Any energy systems analyst would know Iberia-like problems would eventually happen, before even a single wind and solar system were connected, but inane, naive, woke idiots do not want to listen to the pros.
Full speed ahead over the cliff, unless all this wind, solar, battery nonsense is stopped dead by taking away subsidies.
Net Zero to reduce CO2 by 2050 is a suicide pact.
That CO2 is needed for greening the world, that supports abundant fauna, and increases crop yields to feed 8 billion people.
To an extent I share your concern about the effect of renewables on grid reliability. I also understand your point that increasing atmospheric CO2 can increase crop yields. Where we probably disagree is whether increasing atmospheric CO2 contributes to global warming and climate change. I don’t mean to get into a disagreement over this issue, but I’d point out that if global temperatures continue to rise for whatever reason, crop yields will decline. An interesting question is how the combination of increasing CO2 and hotter temperatures will affect crop yields.
Same here on being unqualified! If climate science experts across many disciplines can’t agree on the climate change question then what is the lay person like you or me to think? I choose to believe what the majority of climate scientists believe which is climate change is due in large part to the burning of fossil fuels and that the ramifications of climate change will be serious. But who knows for sure?
I think there have raised the debatable point re can we actually do anything about climate change. I am in the camp that says I doubt it and yet trillions are spent to try. And creating an unstable grid in the process. I think we should pay more attention to physics that this post points out. That science should not be up for debate.
Harry, I am not sure that you believe as i do that humans are contributing to climate change but like you I am unsure whether we can do anything about it. But it’s not because of technical issues. If less coal and natural gas needs to be used then nuclear power is essential. Solar and wind may play a part but we can’t compromise grid reliability. My concern is that there is not the political will to address climate change.
Hi Steven, I appreciate we don't want to get into a climate debate in this thread, however I have a strong science background and I took the trouble to research and write a book on climate and energy issues with a co-author. Due to a clerical error his name is on the book and not mine but we have left it at that because my name is not selling books yet:)
The quest for net zero with subsidised wind and solar on the grid is one of the worst public policy blunders of all time. Trillions have been spent to get more expensive and less reliable power with massive environmental damage.
Awareness of wind droughts could have prevented the debacle but they were not officially discovered until a decade ago by independent Australian investigators while the meteorologists of the world were mute.
Dirt farmers are alert to the threat of rain droughts, how come the wind farmers never checked the reliability of the wind supply to become aware of wind droughts?
Fragile grids are liable to 2 types of failure, one is the wind" drought trap" when there is not enough conventional power to meet the base load on windless nights during extreme weather conditions, a la Texas.
The other is the Spanish situation where fluctuations in the sunlight or any other perturbations in the system lead to cascading failure.
Wind and solar on the grid have failed comprehensively and it is time get them off the grid and depend on conventional power, including coal, to get real reductions in power prices and put a stop to the environmental carnage and the other harms that are inflicted on rural communities.
Speaking as a retired dairy farmer it is heartbreaking to visit country districts where the forests and farmlands are being carved up and previously harmonious communities are divided between the farmers who are prepared to host wind turbines and those who are not.
I mostly agree. But we don’t have to get wind and solar completely OFF the grid. However, they sure should not be 70% of it. That is totally asking for trouble.
I suspect they would most likely go out of business without subsidies and mandates.
The question is, what value do they add up to 70% penetration?
And if it is true that they are not sustainable due to the combination of wind droughts and lack of grid scale storage, why have any on the grid at all?
Unsubsidised off grid is okay including rooftop solar with some reservations about allowing feedback to the grid.
Back of that is the science of warming and CO2 which in my opinion indicates that warming is unequivocally beneficial within any range that we can conceive in the foreseeable future while CO2 is beneficial and a minor factor in warming, if people insist on being worried about global heating:)
I've had so many people ask "What happened in Spain?" This is the most clear, easy to understand explanation of why the lights went out, and the "moral of the story" is quite plain. Thanks.
Electricty is an essential in our modern world and requires to be extremely reliable.
Spain was quick in restoring power when their grid failed, due I believe to the grid connection with France.
The U.K. is also aiming for a very high renewable percentage of renewables but we have not the same lifeline that Spain has. Yes we are connect5ed to the French grid as well but with an asynchronous D.C. link which will not assist in a black start.
