[Schroedingersat]

Well, which technology passes this high-vault bar? Surely not one that is flat and possibly shrinking and is operating at a scale that is similar to that of grid storage and also needs storage to meet variable demand?

[Manuel_D]

None: there is no feasible method of grid storage at the moment. Hence why dispatch-able sources of clean energy are necessary

[Schroedingersat]

So which dispatchable sources can match the scale of energy generation at which renewables saturate the grid then?

[Manuel_D]

I explained this in the first comment to which you responded [1]. Hydroelectricity is by far the most effective source of energy generation, although it has the distinct disadvantage of being geographically limited. Nuclear power is the most effective dispatchable source after that. Every country that has decarbonized their electricity grid has done so primary through a combination of hydroelectricity and nuclear power. No developed country has deployed a majority wind and solar grid, ever.

1. https://news.ycombinator.com/item?id=33636418

[Schroedingersat]

A nuclear reactor requires about 0.5-1 tonnes of fissile material per GW per year and 3 to 6 years up front. Where is it supposed to come from?

[Manuel_D]

Mined, from the earth. Unlike lithium [1] uranium prices are not experiencing cost overruns. And unlike grid storage, nuclear power already makes up 10% of the world's electricity generation. We only need an 8x increase (another 10% of electricity already comes from hydro) instead of a 1000x increase like we do with grid storage. The thing about nuclear energy is that there's so much energy contained in uranium that more exotic forms of extraction like seawater absorption [2] is feasible. Unfortunately the same cannot be said of lithium. Some estimates predict that lithium reserves may be exhausted by EV production alone [3]. The volume of lithium required for batteries is considerably greater than the amount of uranium needed for fission, which makes seawater extraction non-viable.

1. https://tradingeconomics.com/commodity/lithium

2. https://www.forbes.com/sites/jamesconca/2016/07/01/uranium-s...

3. https://www.lowyinstitute.org/the-interpreter/race-lithium#:....

[Schroedingersat]

> Unlike lithium [1] uranium prices are not experience cost overruns

The 2007 Uranium bubble called. They would like to sell you some lithium futures for delivery on 2028 at costs based on an exponential fit.

> And unlike lithium, nuclear power already makes up 10% of the world's electricity generation. We only need an 8x increase (another 10% of electricity already comes from hydro) instead of a 1000x increase like we do with grid storage.

So after adding the first load for these reactors using hope, then operating them for 15 years, what do we do about the other 12TW of energy? What about the heavy casting facilities needed for thousands of reactor vessels? All the other critical minerals such as around half of the world's chromium production, vast quantities of precious metals and 100s of billions of litres a year of sulfuric acid production to process all the incredibly low grade uranium ore?

> The thing about nuclear energy is that there's so much energy contained in uranium that more exotic forms of extraction like seawater absorption [2] is feasible

I thought things that hadn't been done were completely impossible? Or do we get to acknowledge the TWh scale sodium ion supply chains and 100GW per year electrolyser supply chains that are being built right now as being vastly more realistic?

In any event, either this is a complete fantasy or the Vanadium that you necessarily get in much larger quantities even when using a sorbent that is as selective as possible for Uranium will provide half an hour to two hours of storage for capacity exceeding that of the nuclear reactor every time you refuel it. So at least filling the ocean with broken polymer ribbons will have a minor long term benefit.