Thank you Gene and GLF for bringing the tax information to the fore. I was unaware of THAT wrinkle. Thanks for the nod. May I say I was pretty dismayed to see a redacted report given to the public This isn't James Bond folks.
You are welcome. The PSOE has attempted to control the narrative via secrecy. The PSOE's secrecy motivated GreenNUKE to investigate more deeply.. The Spanish nuclear tax scandal and the other scandal that you may learn more about via the suggested search may be sufficient to bring down the PSOE coalition government in Spain. . In GreenNUKE's view, the change to PP is long overdue. The PP already holds more seats than the PSOE. The PP backs continuing to use Spain's seven nuclear power plants. https://english.elpais.com/climate/2025-04-30/massive-blackout-in-spain-reignites-culture-war-over-the-future-of-nuclear-energy.html
It is simply amazing how politicized the whole situation has become worldwide. This points to massive monetary spending on a global scale to move energy into the political arena, this didn't "just happen". Economic Dispatch ruled the power industry, based solely on what it cost to make electricity, for 100 years, we should try it again.
Meredith Angwin noted in her 2020 book that so-called deregulated markets no longer provide economic benefits for providing reliable power. Just the opposite. The states that retain the regulated model with vertically integrated public utilities tend to have reliable, economically-priced power. I believe it is time to reject the RTO - ISO - RO model as a failure and return to state regulation. Unfortunately, the deep-pocketed special interests that foisted this set of policies on us for their economic benefit will resist.
It's been 30 years now, long enough most professional staff has never worked under any other system. Undoing that change would be a stretch unfortunately.
You are quite welcome. This article required extensive research. GreenNUKE remains optimistic that they will be able to learn about the detailed Spanish tax information for the six remaining reactors.
Kathleen Porter is a widely respected in the UK for her reporting of Energy/Grid events over many years. She recently published two blogs related to the Iberian Blackout.
For those people in a hurry I set out three quotes from the end of the second blog and leave you the reader to draw your own conclusions:
Quote 1: A solar inverter was the initial cause of the fault but poor grid code compliance and poor decision-making by REE made this a fatal fault. To summarise, the main events were:
1. A PV inverter caused some frequency oscillations and a drop in voltage including voltage oscillations
2. Two substations in Zaragosa tripped due to transformer taps not adapting fast enough to the increase in voltage after the system responded to the drop caused by (1). These substations at the 55 kV level do not appear to be owned by REE
3. Renewables generators fail to respond to power factor requirements and conventional generators fail to respond to reactive power requirements set out in the grid codes
4. REE fails to schedule enough thermal units for reactive power and initially responds to voltage issues with static rather than dynamic means (as we discussed yesterday with the car up the hill analogy)
5. Lots of wind and solar (PV and thermal) trips inappropriately ie failing to meet fault ride-though obligations. No conventional generation trips until normal operating conditions are breached
6. Voltage falls outside tolerances for conventional generation and frequency falls below 49.5 Hz causing these generators to start to trip further reducing frequency
7. Cascading failure leads to full voltage collapse and blackout
Quote 2:
While we talk about “inertia” as if it’s a single quantifiable value (usually in GVA·s), the term is often a proxy for a much wider set of stabilising properties that synchronous machines provide naturally, because if their physical and electrical characteristics. IBRs, [Inverter Based Resources] particularly batteries can be very good at providing specific services such as fast frequency response, but they lack the default, location-sensitive, and passive characteristics that synchronous machines provide.
The REE report says the blackout wasn’t caused by “inertia”. Technically, it wasn’t caused by a low frequency event, but the system lacked synchronous damping, so the initial voltage instability was not naturally absorbed. It lacked voltage stiffness, so inverter mis-behaviour propagated rapidly, and it lacked a robust synchronous reference, which exacerbated control loop instability. So while “inertia” as a number might not have been the issue, the absence of synchronous behaviour absolutely was.
And it is no coincidence that when the fault propagated into high inertia France it was quickly contained and power to the area was rapidly restored, unlike in low inertia Spain which suffered a full collapse. This could be paraphrased as high-synchronous-generation France vs the high IBR grid in Spain.
Quote 3: The key messages we should take away from the Iberian blackout are:
- Poorly configured inverters can cause catastrophic failures in weak grids
- More attention needs to be paid to voltage control and not just managing frequency
- There needs to be better monitoring of grid code compliance
- The normalisation of deviance often leads to disaster
Fundamentally, TSOs, regulators and energy ministries need to ensure they are not so blinded by their net zero goals that they compromise grid stability, particularly by allowing a gradual erosion of standards that eventually exceeds what grids can cope with. Eleven people lost their lives in the Iberian blackout, so it is vital that the right lessons are learned to avoid any repeat either in Spain or elsewhere.