As the fralities of electrconic devices connected to the grid are well known, why are we making our grid less reliable and less stable than it already is. It's past time to call a halt on more renewables for the U.K. grid, walking a tightrope is not recommended.
Great description as always - easy for the layperson to understand. Thanks. And Happy Mother's Day.
Texas advocates for renewables say that batteries will help with these issues, but they are IBR's as well. If they are set with a low "trip" threshold to protect the equipment that still puts us in a bind and a relatively short time frame for backup as well.
Batteries are being forced on us as the saviors of the grid and with over 1,000 new projects on the ERCOT list our electric is going to get more expensive. I don't believe they will save anything and certainly dig into our pocketbooks.
At this point our politicians don't know what else to do other than let renewables keep building at pace to keep up with the demand. Gas is going to be much slower and harder to attain at this point, it seems.
Can we fix renewables? It’s the wrong question. It shoujd be how much more will it cost to continue with wind and solar? How much time will it take to make them behave in the grid? How much will it cost to retrain the grid operators staff to address the issues when operating with wind and solar? Finally we get to the real question - should we continue with wind and solar in the grid? Are wind and solar grid operation suitable? Why don’t we deploy wind and solar behind the end user meter at their site? Oh . . . Because they’re not economic!! Why then do we continue the fantasy? Oh . . . Free taxpayer money to the wind and solar industry!! What a bunch of grifters , and I include the voters who voted for this idiocy.
I've been closely following all the substack articles I've seen on this topic , and adding consecutive addendums ever since writing "The Pain in Spain" (https://alchristie.substack.com/p/the-pain-in-spain). This is the best one yet. Thanks and kudos to Thomas Shepstone, Meredith Angwin, and Brad Panike (Kilovar 1959).
Dear Meredith: Yes, for stable power grids, we need real inertia. Nuclear power plants such as Diablo Canyon Power Plant [DCPP] (or the former Vermont Yankee Power Plant) provide huge quantities of synchronous grid inertia (SGI) to stabilize the grid frequency, Each of the DCPP twin generator - turbine combinations weighs 500 tons (a million pounds.) The rotating components spin at 1,800 rotations per minute. Rotational inertia is proportional to the square of the rotational velocity. Thus, a million pounds rotating at DCPP provides 25 times the SGI of each million-pound pump-rotor combination rotating at 360 RPM at Helms Pumped Storage. Each of the 371-foot-long DCPP generator-turbine combinations are longer than a U.S. football field. Such large-scale machinery is required to provide the employment and residential electricity needs for three million Californians. DCPP produces about 10% of the dispatchable power generated in California.
More details are found in a March 4, 2024 article at CGNP's GreenNUKE Substack titled, "Why is Grid Inertia Important? Without sufficient synchronous grid inertia, the grid becomes unstable and a blackout occurs." https://greennuke.substack.com/p/why-is-grid-inertia-important There are 72 comments to this article which provide additional details, including a link to a 2018 paper regarding the importance of SGI for the electrically-isolated ERCOT grid. Note the importance of the word, "Synchronous" in SGI. One of my correspondents noted that when a generator is improperly synchronized while being connected, it becomes a motor which can be ripped out of the floor of the building it is located in!
Thank you for posting this Grok summary and a link to the detailed calculations which require 13 pages. This information shows that the 2,256 MWe DCPP provides frequency stability for California's power grid which as of 08 April 2025 had 21,043 MWe of destabilizing solar and 8,373 MWe of destabilizing wind, per https://www.caiso.com/documents/key-statistics-mar-2025.pdf
I'm confused about why we haven't had more IBR disconnect blackouts. The IBR standards in Australia call for disconnect for very precisely specified conditions. Every device is supposed to rigidly follow the spec. So when one device trips, it is because a specified condition has occurred. So why doesn't every device trip at that point? Why didn't every IBR device trip during the Odessa incidents? What am I missing? Can the frequency/voltage vary considerably between points on a network?
I'm a software person. To me the kind of rule that makes sense is "trip if V>Vx+rand()" where Vx is some specific number and rand() is a small random value that is different for every device. Rules like that would result in gradual tripping that would allow time for problems to get fixed, rather than a sudden collapse.
