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Comment by pfdietz | Hacker News Reader

You are repeating a common, but very flawed and invalid, argument there.

Yes, batteries are more efficient than power-to-hydrogen-to-power. But the "cost of inefficiency" is proportional to the number of charge-discharge cycles of the storage system over its economic lifespan. For diurnal storage, you'd be correct, hydrogen is a poor choice. But diurnal storage is only one storage use case. For other storage use cases, such as seasonal storage, or backup against rare prolonged outages of renewable sources, there are relatively few charge/discharge cycles. For those uses, hydrogen is vastly superior to batteries.

The argument that hydrogen would imply use of fossil fuels is nonsense. Fossil fuels are going to have to be kept in the ground in general by punishing legal sanction. What makes production of hydrogen somehow immune to that?

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Seasonal storage of electricity will never be a thing because nowadays it's easier to just build a large solar array somewhere sunny and a long HVDC line. The UK is planning on doing just that:

https://www.power-technology.com/projects/morocco-uk-power-p...

The project is projected to cost close to $22bln, which sounds like a lot, but is still less than the cost of yet-to-be-finished Hinkley Point C.

Seasonal Gas storage will never be a thing, you can just rely on a gas pipeline from Russia, nothing will ever go wrong

That’s an idea that would make even Gerhard Schröder blush.

Seasonal storage will not be a thing, but not for that reason, most places.

Plentiful solar farms in the tropics will synthesize ammonia and ship it in liquid form anywhere. There will be no possibility of embargo.

Cities far inland will rely on transmission lines from the coast, when local reserves run low.

Probably few places will bank more than 2 weeks' worth, locally.

The best thing hydrogen has going for it is that it’s easy to scale up without needing significant increases in mining and processing various minerals.

If you are willing to increase mining, and want the cheapest solution, and you can ignore or solve geopolitics, the “best” solution is neither hydrogen or batteries, it’s to make a several square meter cross-section HVDC loops around the planet, because nighttime winter is never more than 20 Mm from daytime summer and the losses are low enough that it is still worthwhile.

But: you probably still want hydrogen and batteries for the vehicles, and vehicles use so much power that solving transport almost automatically gives you enough used parts to build the storage capacity for the electricity grid, and that even with batteries (and over-provisioning PV, which is fine because of how cheap it is), there would be enough storage for winter.

> and you can ignore or solve geopolitics

That's a hell of an "if" statement there my friend :)

I agree though, in a thousand years there will be a worldwide electricity grid that takes care of the "big picture" energy flows; hydrogen will be created as needed to serve as chemical feedstock to make eg plastics or hydrocarbons for specialized purposes. That or we kill ourselves in the meantime, but since killing everyone is in nobody's best interest I don't think that'll happen. Hopefully.

> That's a hell of an "if" statement there my friend :)

Indeed! It's one of many reasons that "the best" isn't always the real best.

I'm extremely optimistic about technology, but not so about politics.

> several square meter cross-section HVDC loops

Let's take one half-way around the world.

That's 1 sq m * 20000 km = 20000000 m^3. Let's take aluminum because it's cheap. 2.7 tons/cubic meter = 54 Mt.

Multiply by price: $2444 x 54M = $132B for just the wire. That's $16.5 per capita.

But you also need insulators, labor, machinery, design, and so on.

It’s not that high, if you consider that we consume 150 terra watt hours per year worth of energy. Even if we assume a (unrealistically) low cost of 1 cent per watt hour for transportation, it means we spend at least $1.5T to transport our energy per year.

Extremely cheap! Unfortunately global production is currently 64 Mt/year[0], so the world would need to sustain an increased production for a while. (Especially as square meter cross section is the order-of-magnitude answer, not an exact value).

[0] https://en.wikipedia.org/wiki/List_of_countries_by_primary_a...

The best thing hydrogen has going for it is the cost of energy storage capacity can be as low as $1/kWh (vs. 100x that for batteries.) Underground storage of compressed gases can be very cheap.

You mean seasonal storage near the polar circles and emergency generation?

Because in general it's much cheaper to deal with seasonal variations by adding generation than with storage, and 'rare prolonged outages of renewables resources' doesn't even begin to make sense to me.

Let's look at the cost of providing "synthetic baseload" in Germany (with production via renewables just in Germany) in a toy model using real weather data and plausible cost assumptions for wind, solar, batteries, and hydrogen.

https://model.energy/

If you use just wind/PV/batteries, the cost is almost TWICE that if you use wind/PV/batteries/hydrogen. This is for a cost optimized system relative to real historical weather data, in a solution where one is allowed to overproduce if that helps.

So, no, it's not true at all in general that it's much cheaper to deal with seasonal variations with overgeneration rather than including storage.

And, you don't need much storage anywhere, because more can be shipped in. Although if you have salt domes, you might as well use them.

And if you don't have salt domes, you can use more laboriously excavated caverns in hard rock. This would still be an order of magnitude cheaper than batteries per unit of storage capacity.

But, more expensive than other energy storage methods. Sometimes though you really want to store hydrogen, not just any old energy. A disused mineshaft often suffices. The world is absolutely perforated with disused mineshafts, that only need a lid.

A buried LH2 tank can have very, very good insulation. You probably want to flare off or re-liquify any boil-off, because H2 has, all told, something approaching 200x CO2's GHG potential.

More like 11x (depending on the timescale). Hydrogen itself has no GHG potential (no IR absorption), but it does soak up OH radicals that would otherwise destroy methane, so it acts as an indirect methane source.

https://newatlas.com/environment/hydrogen-greenhouse-gas/

That model is odd.

Anyway, change only the assumption that hydrogen storage is free underground and watch its usage plummet into less than half. Change the country to India (that we are talking about) and see it go near zero.

Anyway, it's comparing free underground hydrogen with encapsulated portable batteries. I expect none of those to be very useful on practice.

Huge amounts of natural gas are stored underground in artificial caverns. The same geological formations can be used to store hydrogen. This is not some suspect newfangled technology.

The storage is not free, but it is extremely cheap, compared to the cost per energy capacity of batteries. Ignoring this fact will not make it go away.

> This is not some suspect newfangled technology.

Is there somebody that did a practical small scale run of this?

Hydrogen storage has a huge amount of issues that natural gas doesn't. By its face value, storing hydrogen in a natural container doesn't look viable.

Yes, it's been done it least three places, to act as a hydrogen buffer for ammonia production (decoupling the steam methane reformers from the ammonia plants for greater operational flexibility.)

There are also large scale plans in progress to do it for grid energy storage, for example in Delta, Utah. The salt formation there has enough space for 100 cavities that could, altogether, store enough hydrogen to power the average US grid electrical energy consumption for about a day.

Just to add, after playing a bit more with the model, I can tell why it's odd.

It's supposed to be a very conservative model, with very high probability targets for costs and availability. Because of that, it's focused on public data of mature technologies. But the hydrogen industry mostly doesn't publish anything, and doesn't sell to the general population, so its numbers are all over the place.

It also ignores the equivalently closed numbers from other industries (batteries mostly), in favor of the very public values in open markets. As well as it ignores the more location dependent options, and the less consensual ones (like hydro and nuclear).

Overall, it achieves its goal very well. It's very unlikely that the reality will look like it or worse, it's almost certain it will be better.

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