Excellent. Your final paragraph should be repeated.
"Fundamentally, TSOs, regulators and energy ministries need to ensure they are not so blinded by their net zero goals that they compromise grid stability, particularly by allowing a gradual erosion of standards that eventually exceeds what grids can cope with. Eleven people lost their lives in the Iberian blackout, so it is vital that the right lessons are learned to avoid any repeat either in Spain or elsewhere."
thank you for the great investigation and the part about taxes on nuclear plants. it appears that Ronald Reagan's wisdom of, tax more of something to get less of it is working perfectly in Spain. I guess it is fortunate that people are unlikely to freeze to death there at the next power outage, but their trajectory cannot possibly help their economy going forward .
Thank you. CGNP believes the PSOE government energy policies have led to capital (and employment) flight from Spain. Spain is emulating Germany for the identical ideological reasons.
Nuclear power taxes. Just when I thought I had a handle on all the perverse things going on to put lipstick on the pig we erroneously call "renewables," along comes the nuclear taxes.
Thanks. Spain's electricity policies are being driven by Socialist ideology, not the laws of physics or engineering. As the article shows, there are harmful consequences to this preventable mid-day blackout.. Unfortunately, people died as a result of the policy-caused blackout.
I don’t believe that two more nuclear reactors would have been enough to stabilize grid frequency in the Spain event. If they are the typical large reactors that means they’re about 1 GW each, and about 12 GWs of solar tripped off line. In my opinion, that math doesn’t work.
Dear Ken: The issue is not generator capacity, it is about the quantity of synchronous grid inertia (SGI) that nuclear power plants provide. Please refer to this 2018 ERCOT paper regarding the importance of nuclear power to stabilize grid frequency. "Inertia: Basic Concepts and Impacts on the ERCOT Grid," April 4, 2018, Electric Reliability Council of Texas (ERCOT,) Austin, Texas, USA.
Examination of the mid-day supply stacks after April 28, 2025 for Red Eléctrica (REE) shows the addition of more nuclear and more CCGT has improved the supply of SGI. It does not take much to make a positive difference.
Gene, you know I’m all for nuclear plants and grid inertia, right? I’m just saying that if four nuclear power plants didn’t make a difference, would 33% more really have had a significant impact on grid stability?
Again in my opinion, it probably would not have mattered if two more nuclear plants were online during this major fluctuation voltage in frequency on the grid.
Thank you. GreenNUKE will have more to say about this. Watch for our analysis of the mid-day Red Eléctrica (REE) supply stack before and after April 28, 2025. The problem is the frequency control behavior of the REE system is nonlinear when it gets close to the "Critical Inertia" level. The REE is not well-connected to adjacent power grids, making it more vulnerable to oscillations. The REE system has limited connections to France and Morocco.
The power outputs which you quote are irrelevant to this discussion: the key factor is grid inertia- the ability of rotating assets to damp oscillations in voltage and frequency. This ability can in fact be contributed by non-generating assets such as synchronous condensers - Kilovar notes that the Spanish system has none.
The oscillations in the Spanish grid were eventually traced to a rogue IBR, but because of the lack of SCADA to pinpoint, in real time, such misbehavior, it was not picked up, nor compensated for, in sufficient time to stave off the blackout.
Nuclear assets would have added inertia but, as the article notes, were priced out of contention by tax policy. A purely political, not an engineering, constraint.
Thank you Gene and GLF for bringing the tax information to the fore. I was unaware of THAT wrinkle. Thanks for the nod. May I say I was pretty dismayed to see a redacted report given to the public This isn't James Bond folks.
You are welcome. The PSOE has attempted to control the narrative via secrecy. The PSOE's secrecy motivated GreenNUKE to investigate more deeply.. The Spanish nuclear tax scandal and the other scandal that you may learn more about via the suggested search may be sufficient to bring down the PSOE coalition government in Spain. . In GreenNUKE's view, the change to PP is long overdue. The PP already holds more seats than the PSOE. The PP backs continuing to use Spain's seven nuclear power plants. https://english.elpais.com/climate/2025-04-30/massive-blackout-in-spain-reignites-culture-war-over-the-future-of-nuclear-energy.html
It is simply amazing how politicized the whole situation has become worldwide. This points to massive monetary spending on a global scale to move energy into the political arena, this didn't "just happen". Economic Dispatch ruled the power industry, based solely on what it cost to make electricity, for 100 years, we should try it again.
