[danielrpa]

We don't have proven "far cheaper" alternatives. It is irresponsible to advocate for a fully solar/wind grid if we don't have a single working large scale example that is able to sustain, let's say, a city with 5M people 24/7, all-season (examples including hydro and geothermal don't count as many places can't depend on these).

Don't get me wrong, I love solar and wind and I highly encourage continued investment and buildup so we need less of other forms of energy. However, ignoring nuclear is the same, in practice, as supporting a hybrid fossil/renewables future. If you are fine betting on technological developments such as megascale batteries or other energy storage approaches, you should also be fine betting on the less impressive, incremental improvements needed for reducing nuclear plant costs.

The future will involve many different energy sources, and nuclear fission has to be one of them until we discover a new major energy source (hopefully fusion).

[Gwypaas]

We do not have a working economic nuclear grid. So it is irresponsible to advocate a nuclear grid unless throwing hundreds of billions of taxpayer money at Bechtel and friends is your goal.

[godelski]

Most people right now are just trying to prevent nuclear reactors from being shut down. Despite being 30% of US energy it is 50% of our zero carbon energy. The west coast has done a good job decarbonizing without nuclear, and those numbers are more 10%/20%. Shutting down Diablo Canyon won't do much as the reactor provides <8% of Cal-ISO's energy portfolio (but <1% of emissions) and the change to gas has already been made but if you look at places like TVA (South) it is more 60%/80% (with hydro storage accounting for 80% of the green emissions). Mid-ITSO hasn't replaced their nuclear with renewables, nor has many other places.

Even if you don't believe nuclear is the way to go (which is fine) there is no doubt that when the plants have been decommissioned they have been replaced with fossil fuels. This is wild to the nuclear people. But it is why many (pro and anti-nuclear) people have started to advocate for a "fossil fuel first, nuclear second" strategy. After all, aren't we after carbon emissions? If that's our goal, then the conversation is just if we should build more or if renewables are enough. That's mundane, nuanced, and nit-picky. In this case the two groups shouldn't fight. They should form a coalition, at least for now, and be united against the fossil fuel industry (maybe there's a reason they fund Sierra Nevada). But if we're after cheaper electricity and don't care about carbon, then yeah I do think it makes sense to go after nuclear now and prioritize it. We just need to be clear on what our objectives are. Maybe we forget our actual goals because there's nothing "to do" when we agree and only when we disagree. But we shouldn't ignore our similarities. I for one am more concerned with the climate than a few dollars a year on my electric bill, as I know I pay far more than that for the carbon contamination.

[Gwypaas]

I have never argued to close existing plants as long as they are safe and economical? Nice strawman you are arguing.

Simply take Germany, replaced both nuclear and black coal with renewables. That is what quite small subsidies managed on a greenfield market. In my perfect world Germany would have kept their nuclear and phased out the rest of the coal first.

Today the renewable market is mature and in the exponential scaling phase.

New build nuclear had its chance in 2005, in 2023 it is a laughable prospect.

Or simply have a read:

https://www.energyintel.com/00000180-f7a8-d67b-a3cd-f7faad65...

[pfdietz]

It's worse than that. We don't have commercial reactors capable of powering the world. Thermal burner reactors like this one, if scaled up to provide the world's 18 TW of primary energy consumption, would exhaust economical uranium resources in less than a decade.

[godelski]

> would exhaust economical uranium resources in less than a decade.

This doesn't seem right. Can you show your work? I'm assuming there's no recycling either? I feel like you're off by more than an order of magnitude.

Besides, who suggests using a single method to produce all the electricity? That seems a bit naive, doesn't it? Better to have a portfolio.

[pfdietz]

Recycling of spent thermal reactor fuel doesn't extend things much, since the breeding ratio of today's thermal reactors is much less than 1. CANDU might do a bit better.

The point is that existing nuclear reactors provide only a small fraction of world energy demand. A nuclear powered world has to power everything via nuclear energy, including transportation and industry. To ballpark this, we look at the primary (thermal) energy used by the world, 18 TW, and equate that to thermal energy produced by nuclear (3 GW(th) for a 1 GW(e) power plant.) This would be 6000 1 GW(e) power plants. These would use in excess of 1 million tonnes of natural uranium per year.

