ESO, told The Times that its analysis showed “a need for a powerful locational signal for demand and generation”, which was “critical as we look ahead at how to get to net zero”. For example, Scotland was planning new wind farms capable of generating up to 25 gigawatts of power, about twice as much as already in place, he said. However, peak demand in Scotland was only about 4GW, creating “a massive mismatch” that must be addressed. Cabling from Scotland to England and Wales is limited and even a series of expensive new links are not expected to solve the issue.”

    I think that’s as close as you’re going to get to an admission that the National Grid can’t cope with the dash to renewables. Did the BBC or the Guardian report this? Tumbleweed….

    Despite articles in the Times generally being paywalled, much of it can be read here:


    Liked by 2 people

  6. Mark
    Splitting up the pricing to make a premium paid on generation near load is a very sensible option. That way line losses, which can be significant, are minimised. To that should be added new generation paying at least some of the cost for grid upgrades. especially on spur lines. That would also include the VARs controls
    If you want to go back far enough, Enron bankrupted the Californian power companies with a similar model to what is in the UK. They only offered in generation from stations where there were line constraints getting the power to the consumer.

    Liked by 4 people

  7. This may be vaguely relevant to Jit’s article too:

    “The problem with onshore wind farms”


    “Moreover, you wonder what the government has to gain from trying to build more onshore wind farms. The whole point of last week’s review was supposed to be energy security. But wind farms on their own are not going to provide that. On the contrary, they promise insecurity unless we also construct the means to store massive amounts of energy for days when the wind isn’t blowing and the sun isn’t shining. We already have, in theory, enough installed wind and solar capacity to meet Britain’s average energy consumption of 40 GW. Yet there are often times when wind and solar between them provide less than five percent of electricity used in Britain. At present we can absorb wind energy into the grid because we have gas plants which can be fired up or turned down to make up for a shortfall in energy. But what happens after 2035 – the date when the government has pledged to remove fossil fuels entirely from electricity generation?

    The Energy Security Strategy provides no answer to this whatsoever. Nuclear plants do not have to flexibility to be turned up and down at short notice. Battery storage costs three times as much as generating wind energy in the first place. If we are going to try to satisfy all our energy needs by wind and solar power we have a long, long way to go: wind and solar between them accounted for just 4.2 percent of total energy consumption in 2020.

    The government remains tied to its legally-binding commitment to end all net carbon emissions by 2050 – and yet still has no practical means of getting there. By putting its faith in yet more wind power it is setting itself up for failure – as well as a battle in the shires.”

    Liked by 1 person

  8. Politicians have an uncanny knack of believing they can over-rule the laws of physics. All they have to do is make some pronouncement, or bring in a new regulation, and it will magically happen. Hydrogen can be made at a lower cost than fossil fuels or batteries will become very cheap – that type of thing.And the public at large lets them get away with it.
    How many MPs have a genuine science or engineering background? Do they know the difference between a MW and MWh? How many worked in construction project management? That is where the problem is. We have a ruling class with no engineering literacy..

    Liked by 3 people

  9. More on surge pricing here:

    “Surge pricing for energy is a dreadful idea
    In its crazed pursuit of Net Zero, the government is bringing back electricity rationing.”


    The article concludes:

    “Instead of trying to improve and increase the UK’s energy provision, the government is set on limiting the public’s energy consumption. This is nothing less than the return of electricity rationing.”


  10. Joe, it’s a 100-fold range in output, which is shocking even for a wind sceptic.

    Mark, the Watt-Logic article is very good and rather more authoritative than mine. I recommend everyone to read it. My only quibble was her diagnosis of falling CfD prices, which as we have discussed here, have rather opaque exit clauses, if in fact companies are not free to just drop the contract and run off to sell leccy at commercial prices.

    Chris, thanks for the comment. My understanding of the workings of the grid is rather superficial, hence the simplicity of the model as presented. I think what you are saying is that the frequency issue will cause the grid to fall over before the lack of power does. I need something like “Noddy’s Guide to Running an Electricity Grid,” to explain to me, among other things, how leccy gets from A to B. For instance, at Mark’s link Kathryn Porter talks about the problems of small-scale solar. But I am unclear how far upstream the leccy provided by domestic solar actually gets, i.e. I presume it is trapped at the local scale.