Meredith Angwin noted in her 2020 book that so-called deregulated markets no longer provide economic benefits for providing reliable power. Just the opposite. The states that retain the regulated model with vertically integrated public utilities tend to have reliable, economically-priced power. I believe it is time to reject the RTO - ISO - RO model as a failure and return to state regulation. Unfortunately, the deep-pocketed special interests that foisted this set of policies on us for their economic benefit will resist.
Note the informative March 2021 article coauthored by current National Association of Regulatory Utility Commissioners (NARUC) executive director and former FERC Commissioner Tony Clark, "At the Precipice: The Perils of Utility Restructuring" https://www.wbklaw.com/wp-content/uploads/2021/03/At-the-Precipice_-The-Perils-of-Utility-Restructuring-3.16.21.pdf raises a number of relevant points.
It's been 30 years now, long enough most professional staff has never worked under any other system. Undoing that change would be a stretch unfortunately.
I did not say it would be easy. However for grid reliability, the rollback is necessary.
Thanks, Gene, for verifying (much more elegantly) what I initially suspected and wrote about in "The Pain in Spain" right after the blackout. https://alchristie.substack.com/p/the-pain-in-spain?
You are quite welcome. This article required extensive research. GreenNUKE remains optimistic that they will be able to learn about the detailed Spanish tax information for the six remaining reactors.
Kathleen Porter is a widely respected in the UK for her reporting of Energy/Grid events over many years. She recently published two blogs related to the Iberian Blackout.
The first blog looks at the physics of power grids and the general behaviour of both synchronous generation (gas, hydro and nuclear) and inverter-based generation (wind, solar and batteries). It also relates the theory to the Spanish Grid. https://watt-logic.com/2025/07/16/voltage-inertia-and-the-iberian-blackout-part-1-the-theory/
The second blog uses the concepts from blog 1 to review the report published on June 16 by Red Eléctrica de España (“REE”), the Spanish Transmission System Operator (“TSO”). https://watt-logic.com/2025/07/16/voltage-inertia-and-the-iberian-blackout-part-2-a-faulty-solar-inverter-crashed-the-spanish-grid12088/
The REE report is here: https://d1n1o4zeyfu21r.cloudfront.net/WEB_Incident_%2028A_SpanishPeninsularElectricalSystem_18june25.pdf
For those people in a hurry I set out three quotes from the end of the second blog and leave you the reader to draw your own conclusions:
Quote 1: A solar inverter was the initial cause of the fault but poor grid code compliance and poor decision-making by REE made this a fatal fault. To summarise, the main events were:
1. A PV inverter caused some frequency oscillations and a drop in voltage including voltage oscillations
2. Two substations in Zaragosa tripped due to transformer taps not adapting fast enough to the increase in voltage after the system responded to the drop caused by (1). These substations at the 55 kV level do not appear to be owned by REE
3. Renewables generators fail to respond to power factor requirements and conventional generators fail to respond to reactive power requirements set out in the grid codes
4. REE fails to schedule enough thermal units for reactive power and initially responds to voltage issues with static rather than dynamic means (as we discussed yesterday with the car up the hill analogy)
5. Lots of wind and solar (PV and thermal) trips inappropriately ie failing to meet fault ride-though obligations. No conventional generation trips until normal operating conditions are breached
6. Voltage falls outside tolerances for conventional generation and frequency falls below 49.5 Hz causing these generators to start to trip further reducing frequency
7. Cascading failure leads to full voltage collapse and blackout
Quote 2:
While we talk about “inertia” as if it’s a single quantifiable value (usually in GVA·s), the term is often a proxy for a much wider set of stabilising properties that synchronous machines provide naturally, because if their physical and electrical characteristics. IBRs, [Inverter Based Resources] particularly batteries can be very good at providing specific services such as fast frequency response, but they lack the default, location-sensitive, and passive characteristics that synchronous machines provide.
The REE report says the blackout wasn’t caused by “inertia”. Technically, it wasn’t caused by a low frequency event, but the system lacked synchronous damping, so the initial voltage instability was not naturally absorbed. It lacked voltage stiffness, so inverter mis-behaviour propagated rapidly, and it lacked a robust synchronous reference, which exacerbated control loop instability. So while “inertia” as a number might not have been the issue, the absence of synchronous behaviour absolutely was.
And it is no coincidence that when the fault propagated into high inertia France it was quickly contained and power to the area was rapidly restored, unlike in low inertia Spain which suffered a full collapse. This could be paraphrased as high-synchronous-generation France vs the high IBR grid in Spain.
