[whiddershins]

I listened to a whole Joe Rogan podcast where a guest kept advocating for using nuclear to balance out the intermittent nature of solar and wind.

I could never wrap my mind around how this makes sense. Nuclear has a fixed output, it doesn’t scale up and down the way fossil fuel plants do.

If your nuclear capacity can cover the worst case where solar and wind aren’t producing, it can cover all cases, and the solar and wind become irrelevant.

Seems like the linked concept is similarly making something more complicated in the hopes that somehow makes it better.

Like bundling subprime mortgages.

[gwbas1c]

> Nuclear has a fixed output, it doesn’t scale up and down the way fossil fuel plants do.

This is a very, very old, and very, very solved problem.

Today we'd solve it with batteries: Discharge when demand outstrips supply, recharge when supply outstrips demand.

In the past, nuclear power was often paired with pumped storage: https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...

Today a lot of pumped storage facilities have outlasted the nuclear power plants they were built to support. Instead of pumping at night, they pump when there's excess solar or wind.

[mschuster91]

> Seems like the linked concept is similarly making something more complicated in the hopes that somehow makes it better.

Because battery storage is legitimately better in terms of reaction time and efficiency: pumped hydro is 2 min from 0 to 100%, with a total efficiency ratio between .65-.85 [1], gas plants are at 3-5 minutes (peakers)/up to 30 min (combined power+heat) [2] and .35-.50 efficiency ratio (more if thermal energy is captured, but that only makes sense for non-peaker plants that also provide district heating)... whereas a battery plant's reaction time can be measured in milliseconds.

That's orders of magnitude faster and is what makes decentralized battery storage worth it.

[1] https://um.baden-wuerttemberg.de/de/energie/versorgungssiche...

[2] https://www.ingenieur.de/fachmedien/bwk/erneuerbare-energien...

[3] https://www.deutschlandfunknova.de/nachrichten/australien-ri...

[toast0]

> I could never wrap my mind around how this makes sense. Nuclear has a fixed output, it doesn’t scale up and down the way fossil fuel plants do.

Nuclear can and does regulate its output. And the fuel rods should last longer if you run at less than full output. But fuel cost is not a large component of nuclear energy cost, so it doesn't make a lot of economic sense to operate them far above or below their steady state maximum capacity.

I agree that nuclear doesn't make a good backfill for intermittant sources; but it's not because they can't, it's because the economics aren't good.

[pbmonster]

> Nuclear can and does regulate its output.

They do in France. You kind of have to, if you produce 70% of your power in nuke plants. But in the US, it's not done in any meaningful sense. All US plants run at 100% capacity all the time.

The reason for that is that it's incredibly complicated to ramp a nuke plant. If you take a reactor and reduce its heat output significantly, the currently active volume of fuel moves away from the decay product equilibrium - the reactor poisons its own fuel rods with neutron absorbing decay products. This makes a subsequent increase in output power extremely dangerous and thus impossible in practice. The only way to increase power safely is to wait for the radio poison to decay naturally, which can takes tens of days (and depends on by how much you reduced power).

The only reason the French can ramp the power of their nuclear plants up and down is that they have so many of them, and they are all controlled by a central authority. This means the reactors can take turns in reducing power, each night a different set of reactors poison their fuel and recover slowly over the next week or two.

There is also of course an economic side to this. In the US, nuclear power is so economically risky that planning a plant that is not trying as hard as it possibly can to recoup it's enormous investment would sound crazy to investors. It would make zero economic sense to not run at 100% all the time, and would probably make any newly build plant a billion dollar loss instantly.

[idiotsecant]

That's exactly what you want for easy control of grid stability. Say you typically fluctuate between 100 and 150 GW of demand. You turn on 80GW of nuke, leave it running all the time, and then as resources come available from intermittent sources those can contribute to total load requirements. If you have a wide enough diversity of intermittent sources this works well. The problem with intermittent generation sources is that you must either store energy or overprovision generation to make up for the gaps in availability (or make wildly expensive transmission improvements but that is another discussion). For reasons of expense and reliability you must make a tradeoff between how much of your generation is reliable baseload and how much is intermittent generation. Nuke + intermittent sources is a very good match.

