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Nuclear is back on the table for a green future

nytimes.com

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Re: Nuclear is back on the table for a green future

#791

Post by qsdf38100 »

ncmncm wrote: post #788
qsdf38100 wrote: post #782

Earlier quoted context omitted.

10,000t weight? If it’s made up of rock with a density of 3000kg/m3, it’s 3333 cubic meters, so about 15x15x15 m3. Basically a large building. I’m not sure what kind of shaft can handle it. And even if you can pull it of, 10000t over 1000 meters is only 27 MWh of storage. 1 pumped hydro plant can store hundred of GWh!

(1) Rock is not very dense; pig iron density is 3x rock's. (2) A cube is not the only shape, for a weight. (3) Total capacity is not the only parameter of interest, for utility storage. (4) There is not only one mineshaft. (5) No utility is restricted to using only one kind of storage; different kinds favor different parameters, and we may expect utilities to use different kinds at the same time to maximize value and…

Rock is cheap. The shape is irrelevant. For grid scale, total capacity is what makes it grid scale. No amount of parameter tuning can change the fact that stored energy is at best mass * g * height. Adding more huge mineshafts is irrelevant. You can always add more units, it doesn’t make it more efficient.

Sounds like an Elon Musk solution. Make it bigger, taller, make more of it, and somehow it’ll bend basic physics facts to become the ground breaking disruptor technology of the next century.

Re: Nuclear is back on the table for a green future

#792

Post by WalterBright »

ncmncm wrote: post #774
WalterBright wrote: post #766

Earlier quoted context omitted.

The downside of pumped water, of course, is you need a hydroelectric dam and there are not many sites suitable for that. Those dams also come with significant environmental disruption. The weight system only requires part of a hillside, has a pretty small environmental footprint, and there are lots and lots of hills.

Not true. You can pump water to an existing hydroelectric dam, but you can also just pump it to a pond on a hilltop. No environmental disruption. There are lots of hills. The rail system needs maintained rolling stock and maintained rails. The mineshaft method is overwhelmingly cheaper and more reliable, because all that must be kept working is an electric winch. There are lots and lots of disused mineshafts.

Sorry, you can't make hydropower without constructing a dam, turbines, and completely disrupting the stream. This is environmentally destructive, and due to the scale needed, there are few suitable sites.

There are indeed many unused mineshafts, but a shaft would be only suitable for a small weight, maybe enough for a single house. This does not scale.

Re: Nuclear is back on the table for a green future

#793

Post by ncmncm »

pfdietz wrote: post #767
ncmncm wrote: post #651

Earlier quoted context omitted.

Vogtle will be cancelled before completion. That many $billions for 2GW is nothing short of pathetic. It cannot be cancelled soon enough.

I doubt that. It's too close to completion, sadly for the ratepayers in Georgia.

I guess they can mothball it afterward.

Re: Nuclear is back on the table for a green future

#794

Post by pfdietz »

ncmncm wrote: post #793
pfdietz wrote: post #767

Earlier quoted context omitted.

I doubt that. It's too close to completion, sadly for the ratepayers in Georgia.

I guess they can mothball it afterward.

Why should they? The state utility regulators approved it, so it's going into the rate base. That's not a competitive electricity market down there in the Southeast.

Re: Nuclear is back on the table for a green future

#795

Post by Manuel_D »

bob29 wrote: post #785
Manuel_D wrote: post #737

Earlier quoted context omitted.

> Uhh, mining and uranium enrichment and transportation all require fossil fuels, and more fossil fuel energy than a fueled nuclear produces in electrical energy. Incorrect. Nuclear power actually has the second lowest net CO2 emissions per energy source, second only to hydroelectricity. Less than solar and wind: https://en.wikipedia.org/wiki/Life-cycle_greenhouse_gas_emis...

So wrong its funny. Maybe if you assume the pre-existance of the nuclear supply chain due to a weapons program. I challenge you to actually follow the sources on any of estimates like that, or the hilarious "12g c02/kwhr" quote. It's all ESTIMATES (not measurements) FROM The nuclear industry. But keep on believing.

The estimates are from the IPCC, not from the nuclear industry. This is stated in the article.

Re: Nuclear is back on the table for a green future

#796

Post by pfdietz »

WalterBright wrote: post #792
ncmncm wrote: post #774

Earlier quoted context omitted.

Not true. You can pump water to an existing hydroelectric dam, but you can also just pump it to a pond on a hilltop. No environmental disruption. There are lots of hills. The rail system needs maintained rolling stock and maintained rails. The mineshaft method is overwhelmingly cheaper and more reliable, because all that must be kept working is an electric winch. There are lots and lots of disused mineshafts.

Sorry, you can't make hydropower without constructing a dam, turbines, and completely disrupting the stream. This is environmentally destructive, and due to the scale needed, there are few suitable sites. There are indeed many unused mineshafts, but a shaft would be only suitable for a small weight, maybe enough for a single house. This does not scale.

