Thank you for your comprehensive article regarding California electricity generation. One of the factors neglected by your analysis is the power engineering requirement for sufficient synchronous grid inertia (SGI) to maintain grid frequency stability. An introduction is found in this March 4, 2024 GreenNUKE article, "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 One of nuclear's "superpowers" is the ability to supply abundant and necessary SGI. California's political leaders ignore this physical reality at their peril. Former California Governor Gray Davis was recalled in 2003 for his role in the ENRON-created blackouts in California.
Germany has pushed for increased use of solar and wind while turning off its large fleet of safe, reliable, and cost effective nuclear power plants. The result has been rising power sector emissions and radically higher electricity prices. On the other hand, France with its large nuclear power fleet (about 70% of demand) features lower electricity costs and significantly lower power sector emissions relative to Germany.
Another European nation that is following a course similar to Germany is Spain. Like California, Spain has abundant solar generation and a favorable climate. The Spanish PSOE government has pushed for high levels of subsidized solar and wind generation. Spain also has a unique tax on safe, reliable and cost-effective nuclear power to subsidize unreliable and intermittent solar and wind power. If the PSOE remains in power, Spain plans to shut down its seven nuclear reactors by 2035. However, on April 28, 2025, the Iberian Peninsula (Spain and Portugal) had a massive mid-day blackout. This blackout caused the death of eleven people. The lost productivity and damaged production equipment was denominated in the equivalent of billions of U.S. dollars. The unique Spanish nuclear tax was one of the causes of the blackout. See the July 8, 2025 GreenNUKE article, "The Spanish Version of the 'Duck Curve' is a real killer - This curve underscores the problem of insufficient synchronous grid inertia in Spain on April 28, 2025." https://greennuke.substack.com/p/the-spanish-version-of-the-duck-curve
A government decree for increased use of solar and wind eventually collides the the power engineering requirements for sufficient SGI summarized in the first paragraph above.
BTW, there is a natural experiment underway in California. I believe there would be a good correlation comparing the time series of the ratio of California's retail electric power cost to the national average retail electric power cost. This could be compared to the time series of per capita electricity use in California. California's exorbitant electricity costs diminish per capita electricity consumption.
Thanks. I am concerned about issues related to frequency and voltage stability. The problem is that there is no rigorous data available to model them. I focus on energy stability because there is a wealth of great data. I want my model to be bulletproof against legitimate criticism, and I am willing to underestimate the problem to achieve that. In fact, I have underestimated the costs related to transmission because they are too complex to calculate accurately.
My highly provisional opinion is that in an ultra-high inverter-dominated grid, about 25% of the solar/wind farms will need to be more high-tech than the current farms. They will require grid-forming inverters, software to simulate inertial response, and advanced control systems. The remaining 75% can keep their grid-following inverters, but may require some tweaking. There will be additional costs, but rigorous data is not available.
I believe that with upgraded electronics and software, this problem can be solved. Although there may be a few blackouts until all the bugs are fixed. If cost data becomes available, I will incorporate it into my model. To address energy instability, however, capital costs will need to decrease by at least 75% for solar, wind, and batteries. I think it is extremely unlikely that this will happen.
Thanks, John for your additional details. At the GreenNUKE Substack, there are several articles regarding the cost-effectiveness of supplying SGI via large nuclear power plants. such as DCPP. One of the references in the comments of the March 4, 2024 article regarding the importance of SGI is a link to the important 2018 ERCOT primer regarding SGI. ERCOT chose to minimize connections to the adjacent power grids to minimize FERC oversight. Thus, the ERCOT gird is similar to that of an island with little or no connections to nearby power grids via underwater cables. Note in particular the concept of critical inertia in the ERCOT paper. A few nuclear power plants in conjunction with some large combined cycle natural gas plants can provide the requisite SGI cost-effectively.
On the other hand, grid operator experience with solar, wind, and batteries is limited. CAISO's experience in the 08 16 16 Blue Cut Fire could have served as a warning regarding the risks of inverter-based resources. (IBRs.) Please search both phrases to learn more. There have been limited mitigations regarding IBRs, for incorporating changes in Area Control Error (ACE) systems. New builds instead of retrofits will likely be more cost-effective.
