[AnthonyMouse]

> If you think that renewables have an inherent need for expensive storage then you're holding them to a higher standard than nuclear. This is both inaccurate and ahistorical given all the pumped hydro built specifically to complement nuclear.

It's a different kind of storage. Nuclear generates the same amount of electricity all the time but then there is higher demand during certain parts of the day. You then make up the difference between the baseload and the peak with a different kind of power plant. Typically nuclear is not used with storage at all, it's instead used for baseload with the peaks handled by other types of primary generation, traditionally natural gas or non-pumped hydro that dams a river.

Renewables have entirely variable output, so you need alternative generation with enough capacity to supply the whole grid at any given time, and enough storage to be able to do this for a week or more in the event that renewable generation is low for an extended period of time.

It's the difference between building a grid which is half nuclear and half something else vs. fully duplicating the whole capacity of the grid.

[ZeroGravitas]

I thought I'd neatly encapsulated this with the "baseload and peaking to renewables and firming" slogan but since it appears we need greater depth:

Typically nuclear/renewables is not used with storage at all, it's instead used for baseload/cheap-n-clean-load with the peaks/firming handled by other types of primary generation, traditionally natural gas or non-pumped hydro that dams a river.

Nuclear can trip out in seconds or be put offline by fault investigations or fuel reloading, so you need alternative generation with enough capacity to supply the whole grid at any given time, and enough storage and or firming to be able to do this for a week or more in the event that nuclear generation is low for an extended period of time (like France the other year).

[AnthonyMouse]

> Typically nuclear/renewables is not used with storage at all, it's instead used for baseload/cheap-n-clean-load with the peaks/firming handled by other types of primary generation, traditionally natural gas or non-pumped hydro that dams a river.

But we're trying to get rid of fossil fuels. If you have enough primary generation from hydro dams or something else that doesn't emit carbon to reliably handle the whole grid then that would be the entire solution by itself. There aren't enough suitable hydro sites to handle the whole grid, which means only needing half as many (or only needing enough storage to make up the difference against half as many) is quite an advantage.

> Nuclear can trip out in seconds or be put offline by fault investigations or fuel reloading, so you need alternative generation with enough capacity to supply the whole grid at any given time, and enough storage and or firming to be able to do this for a week or more in the event that nuclear generation is low for an extended period of time (like France the other year).

You're talking about an individual nuclear plant rather than the whole grid. One plant out of dozens or hundreds being temporarily offline is not a big deal, and refueling in particular is easy because it can be scheduled for seasons when power demand is lower.

The issue with renewables is that it can be night or cloudy or still across thousands of square miles at once, and then low generation periods correlate across the whole grid instead of being isolated to an individual plant, and happen randomly based on weather rather than having any ability to be scheduled.

[ben_w]

> The issue with renewables is that it can be night or cloudy or still across thousands of square miles at once

If it was only thousands of square miles, it wouldn't be a problem at all.

Whole of the UK is about 100,000 square miles, not sure how much more if you also include the offshore areas suitable for wind.

Texas is about 270,000 square miles with the same caveat, and (I think) less interconnect capacity to other networks than the UK.

> and happen randomly based on weather

Wasn't that literally the cause of the French reactors having problems? The national weather causing a correlated output reduction in many reactors at the same time?

[AnthonyMouse]

> If it was only thousands of square miles, it wouldn't be a problem at all.

> Whole of the UK is about 100,000 square miles, not sure how much more if you also include the offshore areas suitable for wind.

> Texas is about 270,000 square miles with the same caveat

It isn't "only" thousands of square miles, weather events commonly span areas the size of what you're talking about. It's obviously going to be night across the whole region at once. It's occasionally calm across the whole continental United States. Not often, but it happens.

> Wasn't that literally the cause of the French reactors having problems? The national weather causing a correlated output reduction in many reactors at the same time?

It was a confluence of factors, one of which was French law that prohibited power plants from putting coolant water higher than a certain temperature back into the river. When the river flow is low and the intake temperature is high, meeting the regulatory requirement necessitated reducing heat generation, i.e. power output. The same is true for any thermal power plant (e.g. coal or natural gas). This happened following a period of anti-nuclear sentiment that resulted in labor shortages in the industry, causing other reactors to concurrently be offline for maintenance for an unusually long period of time. Obviously you can make any generation system unreliable through mismanagement/government opposition.

