[danielrpa]

I hope you are not referring to my comment, as I'm not advocating a fully nuclear grid. Instead, I'm advocating nuclear as the replacement for the energy needs that are beyond the reach of renewables in many places - for instance, nighttime consumption in areas without hydro potential.

For those against nuclear, feel free to give an example of a working large scale (supporting 5M+ people 24/7, all seasons) solar/wind deployment in continental Europe with zero dependence on fossil or nuclear.

[pfdietz]

Nuclear is just horrible for filling in the gaps when renewables aren't available. Nuclear needs to run near continuously to even approach (if not reach) being economic. As a fill-in source, the cost will inflate massively, to the point that (for example) combined cycle plants burning green hydrogen would be far cheaper.

[Gwypaas]

I think you have a fundamental misunderstanding how power grids work. They are generally not monopolistic markets anymore.

The problem is that renewables and nuclear are economically incompatible. They compete for the slice that is the cheapest and most inflexible, both requiring dispatchable power to fill the gaps. Renewables easily win this battle as the cost for new built renewables are in the same range as operations and maintenance for paid off nuclear plants.

For nuclear this inflexibility comes from pure economics. It is economic suicide to build a new plant and operate it at 100%, now try operating it at less than 50% on average. Or even worse only nights without wind like you propose.

There are no fully renewable grids yet, 70% is trivially possible as it us already in use, but we see no issues building them.

https://ieeexplore.ieee.org/document/9837910

[ephbit]

> For nuclear this inflexibility comes from pure economics. It is economic suicide to build a new plant and operate it at 100%, now try operating it at less than 50% on average. Or even worse only nights without wind like you propose.

Agree, this mode of operating NPPs wouldn't be economically feasible.

Also, IIRC, running a NPP with load following would generally lead to significantly more wear and tear and thus maintenance costs. Which is why it wouldn't be done this way.

So why not run the NPP as baseload (say instead of coal powerplants) and then renewables like wind/solar (on top of that flat line of generation), which can easily be turned off/on according to current demand? Whenever high renewables generation coincides with a peak in demand, it's a win. Whenever renewable generation diverges from demand it's either turned off or as much of it as possible is stored. Having storage capacity for electricity, to compensate just the day/night demand fluctuation during a 24h day with stored renewable energy is far more easily done than trying to get to 100 % renewable generation. Especially since solar generation is ~ 1/20 in winter vs summer in some regions.

Seems like the obvious way to do it (to me at least), unless one is completely against nuclear power generation.

This mode would obviously make it somewhat more economically challenging for the renewable operators, since their capacity factors would be reduced.

It all comes down to the fundamental challenge that renewables introduce additional fluctuation which has to be compensated somehow. Ways to do this are: throwing away excess generation, following load via flexible demand, modulating fossil plants, adding more storage capacity.

The thing is: storage capacity for seasonal fluctuation which is going to significantly increase (due to heating and other processes becoming more electrified) is nowhere near. Even storage capacity for just 2 weeks of electricity is huge.

Let's say Germany quadruples it's 2022 wind generation capacity, then in the three Dunkelflaute weeks 48-50 of 2022 [1] (when they had ~ 22 % renewable share, mostly wind) there'd now be 100 % renewables. But in the meantime demand in winter might well go up 20-30 GW due to electrification of heating and other uses. Now there's still a gap between demand and renewable generation of say 30 GW that needs to be filled. Let's say the Dunkelflaute lasts not three weeks but 10 days.

30 GW x 10 days = 7.2 x 10^9 kWh

That's the equivalent of ~ 103,000,000 EV batteries with 70 kWh each. And each one of them would need to be 100 % charged before the 10 days Dunkelflaute and it couldn't be used for anything else during the 10 days and it'd be empty afterwards.

This amount of storiage isn't going to happen in the next 15 years.

I assume the actual way situations like this will be dealt with in Germany is: high electricity demand industries will be shut down during such times, home heating will be turned down, coal fired plants will be brought back online, less trains will run, and so on.

