[DennisP]

It's clear that right now we should roll out wind and solar as fast as we can.

However, once those reach high penetration, costs increase rapidly as you attempt to reach 100% clean energy. At that point it helps a lot to have clean dispatchable power. Nuclear plants we start today can fill that role, in areas without available hydro.

https://www.sciencedirect.com/science/article/pii/S254243511...

[est31]

Nuclear power isn't very "dispatchable", it takes long times to be turned on vs off. But it might be useful for seasonal use in the winter when there is less sun.

[klyrs]

https://www.usnc.com/

This is one of the most compelling nuclear plans I've seen. From the sound of it, these would be fine for intermittent power supply

Building a single one wouldn't be cheap, but the modular / standard design can benefit from economy of scale

[pfdietz]

No. Unless you run your nuclear power plant at high capacity factor, the cost of power from it inflates unacceptably. It's an economic issue, not a technical issue.

[piva00]

That's the whole point of nuclear, hydro or coal though, they need to be run at high capacity to be economically viable, have long spin up and down times and are costly to maintain. You use them as the basis of the grid and use wind and solar that are more prone to fluctuations to fill up the demand when necessary, less batteries needed as the base load can always be delivered by nuclear/hydro. Coal is basically dead in the next decade or so.

[dTal]

>use them as the basis of the grid and use wind and solar that are more prone to fluctuations to fill up the demand when necessary

Er, how does this work? You can't control when wind and solar produce power, so how can you use them to "fill up the demand when necessary"? If anything, using a fluctuating source on top of already fluctuating demand just increases the amount of power storage you need.

A power source that ramps up and down quickly is more convenient than one that ramps up and down slowly, but both are miles more convenient than one which ramps up and down uncontrollably.

[DennisP]

At least with solar you know when it won't produce power. You could have enough nuclear for nighttime demand, and build enough solar for the extra daytime demand. You'd have some remaining discrepancies to make up but relatively small ones.

[est31]

Well then you should ask yourself: is building this nuclear reactor cheaper than buying some batteries or converting excess energy to LNG to store it for later? If it is, then a nuclear power plant is economical, if it isn't, you should do the alternatives instead.

[dTal]

Well hang on, the nuclear reactor generates power while the storage only.. stores. You have to include the (lifetime!) cost of the storage plus the presumably renewable energy source you're feeding it with. (Of course you need storage with both systems to cope with demand-side fluctuations, but you'll need a lot more with wind/solar to deal with supply-side fluctuations.)

[pfdietz]

Hydrogen underground, not LNG, but yeah.

For some simulations to help answer when those two options are best:

https://model.energy/

[labawi]

The model doesn't support methane generation.

Hydrogen is cool, but we should also be investing in efficient methane production. AFAICT it's not too hard to make and has immense advantages - existing transport, storage and use infrastructure and market as a heavily traded good. We can use it for most of our energy or carbon needs with today's technology and existing machines with no or easy modifications.

Hydrogen can be more efficient and probably simpler when appropriate but is more finicky, still needs research and will take a lot of time to ramp up.

[pfdietz]

Sorry, the two options were nuclear vs. renewables + storage (batteries and hydrogen). I don't think very large methane storage makes much sense; where does the carbon come from?

[DennisP]

Perhaps that wasn't the best term for the point they're making. From the abstract:

"This paper presents a comprehensive techno-economic evaluation of two pathways: one reliant on wind, solar, and batteries, and another also including firm low-carbon options (nuclear, bioenergy, and natural gas with carbon capture and sequestration). Across all cases, the least-cost strategy to decarbonize electricity includes one or more firm low-carbon resources. Without these resources, electricity costs rise rapidly as CO2 limits approach zero. Batteries and demand flexibility do not substitute for firm resources."

[Manfredo_1]

A nuclear plant costs the same to run at full capacity all year round as it does to run it at partial capacity. Just run the plant at full capacity all year round, and save money by building less solar.

[DiogenesKynikos]

You have to pay off the initial construction costs. Throwing away half the energy you generate means that you're wasting the large up-front costs.