Pumped hydro doesn't require a stream, since it isn't harvesting energy from a preexisting flow of water.

Re: Nuclear is back on the table for a green future

#797

Post by WalterBright »

pfdietz wrote: post #796
WalterBright wrote: post #792

Earlier quoted context omitted.

Sorry, you can't make hydropower without constructing a dam, turbines, and completely disrupting the stream. This is environmentally destructive, and due to the scale needed, there are few suitable sites. There are indeed many unused mineshafts, but a shaft would be only suitable for a small weight, maybe enough for a single house. This does not scale.

Pumped hydro doesn't require a stream, since it isn't harvesting energy from a preexisting flow of water.

How are you going to create a large enough pond?

Re: Nuclear is back on the table for a green future

#798

Post by ncmncm »

sanderjd wrote: post #755
ncmncm wrote: post #680

Earlier quoted context omitted.

You need a very, very large mass, and then rails and rolling stock to carry it. That is why vertical motion in a disused mineshaft is attractive. A single 10,000t weight hanging from a winch has just one moving part, the winch, and cable all in tension, with no preparation of the shaft sides; everything is concentrated at the top. The mineshaft provides isolation from environmental disruption. You get much the same e…

I hadn't heard this sea float / winch idea before! Any links you could dig up for me? Anyone operationalizing this yet?

There was an "Undecided with Matt Ferrell" on YT some weeks back that mentioned a dumb version of it somebody at a university promoted.

That one had the winch and motor / generator at the sea floor, and a big rack of floats. It was, of course, too expensive. This is a common feature of energy storage ideas: people seem to love to promote the most stupidly expensive version of a good idea, and then give up when it is shot down for that.

Certainly, any scheme where you put complicated electromechanical stuff on the sea floor, it will be expensive. And likewise, where the expensive part is only usable with one "unit" of storage. Or anyway it just costs too much or needs perfect weather or something. (E.g., Energy Vault (NRGV) is stupid and their investors will lose their shirts.)

But there is usually a simple variation that lacks these problems.

Re: Nuclear is back on the table for a green future

#799

Post by ncmncm »

qsdf38100 wrote: post #791
ncmncm wrote: post #788

Earlier quoted context omitted.

(1) Rock is not very dense; pig iron density is 3x rock's. (2) A cube is not the only shape, for a weight. (3) Total capacity is not the only parameter of interest, for utility storage. (4) There is not only one mineshaft. (5) No utility is restricted to using only one kind of storage; different kinds favor different parameters, and we may expect utilities to use different kinds at the same time to maximize value and…

Rock is cheap. The shape is irrelevant. For grid scale, total capacity is what makes it grid scale. No amount of parameter tuning can change the fact that stored energy is at best mass * g * height. Adding more huge mineshafts is irrelevant. You can always add more units, it doesn’t make it more efficient. Sounds like an Elon Musk solution. Make it bigger, taller, make more of it, and somehow it’ll bend basic physics…

Efficiency doesn't matter nearly so much as is usually assumed. What matters is cost. Exactly, cost per Wh stored, and per W in and per W out.

Mineshaft storage is very, very efficient, but has an upper limit on energy per mineshaft determined by its depth and how much weight fits in it. The cost of the winch apparatus is amortized over that amount. More mineshafts means more total storage.

Pumped hydro has very, very low cost per Wh stored, but kinda high per W in and out. But thousands of pumped hydro systems were already built, almost, so seem free; they just needed pumps added.

Synthetic H2 and NH3 are very, very cheap per Wh stored. W out uses existing turbines, so seems cheap. W in depends on your electrolysers, which are improving fast.

In batteries, cost per Wh stored has been large, but is different in different chemistries. In a better chemistry it is lower. Flow batteries have lower cost per Wh stored, for any liquid chemistry, but higher per W in or out; and need plumbing and pumps.

Details matter. Numbers matter. Dumb choices make dumb designs. Dumb designs can be improved on.

Drawing conclusions based on dumb choices is just dumb.

Musk is dumb, but just barely smart enough to hire smart people and, sometimes, let them be smart. So, Hyperloop was just dumb, no matter who works on it. Starship is kinda smart, depending on what you can think of to do with it. Mars colonization is dumb. Starlink could possibly be smart, depending on a lot of details.

A wholly new capability, like radically cheaper mass to orbit, can often enable smart ideas. Super-expensive mass to orbit was good enough for weather satellites, planetary probes, and geosynch COMSATs.

Re: Nuclear is back on the table for a green future

#800

Post by ncmncm »

WalterBright wrote: post #797
pfdietz wrote: post #796

Earlier quoted context omitted.

Pumped hydro doesn't require a stream, since it isn't harvesting energy from a preexisting flow of water.

How are you going to create a large enough pond?

Maybe read up? When you just make shit up as you go along, you say dumb things.
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