[eppp]

You could also add time of use pricing to encourage use during peak renewable generation.

[Scoundreller]

My jurisdiction rolled out millions of Time of Use smart meters only to find that residential users really didn’t change their behaviour much. Demand shifting was something like a couple percent and faaaar less than predicted.

It turns out when you run surveys, it’s the people that like to think about answers to questions that respond to them, which isn’t representative.

45pg pdf government report: https://www.auditor.on.ca/en/content/annualreports/arreports... which starts getting good at page 5.

Understated costs and exaggerated benefits. Peak reduction targets ended up with increases in peak demand.

As hard as it is for the HNer to believe, the vast majority of people will just do whatever they want whenever they want.

I see this everywhere: “why would anyone go to this expensive supermarket that sells the same crap as the cheap one I go to? Why would anyone go to that gas station, their price is always higher than the others in the surrounding area. Why would anyone buy that car, it has a terrible TCO, and on and on”

[toast0]

That makes sense. Running laundry or other household equipment when energy is cheaper makes sense, but it requires a different time commitment. Cooking at other times to save energy costs is unlikely.

You'd get more participation if appliances could be smarter without increasing cost. The holy grail of delay freezer defrost cycles until off-peak, and relaxing temperature thresholds a bit to pre-heat or pre-cool towards the end of off-peak and let things go a bit farther off the set point while on-peak aren't realistic for say water heaters, because the increased consumer costs to do that (more expensive equipment, more time to set settings, most likely some signalling or networking to maintain) don't justify the savings.

I'm guessing there's reasonable uptake on smart thermostats that can participate in demand control, because smart thermostats are desirable anyway, network anyway, and can control large enough loads to matter. Not everybody will want it, but I'd be ok with starting peak a degree cooler or warmer than my set point, and letting the temperature float a degree farther during peak, because HVAC uses a lot of kWh and why pay 2x for those... but then I'm in a low energy cost area with flat rates, so maybe I would change my mind after experiencing it. :)

[Scoundreller]

Yeah, basically a human factors approach will work better than asking general users to vastly increase their cognitive load and/or increase capex for a small value of savings.

Free LED light bulb handouts are more effective than complex expensive-to-implement programs requiring user intervention. Mandating low gpm showerheads works better than asking people to take short showers. Better windows per building code works better than asking people to choose the exotic greenbug window, etc.

[knutzui]

ToU pricing can be very effectively used by having an energy management system. This will automatically shift power usage to the most cost efficient times.

[Scoundreller]

In theory. After 15 years, the best most of us in Ontario have is a “4h delay” on a dishwasher and discounted (not free) smart thermostats that you have to install yourself or pay an installer for. I suppose electric cars do a good job here at least.

And this is in new construction.

Overall, it didn’t (and may never) make financial sense to put light users on smart/time of day metering.

[arc-in-space]

>If your nuclear capacity can cover the worst case where solar and wind aren’t producing, it can cover all cases, and the solar and wind become irrelevant.

This is plainly false; nation-wide energy consumption isn't fixed, it adapts to supply. Not all usage of energy is equally valuable, if the prices go up, you might choose to turn off your TV, but you'll probably keep your fridge running. With more energy, more activity can happen at lower prices.

[robertlagrant]

It's definitely not perfect, but e.g. with pumped hydro, you can run it in peak hours when demand exceeds baseline supply.

[datadrivenangel]

Modern nuclear plants can scale much more aggressively than older plants. This is also true of coal plants as well. Still not perfect to have them be load following resources though.

[2OEH8eoCRo0]

> Nuclear has a fixed output

A fixed thermal output or a fixed electrical output?