Isn't this the crux of the argument for investing more money into solar/wind/storage vs nuclear. The solar and wind stuff is already cheap enough, so its storage vs nuclear. Will nuclear get cheaper faster than grid-scale batteries? There is only so much capital that can be invested, and potential advancements in batteries are looking a lot more promising than advancements in nuclear. I think the lion's share of money should be going to renewables and batteries.

Batteries are the most expensive storage. They cost per kWh stored, while others cost mainly only per W inserted or extracted. Only a minuscule fraction of utility scale storage will ever be batteries, so even mentioning batteries only details discussion.

What will it be then? Flywheels?

It will likely have to be a combination of many different types of storage, plus decentralization/distributed storage (electric cars, home & office battery backup), plus smart grids and appliances (time-shiftable smart electric water heaters/HVACs/car chargers), renewable biofuels for peaking, etc., riding on top of a base load of hydro and geothermal. (My vote's for nuclear, but it's wildly unpopular).

They are counting on lithium-ion batteries becoming dramatically cheaper at scale due to increasing demand for electric cars.

There's an entire agency/thinktank/R&D center working on this stuff, NREL: https://www.nrel.gov/analysis/storage-futures.html (or shorter summary: https://www.nrel.gov/docs/fy22osti/81779.pdf). They do a lot of good work, but sadly no one really listens to them, either policymakers or the public :(

Nobody is counting on lithium-ion batteries becoming dramatically ("even") cheaper. Batteries will remain one of the most expensive storage methods. They will be used mainly for load leveling, and in very small-scale systems.

Nukes are not just unpopular, they are also way, way, way more expensive than favored methods.

I'm just paraphrasing NREL there. If you have a better grasp of the industry, which solutions in particular do you see?

I like gravity storage. Pumping water up a hill, or pumping air into an underwater tank to displace water. Seems that you can get quite good efficiency with these approaches.

AFAIK though only pumped water and batteries have been done at anything approaching utility scale. Anything else and you're probably looking at several decades to reach maturity, and then another several decades to roll it out.

All but chemical methods rely only on trivial physics used industrially billions of times worldwide every day. The only open question is which will have become cheapest, in each place, at the time that conditions become favorable to build it.

That time will arrive after we have brought enough renewable generating capacity online that storage would not need to be charged by burning fossil fuel.

There are many storage alternatives, each more attractive for certain circumstances. Undersea methods are particularly cheap, but synthetic fuels -- ammonia and hydrogen -- have advantages that offset higher cost.

What we can be certain of is that Energy Vault (ERGV) investors who get out last will lose badly.

There isn't enough time. The world is already way behind on climate change. Nuclear is a mature and safe technology, on a incidents/pollution/deaths per kWh produced basis. Storage is in its infancy. Yes, more investment in that field would be great, but that's a timescale of decades that we don't have -- especially the rest of the world. Realistically we need something much bigger than the Manhattan Project to even have a chance in hell of making an impact at a utility, much less national or global, scale. There's nothing like that even on the horizon, simply no political will.

Small to medium investors and companies are trying to tackle it at the locality level (Tesla, small utility experiments, etc.), but there are no national or international movements to solve this issue wholesale. And until it is solved, adding more renewable production without storage to an already-capped grid doesn't really help the issue; in fact it worsens it by creating huge peaks and valleys in power production that are then compensated for by fossil fuel peaker plants (because nuclear can't ramp up and down that quickly). California is the example of this.

At the end of the day renewables vs nuclear is a false dilemma. The actual issue is future livability vs present-day profit, and the latter always wins in our political economy. We need vision and political will to get us there, way more investment in both renewables and nuclear, on the timescale of years, not decades, with nuclear providing a band-aid while R&D on storage increases several orders of magnitude.

It's the sort of problem that the private sector cannot easily solve; it would take mass national and international collaboration, or perhaps an arms race.