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Comment by cbmuser | Hacker News Reader

And how much of that _generated_ electricity from solar and wind is actually produced on demand?

Electricity generated from nuclear power can follow the load, neither wind nor solar can do that meaning you will _always_ need backup power plants.

Germany has 50% renewable energy in its electricity mix, yet their greenhouse gas emissions in the energy sector are seven(!) times as compared to France.

There is a reason why China is nuclear power plants like crazy. They understand that electricity is worthless if it can’t be produced on demand.

> https://twitter.com/YanQinyq/status/1368830510210899968

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China has significantly reduced its nuclear ambitions over time. Back in 2009 it planned to have 86 GW of installed nuclear capacity by 2020. It actually reached 47.5 GW in 2020. See this recent post and its children for citations:

https://news.ycombinator.com/item?id=26216394

China is the world's leader in building new nuclear reactors. And in building new solar farms. And in building new wind farms. China is the world's biggest energy producer, so it is going to lead on a lot of absolute energy measures.

China can build reactors cheaper than the West, but it can also build solar farms cheaper than the West. China is adding output from renewables faster than from nuclear projects.

Any numbers on China’s coal plants?

You forgot to mention China is also the world‘s leader in building new coal plants.

I don't particularly want to defend China, but at least they have contributed to the fundamental "victory" economics of solar being able to challenge natural gas.

And yes they are totalitarian, but at least they have some awareness of GHG emissions and are executing on alternative energies and EV and battery production and research.

But at what true cost has this “victory” come at when we know China is more than willing to look the other way when it comes to the environmental costs of mining those resources at least in the short term. https://e360.yale.edu/features/china-wrestles-with-the-toxic...

Solar panels don't need rare earth elements.

Some wind turbine generators use rare earth element permanent magnets, but they only account for 21% of the market. The rest use electromagnets. See Figure 37 in this report:

"IRENA Future of Wind (2019)"

https://www.irena.org/-/media/Files/IRENA/Agency/Publication...

21% is rather significant if we're hoping to scale the installation of wind along with other renewables to entirely replace fossil fuels and nuclear. And of course there is just the regular mining of all the other resources needed to produce these renewables in the first place which might actually be the bigger problem in terms of scale.

"Leading manufacturers of large modern wind turbines, such as Siemens Gamesa Renewable Energy and MHI Vestas Offshore Wind, use permanent magnet generators based on neodymium-iron-boron (NdFeB) in their advanced offshore wind turbines. " https://thinkrcg.com/rare-earth-metals-and-their-role-in-ren...

Our present use of fossil fuels is vast. The effort required to replace fossil fuels will likewise be vast. It includes a lot more mining for metals used in electric vehicles, regardless of whether those vehicles are charged by nuclear electricity or by renewables. It appears technically feasible to scale up metal extraction to the necessary level. Metal extraction has negative environmental impacts, but the impacts of continuing to burn fossil fuels are worse.

Absolutely agree that we need to move off fossil fuels so that to me is a given. And you're right that the problem is vast and will require a vast effort. But that is also the central problem. Renewable prices are coming down due to economies of scale and possibly due to externalities not being fully captured in the price (my main concern) but overall installation at this point is relatively small so it's easy to overlook it because the current prices are so attractive. So the question becomes do these economies of scale hold as we scale up to the necessary levels to replace fossil fuels and nuclear or is there some inflection point where the cost to the environment becomes too great to ignore before we even get there and we find ourselves needing to scramble to build nuclear?

Nuclear requires vastly more resources per kWh than wind, so we aren’t going to hit an inflection point where suddenly nuclear is better for the environment.

That’s largely because Coal had fallen off a cliff almost everywhere else. China got 80% of it’s power from coal in 2010 and that’s down to 57.7% in 2019.

This paints a rather distorted picture. a) Coal plants did not fall off a cliff in western nations by accident and b) upcoming new coal plants in china are huge.

Nuclear can’t follow the load without becoming vastly more expensive. France is heavily dependent on exporting subsidized electricity generated by nuclear at a loss and importing renewable and fossil fuel generated electricity. But even with that massive exchange for load balancing they still have excess nuclear generation driving up costs. Just compare capacity factors between US and France to understand the true story.

It looks fine on paper, but France was dependent on other EU countries avoiding nuclear.

Actually France nuclear industry is harmed by the current chilliness of the EU, lead by germany, toward nuclear power generation. If EDF could choose, they would prefer a bigger market to export its technology inside the EU.

The problem of capacity factors of french nuclear reactors is caused by excess generation by renewables (mostly wind from north sea) that cannot be stopped and is sold at quasi negative rates. It's clear when you see the capacity factor has been decreasing for the last decades without much change in the number of reactors online in France.

Capacity factors have been improving in France as they scale back nuclear production from 87.9% nuclear and 13.9% mostly hydro renewables in 2004 vs to 71.7% nuclear and 21.3% renewables in 2018. https://en.wikipedia.org/wiki/Electricity_sector_in_France#I...

Looking at 2004 they used 8,204 kWh/Hab but produced 9,203, and thus needed to export an even larger fraction before wind/solar took off.

PS: The graph makes it clear why things are improving, their simply cutting back on nuclear. https://upload.wikimedia.org/wikipedia/commons/9/9d/FR_ELEC_...

Wikipedia says the exact opposite:

> Since 1990, each year, France roughly exports 10% of its annual production. Its annual exchange sold has always remained positive.

https://en.wikipedia.org/wiki/Electricity_sector_in_France#I...

Positive next exports of subsidized nuclear power isn’t a good thing. It’s the same thing as US corn exports where the cost of production is larger than market rates and it’s government subsidies that keeping things going.

If what you say is true then yes, but it doesn't sound logical. Why would the French government take taxpayers' money, put that into nuclear facilities, then sell the surplus to other countries if it's such a clear loss of money? Wouldn't it be more economical to either have other types of energy production facilities or import the power instead?

I'm going to need sources, preferably Wikipedia or something similarly peer-reviewed (not a random blog or opinionated organisation), for this to make sense to me.

Why would the French government take taxpayers' money, put that into nuclear facilities, then sell the surplus to other countries if it's such a clear loss of money?

Because they've built them to serve peak demand.

Just to add a bit of context: 50% sounds great, but Germany uses ~3.7PWh of energy only 0.6PWh of which is electricity. Renewable energy production is 8% of energy consumption. No large-scale storage needed if 92% of your energy can be generated from fossil fuels on demand. So far so good, but we have much more than 92% of the work still ahead of us since it will become harder as we need storage and use up the available physical space.

Source: https://en.wikipedia.org/wiki/Energy_in_Germany

Nuclear isn't on demand power like natural gas or hydro. It is consistent (like coal, unlike solar or wind), but you can't turn it off when you don't need it! Ideally, you can pair it up with some batteries or pumped hydro to save the power you generate when it isn't in demand. Practically speaking, a nice mix of different sources can cover for each's weaknesses.

It is to a point possible to follow the load with a nuclear power plant by changing moderator setup, but only base load and not peak. Blocks cannot be easily stopped and started, but they can be throttled enough to handle the changes in demand. It is hour-scale tuning.

You absolutely can turn it off when you don't need it.

Restarting a reactor takes quite some time even with nuclear power densities.

See "xenon poisoning".

You can see on demand modulation[1], it's possible to variable 5% per minute of the full power generation of all nuclear reactors (of 60 GW).

[1]: https://www.rte-france.com/eco2mix/la-production-delectricit... look at 3 september 2018 for example, min is 36GW, max is 41GW, on one day.

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