[JohnCClarke]

I suspect that the push for civilian SMRs is a disguised subsidy for the naval reactor programme. This is shortsighted because (1) for electricity renewables are cheaper than nuclear, and (2) large naval vessels are enormously vulnerable to drones.

Ukraine's success against Russia's Black Sea fleet proves this for surface vessels. Similarly, it is easy to imagine a swarm of small underwater drones detecting, tracking and trailing nuclear submarines.

The UK government's is more focussed on providing juicy contracts to large corporations than realistic preparations for the future.

[Closi]

> This is shortsighted because [...] electricity renewables are cheaper than nuclear

This is an oversimplification - Renewables are cheaper than nuclear, but they are also less reliable than nuclear in the sense that when the wind stops blowing, power stops being generated. Also if you include the cost of energy storage to survive a week or two without substantial wind, suddenly it's not the cheaper anymore.

A mixed nuclear + renewables grid would reduce the total cost because nuclear can provide a stable base load which isn't affected by seasonality. Modern plants can also ramp up/down to some extent to balance the overall system.

That's why you need an energy mix rather than just putting all your eggs in a single source.

[adrianN]

Either you build enough nuclear to cover 95% of peak demand and essentially only run it a few weeks a year (because most of the time you have plenty of renewable supply) for terrible ROI or you need storage and peaker plants anyway. Nuclear energy is mostly interesting for cross subsidizing a military nuclear program by keeping relevant skills in domestic supply.

[hdgvhicv]

What good is a “base load” when the problem is peak demand. You’re saying nuclear gets to take the easy stuff and another industry can worry about peaker plants.

I suspect you need far ledd in peaker capacity - both GW and GWh - with a 100% wind than 100% nuclear if you spend the same amount on wind and nuclear.

[Closi]

I'm just going on the fact that most energy experts say a diversified mix is what you usually want - although my lay assumption would be that if you have a portion of your energy need covered by a stable base load, you need less batteries per wind turbine etc and it lowers overall energy risk.

e.g. lets pick two overly-simplified hypothetical scenarios where you can have a 50/50 nuclear/wind mix, or 100% wind mix.

And then lets say in a shortage scenario you can: - Suppress demand / demand shift (say you can reduce/shift demand 10% hypothetically)

- Import energy, up to 20% of your total requirement

In this simple scenario, in a 100% wind scenario, you would need to cover 60% of your energy need with batteries (every 1% of wind needs 0.6% of batteries), but in the 50/50 mix scenario the 50% of wind only needs to cover 10% with batteries (i.e. every 1% of wind needs 0.2% of batteries)

In reality there will be other things, like you might also have burst-gas power etc.

I'm not saying the numbers above are correct - just trying to show in theory that a mix / base load can still help reduce the level of batteries/storage required and make the energy mix more economic.

[Melatonic]

For civilian use I believe this has proven unnecessary (assuming mix of wind, solar, etc) plus battery and other storage

Still seems like a worthwhile pursuit though

[DoctorOetker]

nuclear energy still causes a lot of prompt heating

other forms of renewables could generate electricity while cooling the planet.

a super chimney (perhaps suspended with balloons) piercing the tropopause and carrying either air in open or closed loop fashion, or a "refrigerant" (not necessarily a harmful one, could just be moist air, or any other medium of thermal exchange, like a gravity assisted heat siphon) in a closed loop could generate power while cooling the planet, it would also be base load given the large temperature difference between surface level and tropopause (which persists day and night, summer and winter). Obviously this can also be used to desalinate sea water by freeze desalination.

as soon as such technology takes off and multiple blocs make use of such technology, they will probably even get into arguments about how long or what fraction of the time each nation state is allowed to generate power this way (arguing it was our Western excessive CO2 consumption to which we have to thank this excess heat availability, and India countering that we should take into account their proper share of excess CO2 due to the underground coal mines that have been burning uncontrollably for decades on end, etc...) to the point of nation states attacking each others superchimneys.

