And all of this is confused by the way the nuclear industry uses the term "load following". You'd think it means "changing the power output from moment to moment to match electricity demand" but for nuclear plants it means "changing from one pre-planned constant level to another pre-planned constant level, up to four times per day".[0] There are only three[1] sources of electricity that can be ramped freely enough to exactly match demand: hydro, simple-cycle gas turbines and batteries. All electrical supplies will need some of those three mixed in. Which is why France is still 10% hydro and 10% natural gas in their electricity supply.
0: Some of the most modern Russian plants can move to +-20% of their current target at 10% per minute, but "the number of such very fast power variations is limited, and they are mainly reserved for emergency situations." per your source.
1: OK, there are some obsolete ways too, like diesel generators. At least obsolete at the scale of the electricity grid.
5% of nameplate capacity.
> You'd think it means "changing the power output from moment to moment to match electricity demand" but for nuclear plants it means "changing from one pre-planned constant level to another pre-planned constant level, up to four times per day"
Which is clearly invalidated by the very source I provided, and which you then somehow quote back at me.
> "the number of such very fast power variations is limited, and they are mainly reserved for emergency situations." per your source.
Imagine if you didn't omit the full quote/context:
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Also, AES-2006 is capable of fast power modulations with ramps of up to 5% Pr per second (in the interval of ±10% Pr), or power drops of 20% Pr per minute in the interval of 50-100% of the rated power. However, the number of such very fast power variations is limited, and they are mainly reserved for emergency situations.
--- end quote ---
Oh look. What's limited is an actual emergency ramp up of 5% per second or power drops of 20% per minute.
Which is literally an emergency that is not needed in a power grid.
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Let me quote page 10 of your source "In brief, most of the modern light water nuclear reactors are capable (by design) to operate in a load following mode, i.e. to change their power level once or twice per day in the range of 100% to 50% (or even lower) of the rated power, with a ramp rate of up to 5% (or even more) of rated power per minute". Your own source defines "load following" as changing the targeted power level once or twice per day.
Again on page 14 (about how the French currently run their nuclear plants): "The nuclear power plants operating in the load following mode follow a variable load programme with one or two power changes per period of 24 h". Weirdly enough this is contradicted by table 2.1 on page 20 where they do four changes per day.
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> Oh look. What's limited is an actual emergency ramp up of 5% per second or power drops of 20% per minute.
If you look at table 2.4 on the same page it states that it (the Russian VVER-1200) can do the 5% per second/20% per minute emergency change 20 000 times over the lifetime of the reactor. The 10% per minute change can also only be done 20 000 times over the lifetime of the reactor. Table 2.2 on page 21 helpfully calculates that 15 000 cycles is once per day for 40 years, so the VVER-1200 only can do a bit more than one >5% change per day (outside of emergencies) assuming a similar 40 year lifespan. And that was the point of my footnote: that nuclear plants technically can go faster than 5% but not up and down on a minute-by-minute basis.
If you keep jumping around with your arguments, nothing is extreme.
Your original claim started with claiming cold starts (which most power plants including gas turbines don't do, ever) and that coal and nuclear aren't fast.
Nuclear is plenty fast.
I never claimed gas power stations were slow, or that they were slower than nuclear.
> If you look at table 2.4 on the same page it states that it (the Russian VVER-1200) can do the 5% per second/20% per minute emergency change
Let me slowly walk you through that statement:
--- start quote ---
can do the 5% per second/20% per minute emergency change
emergency change
emergency
--- end quote ---
> And that was the point of my footnote: that nuclear plants technically can go faster than 5% but not up and down on a minute-by-minute basis.
No idea what your footnote was about, and how it is relevant.
> None of the power plants ever do a "fast cold start"
Somewhere in each grid you will have “black start” capacity contracts, dunno if nuclear can fills this role (or if grids exclude nukes for one reason or another).
Plenty of peaker plants built with the intention of running double digit hours per year and therefore the tradeoff supports being largely “off” in between those calls. Batteries might fill that gap.
The obvious counterexample is Chernobyl, where a big contributor was the fact that they were unable to scale it down & back up as desired. Yes, nuclear reactors can scale down rapidly - but you have to wait several hours until it can scale back up!
Besides, the linked paper only covers load-following in a traditional grid (swinging between 60% and 100% once a day) and barely touches on the economic effects. The situation is going to look drastically different for a renewables-first grid, where additional sources are needed for at most a few hours a day, for a few months per year.
> You don't shut down power plants. None of the power plants ever do a "fast cold start"
Gas turbines can. Hydro can. Battery storage can.
If you are going to curtail, you curtail other sources including solar and wind.
Nuclear fits quite well for the baseload you need. It's more expensive, but if you are going to need X capacity 24x7 and build nuclear, you simply build enough to provide just that plus perhaps a few extra for redundancy when another one goes offline. Then use gas peakers for the "oh shit" days difference between what nuclear is providing and solar was expected to but could not.
I don't understand the fascination folks have about nuclear not being able to following the grid. They don't need to, since they only ever remotely make sense when operated 24x7 at 100%. If you always have 1TW of grid usage every night during your lowest usage period - build that much nuclear as your starting point and figure out the rest from there. Nuclear's share of the total mix should be a straight line on a graph outside of plant shutdowns for maintenance.