So it'd maybe look like a "80 % renewable grid". But in reality it could better be described as "electricity demand reduced to match renewable generation".

[1] https://energy-charts.info/charts/renewable_share/chart.htm?...

[Gwypaas]

Power grids operate like marginal cost markets. Why would I as a consumer buy more expensive nuclear power when abundant renewables are available?

That is why the comment started with, (knowing you are not the same person as GP):

> I think you have a fundamental misunderstanding how power grids work. They are generally not monopolistic markets anymore.

In a monopolistic market what you propose is how it worked. The government/utility decided what power generation it wanted and the customers paid the resulting electricity rates without any choice.

Given the possibility of cheap distributed generation today what will happen if you force nuclear costs on consumers is that they will build local renewable generation and lower their grid utilization. Like we see with rooftop solar, just on a much grander scale.

The end result is again a marginal price market, but now with added inefficiencies.

[ephbit]

> Power grids operate like marginal cost markets. Why would I as a consumer buy more expensive nuclear power when abundant renewables are available?

I think this is an incomplete description of the system.

The missing element here is the fact that independently of what an individual electricity customer (private/commercial/..) chooses to do, the government/burocracy still ultimately mandates for grid operators, utilities and power companies to operate their technology in such a way that the grid can remain stable and deliver enough electricity to power (practically) all uses, whatever they might be at a certain point in time, even when renewable generation is at only say 15 % of max capacity.

This makes companies build/maintain (and get paid for) backup powerplants. They're needed and maintained for stability reasons, (pretty much) regardless of their cost of electricity generation per kWh. The market price is not really relevant, since grid stability is hugely more important to everyone (individual persons, businesses, political parties) than spot market price.

> Given the possibility of cheap distributed generation today what will happen if you force nuclear costs on consumers is that they will build local renewable generation and lower their grid utilization.

Applauding cheap distributed generation of fluctuating renewables (note: I'm in favour of their deployment) without mentioning that there are times when they simply don't deliver, so that other (flexible, reliable) sources have to fill in paints an incomplete picture. Without the fossil/nuclear backup plants the spot price would skyrocket to a degree such that everyone in posession of a smart meter and flexible price contract (and withouts state subsidized electricity) would just stop consuming because a kWh might suddenly cost a few $/€.

The market might be the market. But the grid is a technical system and its stability is a parameter which most prioritize higher than cost/kWh, which is why it's a hidden cost, that's not directly attributable to renewables and so as long as the grid cannot deliver 100 % renewables at _all_ times, "cheap renewable electricity", that's cheaper than fossil/nuclear is a somewhat naive take.

Imagine customers getting to choose between 2 different electricity contracts:

A) 100 % renewable electricity; subject to availability; gets delivered according to current generation; if demand exceeds generation, every customer gets curtailed to a fraction of their actual demand, according to their usual consumption so that demand=generation

B) 24/7 electricity; varying percentage of renewables; some nuclear/gas/coal in the mix

How low would you have to set the price/kWh of A relative to B for getting say even just 1 % of customers? 1/5? 1/10?

Now would any company running such a 100 % renewable fleet and offering A contracts have an easy time running their business with economic success, because "renewable generation is so much cheaper than fossil/nuclear"?

Yes, marginal cost/kWh of nuclear/fossil might be higher than wind/solar. The reason is obvious: they provide stability/reliability for the grid, so until the grid is 100 % renewable, 1 nuclear/fossil kWh is simply more valuable than 1 renewable kWh.

What do people do who "build local renewable generation and lower their grid utilization", when their own generation doesn't meet their demand because it's winter? Right, they draw power from the grid, from some gas/coal/nuclear plant.

[Gwypaas]

> The missing element here is the fact that independently of what an individual electricity customer (private/commercial/..) chooses to do, the government/burocracy still ultimately mandates for grid operators, utilities and power companies to operate their technology in such a way that the grid can remain stable and deliver enough electricity to power (practically) all uses, whatever they might be at a certain point in time, even when renewable generation is at only say 15 % of max capacity.