[TheOtherHobbes]

If you invest in battery and storage tech you'll get reliable storage long before the first "baseload nukes" start contributing to the grid.

Storage tech has been criminally underfunded and under-researched. There are many, many options. But because of poor investment decisions and lobbying from the usual suspects the tech is around twenty years behind where it could be.

[jayflux]

That’s simply not true, or at least not today.

First of, the UK are investing in battery storage, there’s already a rollout of grid-level battery systems across the country*.

None of them hold capacity for longer than 2 hours before they need to start discharging. In fact, the record breaking duration is 6 hours. This is great as a short buffer, but it’s not “storage”.

To put this in perspective, last year the UK went 2 weeks without any significant wind, so a 2 hour buffer is nothing. This is why Hydrogen is still being kept as an option for long term storage.

https://stateraenergy.co.uk/projects/thurrock-storage

https://rhomotion.com/news/longest-duration-battery-energy-s...

[ViewTrick1002]

The ratio between GW and GWh is always an optimization of the fixed costs vs potential profit.

A 4 hour battery can run at 50% for 8 hours or 25% for 16 hours.

The determining factor is what the market needs.

[_n_b_]

> I suspect that the push for civilian SMRs is a disguised subsidy for the naval reactor programme

It absolutely isn’t. There is very little crossover between the RR SMR (which is 470 MWe, not really an ‘SMR’ by IAEA definition) and a submarine reactor core. Sub cores are smaller and optimised for different conditions. They’re vastly different tech. The teams at RR working on these are totally distinct with no crossover.

RR just got £9B for sub NSSS work. They don’t need a back door subsidy when they have a big cheque coming right through the front door!

If anything, UK govt is prioritising domestic technology, whether or not that’s the best from a purely economic point of view.

[ViewTrick1002]

It is all about having the workforce able to deliver on the military ambitions.

This has been well known for a while, and western governments have started to say the quiet part out loud to justify the insanely large handouts required to build civillian nucleaar power.

https://theconversation.com/military-interests-are-pushing-n...

[throw0101a]

> I suspect that the push for civilian SMRs is a disguised subsidy for the naval reactor programme.

Ontario, Canada is building a bunch of BWRX-300 SMRs and don't really have a desire for a naval reactor programme:

* https://www.cbc.ca/news/canada/toronto/carney-ford-announce-...

* https://www.opg.com/projects-services/projects/nuclear/smr/d...

* https://www.gevernova.com/news/press-releases/ge-vernova-hit...

Canada is currently looking at new submarines, and the final two candidates are both SSKs (and not nuclear SSNs):

* https://www.defensenews.com/naval/2025/08/28/canada-shortlis...

* https://www.canada.ca/en/public-services-procurement/news/20...

As an Ontario resident I wish they chose to build more CANDUs (which, AIUI, they are planning to do as well) rather than SMRs: our grid is in more need of 'bulk power', and SMRs are better suited to small grids (like the Canadian Maritimes) or small sites (like in Poland: replacing previous smaller scale coal plants).

[mr_toad]

> Similarly, it is easy to imagine a swarm of small underwater drones detecting, tracking and trailing nuclear submarines.

Those are called torpedoes.

[Retric]

It’s way cheaper to build a drone that doesn’t need to travel quickly or carry huge amount high explosives.

[greedo]

How is a slow, lightly armed drone going to damage a nuclear submarine that can both outrun and outdive it?

[Retric]

The drone’s goal is to locate it, you’d then send something else to destroy it if you’re in an actual war.

America uses surface buoy’s to similar effect, going underwater would allow drones to be harder to detect. https://idstch.com/military/navy/navy-researching-new-buoy-t...

Of note you don’t necessarily need to be able to track a sub everywhere, an invisible underwater “fence” may be good enough.