Quote 3: The key messages we should take away from the Iberian blackout are:
- Poorly configured inverters can cause catastrophic failures in weak grids
- More attention needs to be paid to voltage control and not just managing frequency
- There needs to be better monitoring of grid code compliance
- The normalisation of deviance often leads to disaster
Fundamentally, TSOs, regulators and energy ministries need to ensure they are not so blinded by their net zero goals that they compromise grid stability, particularly by allowing a gradual erosion of standards that eventually exceeds what grids can cope with. Eleven people lost their lives in the Iberian blackout, so it is vital that the right lessons are learned to avoid any repeat either in Spain or elsewhere.
Excellent. Your final paragraph should be repeated.
"Fundamentally, TSOs, regulators and energy ministries need to ensure they are not so blinded by their net zero goals that they compromise grid stability, particularly by allowing a gradual erosion of standards that eventually exceeds what grids can cope with. Eleven people lost their lives in the Iberian blackout, so it is vital that the right lessons are learned to avoid any repeat either in Spain or elsewhere."
thank you for the great investigation and the part about taxes on nuclear plants. it appears that Ronald Reagan's wisdom of, tax more of something to get less of it is working perfectly in Spain. I guess it is fortunate that people are unlikely to freeze to death there at the next power outage, but their trajectory cannot possibly help their economy going forward .
Thank you. CGNP believes the PSOE government energy policies have led to capital (and employment) flight from Spain. Spain is emulating Germany for the identical ideological reasons.
and here I thought it was a two horse race, Germany and the UK, but perhaps Spain is a dark horse in this race
Yes. The PSOE plan is to tail Germany.
Great stuff, thanks for posting.
Nuclear power taxes. Just when I thought I had a handle on all the perverse things going on to put lipstick on the pig we erroneously call "renewables," along comes the nuclear taxes.
Thanks. Spain's electricity policies are being driven by Socialist ideology, not the laws of physics or engineering. As the article shows, there are harmful consequences to this preventable mid-day blackout.. Unfortunately, people died as a result of the policy-caused blackout.
All the edgy socialists know that bourgeois eggs must be sacrificed to build a proletarian omelette.
This solar-powered omelette is very impractical, expensive, and lethal to boot. :-(
I don’t believe that two more nuclear reactors would have been enough to stabilize grid frequency in the Spain event. If they are the typical large reactors that means they’re about 1 GW each, and about 12 GWs of solar tripped off line. In my opinion, that math doesn’t work.
Dear Ken: The issue is not generator capacity, it is about the quantity of synchronous grid inertia (SGI) that nuclear power plants provide. Please refer to this 2018 ERCOT paper regarding the importance of nuclear power to stabilize grid frequency. "Inertia: Basic Concepts and Impacts on the ERCOT Grid," April 4, 2018, Electric Reliability Council of Texas (ERCOT,) Austin, Texas, USA.
https://www.ercot.com/files/docs/2018/04/04/Inertia_Basic_Concepts_Impacts_On_ERCOT_v0.pdf
Examination of the mid-day supply stacks after April 28, 2025 for Red Eléctrica (REE) shows the addition of more nuclear and more CCGT has improved the supply of SGI. It does not take much to make a positive difference.
Gene, you know I’m all for nuclear plants and grid inertia, right? I’m just saying that if four nuclear power plants didn’t make a difference, would 33% more really have had a significant impact on grid stability?
Again in my opinion, it probably would not have mattered if two more nuclear plants were online during this major fluctuation voltage in frequency on the grid.
Thank you. GreenNUKE will have more to say about this. Watch for our analysis of the mid-day Red Eléctrica (REE) supply stack before and after April 28, 2025. The problem is the frequency control behavior of the REE system is nonlinear when it gets close to the "Critical Inertia" level. The REE is not well-connected to adjacent power grids, making it more vulnerable to oscillations. The REE system has limited connections to France and Morocco.
The power outputs which you quote are irrelevant to this discussion: the key factor is grid inertia- the ability of rotating assets to damp oscillations in voltage and frequency. This ability can in fact be contributed by non-generating assets such as synchronous condensers - Kilovar notes that the Spanish system has none.
The oscillations in the Spanish grid were eventually traced to a rogue IBR, but because of the lack of SCADA to pinpoint, in real time, such misbehavior, it was not picked up, nor compensated for, in sufficient time to stave off the blackout.
Nuclear assets would have added inertia but, as the article notes, were priced out of contention by tax policy. A purely political, not an engineering, constraint.