> This makes companies build/maintain (and get paid for) backup powerplants. They're needed and maintained for stability reasons, (pretty much) regardless of their cost of electricity generation per kWh. The market price is not really relevant, since grid stability is hugely more important to everyone (individual persons, businesses, political parties) than spot market price.

Yes, in for example Sweden these extra costs borne by all consumers for reserves and balancing markets are in the range of $0.0X cents/kWh delivered. You are not financing a nuclear plant with that.

> Applauding cheap distributed generation of fluctuating renewables (note: I'm in favour of their deployment) without mentioning that there are times when they simply don't deliver, so that other (flexible, reliable) sources have to fill in paints an incomplete picture. Without the fossil/nuclear backup plants the spot price would skyrocket to a degree such that everyone in posession of a smart meter and flexible price contract (and withouts state subsidized electricity) would just stop consuming because a kWh might suddenly cost a few $/€.

Why would a consumer that decided to sidestep the grid care? They care about the average price of all their consumed energy, not the fluctuations. Peak shaving is already a market. Although mostly to sidestep infrastructure costs related to upgrading grid size.

> A) 100 % renewable electricity; subject to availability; gets delivered according to current generation; if demand exceeds generation, every customer gets curtailed to a fraction of their actual demand, according to their usual consumption so that demand=generation

> B) 24/7 electricity; varying percentage of renewables; some nuclear/gas/coal in the mix

Consumers choose a mixture of A and B, because the grid is not only renewables. We will likely need gas backup for another decade or so. Perfect is the enemy of good. Your view of the grid is from the 70s, when "baseload" was the god. That is not the case anymore.

Grids are dynamic and driven by price signals. All price fluctuations are business opportunities. With the marginal pricing model we have today, nuclear requires the whole sale average prices over a year to be ~$120-200/MWh, I and everyone except people advocating for nuclear find such prices unacceptable. That is Ukrainian war gas crisis prices locked in until the plant is paid off, who wants that?

Thus the discussion inevitably spirals into "grid costs", "backups" and what else. Because lets through government actions force nuclear to exist to get a better number on your pet metric of "actual price". All while the world moves on.

I think you haven't had a read, it was linked in the comment you replied to but I can give it to you again:

https://ieeexplore.ieee.org/document/9837910

Read and come back, stop thinking we live in the 70s.

[ephbit]

> Yes, in for example Sweden these extra costs borne by all consumers for reserves and balancing markets are in the range of $0.0X cents/kWh delivered. You are not financing a nuclear plant with that.

Whatever the ascribed fee/kWh for financing backup power plants that's written on some electric power bill might be, (whether it's 0.05 $/kWh or 0.20 $/kWh) it's completely irrelevant. If there's a backup plant being maintained and run somewhere in your country (or the neighbouring), the people are somehow paying for it. If the fee on the electricity bill is too low to actually cover all the costs, then it's still payed for by the people, through taxes or other fees or whatever. Doesn't matter at all. The backup plant, be it nuclear or fossil, is being financed. Why is that? Because people don't want rolling blackouts and politicians know that.

> Why would a consumer that decided to sidestep the grid care? They care about the average price of all their consumed energy, not the fluctuations. Peak shaving is already a market. Although mostly to sidestep infrastructure costs related to upgrading grid size.

If by sidestepping the grid you mean an almost/entirely self-sufficient household (all year, not just summer), then we're talking about which percentage of households of the northern hemisphere? Is it 1 % or 0.1 % or 0.01 %? These aren't the people who'd care, true. But the issue is obviously not with them but with the other ~ 99.x %.