The coolant temperature limit is a design issue. There are known designs that avoid it, e.g. situate the plant on a larger river or body of water that would provide enough cooling water even on the hottest of days, or use cooling towers instead of river water.

Conversely, it's not obvious how you design a wind turbine that can provide power when there's no wind.

[ben_w]

> The coolant temperature limit is a design issue. There are known designs that avoid it, e.g. situate the plant on a larger river or body of water that would provide enough cooling water even on the hottest of days, or use cooling towers instead of river water.

> Conversely, it's not obvious how you design a wind turbine that can provide power when there's no wind.

Sure it is, and you've pretty much said the solution yourself on a previous comment with a different context:

> You're talking about an individual nuclear plant rather than the whole grid.

Just as all the reactors can have a correlated failure for whatever reason, so too can all the wind. But wind and nuclear aren't the only systems.

I'm not going to investigate if the wind really does go to zero on both sides of the Rockies — though that does seem unlikely, I'm willing to just agree it does for the argument.

Dunkelflaute — lack of both wind and solar — normally only last 24 hours even in the much smaller Germany. Of course you have to size your systems to cope with the once-every-generation events: how long this is is a matter of observation, and I can't be bothered to download and process the satellite data to find that out for the USA for this comment (but it's not hard, that was part of my first proper job about 20 years ago for unrelated research about squid). Also, while high-altitude winds are not normally affected in the same way as surface winds, and flying turbines have been demonstrated to take advantage of this, e.g. https://en.wikipedia.org/wiki/KiteGen I'm just going to ignore them here.

The USA's current average (annual) electrical draw is 455.3 gigawatts, while the installed hydro capacity has a nameplate capacity of 102.8 GW with another 12 GW known. How long could they provide this, I do not know, but these things do already exist, and that's already a quarter of your instantaneous needs all by themselves.

Batteries exist, and are getting very cheap: while production is currently limited, the supply needed for the electrification of cars is by itself enough to get over any Dunkelflaute — the total need per year only requires an average household to cycle a car-sized battery 1-3 times. And that's without any support from hydro.

And the maximum size for a grid isn't a country: the USA, despite Texas being awkward, already has some interconnects to Canada and Mexico. While I'm not suggesting it's likely or coming any time soon, China has been massively expanding in many areas including the production of aluminium, and they now produce enough by themselves to build every three years a complete global power grid with one ohm resistance. They've already suggested connecting themselves to South America — if they do or don't is more a political decision about soft power projection rather than anything else, same as the Belt and Road initiative.

And that would work without any support from hydro or batteries, and would still work just fine even if you only went one of wind and PV rather than diversifying.

[belorn]

Looking at this from a historical perspective, Nuclear with other types of primary generation did not generate a highly variable grid. Its a recent phenomena in Europe that has caused spot prices jumps from negative to 2$ per kWh, which the primary blame being put in volatile energy production.

If we are claiming that nuclear is similar to renewables, we should expect regions where nuclear is being decommissioned to have an increase in renewables with no increase in natural gas consumption. This is however not the case. This has been demonstrated by the decommissions of nuclear plants in Germany and Sweden, with fossil fuel emissions being increased as a direct results. To take Sweden as an in-depth example, after the decommission of their south based nuclear power plant the two major natural gas plants in the region went from operating a few times a year to running almost 24/7, only shutting down briefly during optimal weather conditions. They are now the highest source of pollution in that region, and more natural gas plants are being planned for construction. As a result the government funding for the "reserve energy" has increased significantly (ie, fossil fuel subsidies).

[ZeroGravitas]

Germany's gas generation has indeed been flat while nuclear and coal is being phased out, so I guess you've very strongly proved my point.

https://ourworldindata.org/grapher/electricity-prod-source-s...

I'm also not seeing your claimed Swedish impact in the data:

https://ourworldindata.org/grapher/electricity-prod-source-s...

Also worth bearing in mind that support payments generally are used to keep fossil plants open because they no longer burn enough fossil fuels to earn a profit from energy sales. It's an insurance policy which needn't ever burn any fuel to be worthwhile.

[AnthonyMouse]

> Germany's gas generation has indeed been flat while nuclear and coal is being phased out, so I guess you've very strongly proved my point.

That graph shows domestic generation falling by more than 100TWh and being replaced by "nothing" -- which is to say nothing shown on that graph, because now instead of generating and exporting electricity they're importing it:

https://ourworldindata.org/grapher/net-electricity-imports?t...