[greedo]

How is a small drone, with limited power and a small sensor suite going to detect the quietest ships in the ocean? And then transmit tracking data? SOSUS is basically gone since the USN hates AWS work (much like the Air Force hates CAS). IUSS never went anywhere as far as I can research (see above why), and really isn't the same as a drone system.

[Retric]

It’s a huge design space. One easy to understand example is a passive sonar underwater drone that stays close enough to the surface to gather sunlight and easily communicate with satellites without also being visible on the surface or making sounds from surface wave action. It can then send high frequency radio signals to satellites which rapidly attenuate through the ocean creating a near perfect stealth system vs subs. The option exists to deploy a string of much deeper sensors via a tether.

Another option is close equivalents to the existing systems dropped from aircraft, though with significantly more stealthy deployment.

Etc etc.

[AnonymousPlanet]

People often underestimate the amount of storage you need for renewables. Depending on the geographic location you might be looking at tens of TWh. The cost for renewables then suddenly becomes much higher.

I recommend everyone who is using the cost argument to actually do the math on this first. It might be an eye opening experience. It certainly was for me.

[mqus]

Could you share your numbers as well? According to [1], the UK currently needs about 300TWh per year. Lets say we go entirely solar+wind+battery(whatever that means) and assume that battery has to bridge a gap of at most 7 days (meaning no wind and no solar at all during this time, which is at most a few days at a time). This adds up to 300/365*7= 5,8TWh of max capacity. Lets take it safe, round up and say we need 10TWh (which is already not "tens of TWH", but "ten"). [2] Says that grid-scale batteries come at around 350$ per kWh right now. kWh -> TWh is factor 1 billion (10^9), meaning if we want to build 10TWh of storage, it will cost 3,5 Trillion Dollars. Impressive number indeed. But there are multiple asterisks here.

1. This calculation takes into account that there is no exchange with mainland europe and no gas power plants or other sources of power (e.g. hydro or hydro storage). This sharply reduces the need for batteries. 2. Battery costs will fall in the next decades, compared to nuclear, which will take a long time (if ever) until costs will fall.

[1] https://www.statista.com/statistics/322874/electricity-consu... [2] https://docs.nrel.gov/docs/fy25osti/93281.pdf

[crote]

The problem is that the math is often done using faulty assumptions, such as expecting to rely solely on batteries to store enough energy to last several months.

In practice there are never long periods with and zero wind and zero solar and zero import capacity. Place the right price on electricity during peak demand, and suddenly the market is more than happy to install an overcapacity of wind & solar. Gigawatt-capacity cables to neighboring countries? Already being built!

A country like the UK needs an average electricity input of 45GW. It is totally fine to serve that with 60GW of wind operating at 25% capacity, 60GW of solar operating at 25% capacity, and 15GW of import operating at 100% capacity.

[gregbot]

Import from where? Neighboring countries with similar weather? I think they will be asking you to import to them when you need it most.

[osn9363739]

Can you share the math?

[wbl]

Ukraine's success proves that you need to actually have people guarding ships against intrusion. This is not a new lesson ever since the Raid on the Medway.

[greedo]

It's dangerous to extrapolate much from the performance of the Russian Navy in the Black Sea. While Ukraine has had remarkable success in almost completely shutting down Russian naval activity in the Black Sea, it's not all due to the superiority of drones. Russian incompetence, both in naval strategy as well as operations is endemic, and the fate of the Moskva and other systems isn't indicative of a widespread vulnerability of surface vessels to drone systems. The Moskva was sunk with cruise missiles, primarily ones developed from Soviet era missiles (Kh-35). Much has been written about the materiel state of the Moskva, as well as operational decisions/inadequacies that lead to its demise.

Surface drones work well when air cover is limited/restricted. Tracking them via radar is difficult due to surface noise, but it can be done. Countering them isn't an impossible task either, it, like other threats are handled systematically. The Russians have a relatively slow OODA loop, and Ukraine has been very successful in leveraging their superiority.