    Ron, you mention energy quality. It would be useful if someone had worked out a new metric for assessing the utility of different generators, of which the direct cost is but one component. It’s also something mentioned at Watt-Logic. It’s something I’ve thought about, and I have an idea how it could be done, but my method does involve some fairly arbitrary values being applied.

    Liked by 1 person

  11. Mark, I like the Spiked article, but I don’t agree with:

    Instead of trying to improve and increase the UK’s energy provision, the government is set on limiting the public’s energy consumption. This is nothing less than the return of electricity rationing.

    If this was genuine rationing, the likes of Sir John Armitt would have his electricity rationed too. But he won’t. It’s more like pricing much of the populace out of the freedom to use energy whenever they want it. I would welcome actual rationing, because it would only last for twenty minutes. Our overlords would never put up with their own lifestyles being curtailed.

    Liked by 2 people

  12. Chris:

    Politicians have an uncanny knack of believing they can over-rule the laws of physics.

    I call this farming unicorns, which is easy to do. You make a law that unicorns must be produced in large numbers at a set date (let’s say 2035). You buy lots of land to put the farms on. You clear the trees. You build a fence around the farms. You buy farm machinery, make barns and feed silos, employ people and train them up. Everything goes very well, right up to the point when the unicorns are supposed to arrive.

    Liked by 4 people

  13. I think farming unicorns, at least as described, misses the crucial moral dimenson. It is because the motives of those advocating the farming of unicorns are so pure that the fabled animals will, assuredly, arrive.

    Translating back to the boredom of energy engineering and the laws of physics, the motivation for wind power and the like includes not only saving the planet but caring for the poorest who are bound to suffer most from a climate in crisis – a crisis that is wholly due to evil fossil fuel forces *not caring*.

    Once I put it like this I’m sure we all understand that the laws of physics are going to have to give way and bow down. The unicorns will appear.

    Liked by 3 people

  14. Everyone involved seems oblivious of the overriding necessity to employ virgins. Anything less leads to heartache and empty unicorn farms. This necessity has been known since medieval times but due to great scarcity, energy barons have sought alternatives, to date without success.

    Liked by 2 people

  15. One thing that helps politicians get away with these ridiculous plans is self styled academic experts telling them what they want to hear. There are two main figures here — Mark Jacobson and Amory Lovins. Jacobson had the ear of former NY governor Andrew Quomo and may have been indirectly responsible for shutting down Indian Point. Amory Lovins was influential on Germany’s Energiewende. This episode of the Decouple with frequent guest Mark Nelson is pretty much a biography of Amory Lovins and his influence:


  16. Jit,

    How appropriate that the picture adorning your article is of a bemasked Ms Sturgeon (outside) and today she is under fire for breaking her own covid rules by being unmasked inside a barber’s shop while on the campaign trail. Given that she called for Boris to resign over Partygate and the fines, will she now call for her own resignation? At least I’m consistent – I’d be delighted to see the back of both Boris and Nicola.


  17. There is a lot of bits and pieces of statements that aren’t correct but here is no easy explanation. I will try to make comments on specific issues and maybe others can piece it all together.