Your argument only works in entirely state controlled systems, not in free energy markets of independent suppliers. Which is why nukes don’t get built.
Nukes don't get built because:
- billions (if not trillions) of subsidies were poured into wind and solar over decades to make them viable while nuclear energy was addled with additional taxes, reactor closures, and very few new reactor licenses
- decades of fear-mongering led to loss of expertise in building new nuclear power plants (and instead South-East Asia has been picking up speed in building new reactors) [1]
In 2015 nuclear was significantly cheaper than most other types of energy across most markets: https://world-nuclear.org/images/articles/REPORT_Economics_R... (Figure 12, in some markets including the then-emerging renewables). And yet renewables were enjoying unprecedented amounts of subsidies and money poured into them while nuclear... Oh we know what was happening to nuclear, just look at Germany.
[1] Here's EU's own report: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=COM:2025...
Renewables: 80-80 billion euro in subsidies a year.
Fossil fuels: 60-140 billion euro in subsidies a year.
Nuclear: good luck finding the thin orange line in the graph. (1% of subsidies)
--- start quote ---
As shown on Figure 4 , solar energy received by far the largest share of subsidies, both historically and in 2023 (EUR 21 bn), followed by biomass (EUR 9 bn) and wind power (EUR 7 bn). Hydropower received marginal financial support (~EUR 1 bn), while subsidies targeting multiple renewable technologies (such as tax reductions on green technology or public aid for investment projects) jumped to EUR 23 bn by 2023.
Subsidies for nuclear energy dropped from EUR 7.9 bn in 2021 to 3.7 bn in 2022 and 4.1 bn in 2023. Of the 14 MS providing nuclear subsidies, France (EUR 2.9 bn) accounted for the biggest share, followed by Germany (EUR 0.8 bn) , Spain and Belgium (EUR 0.1 bn each).
--- end quote ---
It was fraud from the top down and the manufacturer went bankrupt. I paid more for power in SC than I ever did when I lived in “summer all year” Florida. But I guess I got a token check in the mail some years later.
Plant got completely abandoned and I got to help subsidize this failure.
China: "Nearly every Chinese nuclear project that has entered service since 2010 has achieved construction in 7 years or less." [1] Building over 40 reactors since 2005
[1] https://thebreakthrough.org/issues/energy/chinas-impressive-...
Even china, a nuclear construction scale/cost/time success story, can’t make them compete with renewables.
What matters is “share of the grid when solar literally cannot provide the power at any price”.
In a well designed and functional grid share of nuclear power should be close to 100% of the latter and the lowest percentage of the former you can get away with.
It’s better to think of nuclear as energy storage with a really really long lasting battery that costs the same to run it 24/7 or 1 hour a month.
Ideally it would be replacing close to all baseload/reliable power on the grid outside of hydro - with hydro being your peakers instead of natural gas for topologies amenable to it. The power share graph should look like nuclear at close to 100% at night less wind and battery storage that backs wind unreliability - and that graph remaining flat throughout the peak daytime hours with other energy sources kicking in such as solar, hydro, duck curve sized battery arrays, etc.
Solar is so cheap it will push nukes off the grid during the day, you don’t get credit just because it’s more reliable. People will just build more and more solar till the nukes share in the day is zero. And at night people are incentivized to build more wind and batteries, because you can still undercut the expensive nuke power and push it off. When the wind doesn’t blow at night there’s gas and hydro peakers. And more and more batteries. There’s increasingly no room left for nukes that have to be sold at 100% for 100% of the time to still be the most expensive form of energy.
The only way nukes have a role at scale today is if you have state intervention in the market to force the grid to buy your nuke power at close to 100% at the baseline share you described, because you have a nation-state goal of reliability that you prioritize higher than cost. Essentially subsidizing the nukes. And I’m sympathetic to that goal, but that’s not mostly not what western markets do, and not what they will do. Making power deliberately more expensive is unpopular, and not neoliberal marketism
You mean the obsolete design that is not used even in old reactors, not to say of modern designs?
Quote:
--- start quote ---
The minimum requirements for the manoeuvrability capabilities of modern reactors are defined by the utilities requirements that are based on the requirements of the grid operators. For example, according to the current version of the European Utilities Requirements (EUR) the NPP must at least be capable of daily load cycling operation between 50% and 100 % of its rated power Pr, with a rate of change of electric output of 3-5% of Pr per minute.
--- end quote ---
> The situation is going to look drastically different for a renewables-first grid, where additional sources are needed for at most a few hours a day, for a few months per year.
Ah, to live in these mythical times...
Nuclear plants provide base load and they are extremely fast at ramping up/lowering production. All modern nuclear plants are capable of changing power output at 3-5% of nameplate capacity per minute: https://www.oecd-nea.org/upload/docs/application/pdf/2021-12...
You don't shut down power plants. None of the power plants ever do a "fast cold start"
> The end result now is that electricity in Europe is the most expensive on the World, so all manufacturing is moved to Asia
The production moved to Asia due to extremely cheap labor, not due to electricity costs.