Stupid question: A nuclear plant has inertia because the reactor creates steam which spins a turbine & generator. The turbine & generator is the component with the inertia, not the reactor. Doesn’t solar thermal work basically the same way? And hydro? Maybe co-generation bio too? I’m not sure exactly how co-generation actually works (or even what it actually is) but anything that has a spinning generator is going to have inertia, isn’t it?
Now that I think about it, a rotating wind turbine obviously has a titanic amount of physical inertia - those blades are huge and tied to a generator through some sort of transmission. I guess that the power from each turbine (which has it’s own generator mounted up at the top of the mast) is combined somehow and the frequency “matched” and somehow made to be 50 or 60 hertz? The wind farm must have some sort of “grid” within itself to combine the output of all the generators and make it all synchronize at the grid frequency. That is a pretty complicated control problem so it does seem like it might be possible to add synthetic inertia via the already present complex control system that must be there. It certainly wouldn’t be free, but it does seem like it could be made to work. Sorry this part is more me just musing about how a wind farm must have some other components beyond what’s on the towers to actually deliver usable power to the grid.
Good questions, Tom. I think SmithFS answered this quite well.
Most wind turbines make AC power that varies with the wind. It is not the same frequency as the grid power. So the wind-AC is put through a rectifier and comes out as DC. The DC is then put through an inverter to join the grid.
In some cases, the AC power from the inverter also requires a synchronous generator, which is quite expensive.
Meredith nailed it here - the term is formally called "synchronization". Generators on the grid synchronize at 60Hz in the US and 50Hz in Europe. There is no wiggle room since frequency fluctuations can damage equipment and reduce reliability. Maybe someone who is a utility operator can correct me but we're talking 60.000001Hz levels of accuracy and wind cannot turn at this expected rate all the time, hence the inversion to DC and back to AC to synchronize with the grid.
Hydro and solar thermal indeed also use synchronous generators and turbines, so they are effective at supplying grid inertia. Hydro is severely limited by geography. Solar thermal has proven to be impractical, that is even less impractical than already impractical solar PV.
And interesting future problem might be many types of fusion power plants which use direct energy conversion, ions to electricity, also low inertia, a good example is Tri-Alpha Energy:
Wind turbines can drive synchronous generators but it is more economical to use asynchronous permanent magnet generators and inverters. Which allow the blade rpm to be optimized according to wind velocity and weigh a lot less. In either instance there is inertia but it would be much lower than for traditional power plants and not reliable since the median output is only ~15% of full output.
So apart from expensive synchronous capacitor with flywheels, I believe the only effective way to do it is with specialized battery banks driving fast response, high output inverters. These are quite different from the energy storage battery banks currently buffering wind & solar, due to intermittency. So another added cost which I've read is 50% of the cost of the original solar or wind facility. Reminds you of buying a mobile phone, low up front cost but you'll get nailed on additional charges once you signed the deal.
SmithFS - Thank You for answering my questions. You seem pretty knowledgeable on this stuff so if I can beg for a further indulgence: you mentioned needing a battery bank driving fast response high output inverters. Inertia is required to respond to (I’d kind of say “fight”) drops in grid frequency, the wind farm we are thinking about is an operating power plant. Why can’t its output be used to oppose the frequency drop? That is to drive the inverters rather than using batteries?
This really seems to me like a case of the solar and wind plants being allowed to “cheap out” and not contribute to grid stability. Just rely on the rest of the grid to damp out fluctuations. If there’s a problem, I’ll just check out and wait for someone else to fix the problem. Easier that way and as long as there’s only a few free riders, who cares? Classic free rider problem. The grids are governed things, the governers need to be charging the free riders and using the money to pay the contributors. Of course, the whole thing is about using political influence to suck up subsidies so that’s not likely to happen.
They can do some which is being planned, at added expense of course. But the big difference is generators (or motors) can supply large surges in power, both reactive and real power, driven by the high momentum of the large generator rotor & the turbine inertia. No doubt you are aware of how motors pull a big surge of power during startup, in the same way generators can supply a surge of power without having an oversized driver. So if you really want to duplicate that with wind & solar you would need a fast response or high "C rate" battery bank with greatly oversized inverters to supply that surge in current. And with the wind & solar shutdown most of the time, the added cost is harder to justify. A lot of cost for grid protection only available 10-30% of the time. Quite doable but a very significant added expense.