  18. Sorry for the split Jit
    I think you are correct in assuming that the frequency variations will cause the grid collapse. Trip a big generator or a heavily loaded double set of lines and the grid operators have kittens. Every country’s grid has different limits but normally there is both low frequency and rate of change of frequency protection. And the variance allowed in frequency is not that great. For those big generators, they often trip out at just 49Hz to protect the big turbine last stage blades. If the frequency is much lower, you will turn the stator core into a pile of molten steel and copper, so there is over-fluxing (V/Hz) protection for that as well.
    There is a linkage between voltage, phase angle and frequency but the explanation of how it all fits together ties even grid engineers up in knots. I work in generation, not transmission, so I see everything from that perspective. But simplified, the frequency has to be the same over the grid, but the voltage varies depending on location – higher at generators, lower at load. The relationship between current and voltage (the phase angle) varies as well, depending on line loads and generator AVR and the transformer settings. But basically, the higher the phase angle, the more inefficient the grid is, wasting energy to make heat. It is measured in units of MVAr, (r stands for reactance,(inductance)) which is at right angles to MVA. To make it more complex, voltage leading current is positive, lagging is negative VARs. If the VARs gets too much, grid or generator goes out of sync. The dreaded pole slip. The frequency as I said earlier indicates the balance.
    The asynchronous generators (wind and solar) use a signal from the grid to give the output voltage and frequency. They cannot support the grid unless they have a lot of extra equipment, which they won’t fit so it is a grid cost. To connect to the grid, one has to make sure the three phases match the voltage, frequency and voltage sine waves timing of the grid Then the CB can close and the unit loads up. Get it wrong and the instantaneous loads will destroy a lot of equipment. .
    That lack of internal signal why it is very hard to get the unreliables to run on just them, because no stable inputs.
    The basic reason why AC electricity flows from generators to load is the generators are at slightly higher voltage. The lines are so low resistance that just a little bit drives it. Generators pump power into the grid because they are ever so slightly ahead of the grid. Of course the pedants will correctily point out this isn’t always true, especially if one end of the grid has different MVAr to the other. but to explain that gets into a long even more soporific article. .
    The scary thing is that what I wrote above is just the simplified version. Not surprising that good High Voltage/ Grid electrical engineers (I am not one) aren’t that common.

    Liked by 1 person

  19. Chris, thanks for the explanation. The dim is slightly brighter.

    A good test of whether you understand something is if you can explain it to someone else – and I certainly fail there. I think I ought to force myself to understand the way the grid works, otherwise my confident statements that we’re heading off a cliff have no more behind them than confident statements from the other side that everything is going to be fine. So plenty of reading for me to do on this topic. My approach in the model above – an attempt at pure logic, treating electricity like a commodity that can be delivered like cabbages – only takes things so far.

    Which leads me to the question: how many of our decision makers actually have the first clue about what makes the electrons squirt out of the wall socket?

    Ron, thanks for the link, which indirectly led me to Gail Tverberg’s recent posting with the fairly ominous title “Limits to Green Energy Are Becoming Much Clearer.”

    This paragraph sounds very much like my own conclusion, made with complete ignorance of the relevant physics:

    Wind and solar don’t replace “dispatchable” generation; they provide some temporary electricity supply, but they tend to make the overall electrical system more difficult to operate because of the variability introduced. Renewables are available only part of the time, so other types of electricity suppliers are still needed when supply temporarily isn’t available. In a sense, all they are replacing is part of the fuel required to make electricity. The fixed costs of backup electricity providers are not adequately compensated, nor are the costs of the added complexity introduced into the system.

    Her post has 4000 comments.


    Liked by 2 people

  20. Jit
    Rather than cabbage supply think of it as the town water supply from a tiny storage lake supplied by pumped wells. Inflows have to match outflows exactly, otherwise you have a flood or dry taps.
    On Robins blog, those are my comments as chrism56


  21. Mike, thanks for the link to the podcast about Amory Lovins. It’s an educational discussion. It seems as if there are two types of electricity grid: one focussed on improving supply, the other on reducing demand. Or to my way of thinking: thrift and wealth. The most efficient folk are undoubtedly the poorest: is this also where demand reduction leads? Supply vs. demand. Simple vs. complex. Dumb vs. smart. Nuclear or no nuclear.

    A take-home message on the question of efficiency vs oversupply was that the cost of a small shortfall is larger than the cost of a large oversupply.

    Mark Nelson is a little too sure of himself for a diffident Brit like me. But he seems to know his onions. A memorable phrase of his was “nuclear is an expensive way to make cheap electricity. Wind is a cheap way to make expensive electricity.” (I may have paraphrased slightly.)


