[Manuel_D]

> at ~3g/kg the uranium only has about 10x as much energy as you'd get by burning the polymer or 5x in the current nuclear fleet (wonder how much it takes to make?). There goes the much vaunted EROI unless you get quite a few reuses (hint: you only get a few).

Except the polymer is re-usable.

> The longer you leave it, the more Uranium gets displaced by Vanadium. At 2 months you get 5x as much.

Until it's saturated, then you can leave it out all you want and it won't collect any more. And I had thought you were referring to lithium seawater extraction - you just tossed out vanadium without actually explaining how you'd use it and I assumed you mistyped lithium.

Unfortunately vanadium redox batteries are not nearly built at the scale of lithium batteries - which are themselves not built at a scale large enough for grid storage - as well as poorer round trip efficiency.

[Schroedingersat]

> Except the polymer is re-usable.

A few times: https://www.ornl.gov/publication/investigations-reusability-...

As I said, there goes your eroi. At 10mg/kg you're producing 10,000 tonnes of polymer per year per reactor and harvesting it 3-6 times. This is supposed to be economical? That's 10 million tonnes of plastic waste per year just for one terawatt or 10% of world plastic waste to replace FF electrical generation.

> Until it's saturated, then you can leave it out all you want and it won't collect any more.

If you leave it in too long the Uranium starts going out because Vanadium has higher concentration and similar affinity. But long before that, your polymer breaks down and becomes microplastic pollution.

> Unfortunately vanadium redox batteries are not nearly built at the scale of lithium batteries - which are themselves not built at a scale large enough for grid storage - as well as poorer round trip efficiency.

So now we're back to this incoherent dissonance where doing something once on a tiny test platform makes it a definite solution to world energy, but something being produced at GWh scale in the real world is not big enough? That's a truly stellar amount of double think you've got going on there. I'm sure there'll be even more interest when your magic $20/kg unlimited supply vanadium machine running at 20x current total production is up and running.

[Manuel_D]

> A few times: https://www.ornl.gov/publication/investigations-reusability-...

The adsorbent loses efficiency after a couple elution cycles, but it is regenerated by an alki wash. Read this [1] if you want a better explanation. No, you do not need to keep producing tons and tons of polymer. You have to treat it with chemicals after a couple cycles, but you don't need to throw the whole polymer away and start anew.

Regardless, this whole seawater extraction tangent is only a contingency if no new terrestrial reserves of uranium are found. Unlike intermittent sources which require massive amounts of grid storage, uranium seawater extraction isn't going to be necessary any time soon which is why I'm not super concerned about how seawater extraction isn't being commercialized.

On the other hand, renewables are already starting to saturate the market during peak production today. In order to make intermittent sources viable we need storage systems now. It's not dissonance, it's the fact that there are presently functioning alternatives to seawater extraction that will continue to work for the near to mid term future. Whereas there are no storage systems capable of delivering energy at grid scale.

1. https://www.osti.gov/servlets/purl/1423067

[Schroedingersat]

> The adsorbent loses efficiency after a couple elution cycles, but it is regenerated by an alki wash. Read this [1] if you want a better explanation.

..The longest lasting method in that paper is a scale model in idealized conditions of the same method I linked to but the first was in more realistic conditions... they ran one in the ocean but not more than once.

> Regardless, this whole seawater extraction tangent is only a contingency if no new terrestrial reserves of uranium are found. Unlike intermittent sources which require massive amounts of grid storage, uranium seawater extraction isn't going to be necessary any time soon which is why I'm not super concerned about how seawater extraction isn't being commercialized.

So we're back here. To match the scale of renewable when they start to run into the constraints that require scaling up storage, you need about 3TW by 2030 (before then a mix is viable along with using surplus for replacing non-electrical fossil fuels such as H2). That's 10,000 tonnes of fissile material up front, and another 10,000 every reload. You need to open every mine on the planet today and empty them by 2040. Then your sea mining rig needs to be ready to go (and hilariously has to be installed on a greater net capacity of offshore wind turbines than the capacity of nuclear reactors it supplies). After that you still need just as much storage for variable loads because ramping isn't an option as idle capacity would reduce your fuel runway by 6 years.

All this because you think lithium production can't double when the extraction started a year ago? It's actually a comically bad plan. Well done. The bit where it needs the wind turbines was comedy gold.

[Manuel_D]

> ..The longest lasting method in that paper is a scale model in idealized conditions of the same method I linked to but the first was in more realistic conditions... they ran one in the ocean but not more than once.