My impression is, you're failing to see, just how high spot prices and thus peaks in a flexibly priced contract would jump, if your grid were underpowered by let's say 30 % of actual demand. The only reason you're not seeing such high prices, is because those fossil/nuclear plants are somewhere (either in your country or in some neighbouring) ready to run. Nobody knows just how high the price/kWh would spike, were there a few days with just 70 % of electricity available compared to the usual demand curve (in some country where heating is electricity based). But it would either need to settle damn high, so that only consumers who're willing to pay a lot, still actually consume while enough others are effectively deterred from consuming by the high price so that reduced demand=generation. Either that, or you'll have rolling blackouts or some other intervention to reduce demand, which effectively violates the way that people/businesses in prospering countries are used to operating, i.e. drawing as much power as they see fit, whenever they see fit.

I'm happy to learn about other ways of meeting consumers needs, when dealing with a "significantly less renewable electricity available than urgent demand and regrettably no backup power plants" situation.

I very much doubt people would settle with regularly being in the situation of either (A) being priced out of using electricity or (B) having to turn off their heat pumps or aircon and not use their kitchen stoves during certain hours. No, they'd tell their politicians to (C) bring those fossil/nuclear plants online "chop-chop".

---

> Consumers choose a mixture of A and B, because the grid is not only renewables.

No. Noone is actually choosing or would choose A, not even partially. Or can you name an instance when someone did not do XY (drive their EV, go by train, heat/AC their home, cook some food, ..) which they really wanted to do, because there wasn't enough electricity available in that moment? And no, when someone chooses to charge their EV a little less or accepts a waiting time for their EV to be charged to then make their trip doesn't count, because they were obviously flexible enough. Sure, many industries now closely watch electricity prices and sometimes throttle/halt production. Doesn't count either, when choosing operating times according to electricity prices is part of the business model.

> We will likely need gas backup for another decade or so.

Absolutely. It simply wouldn't work without them, or rather: people will vote whoever would get enough such plants running again, were there any shortage and they wouldn't care about their state spending billions to get it done.

> Your view of the grid is from the 70s, when "baseload" was the god. That is not the case anymore.

Not really, I think. Baseload is not the god, it never was. Stability is, and always was. My view of the grid is about stability and the simple fact, that people just wouldn't accept if the gaps that renewable sources leave (until they're overbuilt 3x .. 4x ..? and there's enough storage) weren't filled in by fossil/nuclear generation.

---

> With the marginal pricing model we have today, nuclear requires the whole sale average prices over a year to be ~$120-200/MWh, I and everyone except people advocating for nuclear find such prices unacceptable. That is Ukrainian war gas crisis prices locked in until the plant is paid off, who wants that?

I doubt we'll see electricity prices fall in the next 10 years.

Looks like in Germany people won't be able to blame it on "nuclear generation clogging the net" then.

> Thus the discussion inevitably spirals into "grid costs", "backups" and what else. Because lets through government actions force nuclear to exist to get a better number on your pet metric of "actual price". All while the world moves on.

As to "world moves on". Well, you wrote it yourself: "We will likely need gas backup for another decade or so."

I think our grids will cling to gas powered plants for quite a bit longer than that.

Interestingly, according to some institute, "researchers found that new gas-fired power plants with an installed capacity of 23 GW must be built by 2030."

https://www.cleanenergywire.org/news/germanys-new-energy-tar...

Newly built gas plants ... I don't think they'll only be run for ten years.

> Read and come back, stop thinking we live in the 70s.

> https://ieeexplore.ieee.org/document/9837910

Thanks for reminding me. Quite a few pages there. Did you read them all?

I like this nicely cushioned quote from the chapter "D. RAW MATERIAL DEMAND FOR 100% RENEWABLE ENERGY SYSTEMS" (p. 78191):

> All in all, there appears to be reason for moderate optimism that material criticalities will not represent an unsurmountable roadblock towards the transition to 100% RE systems. However, it is also clear that it will be a formidable challenge to ensure the timely availability of resources while simultaneously minimizing the negative impacts of extraction on humans and the environment. This needs to be a focus of upcoming research.

Reminds me of all the stubborn renewable optimists who IMO do the world a disservice by neglecting the inevitability of degrowth.