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Comment by avsteele | Hacker News Reader

Please correct me if I'm wrong but my understanding is that nuclear doesn't ramp up/down very well either. Most nuclear plants use fission for the base load but gas or other fossil fuel generators for the variable part. Since in Germany green power in the form of solar/wind are even more variable, this makes Nuclear + Solar/Wind a bad combo.

Wind and solar don't even make sense for Germany given their climate/geography.

Germany should ditch the green and use its amazing engineering to build better nuclear reactors, IMO.

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52% of Germany's energy production in 2021 was from renewables [1], which are productive now, don't need decades of planning and construction, have zero costs for waste and a perfectly clear risk profile for the next centuries.

I don't see how wind and solar don't make sense.

[1] https://www.destatis.de/EN/Press/2021/09/PE21_429_43312.html

> I don't see how wind and solar don't make sense.

Wind and solar make total sense. All we need to do is overbuild wind/solar generation + invest in energy storage capacity. This can be done relatively quickly, certainly much more quickly than building new nuclear plants.

What kind of grid scale storage can be built quickly?

hydro, but thats also something we do not built because it's not environment friendly (takes a lot of space and kills species living there and might need to move people). keep in mind we are not china they basically do everything lately to grow their energy, hydro, nuclear, wind, solar the full mix, something which would not be possible in germany, because people would go full madness, heck even wind already is something that some people do not like.

Compared to building reactors, anything is quick.

Not really, a reactor is operational in 10-20 years, while expanding lithium mining and battery production will easily take much longer. Not to mention the energy and CO2e cost of manufacturing the batteries.

In Nissan Leafs alone (450k) there is over 10GWhr of battery capacity. Grid scale batteries are just a capital problem. No breakthroughs necessary.

There is no excess battery manufacturing capacity available. It is constrained by both facilities and raw materials. Capacity will increase but at a slow rate. More capital can't solve that problem, it's like pushing on a string.

This is exactly how capital works. We can make more battery factories.

Eventually yes, but that will take many years. It won't do anything to prevent power shortages in Germany over the next 5 years or so. I don't think you understand how long it takes to ramp up production across the entire supply chain, and that allocating more capital won't significantly accelerate timelines.

> 52% of Germany's energy production in 2021 was from renewables

44% in 2021 according to the graph you linked and 52% in 2020.

You're right, thanks!

Interestingly the energy consumption from renewables is at 43%, ie. considerably lower than production. I guess the difference is accounted for by the exports at peak wind/sun at the expense of other sources. Probably french nuclear plants as some other poster here noted, ie. Germany takes the cream of the top and lets others provider the expensive base load or just burns dirty lignite and coal.

[1] https://www.cleanenergywire.org/news/renewables-cover-43-ger...

> don't need decades of planning and construction

Well they aren't produced in Germany so if CoVid continues, good luck getting those solar panels.

> have zero costs for waste

Used up windmill blades are buried into the ground and we still have to find a good way to recycle batteries.

> perfectly clear risk profile

Like fucking over the neighbouring countries by using them as batteries or using Russian gas?

> Please correct me if I'm wrong but my understanding is that nuclear doesn't ramp up/down very well either.

Correct. Nuclear reactors can't be turned on/off quickly. They are suitable to handle the base load, in other words, but can't be used as peakers.

> Wind and solar don't even make sense for Germany given their climate/geography.

Uhm, respectfully, that is a load of nonsense. Cf. https://en.wikipedia.org/wiki/Renewable_energy_in_Germany

> Germany should ditch the green and use its amazing engineering to build better nuclear reactors, IMO.

Well, if they start that plan today, it may be done in 30 years. Which is way, way, way too late.

Imo, the more sensible path here is to keep the existing nuclear plants running, decommission the that awful lignite power generation asap, while building out energy storage capacity (grid scale batteries - there are many kinds of approaches, e.g. electrical batteries, reservoir storage and some seriously weird ones involving lots of blocks of concrete). That could be done in the space of a decade.

Any new nuclear plants would not even be out of the design stage in 10 years.

I never understood the argument that nuclear takes too long, so instead we implement new technologies that have never been done at scale.

What if we run into unexpected problems with energy storage that push their timeline out even longer than 30 years? Seems better to do both, and accept the risk that we paid for too much clean energy in the end.

I know they generate a moderate fraction now, that's the point of my post. I think they are backing themselves into a corner.

The problems to date include very high energy prices. Even larger challenges await; these will grow as renewables they become a larger fraction of total output. Renewable variability isn't a problem when they are a small fraction, but a very large one when they are a large percentage. These are unsolved problems. Land use is also an issue.

French nuclear plant can ramp up/down 80% in 30min, but it's true that many nuclear plant can't

This is wrong. Nuclear reaction output can be modulated on the order of milliseconds, practically visible as the temperature of the core, which varies on seconds to minutes. They can be used as peaker plants if so designed. In the US at least, the issue is that energy output must be telegraphed 4+ hours in advance.

If I had to guess this is a constructed incentive to make nuclear less desirable than coal or gas under the guise of safety.

The technical ramp up/down issue is often conflated with amortized capital cost.

Nuclear, in order to provide electricity at a competitive rate, needs >90% capacity factor. That means it can't ramp up/down and stay in business, not that it can't ramp up/down. Since the fuel is trivially cheap, ramping down does not provide any economic savings. The opposite is true for an CCGT plant.

... and that is the fundamental reason why there isn't any pressure to build new nuclear in the US (I am less familiar with PPAs and grid regulation in the EU).

Nuclear plants can adjust reasonably quickly in theory, but most plants don’t have the equipment to do in practice.

This is because nuclear has a very low marginal cost of power - a kJ is very cheap if you’ve already built the plant - so the plants are intended to run full-tilt to make the most of your very expensive asset.

Nuclear reactors actually produce a family of decay products as they run, some with longer decay times and neutron absorbing cross sections than others... things get less stable as you rapidly ramp levels up and down, so it is avoided at all costs. Uranium based fuel generates about 1/10 of its operating heat for a very long time, which is why it has to be kept in cooling ponds after removal from the reactor.

Coal plants take time to get to temperature and pressure, furthermore the generators themselves have a limited number of stop/start cycles, as cracks radiate outward from the center of the rotor shaft over time. (They are cast in a centrifugal fashion, in a vacuum, to reduce voids to). Periodically the center of the shaft is bored to remove the cracks, but there is a finite amount of material that can be removed.

Gas turbine spool up/down quickly, but cost 2 or more times the cost of other fossil fuel sourced generation.

Hydro is awesome, if you have it, but global climate change is causing precipitation patterns to shift.

Large scale hydro also has non-negligible methane production due to all the plant matter decaying in placid water...

And the fish are done for too.

Nuclear reaction output can be modulated on the order of milliseconds, practically visible as the temperature of the core, which varies on seconds to minutes. They can be used as peaker plants if so designed. In the US at least, the issue is that energy output must be telegraphed 4+ hours in advance.

If I had to guess this is a constructed incentive to make nuclear less desirable than coal or gas under the guise of safety.

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