Adding to your point on inertia-free inverters or Grid Following Inverters (GFLs): These are the most common type of inverters, especially for PV, and are widely deployed in Spain. GFLs get their frequency and voltage from the grid. When frequency and voltage fluctuates, GFLs follow the fluctuations.
A sudden loss of generation, because wind slows, dense clouds pass over, an intertie trips, or an unexpected demand spike draws down frequency, GFLs follow that frequency drop, increasing the rate of frequency decline.
Automatic Generation Control (AGC) kicks in to support frequency and manual operators may initiate load shedding but with the rapid frequency drop, it's easy to imagine the support is too little and too late, triggering Under Frequency Load Shedding (UFLS).
Now the GFLs are trying to lock on a moving target: voltage and frequency are swinging. With low inertia, even small disturbances get amplified. Some GFLs may trip offline, unable to maintain phase lock.
This causes more instability: rapid swings or even frequency oscillations, especially in weak grid areas, and a system blackout.
Great article
Any energy systems analyst would know Iberia-like problems would eventually happen, before even a single wind and solar system were connected, but inane, naive, woke idiots do not want to listen to the pros.
Full speed ahead over the cliff, unless all this wind, solar, battery nonsense is stopped dead by taking away subsidies.
Net Zero to reduce CO2 by 2050 is a suicide pact.
That CO2 is needed for greening the world, that supports abundant fauna, and increases crop yields to feed 8 billion people.
To an extent I share your concern about the effect of renewables on grid reliability. I also understand your point that increasing atmospheric CO2 can increase crop yields. Where we probably disagree is whether increasing atmospheric CO2 contributes to global warming and climate change. I don’t mean to get into a disagreement over this issue, but I’d point out that if global temperatures continue to rise for whatever reason, crop yields will decline. An interesting question is how the combination of increasing CO2 and hotter temperatures will affect crop yields.
I'm far from any sort of climate expert. I did read Steven Koonins book but don't think that qualifies me to have any opinion.
However, I am quite sure that there is absolutely nothing we can do about it.
Same here on being unqualified! If climate science experts across many disciplines can’t agree on the climate change question then what is the lay person like you or me to think? I choose to believe what the majority of climate scientists believe which is climate change is due in large part to the burning of fossil fuels and that the ramifications of climate change will be serious. But who knows for sure?
I think there have raised the debatable point re can we actually do anything about climate change. I am in the camp that says I doubt it and yet trillions are spent to try. And creating an unstable grid in the process. I think we should pay more attention to physics that this post points out. That science should not be up for debate.
Harry, I am not sure that you believe as i do that humans are contributing to climate change but like you I am unsure whether we can do anything about it. But it’s not because of technical issues. If less coal and natural gas needs to be used then nuclear power is essential. Solar and wind may play a part but we can’t compromise grid reliability. My concern is that there is not the political will to address climate change.
Well a lot of political will has gone into funding all sorts of clean energy etc in the name of combatting climate change.
Hi Steven, I appreciate we don't want to get into a climate debate in this thread, however I have a strong science background and I took the trouble to research and write a book on climate and energy issues with a co-author. Due to a clerical error his name is on the book and not mine but we have left it at that because my name is not selling books yet:)
https://www.amazon.com.au/s?k=Rafe+Champion&i=stripbooks&crid=GZ66NWUYZ193&sprefix=rafe+champion%2Cstripbooks%2C262&ref=nb_sb_noss
The quest for net zero with subsidised wind and solar on the grid is one of the worst public policy blunders of all time. Trillions have been spent to get more expensive and less reliable power with massive environmental damage.
Awareness of wind droughts could have prevented the debacle but they were not officially discovered until a decade ago by independent Australian investigators while the meteorologists of the world were mute.
https://rafechampion.substack.com/p/the-late-discovery-of-wind-droughts
Dirt farmers are alert to the threat of rain droughts, how come the wind farmers never checked the reliability of the wind supply to become aware of wind droughts?
https://open.substack.com/pub/rafechampion/p/we-have-to-talk-about-wind-droughts.
Fragile grids are liable to 2 types of failure, one is the wind" drought trap" when there is not enough conventional power to meet the base load on windless nights during extreme weather conditions, a la Texas.
https://www.flickerpower.com/index.php/search/categories/general/escaping-the-wind-drought-trap
The other is the Spanish situation where fluctuations in the sunlight or any other perturbations in the system lead to cascading failure.
