[ben_w]

Not in this case I'm not — I'm saying here that "nuclear won't save it", which is different, especially as there are many other solutions.

You yourself elsewhere on this post are promoting hydrogen storage (I wish all the luck to whoever is working on that); I'm personally in favour of a global power grid; there's a bunch of fusion startups that may or may not get past the political hurdles plaguing fission even if/when they succeed at net power; genetically engineered bio-oils are also a possibility (as feedstock not just as fuel!); geothermal and tidal are also renewable but not seasonal.

But on the other hand, I am worried about non-aligned AI, about biodiversity loss, about peak phosphorus, and a whole bunch of other things.

[_hypx]

A global power grid is a far greater fantasy than building hydrogen storage, just FYI.

[ephbit]

There's a key difference between the current - mostly chemicals (coal, oil, uranium) based - system of providing people/machines/devices all over the world with energy and some proposed system where most energy is delivered in the form of electricity, generated from renewable sources.

Using chemicals to transport energy immediately leads to greater resilience because these chemicals always have a buffering effect, so they can buffer shorter and longer disruptions.

Many people appear to not have this in mind, when they propose a global electrical grid to power almost everything. An electrical grid is much more fragile than a chemicals based transportation system.

As soon as we see the first big tankers transporting green ammonia all over the world, say from Namibia or Australia or wherever, each one of these will contain weeks worth of ammonia (for some industrial site or whatever), which will mean added resilience since there's no one pipeline that can be damaged. Ships can flexibly go from any one to any other port.

But not only that. Due to the high energy density of chemicals, the chemical transportation system also has a much higher capacity than HVDC. Several ships can go from one place to another at the same time, and queue up at the point of arrival, while electricity from two sources to one destination would add up at some point in the grid.

Example:

> .. the vessels could carry about 58,000 tonnes of ammonia .. [1]

58,000 tonnes x 22.5 MJ/kg = 362.500.000 kWh = 362.5 GWh

Assuming a power generation efficiency of 0.4 (-> 145 GWh electricity), this is roughly equivalent to a 1 GW powerplant delivering power for 6 days.

Imagine trying to transport 145 GWh from Australia to Europe, or even just from windy Greece to Germany with HVDC. You'd need the 100 % capacity of a 2 GW HVDC line (1500 km long) over 3 days to transmit it all, during which this line could not be used for any other transmission purpose.

[1] https://www.icis.com/explore/resources/news/2021/08/10/10672...

[_hypx]

Thanks. You should reply to ben_w on this topic. That person is oblivious to the challenges of his HVDC dreams.

[ben_w]

Only because of the politics (if Texas can't get out of its own way, what chance international coordination?), and in that regard the comparison is "why not nuclear when it works?"

The tech is already known, the boring standard models of HVDC cable are good enough, the time it would take to build that capacity of cables is large but not ridiculously so.

[_hypx]

You do realize that hydrogen storage is also already known? The boring method of storing hydrogen in underground salt domes and caverns is well understood. This is all way more practical than crisscrossing the oceans with HVDC lines. And it completely evades all of the political showstoppers that a global grid would run into.

[ben_w]

Hydrogen leaks, damages storage vessels and pipes, cryo more so.

> The boring method of storing hydrogen in underground salt domes and caverns is well understood. This is all way more practical than crisscrossing the oceans with HVDC lines

Ah, no. Salt caverns aren't available everywhere. Getting the hydrogen around isn't easier than getting the electricity the hydrogen makes around.

Also storage is normally my pro-hydrogen talking point when I'm facing a hydrogen skeptic and saying why it's not the totemic bad thing you're acting like you think I'm saying it is — but grid storage is however the not the actual core issue the non-totemic skeptics in this thread actually have, they're talking about other things.

(That said, props for linking to a home h2 storage solution in that other thread).

Heck, when people say hydrogen can't be stored, I point at the 4 GWh hypersonic storage tube that the US government regularly built for single use.

But that's not the substantive sticking point for rolling to doubt.

[_hypx]

For underground salt domes and caverns? Leaks and damaged vessels are a non-issue.

Salt caverns are everywhere. In fact this is how we store natural gas today.

And the capacity is truly insane. It is on the order of PWhs: https://www.pv-magazine.com/2020/06/16/hydrogen-storage-in-s...

Not to mention that hydrogen pipelines move energy more cheaply than cables: https://www.brinknews.com/could-hydrogen-replace-the-need-fo...

[ben_w]

> Salt caverns are everywhere.

Do you have a map showing this?

Because AFAICT, they're mainly found in the same places as oil reserves, which is definitely not everywhere.

(PWh isn't remotely surprising for me, let alone insane; it is however necessary scale for any such storage system).

> AD VAN WIJK: By pipeline. That’s the interesting thing: It is about 10 times cheaper to transport energy by a hydrogen pipeline than by an electric cable. That makes it possible to transport electricity very cheaply from somewhere like North Africa to the demand centers in Europe, for example.

First I've heard of that claim; thanks!