Primarily from France, which is using nuclear, hydro and natural gas (in that order).

[ZeroGravitas]

The net import in 2023 was only 10TWh so you've over explained this by x10, so something else must be going on than just importing nuclear from France (which is roughly 8TWh that year)

France is the biggest single source of imports but not the majority of imports since Germany imports from a range of countries and the energy mix of imports is roughly:

> the shares of RE, nuclear, and fossils in Germany net imports were 59%, 33%, and 8%, respectively.

https://www.renewable-ei.org/en/activities/column/REupdate/2...

Nice graph: https://www.renewable-ei.org/realfiles/pdfimage/1721291204_6...

And this makes sense as imports work on the merit order effect, with the cheapest going first. Why buy fossil electricity from one neighbour if another has cheap wind available.

[AnthonyMouse]

> The net import in 2023 was only 10TWh so you've over explained this by x10, so something else must be going on than just importing nuclear from France (which is roughly 8TWh that year)

They were previously exporting 90TWh.

> the shares of RE, nuclear, and fossils in Germany net imports were 59%, 33%, and 8%, respectively.

That's still a pretty big proportion of nuclear and fossil fuels, and it's not clear that the way they're calculating that actually works. Imports are going to be needed at times of high demand or low renewable output, when baseload capacity is being consumed for domestic use by the exporting country and incremental power for export has to come disproportionately from peaker plants, i.e. fossil fuels (or lower curtailment by nuclear in France).

Moreover, they're counting hydro under renewable, e.g. Norway is "99% renewable" but is in fact 88% hydro.

[ViewTrick1002]

In California the lowest yearly demand is ~13 GW. The yearly peak is ~48 GW.

Assume that 3 reactors at a time are in revision during the spring and autumn. This means the "base demand" is 16 GW.

I don't see a material difference in handling 32 GW or 48 GW of dispatchable power generation, assuming the lowest possible renewable generation is zero for the renewable side (which is not the case.)

The other option would be having more nuclear plants and turning them off for large parts of the year. That is incredibly expensive.

All this entails forcing the customers to pay for more expensive nuclear energy rather than utilize cheaper energy when it is available.

In reality the more expensive nuclear power plants are turned off.

https://markets.businessinsider.com/news/commodities/energy-...

[AnthonyMouse]

You're using the instantaneous numbers, which matters for the peak (because if you hit 48 GW for just one hour you still have to meet the demand) but not the trough (because having overcapacity for a negligible number of hours a year is fine). The real base demand number for California is ~24 GW:

https://www.eia.gov/todayinenergy/detail.php?id=42915

Which is a pretty sizable fraction of 48 (not that 16 wasn't).

> The other option would be having more nuclear plants and turning them off for large parts of the year.

Nobody is going to do this. It doesn't make sense to build entirely nuclear plants. It does make sense to build some more than we have now.

[ViewTrick1002]

That is the average base demand over a year. Meaning for about half the year it will be less and you have to shut down parts of the nuclear fleet.

Either way, solving a 24 GW or 35 GW on top of ~20 GW something base is about as easy. Nuclear simply does not fit modern grids.

> Nobody is going to do this. It doesn't make sense to build entirely nuclear plants. It does make sense to build some more than we have now.

Exactly. Which is why nuclear power does not fit modern grids, because they will be required to shut down. As is seen time and time again in Europe when no one wants their expensive energy.

[AnthonyMouse]

> That is the average base demand over a year.

Then it's not clear where you came up with 13 GW, which is inconsistent with the ~24 GW from the Department of Energy.

> Either way, solving a 24 GW or 35 GW on top of ~20 GW something base is about as easy.

Needing 48GW instead of 24GW would literally double the cost, on top of doubling the cost of renewable generation since you'd need an average of 48GW of that instead of 24 to avoid regular use of a backup system which is presumably fossil fuels. That is not a small difference.

> Which is why nuclear power does not fit modern grids, because they will be required to shut down.

There is no point at which they shut down. They provide baseload. You get 24 GW from nuclear, which is the minimum load on the grid. If you also get something from renewables at this time, that's when you charge your batteries for later. This won't get you a week but allows you to do peak shaving. If the load is 48GW and you get 24GW from nuclear and 24GW from renewables, everything is fine. If the load is 48GW and you get 24GW from nuclear and anything less from renewables, now you discharge the batteries.

And then you only need 24 GW of peaker plants in the event that the batteries are dead and current load exceeds current generation.