[Manfredo_1]

Right. If we build nuclear plants to fulfill peak energy demand (which coincides with a lack of energy production from solar) then there's not reason not to just run the nuclear plants 24/7 and skip building solar altogether. This is why nuclear power and intermittent sources end up being a dichotomy in practice.

Solar does provide a good way to mitigate carbon emissions in the meantime, even if it's role in a fully decarbonized economy is dubious. It's fast to build and makes a good complement for gas plants. Turn off the gas when the solar cells are collecting, and you can save a good deal of emissions.

Solar also has niche use cases that make sense even with nuclear power. Rooftop solar is a good way to offset air conditioning energy use. In this case, the solar energy collected by the panels are intrinsically connected to the power demand of the air conditioning unit. Plus the energy production and energy demand are co-located.

[DiogenesKynikos]

You're missing the point, which is that if you don't use a nuclear plant to 100% capacity (or run at 100% capacity and throw away most of the energy), you end up paying more for every Joule you actually use.

How much would it cost to build nuclear power generation capacity to meet peak demand, vs. building a grid with renewables, long-term transmission and storage? The levelized cost of solar and wind power is way below that of nuclear power (and that difference will become much larger if you're only fully utilizing nuclear power during the daily peak demand), so the question is how much storage and transmission add for renewables.

[AnthonyMouse]

One of the interesting possibilities for new nuclear plants is on-site thermal storage. Store heat from the reactor in a heat sink when solar is generating, use the heat to generate power when it isn't. That handles the daily load variation and lets you trade half the required nuclear capacity for cheap solar.

It also means you have more turbines on site than the reactor needs on its own, so you can add a furnace burning whatever you like (hydrogen, biofuels, synthetic methane), and that handles the days when renewable output is below average.

[dTal]

+1 I wish this were further up. Reliable power is always better than unreliable power. "Base load" is a misleading concept because people conflate supply-side and demand-side fluctuations, which are generally unrelated except in "niche use cases" like you mention. You always need some sort of storage or on-demand generation to deal with demand fluctuations. With wind/solar, you need extra storage to smooth out supply fluctuations.

[dTal]

It's strictly better than wind and solar, which take an indeterminate and totally uncontrollable amount of time to turn on and off.

[pfdietz]

Nuclear would be utterly terrible for filling in the last part of a renewable-dominated grid. As in, ludicrously expensive, compared to other non-nuclear, non-fossil alternatives.

The article you point to talks about "firm, low carbon sources". This kind of source for this last bit would be something like hydrogen, not nuclear. A nuclear reactor operating at 10% capacity factor to "fill in" for renewables would be producing power at $1/kWh or more, which is uncompetitive vs. hydrogen by a massive margin.

[dTal]

You can invert this and say that solar/wind would be utterly terrible at "filling in the last part" of a nuclear-dominated grid.

The inability to generate constant, reliable power is a weakness, not a strength.

[pfdietz]

Right. It's one or the other generally (although some solar could help nuclear if demand peaks on sunny days).

However, unless nuclear gets a lot cheaper, it's looking like the nuclear dominated grid is going to be more expensive than the renewable dominated grid, even taking the cost of intermittency into account.

[DennisP]

They specifically cited nuclear. I don't think operating it at 10% capacity factor is what they mean.

[pfdietz]

They very carefully didn't mention hydrogen at all. They compared nuclear vs. renewables + batteries. It's almost as if they were setting up renewables to fail. Imagine that, in a study where half the authors are from the Department of Nuclear Science and Engineering.

Yes, if you had nuclear, you'd operate it at high capacity factor. That isn't nuclear filling in for renewables, that's using nuclear instead of renewables. It's really mostly one or the other.

[sampo]

> costs increase rapidly as you attempt to reach 100% clean energy.

France has been running at 75%-80% nuclear for 30 years.

[selectodude]

Heck, the State of Illinois gets over 50 percent of its electricity from nuclear and 1/8th of the entire country's nuclear generation. We can do it, even in the USA.