Is the threat a universal one or limited to the UKR/Russian conflict? A little of both. We've seen where an unprepared ship can be easily damaged by a small boat laden with explosives (USS Cole). We've seen the Ukrainians shut down Russian activity in the Black Sea, even going so far as to down unwitting aircraft that didn't respect the threat. But militaries adapt, especially to proven threats. Witness how the West responded to the sinking of the Eilat in 1973. It developed countermeasures and weapon systems for the threat of cruise missiles, while simultaneously developing their own cruise missiles (Harpoon/Exocet/Otomat/Penguin).

Will undersea drones prove as concerning? I doubt small swarms of UUVs will proliferate like we've seen with FPV drones. Flying through the air is much much easier than operating in water. Propulsion, C2, and targeting is quite difficult underwater compared to UAVs. Both range and payload are a challenge, so I don't believe that a swarm of "small underwater drones" will be able to detect the quietest ships in the ocean any time soon, much less track and trail something that can travel at speeds above 40kts with ease.

Now will large UUVs have a role in future naval combat? Undoubtedly.

[ReptileMan]

Russia's naval prowess have always been a joke so you can't make too many conclusions.

[Melatonic]

It would also provide a steady source of tritium for upkeeping nuclear weapons

[DoctorOetker]

This: nuclear energy is a subsidy for nuclear weapons.

[FridayoLeary]

As for point one they are much less reliable because they are intermittent. I'm skeptical of how much cheaper renewables are. I haven't noticed energy prices declining recently. Correct me if i'm misinformed. I'm slightly confused by point 2. What are you saying, because soviet technology is getting sunk a lot we should stop bothering with having a navy?

Either way you are giving way to much credit to the power of the UK military industrial complex.

[zoul]

Solar power is very cheap and still getting cheaper:

https://www.statista.com/chart/35117/levelized-cost-of-energ...

[chickenbig]

Solar power doesn't work well in the UK in winter, with 1/3 of the energy output of summer months.

Taking the limit of free solar power, what would the storage requirements look like for the UK?

[TheOtherHobbes]

The UK is aiming for around 27GW of battery storage by 2030.

But it's not a simple picture. The grid needs to be expanded to distribute power from renewables more efficiently, batteries aren't the only storage option, and the concept is still too centralised.

A combination of distributed rooftop solar with domestic batteries, maybe local storage in substations, strategic national storage, and a mix of sources would be a more effective strategy than trying to park huge batteries around the country in the hope they'll be big enough.

The UK still has a post-war mindset around energy which doesn't make sense in the 21st century.

[chickenbig]

> The UK is aiming for around 27GW of battery storage by 2030.

How many GWh? Citation please.

[lostlogin]

I’m not OP but: https://www.carbonbrief.org/analysis-how-the-uk-plans-to-rea...

It’s either 27 or 27GW they are installing sorry.

[crote]

So build three times as much? Solar has gotten cheap enough that such solutions are quite viable these days. And as a bonus, electricity will be basically free during the summer.

[DoctorOetker]

take a look at all the roofs next winter, if its anything like the other side of the canal, you'll see that the average roof coverage is substantially less than 1/3.

[dan-robertson]

The Royal Navy only uses nuclear power for submarines, at least for now (unlike USN which uses it for big aircraft carriers)

[lazzurs]

Making the two new UK aircraft carriers dependent on natural gas has to be one of the worst military procurement decisions of the modern era.

[dan-robertson]

In World War II, it was in hindsight a poor decision for the Royal Navy to stick with coal and an expectation of nearby friendly ports to refuel. The USN having oil-burning ships that could be more easily refuelled at sea meant an increased range and this made a difference in the pacific with most formerly friendly ports in the hands of the enemy. The Royal Navy may have been less happy with oil than coal due to not having a source on the British mainland.