Large DC inverters such as the 3,900 MW inverter at the southern terminus of the Pacific DC Intertie at the Sylmar Converter Station integrate with ACE systems, so they can simulate a large nuclear power plant. However, such examples are limited. These systems are much more seismically fragile than nuclear power plants. The Sylmar Converter Station was completely destroyed in the 1971 Sylmar Earthquake.
Kauai Island Utility Cooperative - KIUC.coop in the Hawaiian Islands has begun work on grid forming inverters (GFIs.) The capacity of the pair of grid forming inverters there are each far less than 100 MW. IEEE Spectrum has a good overview article which is available at no cost when their website is provided with a valid email address. Despite California having over 11,000 MW of battery electric storage systems (BESS) there are only lab-scale projects involving California GFIs.
In summary, the most cost-effective way to supply sufficient SGI for a regional grid is a few nuclear power plants. Spain's experience with the April 28, 2025 mid-day blackout is an example of a set of failed PSOE government policies.
Thanks, Gene. There’s a lot of interesting stuff here. I strongly agree with your point that nuclear plants can provide a voltage, frequency, and phase reference for grid-following inverters. This is yet another reason why DCPP should not be closed. If California policymakers would come to their senses and build a few more nuclear plants and extend DCPP, this issue could be resolved. Of course, the high cost of semi-dispatchable solar power remains unresolved.
Grid-forming inverters exist, but they are still in the demonstration phase. As far as I know, there's no requirement in California (or anywhere in the U.S.) that new solar farms have to use them. I could find no evidence that any solar farms in the queue are planning to use them. You would think this issue would have some resolution with so little time left to achieve milestones.
It’s ironic that nuclear power can make future solar farms cheaper.
Thanks. The installation of grid forming inverters in California might alert ratepayers that they are paying for practically useless hardware. :-(
The eminent scientists and engineers at the California Council for Science and Technology (CCST) delivered this message 14 years ago. They were ignored. Here's a short version of the pair of reports they were asked to prepare for the California Energy Commission by Nobel Laureate Burton Richter, Ph.D.
"CCST Report on Nuclear Power in California’s 2050 Energy Mix," Burton Richter, Ph.D. (Nobel Laureate), July 15, 2011,
The summary of the CCST reports is the most cost-effective way to modernize California's power grid and decarbonize the power sector is for the state to build about 30 new Diablo Canyon Power Plants.
Note also that more reliable grids without solar or wind tend to be less expensive and have lower emissions than those grids that include solar and wind.
Interesting read having worked inside the California energy system. There is also the public- private power battle that has always gone on in California with public power trying to stay independent from all the CAISO madness.
In your experience making public policy plans for energy do you ever consider the business opportunity of making use somehow of the curtailed energy? I don’t have a solution in mind but I lived through the shortages of the Energy Crisis and I am in awe that I now live in the time of Energy Abundance. Discarding zero-cost electricity seems like we are wasting a resource.
Or the business opportunities in energy trading? I know that oil, natural gas, and electricity have markets where traders provide price stability and are paid well in some cases.
It seems to me that the cost of production is only part of the electricity business.
I have analyzed the feasibility of producing hydrogen using curtailed energy from solar, wind farms, and nuclear plants. Most industrial processes require highly stable energy inputs, but hydrogen is an important exception. PEM electrolyzers can operate in a highly variable environment. However, to make this work, you need cheap regional mass storage of H2 and a way to deliver high power surges to the electrolyzers. The power surges are the result of low capacity factors of solar and wind farms, which are compensated for by overbuilding capacity. Mass storage can be plausibly achieved using salt domes, but the current transmission system cannot handle the power surges from solar and wind farms. Ultimately, my analysis showed no reduction in cost when using solar or wind power, but did show a significant decrease in land use.
Using nuclear power is easier than using solar and wind energy because it eliminates the power surges. This approach is compatible with the current transmission system. The goal here is to run the nuclear plants at maximum output, 24 hours a day, every day of the year. The electrolyzers activate when consumer demand is satisfied. The electrolyzers are thus load-balancing consumer demand. This makes full use of all the nuclear capacity. The nuclear plant is either making electricity for consumers or making hydrogen. I was able to show some savings, but that’s based on the cost maturity of all the components.