[godelski]

I'm asking for the math or a source, because I'm not able to verify your claim and it doesn't match my prior understanding. Especially the recycling comment, as utilization is quite low, allowing for massive amounts of reenrichment. It also doesn't match my understanding of the AP1000 which has a similar uranium consumption rate to CANDU 6. Not burnup, uranium consumption. The thermal energy estimate also seems naive and a bit obtuse as you're also including many things that one typically would not account for when discussing energy production. And again, it also seems naive to pigeon hole the entire world's energy consumption onto a single energy source, as if we did something similar for solar, hydro, oil, etc we'd find massively unsustainable numbers as well.

I want straight numbers and links, because something isn't adding up.

[pfdietz]

Well, let's pull up a first results from googling:

https://www.scientificamerican.com/article/how-long-will-glo...

5.5 million tonne resource, 70,000 tonne/year consumption in current reactors

If you object to the thermal energy estimate I encourage you to do better. You might also take into account that energy demand will naturally increase as the lesser developed world continues its rapid growth (much faster in percentage terms per year than in the West.)

[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.

[tpm]

> nuclear fission has to be one of them

Unless for example green hydrogen manufacture, storage, and peaker plants are shown to be cheaper. Let's see in 10 years.

[_aavaa_]

That would have to almost be a literal miracle given the round trip thermodynamic efficiency limit.

[pfdietz]

Not really. For long term storage, the cost of a unit of energy storage capacity becomes more important than the round trip efficiency. This is all the more the case when the cost of the input energy declines.

For seasonal storage, hydrogen is vastly better than batteries, even with a RTE of 40%. That's because the cost of an underground hydrogen storage cavern can be as little as $1 per kWh of storage capacity.

[_aavaa_]

But the units of energy you need to store are directly related to your efficiency.

[pfdietz]

Efficiency of the discharge part, yes. But that's a less than factor of 2 effect that can't overcome the two orders of magnitude superiority over batteries in cost per unit of storage capacity.

[_aavaa_]

Compared to batteries maybe, but that’s not the only alternative, and isn’t even the main alternative for long term storage.

Hydro being the simplest long term alternative.

Even if we stay with batteries, they’re price is continuing to trend down. That two order of magnitude you quote is only going to get smaller. What can’t be overcome is again the thermodynamic limit.

[tpm]

I don't see how is that relevant. When for example PV energy is abundant and cheap enough to power green hydrogen manufacture, then it's a game of scale, not thermodynamical efficiency.

[_aavaa_]

We should be so lucky as to have so much excess energy to throw away freely of green hydrogen.

But that future is nowhere in sight.

For starters we currently have 90 million tones of H2 that is made from fossil fuels. We should focus on making that green before we consider NEW use cases for it.

As for what to do with the excess energy:

1. Store it in hydro 2. Make water.

#2 is real informative. To make 1 kg of H2 you need ~9kg of pure water (let’s call it 10 for simplicity) and 50-65kWh of electricity. To make those 10 kg of water by desalinating seawater you need 0.035 kWh.

So instead of creating 1 kg of hydrogen, we could create 13,800-18,000 kg of pure water.

Given all the water problems we’re having, that might be a smarter use of that energy.

[tpm]

Every time the spot price goes to 0 or less we are throwing energy away. This is already happening. Every time we could be instead generating hydrogen, or desalinating water, whatever we are not doing right now. But with the ensuing enormouos rise in PV and wind this will get much much worse. Eventually something will use that energy. Why not generate supply for the time when sun is not shining? I don't really care if it's hydrogen, ammonia (easier to store) or pumped hydro (probably best, but not enough capacity possible) or something else.

Also not every country has access to sea and while here in EU the energy markets are interconnected, it's not perfect. And some countries have enough water, no need to desalinate.

[_aavaa_]

The difference is that energy prices don’t go below 0 for solar. They go below zero for coal, gas, and nuclear since you can’t shut the plants down on a whim. But you can with solar. You aren’t throwing energy away by turn off panels or stopping turbines, the wind blows and the sun shines for free, whether or not we capture it. The concept that energy price can go negative only comes into the picture because of things like gas, coal, and nuclear where we have to active produce heat to turn into electricity.

As for ammonia being easy to store. Yes, but only compared to hydrogen. But now you have a highly toxic gas. And, creating ammonia from hydrogen is another extremely energy intensive process.