Sure, they may need to regenerate the adsorbent after just one use. But the polymer survives. Even if the adsorbent retains most of its efficacy after one elution cycle, it could be more efficient to refresh it to maximize the material collected per trip. You seemed to have been under the impression that the entire polymer needed to be replaced when you talked about how it'd be more effective to burn the polymer: "at ~3g/kg the uranium only has about 10x as much energy as you'd get by burning the polymer or 5x in the current nuclear fleet"

For what it's worth I am confident that lithium ion battery production will continue to increase and double, triple, or even quadruple over the next century. But that will be barely enough just to satisfy EV demand for batteries. Even just provisioning 12 hours of grid storage worldwide would need 30,000 GWh at present electricity demand. That's close to a century of production at present rates. Doubling, tripling or even quadrupling production still means we'd need to dedicate several decades worth of battery production just to satisfy 12 hours of present electricity demand. Not to mention the fact that electricity demand is going to increase as more transport moves to EVs and as poorer countries develop. Not to mention the fact that these batteries need to be replaced after a few thousand cycles.

I'm confident about battery production doubling or tripling, it's the factor of 10 to 20 that I'm more skeptical of - and that's the kind of increase we'd need to make battery grid storage feasible.

[Schroedingersat]

The polymer is the sorbent. Please actually read the sources you send. Normally it is on a higher strength belt, but this scheme puts it in a plastic shell. That's the bit their charts show with tens of thousands of tonnes needed per fuel load (which turned out to be optimistic when someone checked).

> For what it's worth I am confident that lithium ion battery production will continue to increase and double, triple, or even quadruple over the next century. But that will be barely enough just to satisfy EV demand for batteries. Even just provisioning 12 hours of grid storage worldwide would need 30,000 GWh at present electricity demand. That's close to a century of production at present rates.

You're off by over a factor of 3. There's around 1TWh/yr now, and 5TWh/yr under construction due before 2030. And only a few hours needs to be high power. The rest can be thermal, PHES, CSP dispatch, virtual batteries via load shifting, hydrogen for emergencies, and so on.

> I'm confident about battery production doubling or tripling, it's the factor of 10 to 20 that I'm more skeptical of - and that's the kind of increase we'd need to make battery grid storage feasible.

It's happened, if it were a nuclear project then it'd be at the stage where they've already declared it finished, but shut it down straight after loading and said it will reopen in a month. Other industries do things a little differently, but either way it'll mostly be running around 2028

[Manuel_D]

I'm not sure why you're fixating on the plastic shell, that's just one of several delivery mechanisms for the adsorbent polymer. The belts attached to weights is a more common proposal. Regardless, each elution cycle - that is cycles of putting the polymer out to sea, and harvesting the captured uranium - does decrease effectiveness. But after several elution cycles the polymer is refreshed. Even the more pessimistic study you linked to found that it'd cost $830/Kg on the upper bound. This is only 8x the cost of existing mining methods, and wouldn't substantially increase the cost of nuclear power because enrichment is a bigger component of fuel cost than extraction. And construction is a bigger cost than fuel, too.

We also don't make a terawatt of batteries per year. 2021's total lithium ion battery production was less than half a terawatt [1]. Most estimates place it between 300 and 500 GWh. Don't confuse predicted capacity with actual production figures. Production is often half of projected capacity or even less [2]. You're overstating battery production by at least a factor of two.

And as far as predictions about battery growth goes, we can't build an electricity grid on predictions. People said we'd be harnessing fusion by the end of the millennium. People said we'd all be using VR headsets as the primary means of interacting with computers back in the mid 2010s. People make all sorts of predictions about what could happen. Actually making it happen is a whole different story. The way to make the case that battery production can reach 5,000 TWh per year is to deliver 5,000 TWh of batteries. We haven't even accomplished a tenth of that.

By comparison several countries have transitioned most of their electricity generation to nuclear, and plenty more have built 30-40% of their generation capacity with it and don't need any more because they have hydroelectricity. The viability of nuclear power isn't a prediction, it's historical precedence. Nobody has built any significant amount of grid storage. Nobody developed countries has generated more than 50% of their electricity from wind and solar. This has, on the other hand, been done with nuclear. Demonstrated precedence vs. eager predictions. I'm much more keen on betting the future of planet on the former.

1. https://www.interactanalysis.com/lithium-ion-battery-market-....

2. https://www.spglobal.com/mobility/en/research-analysis/growt....