Wind and solar on the grid have failed comprehensively and it is time get them off the grid and depend on conventional power, including coal, to get real reductions in power prices and put a stop to the environmental carnage and the other harms that are inflicted on rural communities.
Speaking as a retired dairy farmer it is heartbreaking to visit country districts where the forests and farmlands are being carved up and previously harmonious communities are divided between the farmers who are prepared to host wind turbines and those who are not.
I mostly agree. But we don’t have to get wind and solar completely OFF the grid. However, they sure should not be 70% of it. That is totally asking for trouble.
I suspect they would most likely go out of business without subsidies and mandates.
The question is, what value do they add up to 70% penetration?
And if it is true that they are not sustainable due to the combination of wind droughts and lack of grid scale storage, why have any on the grid at all?
Unsubsidised off grid is okay including rooftop solar with some reservations about allowing feedback to the grid.
Back of that is the science of warming and CO2 which in my opinion indicates that warming is unequivocally beneficial within any range that we can conceive in the foreseeable future while CO2 is beneficial and a minor factor in warming, if people insist on being worried about global heating:)
Thank you for the input. I appreciate it.
I've had so many people ask "What happened in Spain?" This is the most clear, easy to understand explanation of why the lights went out, and the "moral of the story" is quite plain. Thanks.
Thank you so much, Ed! I appreciate your note.
Electricty is an essential in our modern world and requires to be extremely reliable.
Spain was quick in restoring power when their grid failed, due I believe to the grid connection with France.
The U.K. is also aiming for a very high renewable percentage of renewables but we have not the same lifeline that Spain has. Yes we are connect5ed to the French grid as well but with an asynchronous D.C. link which will not assist in a black start.
As the fralities of electrconic devices connected to the grid are well known, why are we making our grid less reliable and less stable than it already is. It's past time to call a halt on more renewables for the U.K. grid, walking a tightrope is not recommended.
Great description as always - easy for the layperson to understand. Thanks. And Happy Mother's Day.
Texas advocates for renewables say that batteries will help with these issues, but they are IBR's as well. If they are set with a low "trip" threshold to protect the equipment that still puts us in a bind and a relatively short time frame for backup as well.
Batteries are being forced on us as the saviors of the grid and with over 1,000 new projects on the ERCOT list our electric is going to get more expensive. I don't believe they will save anything and certainly dig into our pocketbooks.
At this point our politicians don't know what else to do other than let renewables keep building at pace to keep up with the demand. Gas is going to be much slower and harder to attain at this point, it seems.
Pray for us this summer!
Can we fix renewables? It’s the wrong question. It shoujd be how much more will it cost to continue with wind and solar? How much time will it take to make them behave in the grid? How much will it cost to retrain the grid operators staff to address the issues when operating with wind and solar? Finally we get to the real question - should we continue with wind and solar in the grid? Are wind and solar grid operation suitable? Why don’t we deploy wind and solar behind the end user meter at their site? Oh . . . Because they’re not economic!! Why then do we continue the fantasy? Oh . . . Free taxpayer money to the wind and solar industry!! What a bunch of grifters , and I include the voters who voted for this idiocy.
Prime example of the Sunk Cost Fallacy in action.
I've been closely following all the substack articles I've seen on this topic , and adding consecutive addendums ever since writing "The Pain in Spain" (https://alchristie.substack.com/p/the-pain-in-spain). This is the best one yet. Thanks and kudos to Thomas Shepstone, Meredith Angwin, and Brad Panike (Kilovar 1959).
this is great - learned a lot
Excellent piece Meredith. Technically sound and understandable.
Thank you, Lee! I am so pleased to see this praise from a transmission expert!
Dear Meredith: Yes, for stable power grids, we need real inertia. Nuclear power plants such as Diablo Canyon Power Plant [DCPP] (or the former Vermont Yankee Power Plant) provide huge quantities of synchronous grid inertia (SGI) to stabilize the grid frequency, Each of the DCPP twin generator - turbine combinations weighs 500 tons (a million pounds.) The rotating components spin at 1,800 rotations per minute. Rotational inertia is proportional to the square of the rotational velocity. Thus, a million pounds rotating at DCPP provides 25 times the SGI of each million-pound pump-rotor combination rotating at 360 RPM at Helms Pumped Storage. Each of the 371-foot-long DCPP generator-turbine combinations are longer than a U.S. football field. Such large-scale machinery is required to provide the employment and residential electricity needs for three million Californians. DCPP produces about 10% of the dispatchable power generated in California.