Thank you for your comprehensive article regarding California electricity generation. One of the factors neglected by your analysis is the power engineering requirement for sufficient synchronous grid inertia (SGI) to maintain grid frequency stability. An introduction is found in this March 4, 2024 GreenNUKE article, "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 One of nuclear's "superpowers" is the ability to supply abundant and necessary SGI. California's political leaders ignore this physical reality at their peril. Former California Governor Gray Davis was recalled in 2003 for his role in the ENRON-created blackouts in California.
Germany has pushed for increased use of solar and wind while turning off its large fleet of safe, reliable, and cost effective nuclear power plants. The result has been rising power sector emissions and radically higher electricity prices. On the other hand, France with its large nuclear power fleet (about 70% of demand) features lower electricity costs and significantly lower power sector emissions relative to Germany.
Another European nation that is following a course similar to Germany is Spain. Like California, Spain has abundant solar generation and a favorable climate. The Spanish PSOE government has pushed for high levels of subsidized solar and wind generation. Spain also has a unique tax on safe, reliable and cost-effective nuclear power to subsidize unreliable and intermittent solar and wind power. If the PSOE remains in power, Spain plans to shut down its seven nuclear reactors by 2035. However, on April 28, 2025, the Iberian Peninsula (Spain and Portugal) had a massive mid-day blackout. This blackout caused the death of eleven people. The lost productivity and damaged production equipment was denominated in the equivalent of billions of U.S. dollars. The unique Spanish nuclear tax was one of the causes of the blackout. See the July 8, 2025 GreenNUKE article, "The Spanish Version of the 'Duck Curve' is a real killer - This curve underscores the problem of insufficient synchronous grid inertia in Spain on April 28, 2025." https://greennuke.substack.com/p/the-spanish-version-of-the-duck-curve
A government decree for increased use of solar and wind eventually collides the the power engineering requirements for sufficient SGI summarized in the first paragraph above.
BTW, there is a natural experiment underway in California. I believe there would be a good correlation comparing the time series of the ratio of California's retail electric power cost to the national average retail electric power cost. This could be compared to the time series of per capita electricity use in California. California's exorbitant electricity costs diminish per capita electricity consumption.
Thanks. I am concerned about issues related to frequency and voltage stability. The problem is that there is no rigorous data available to model them. I focus on energy stability because there is a wealth of great data. I want my model to be bulletproof against legitimate criticism, and I am willing to underestimate the problem to achieve that. In fact, I have underestimated the costs related to transmission because they are too complex to calculate accurately.
My highly provisional opinion is that in an ultra-high inverter-dominated grid, about 25% of the solar/wind farms will need to be more high-tech than the current farms. They will require grid-forming inverters, software to simulate inertial response, and advanced control systems. The remaining 75% can keep their grid-following inverters, but may require some tweaking. There will be additional costs, but rigorous data is not available.
I believe that with upgraded electronics and software, this problem can be solved. Although there may be a few blackouts until all the bugs are fixed. If cost data becomes available, I will incorporate it into my model. To address energy instability, however, capital costs will need to decrease by at least 75% for solar, wind, and batteries. I think it is extremely unlikely that this will happen.
Thanks, John for your additional details. At the GreenNUKE Substack, there are several articles regarding the cost-effectiveness of supplying SGI via large nuclear power plants. such as DCPP. One of the references in the comments of the March 4, 2024 article regarding the importance of SGI is a link to the important 2018 ERCOT primer regarding SGI. ERCOT chose to minimize connections to the adjacent power grids to minimize FERC oversight. Thus, the ERCOT gird is similar to that of an island with little or no connections to nearby power grids via underwater cables. Note in particular the concept of critical inertia in the ERCOT paper. A few nuclear power plants in conjunction with some large combined cycle natural gas plants can provide the requisite SGI cost-effectively.
On the other hand, grid operator experience with solar, wind, and batteries is limited. CAISO's experience in the 08 16 16 Blue Cut Fire could have served as a warning regarding the risks of inverter-based resources. (IBRs.) Please search both phrases to learn more. There have been limited mitigations regarding IBRs, for incorporating changes in Area Control Error (ACE) systems. New builds instead of retrofits will likely be more cost-effective.
Large DC inverters such as the 3,900 MW inverter at the southern terminus of the Pacific DC Intertie at the Sylmar Converter Station integrate with ACE systems, so they can simulate a large nuclear power plant. However, such examples are limited. These systems are much more seismically fragile than nuclear power plants. The Sylmar Converter Station was completely destroyed in the 1971 Sylmar Earthquake.
