[Aperocky]

> simply a form of energy storage

A very bad one at converting from/to electricity. Obviously, if you start from something else, e.g. dinosaur, then it's great.

But if you want to use it to store electricity, it's extremely poor due to the conversion involved, any kind of battery (and iron battery is a promising one!) is much better.

[ncmncm]

Batteries will always be the most expensive alternative.

[Aperocky]

For single use, sure.

[ephbit]

> ... any kind of battery (and iron battery is a promising one!) is much better.

Good luck trying to break even with as many batteries as would be needed for weeks or months worth of energy/electricity.

[ncmncm]

Nobody needs "weeks or months" of storage.

If local storage looks likely to be used up, and you can't schedule power from a transmission line, you order a shipment of ammonia from any of many tropical solar farms.

[ephbit]

Sure everyone does.

Let's say renewable electricity generation capacity increases significantly (which needs to happen as we all know), then due to fluctuations around the year of solar irradiation alone there need to be weeks if not months worth of electricity storage (in whatever form).

Ammonia is exactly that, storage of energy that gets converted to electricity, to keep up with grid demand. Ammonia then _is_ your weeks/months worth of storage.

[ncmncm]

Hint: many places do not, in fact, experience annual reduced insolation, and can produce equally year-round. We call those places "tropics", maybe you have heard of them.

Do you think utilities store months of fuel, nowadays? Or do they rely on regular deliveries? Do you think relying on regular deliveries of ammonia, in winter, would be much different from relying on deliveries of NG year-round, as today?

[ephbit]

> ... many places ...

Yet I'd assume _most_ places in the global west still have fluctuating irradiation and wind to a degree that makes weeks worth of storage necessary.

> Do you think utilities store months of fuel, nowadays?

The utilities probably only to a certain degree. But it doesn't really matter who stores the fuel, right?

> The United States has the world's largest reported strategic petroleum reserve, with a total capacity of 727 million barrels. If completely filled, the U.S. SPR could theoretically replace about 60 days of oil imports. [1]

These reserves are of course not used to supply power plants.

But I'd bet as soon as the renewable slice of electricity generation exceeds some 50-60 % of total supply, the authorities will not have days but weeks or maybe months worth of natural gas or hydrogen or ammonia stored to supply the grid (with according power plants) over extended periods of low renewable generation.

Just thinking about how essential the electric grid is for society to work, convinces me that it won't be days worth but significantly more.

[1] https://en.m.wikipedia.org/wiki/Global_strategic_petroleum_r...

As to deliveries from around the world. Any country will of course make a trade off between the political goal of independence or self sufficiency and economic considerations. Countries that have sufficient renewable electricity generation potential to be independent from external supplies will rather try to avoid external dependency, don't you think?

Which would require storage.

Also, imagine what happens as combustion engine cars get replaced more and more by EVs. The strategic petroleum reserves probably become less important and grid stability becomes more important. And I don't think the EV batteries are going to provide enough buffer to enable a stable grid all year round.

[ncmncm]

Almost all countries have "external energy dependency" today, US conspicuously among them. Why would they all, suddenly, need independence, just because they use renewables?

You miss the point about the tropics, again. Places with reliable insolation will be exporters of synthetic fuel. None will have monopoly power, because the sun shines on them all equally. Northern countries may buy as much as they can use from them, so will not need more storage than for the time until the next shipment.

The US keeps a "strategic petroleum reserve" specifically because it has been subject to embargo by a limited group of producers. There can be no such embargo of synthetics from renewables, so no value in any such "strategic reserve".