More details are found in a March 4, 2024 article at CGNP's GreenNUKE Substack titled, "Why is Grid Inertia Important? Without sufficient synchronous grid inertia, the grid becomes unstable and a blackout occurs." https://greennuke.substack.com/p/why-is-grid-inertia-important There are 72 comments to this article which provide additional details, including a link to a 2018 paper regarding the importance of SGI for the electrically-isolated ERCOT grid. Note the importance of the word, "Synchronous" in SGI. One of my correspondents noted that when a generator is improperly synchronized while being connected, it becomes a motor which can be ripped out of the floor of the building it is located in!
Hi Gene,
I asked Grok to calculate the grid inertia of one of DCPPs turbine generators and here are the numbers
Moment of Inertia: I approx 432,750 kg - m2
• Kinetic Energy: E approx 7,691 MWs
• Inertia Constant: H approx 6.41 seconds.
This inertia (~7,691 MWs per unit, ~15,382 MWs for both) significantly stabilizes California’s 60 Hz grid,
https://grok.com/share/c2hhcmQtMg%3D%3D_9c0f1507-ed90-4846-bd82-1ed44ae258af
Thank you for posting this Grok summary and a link to the detailed calculations which require 13 pages. This information shows that the 2,256 MWe DCPP provides frequency stability for California's power grid which as of 08 April 2025 had 21,043 MWe of destabilizing solar and 8,373 MWe of destabilizing wind, per https://www.caiso.com/documents/key-statistics-mar-2025.pdf
Updated list in our post from this morning to include this article on that list.
Great work, Meredith!
I'm confused about why we haven't had more IBR disconnect blackouts. The IBR standards in Australia call for disconnect for very precisely specified conditions. Every device is supposed to rigidly follow the spec. So when one device trips, it is because a specified condition has occurred. So why doesn't every device trip at that point? Why didn't every IBR device trip during the Odessa incidents? What am I missing? Can the frequency/voltage vary considerably between points on a network?
I'm a software person. To me the kind of rule that makes sense is "trip if V>Vx+rand()" where Vx is some specific number and rand() is a small random value that is different for every device. Rules like that would result in gradual tripping that would allow time for problems to get fixed, rather than a sudden collapse.
Stupid question: A nuclear plant has inertia because the reactor creates steam which spins a turbine & generator. The turbine & generator is the component with the inertia, not the reactor. Doesn’t solar thermal work basically the same way? And hydro? Maybe co-generation bio too? I’m not sure exactly how co-generation actually works (or even what it actually is) but anything that has a spinning generator is going to have inertia, isn’t it?
Now that I think about it, a rotating wind turbine obviously has a titanic amount of physical inertia - those blades are huge and tied to a generator through some sort of transmission. I guess that the power from each turbine (which has it’s own generator mounted up at the top of the mast) is combined somehow and the frequency “matched” and somehow made to be 50 or 60 hertz? The wind farm must have some sort of “grid” within itself to combine the output of all the generators and make it all synchronize at the grid frequency. That is a pretty complicated control problem so it does seem like it might be possible to add synthetic inertia via the already present complex control system that must be there. It certainly wouldn’t be free, but it does seem like it could be made to work. Sorry this part is more me just musing about how a wind farm must have some other components beyond what’s on the towers to actually deliver usable power to the grid.
Good questions, Tom. I think SmithFS answered this quite well.
Most wind turbines make AC power that varies with the wind. It is not the same frequency as the grid power. So the wind-AC is put through a rectifier and comes out as DC. The DC is then put through an inverter to join the grid.
In some cases, the AC power from the inverter also requires a synchronous generator, which is quite expensive.
Meredith nailed it here - the term is formally called "synchronization". Generators on the grid synchronize at 60Hz in the US and 50Hz in Europe. There is no wiggle room since frequency fluctuations can damage equipment and reduce reliability. Maybe someone who is a utility operator can correct me but we're talking 60.000001Hz levels of accuracy and wind cannot turn at this expected rate all the time, hence the inversion to DC and back to AC to synchronize with the grid.