Kauai Island Utility Cooperative - KIUC.coop in the Hawaiian Islands has begun work on grid forming inverters (GFIs.) The capacity of the pair of grid forming inverters there are each far less than 100 MW. IEEE Spectrum has a good overview article which is available at no cost when their website is provided with a valid email address. Despite California having over 11,000 MW of battery electric storage systems (BESS) there are only lab-scale projects involving California GFIs.
In summary, the most cost-effective way to supply sufficient SGI for a regional grid is a few nuclear power plants. Spain's experience with the April 28, 2025 mid-day blackout is an example of a set of failed PSOE government policies.
Thanks, Gene. There’s a lot of interesting stuff here. I strongly agree with your point that nuclear plants can provide a voltage, frequency, and phase reference for grid-following inverters. This is yet another reason why DCPP should not be closed. If California policymakers would come to their senses and build a few more nuclear plants and extend DCPP, this issue could be resolved. Of course, the high cost of semi-dispatchable solar power remains unresolved.
Grid-forming inverters exist, but they are still in the demonstration phase. As far as I know, there's no requirement in California (or anywhere in the U.S.) that new solar farms have to use them. I could find no evidence that any solar farms in the queue are planning to use them. You would think this issue would have some resolution with so little time left to achieve milestones.
It’s ironic that nuclear power can make future solar farms cheaper.
Thanks. The installation of grid forming inverters in California might alert ratepayers that they are paying for practically useless hardware. :-(
The eminent scientists and engineers at the California Council for Science and Technology (CCST) delivered this message 14 years ago. They were ignored. Here's a short version of the pair of reports they were asked to prepare for the California Energy Commission by Nobel Laureate Burton Richter, Ph.D.
"CCST Report on Nuclear Power in California’s 2050 Energy Mix," Burton Richter, Ph.D. (Nobel Laureate), July 15, 2011,
https://ccst.us/wp-content/uploads/071511richter.pdf
The summary of the CCST reports is the most cost-effective way to modernize California's power grid and decarbonize the power sector is for the state to build about 30 new Diablo Canyon Power Plants.
Note also that more reliable grids without solar or wind tend to be less expensive and have lower emissions than those grids that include solar and wind.
Interesting read having worked inside the California energy system. There is also the public- private power battle that has always gone on in California with public power trying to stay independent from all the CAISO madness.
Great job. There is a lot of information here and must have taken quite an effort to assemble. I appreciate your work.
John, this is very thorough, thank you.
In your experience making public policy plans for energy do you ever consider the business opportunity of making use somehow of the curtailed energy? I don’t have a solution in mind but I lived through the shortages of the Energy Crisis and I am in awe that I now live in the time of Energy Abundance. Discarding zero-cost electricity seems like we are wasting a resource.
Or the business opportunities in energy trading? I know that oil, natural gas, and electricity have markets where traders provide price stability and are paid well in some cases.
It seems to me that the cost of production is only part of the electricity business.
I have analyzed the feasibility of producing hydrogen using curtailed energy from solar, wind farms, and nuclear plants. Most industrial processes require highly stable energy inputs, but hydrogen is an important exception. PEM electrolyzers can operate in a highly variable environment. However, to make this work, you need cheap regional mass storage of H2 and a way to deliver high power surges to the electrolyzers. The power surges are the result of low capacity factors of solar and wind farms, which are compensated for by overbuilding capacity. Mass storage can be plausibly achieved using salt domes, but the current transmission system cannot handle the power surges from solar and wind farms. Ultimately, my analysis showed no reduction in cost when using solar or wind power, but did show a significant decrease in land use.
Using nuclear power is easier than using solar and wind energy because it eliminates the power surges. This approach is compatible with the current transmission system. The goal here is to run the nuclear plants at maximum output, 24 hours a day, every day of the year. The electrolyzers activate when consumer demand is satisfied. The electrolyzers are thus load-balancing consumer demand. This makes full use of all the nuclear capacity. The nuclear plant is either making electricity for consumers or making hydrogen. I was able to show some savings, but that’s based on the cost maturity of all the components.
Thanks for another excellent case study and (to my mind, water-tight) argument.