Today, it seems unlikely that a Royal Navy aircraft carrier will be far from friendly ports. More likely for it to be used to launch air attacks against a relatively weak adversary (think of something like the military actions near the Arabian peninsula in the last 50 years or so). There are also Royal Navy oilers and other logistics ships that can replenish fuel or other resources.

[7952]

Its fuelled with diesel, not natural gas. And all carriers need refuel at some point for their embarked aircraft.

[crote]

Sounds like it is time to dust off those nuclear-powered airplane blueprints from the 60s!

[7952]

The USN have a research project around using electricity to produce synthetic fuel from sea water.

[0x000xca0xfe]

Renewables are cheap but storage isn't.

[Retric]

Storage is cheaper than peaking power which is why it’s common to add huge battery bank to solar power plants. It’s simply more profitable to add storage.

Net result renewables currently save you money until ~80% annual electricity supply. At which point adding more batteries and generation to cover overnight demand is cheaper than adding nuclear to the mix. In such a mix, Nuclear saves a little per kWh overnight and cost way more per kWh during the day, net result it’s more expensive as baseload. But, operating nuclear only at night drives up per kWh costs above storage.

Due to plant lifespans, new nuclear is already a poor investment which is why it’s rare, which then drives up construction costs. It’s a viscus cycle which ultimately dooms nuclear without massive subsidies which become hard to justify.

[Closi]

> Net result renewables currently save you money until ~80% annual electricity supply. At which point adding more batteries and generation to cover overnight demand is cheaper than adding nuclear to the mix.

Assume you mean more expensive than nuclear in the second point?

Agree with your point although it's about wind in the uk rather than solar, and about being able to last a few weeks if there is calm weather rather than a day without sun, which is when having a nuclear baseload makes sense.

[Retric]

> Assume you mean more expensive than nuclear in the second point?

No, but I clarified the comment. My point is when taken in isolation nighttime nuclear costs less than nighttime batteries on a near zero carbon grid, however the economics operate 24/7/365. Nuclear heavily favors 24/7 operations so gaining 3c/kWh at night while losing 6c/kWh during the day is a net loss. Operating only at night almost doubles nuclear’s cost per kWh so you’d lose money anyway.

> weeks if there is calm weather rather than a day without sun, which is when having a nuclear baseload makes sense.

If you don’t have enough energy for a few days randomly you need peaking power generation not baseload. Nuclear is really bad at ramping up to meet sudden shortfalls.

The scenario you described is one of the very few cases where hydrogen might make sense assuming all fossil fuel use is banned. Without that natural gas is going to win to prevent random outages every few decades.

[epistasis]

In 2025 storage is cheap too, it's just that there's no need for it until you already have a large amount of renewables.

2025 is the year that storage is really being deployed in a serious manner in the US, more than 18GW most likely:

https://www.eia.gov/todayinenergy/detail.php?id=65964

You can see on the map at the bottom of this page that almost all the batteries are in areas that already have high amounts of renewables:

https://www.eia.gov/todayinenergy/detail.php?id=64586

And the prevalence of batteries in Texas means that they must be cost effective, because all grid assets in Texas are from private investors risking their own capital, and there is zero incentive for batteries except for their profit generative capacity.

[Closi]

> You can see on the map at the bottom of this page that almost all the batteries are in areas that already have high amounts of renewables:

It could be - but the battery investments map also align with the map below which shows that these states (Texas & California) are also states suffering from blackouts.

https://worldpopulationreview.com/state-rankings/power-outag...

So while this could mean that storage is cheap, it could also mean 'Texas's mix and grid is unstable, particularly as it's not connected to the national grid, and this has opened the opportunity to profit from higher levels battery arbitrage that doesn't exist in a better balanced grid'

[abathur]

There's quite a lot of pricing data available for the energy market and it might be possible to approximate battery profitability by rerunning normal and long-tail history.

See https://www.ercot.com/mktinfo/prices and https://www.ercot.com/gridmktinfo/dashboards and https://www.ercot.com/gridmktinfo/dashboards/energystoragere... for example.