  22. Chris/Ron

    I have now read the Kiwi Thinker series and found it highly educational. Highly recommended if, like me, you struggle to understand the workings of an electricity grid.


  23. Jit I am pleased we wrote it at a level people like you can understand. It is about 95% correct. To cover the last 5% would need a novel length explanation and then some.. And some things still happen that has everyone scratching their heads. Bad data explanations can cover a multitude of sins.


  24. Chris, if this has to do with active/reactive/complex power then it’s something I think I ought to understand. But I don’t know if my brain has grown enough wrinkles yet. I should search out youtube lectures on the topic.

    I am already prepared to pontificate about the future of the UK grid, so I probably have a duty to improve my so far only tenuous grip on how AC works! In fact perhaps anyone who plugs any appliance into a wall socket has some sort of obligation to at least try to understand how the juice got there.


  25. Knowing how AC at the wall socket works puts you ahead of most of the population, and almost all MPs.
    I have never believed in UTube videos on complex issues.. They often gloss over important points. More emphasis on presentation than substance. It is McLuhan’s quote about the medium is the message write large. My two go to documents are the books put out by CEGB on grid operation and the EPRI system operations training manual. All old fashioned stuff. I like to read the text, look at the diagrams and alternate between the two as I get a better grasp of the principles.
    But the problems with grids isn’t steady state or predictable load changes. It is when you get a lightning strike on a heavily loaded line Or a big unit trips off. Then funky things start to happen. A good object lesson on issues like this is the final report on the South Australian blackout put out by AEMO. They show how quickly from manageable to disaster.

    Liked by 1 person

  26. Thanks for the comment Richard. Pity I can’t put blog commenting down as CPD for my Chartered renewal.
    Jit – up post you made the comment “the cost of a small shortfall is larger than the cost of a large oversupply.” I would be more emphatic than that. The core grid is sacrosanct – it is the chess king and MUST be protected at all costs. The system operator can tolerate spur lines or even major switchyards going down, but not the central core. If it goes black – modern society instantly ceases to function- nothing will work, except maybe looters!
    To protect the grids, they have plans for circuits and loads that can be shed. These can be quite brutal and they will switch of suburbs or even cities without warning. This is all to keep the load matching available generation. However, it is all seat of the pants stuff. Go back to the reports of the Texas power cuts where they talked about being only 5 minutes from System Black. This is what they are describing. Frequency falling, voltages going haywire , the optional loads already shed and they are starting to eat into dropping high priority circuits. Not a good place to be.
    If the grid goes black, you are unlikely to restore power to maybe 50% of the customers within a day – longer if you have major transmission lines or grid transformers down. It is a nightmare situation.
    Where this leads to is your model must have an essential core that has to stay within certain very tight frequency and voltage limits. There has to be dispatchable predictable generation. It does help if some loads are able to be varied to match supply, but it is easier said than done. When the base generation is big enough, you can tolerate variability, but if on a minute to minute basis, this is more than about 1%, you are asking for trouble.

    Liked by 1 person

  27. Sorry about that Chris – you went into spam for some reason, along with SueGax, JaneGax, UgoGax, AshGax, MaryGax, IvyGax, PaulGax and MiaGax. I don’t know why you got sent there. WordPress mysteries.

    Regarding blackouts, what will become of us when we have very little dispatchable supply? I mean in the event of trying to start up again, wind is useless, gas is gone, so…?

    [The Gaxes, it appears, run an international pharmaceutical company, to judge from the links they are trying to publish. It’s obviously a family affair.]


  28. Jit – Thanks for the explanation. I was certain I had no links and hadn’t used any dodgy words.
    I can answer your query quite simply. If the grid is fully asynchronous (batteries, solar, wind) the grid can’t start. There is no stable power supply for the electronics to take as a reference. And there is nothing to give the phase angle relationship between current and voltage as things change. Maybe if you damped down the controls (can you put a VSD on Valium?) you would sort of get up, but things would be very dodgy


  29. I used to have contrary views to Tony on Jo’s site over some of the details in the claims he made there. He didn’t understand the grid – I am not an expert on it but I can quickly spot who knows less – usually they are the ones making grand pronouncements (Tony rarely did this). But generally I agreed with what he posted.