Hydro and solar thermal indeed also use synchronous generators and turbines, so they are effective at supplying grid inertia. Hydro is severely limited by geography. Solar thermal has proven to be impractical, that is even less impractical than already impractical solar PV.
And interesting future problem might be many types of fusion power plants which use direct energy conversion, ions to electricity, also low inertia, a good example is Tri-Alpha Energy:
https://tae.com/fusion-power-page/
Wind turbines can drive synchronous generators but it is more economical to use asynchronous permanent magnet generators and inverters. Which allow the blade rpm to be optimized according to wind velocity and weigh a lot less. In either instance there is inertia but it would be much lower than for traditional power plants and not reliable since the median output is only ~15% of full output.
So apart from expensive synchronous capacitor with flywheels, I believe the only effective way to do it is with specialized battery banks driving fast response, high output inverters. These are quite different from the energy storage battery banks currently buffering wind & solar, due to intermittency. So another added cost which I've read is 50% of the cost of the original solar or wind facility. Reminds you of buying a mobile phone, low up front cost but you'll get nailed on additional charges once you signed the deal.
SmithFS - Thank You for answering my questions. You seem pretty knowledgeable on this stuff so if I can beg for a further indulgence: you mentioned needing a battery bank driving fast response high output inverters. Inertia is required to respond to (I’d kind of say “fight”) drops in grid frequency, the wind farm we are thinking about is an operating power plant. Why can’t its output be used to oppose the frequency drop? That is to drive the inverters rather than using batteries?
This really seems to me like a case of the solar and wind plants being allowed to “cheap out” and not contribute to grid stability. Just rely on the rest of the grid to damp out fluctuations. If there’s a problem, I’ll just check out and wait for someone else to fix the problem. Easier that way and as long as there’s only a few free riders, who cares? Classic free rider problem. The grids are governed things, the governers need to be charging the free riders and using the money to pay the contributors. Of course, the whole thing is about using political influence to suck up subsidies so that’s not likely to happen.
They can do some which is being planned, at added expense of course. But the big difference is generators (or motors) can supply large surges in power, both reactive and real power, driven by the high momentum of the large generator rotor & the turbine inertia. No doubt you are aware of how motors pull a big surge of power during startup, in the same way generators can supply a surge of power without having an oversized driver. So if you really want to duplicate that with wind & solar you would need a fast response or high "C rate" battery bank with greatly oversized inverters to supply that surge in current. And with the wind & solar shutdown most of the time, the added cost is harder to justify. A lot of cost for grid protection only available 10-30% of the time. Quite doable but a very significant added expense.
Adding to your point on inertia-free inverters or Grid Following Inverters (GFLs): These are the most common type of inverters, especially for PV, and are widely deployed in Spain. GFLs get their frequency and voltage from the grid. When frequency and voltage fluctuates, GFLs follow the fluctuations.
A sudden loss of generation, because wind slows, dense clouds pass over, an intertie trips, or an unexpected demand spike draws down frequency, GFLs follow that frequency drop, increasing the rate of frequency decline.
Automatic Generation Control (AGC) kicks in to support frequency and manual operators may initiate load shedding but with the rapid frequency drop, it's easy to imagine the support is too little and too late, triggering Under Frequency Load Shedding (UFLS).
Now the GFLs are trying to lock on a moving target: voltage and frequency are swinging. With low inertia, even small disturbances get amplified. Some GFLs may trip offline, unable to maintain phase lock.
This causes more instability: rapid swings or even frequency oscillations, especially in weak grid areas, and a system blackout.
Hi Gene,
I asked Grok to calculate the grid inertia of one of DCPPs turbine generators because I know you like numbers!
Moment of Inertia: I approx 432,750 kg - m2
• Kinetic Energy: E approx 7,691 MWs
• Inertia Constant: H approx 6.41 seconds.
This inertia (~7,691 MWs per unit, ~15,382 MWs for both) significantly stabilizes California’s 60 Hz grid,
https://grok.com/share/c2hhcmQtMg%3D%3D_9c0f1507-ed90-4846-bd82-1ed44ae258af
Great article Meredith. Easy to understand in layman’s terms
You have a knack for that sort of thing!