[epistasis]

That looks to be a population map:

https://xkcd.com/1138/

Which is what you would expect of a stat of "number of outages per state". If it's not normalized for land area, population, and all the other primary contributors to the total number of outages it's a useless stat. San Francisco has more people in it that the entire state of Wyoming.

Texas' power is also cheap, so to justify batteries they would have to not raise the cost of electricity that much.

The current cost of grid batteries is hidden, but it's not too hard to find out, and it is indeed quite cheap. But if there's no mechanism to get paid, ie ability to do time arbitrage in the energy market, then they do not get deployed.

Electricity market design and the ability of ISOs/PUCs/utilities to adapt to changing technology are bigger barriers to batteries than their price.

[detritus]

...just quite yet.

[OJFord]

> electricity renewables are cheaper than nuclear

Are they still if you include storage, vs. nuclear's continuous generation?

[hdgvhicv]

Continue generation is great if you have continues demand. The U.K. does not have that (especially if you include heating and travel which is currently mainly provided by gas)

[OJFord]

Even if you think everything shuts down at night, how can you think busy consumption days are highly correlated with the windiest & sunniest & waviest days?

Renewables are great, let's do more of that too, but it's patchy supply, and yes demand is patchy, but they don't match - so you need storage too, and that problem is eased by having non-patchy (coal, gas, nuclear) supply for the lesser more constant load demanded.

[jayflux]

That’s quite an odd statement to make.

The UK certainly does have continuous demand, our overall energy demand has rarely fallen below 25GW in the past couple of years. Right now gas makes up for much of that, the goal here is to replace gas with nuclear, using gas as baseload generation isn’t wise long term.

Source: https://grid.iamkate.com/

[hdgvhicv]

Our demand varies from 25 to 45GW

Saying “nuclear can handle the easy part” doesn’t help. You still need 20GW of extra capacity to cope.

It’s like saying “wind can handle the bulk of the capacity you just need to top up the rest”.

[jayflux]

I’m sorry I struggle to understand your comment, but I’ll have a go.

> Saying “nuclear can handle the easy part” doesn’t help.

That’s literally how baseload works, look at France’s energy mix for an example, they have nuclear handle the bulk of their demand (at least the very minimum it will ever be) and renewables + transfers handle the rest, if renewables goes up they export it or lower their nuclear output (yes, their nuclear output can be modulated).

> You still need 20GW of extra capacity to cope

The goal isn’t to replace the entire energy mix with Nuclear, the goal is to add enough nuclear in the mix so that we don’t need gas being generating all year round (gas sets the price in the merit order so we don’t want it on 24/7). If you added just 6GW of nuclear you’d be achieving that on some days.

[stevesimmons]

> gas sets the price in the merit order so we don’t want it on 24/7

I never quite understood the logic for this. Sure, if you overlay a simple upward sloping cost curve on a downward sloping demand-price curve, the market-clearing price is where they intersect, and that in practice much of the time is a gas generator.

But there must be a million other aspects that can affect what price needs to be paid to secure the capacity below that point. Surely only part of the total area under that market-clearing price needs to accrue to the generators?

And if generators are getting windfall profits, can't the market rules be adjusted so more of it can given to the consumers in the form of lower energy prices?

Can someone explain this? Maybe that is what actually happens, just it is too complex for the mass media.

[hdgvhicv]

So if wind produced 35gw and nuclear 20 and demand is 30GW, you just say “well nuclear is the base load and wind needs to be curtailed”

What about when nuclear produces 20GW and wind 5 and demand is 35gw

Of nuclear costs the same as wind then why not have nuclear produce the full demand?

[gorgoiler]

I’ve been a huge fan of Morley’s 12-bit color palette since I first saw it:

https://iamkate.com/data/12-bit-rainbow/

I had completely overlooked that it was for this power-usage visualization.