  30. dfH
    I don’t think I have commented on Jo’s blog since the Callide failure. That was another one where people didn’t understand the grid and what it does, particularly when a CB doesn’t open when it should.
    A very sobering object lesson in how much energy there is in steam turbines.

    As a secondary fact and pertinent to this it shows how easy it can be to have a cascade event that will black the grid.


  31. “Scotland’s wind success story bolstered by £323m stability investment”

    The imminent closure of nuclear power stations in Scotland and northern England, and the rising number of onshore and offshore wind farms in Scotland, will lead to a loss of inertia which poses a potential stability risk as inertia is needed to maintain frequency on Britain’s electricity system.

    So far so good. Then:

    Following a successful tender, the ESO has awarded 10 contracts to four companies worth a total of £323 million which provide net zero solutions to stability issues.

    For “worth” read “costing.” Net zero solutions to stability issues… what might they be?

    Five of the successful solutions are synchronous condensers – ‘green’ motors with free-spinning flywheels which boost inertia and SCL. The other five solutions will comprise what is thought to be a world-first use of new grid forming converters at multiple locations across a region to improve inertia and SCL when disturbances occur in the electricity system.




    Chris – I have begun to read the AEMO SA report. It could take a while at 273 pages. It remains to be seen how much I will understand.

    Liked by 1 person

  32. Chris – thanks for your input on grid issues, I/we/the public need as much info on this to prepare for the worst.

    from your link above – Important notice bit

    partial quote – “Accordingly, to the maximum extent permitted by law, AEMO and its officers, employees and consultants
    involved in the preparation of this report:
    • make no representation or warranty, express or implied, as to the currency, accuracy, reliability or
    completeness of the information in this document; and
    • are not liable (whether by reason of negligence or otherwise) for any statements or representations in this
    document, or any omissions from it, or for any use or reliance on the information in it”

    well that gives me confidence – wonder how much money was spent?


  33. df – that is just boilerplate legal disclaimer. All the AEMO is saying is don’t use this report as a basis for a liability case against either the utility or power company, especially one for negligence. The information in the report is factual and not disputed
    An acquaintance of mine was actually one of the people allowed to go in to do the inspection of the plant in the first week. He agreed with my assessment that the only thing that would able to be salvaged was the nameplate!


  34. df
    The other important piece of information was the report I posted the link to was only the preliminary one. Here is the final report.

    Click to access trip-of-multiple-generators-and-lines-in-qld-and-associated-under-frequency-load-shedding.pdf

    I don’t have the links filed, only the reports sorry, and their file names have to be guessed in search engines..
    Though it isn’t written in the report, the grid operators phoned the Callide control room to say that they were importing a lot of MW. The control room said no, they couldn’t be, their displays showed the CB was open. Similar type issues to incidents like 3 Mile Island.
    But the only reason the grid stayed on was the machines’ inertia. An asynchronous grid would have tripped and gone black. .


  35. I have written a number of articles with Planning Engineer that are on Climate Etc about the Australian grid. They expand on many of the issues I commented on in the above post if people want more detail on grid operation

    Liked by 1 person

  36. Question Chris, which I cannot find an answer to anywhere. Synchronous condensers are increasingly being used to provide reactive power and inertia, either purpose-built, or by converting existing synchronous generators to condensers. What powers purpose built synchronous condensers? Do they run on electricity or fossil fuels? What powers repurposed synchronous generators running as condensers? Do they still run on fossil fuels?


  37. Thanks Chris. Replacing synchronous generators which supply both energy and inertia to the grid at relatively low cost with expensive synchronous condensers which consume energy, just in order to rectify the imbalance generated by intermittent unreliables doesn’t seem very sensible to me, I must admit!


  38. Jaime
    Nothing about replacing cheap and reliable generation with an unreliable and complicated system system make any sense to me either, but we live in an Alice in Wonderland Orwellian dystopia so it is to be expected. .

    Liked by 3 people

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