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Comment by Arnt | Hacker News Reader

I think the answer you may be looking for is: Nuclear reactors are unreliable. Compare them to solar, which is very different.

Solar produces power according to sunshine, with no moving parts, and if a panel breaks the rest of the panels go on working, so the failure is a small deterioration in power output. Nuclear plants are differently unreliable, because they have lots of moving parts and elaborate maintenance procedures, and during maintenance a plant produces 0% power instead of that small deterioration. The unreliability is on a different timescale, both better and worse than solar.

France has lots of reactors, but they're not all up, and you can't expect all to be up, so sometimes they'll have this problem. IIRC they had something similar in 2016, which they were able to solve using imports.

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> Nuclear reactors are unreliable. Compare them to solar, which is very different.

> Solar produces power according to sunshine

So, according to weather. Which isn't exactly renowned for being reliable.

This is about wind power, not solar, but another tweet I saw recently mentioned "Solar availability in mid-winter: 0 %" It's also in Swedish, but the picture speaks for itself. https://mobile.twitter.com/HenrikSundstrom/status/1472654421...

You clearly don’t work in solar. The panels move on trackers, the panels have to be cleaned of dust and snow, vegetation around the panels has to be cut, inverters fail, etc. there are many moving parts and maintenance required.

That sort of maintenance can easily be done without the need for specialised engineers. A gardener can mow the lawn, a janitor can clean the panels, and most solar plants are not on tracks but static.

But that's not what I had in mind. When an inverter fails, it has to be replaced, and meanwhile a few panels don't produce power. A few, as opposed to all. You get many small failures that cause the plant to produce ninety-some per cent of its possible output instead of the nuclear kind, where the plant is down and produces zero energy, and can't be turned back on even with several days of advance warning.

Nuke is 'reliable' in a much more important way - the plant outages are scheduled and the generation is scheduled. You can (and do) bet the health of the grid on nuke having the output you plan when you plan for it to be there. This is referred to in generation industry jargon as 'dispatchable' power. This makes a modern zero-sum storageless grid work. Solar is non-dispatchable. You can estimate what power output will be available, you can over-provision generation and store it in expensive batteries, but you simply can not rely on it being there and expect the grid to stay online.

It turns out that regular plant maintenance outages aren't particularly important compared to not being able to properly plan generation.

Of course you can decide that. That's what the French did before the price peak in 2016. The thing is that only some of the decisions involved plannable dates.

They decided that when problems were discovered such that redundant security mechanisms weren't, then the problems should be fixed, with time limits. They decided what kind of problems should require fixes within set time limits, and they decided what those time limits should be.

And they decided that some reactors should be taken down for planned maintenance in specific periods.

When problems were discovered at inoppportune moments, the decisions combined to leave them with too few operational reactors.

Nuclear plants are "dispatchable" in the same way wind farms are "dispatchable" - you can just not feed as much of the power you are creating into the grid.

Gas and hydro are actually dispatchable. You can dial down the power you are using and actually use it later.

False. You can’t make more power out of a wind farm than there is wind.

Of course. But also not much less. If you have a 50-unit wind farm you'll have a lot of problems that reduce your output to 98% of what the wind allows until you can fix them. Not so many that reduce output to 0% of what the wind allows.

Did I say you could?

Dispatchable means you can turn it on and turn it up when you want to.

That was my point.

Colour me confused, a nuclear power plant the operators can choose how much power they make every day and generally choose as much as possible, a wind farm they can set a limit for the maximum power generated but the actual power generated could be anywhere from zero to the set maximum depending on the wind speed.

nuclear is more often considered baseload generation as opposed to dispatchable but wind is not baseload or dispatchable since it is not possible to control the wind speed.

>a nuclear power plant the operators can choose how much power they make every day

No. They cant.

It takes 24-48 hours for them to ramp production up or down and this is both expensive and difficult. This is far too slow to be useful. Natgas takes ~7 seconds-minutes to go from 0-100% and it's cheap and easy. Same for batteries. Hydro is slower but still in the order of minutes/seconds. This IS useful.

When nuclear plants have claimed ramp up/down speeds quicker than that they are always still producing the same amount of energy at the same cost they are just wasting some of it.

The nuclear industry tries to blur these distinctions.

>but wind is not baseload or dispatchable since it is not possible to control the wind speed.

Wind can often pull the same "trick" nuclear does where if the grid only wants 100MW but it's producing 150MW it can just let 50MW go to waste.

This isnt really "dispatchable" either but sometimes wind energy advocates pull the same trick.

Wind farms can’t plan to make 100 MW or 150 MW or 50 MW on Tuesday next week if there is no wind.

Nuclear can.

I agree nuclear isn’t dispatchable, natural gas is. But wind is not dispatchable nor is it baseload so making a comparison to nuclear and pretending there is firm energy out of a wind farm on a given day is false to me.

>Wind farms can’t plan to make 100 MW or 150 MW or 50 MW on Tuesday next week if there is no wind.

Once again, nobody said it could.

You can dispatch nuclear power plants.

Its just that their high costs make that an uneconomical decision. Nuclear fuel is damn near free, so why would you ever want to turn it off unnecessarily? Only if the price of electricity reaches into negative-territory is it economically viable to turn off a nuclear power plant.

Same thing with wind / solar. As long as the price of electricity is positive, there's no point in turning them off.

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Now think about coal / natural gas. The price of fuel in these cases dominate. Which means its economically viable to turn off when the price of electricity drops (even if its still above $0).

Nuclear fuel is not free but it is cheap, especially compared to the eye watering capital costs of nuclear power.

It is helpful to turn off power production to stabilize the grid. It's not always about production costs. This is why nuclear plants and wind turbines sometimes just "waste" excess energy.

> I think the answer you may be looking for is: Nuclear reactors are unreliable. Compare them to solar, which is very different.

You should come in southern Germany to see how reliable is solar when half of the year there is foggy.

Right. Solar depends on the weather and is unreliable in that respect, but reliable against mechanical problems. Nuclear is the opposite. More and less reliable.

In 2011 the nuclear industry promised rolling blackouts by now:

https://theguardian.com/environment/2011/may/23/germany-nucl...

Pretty sure they didnt envision Germany having cheaper winter electricity than France.

All I can find evidence for is a balloon that short circuited a substation, which is a blackout that is unlikely to have been prevented by a nuclear reactor.

> Pretty sure they didnt envision Germany having cheaper winter electricity than France.

Unfortunately that does not reflect at all in the consumer price. We have been taking top spots in the energy price rankings for years now and there is no real hope for improvements.

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