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Comment by ajross | Hacker News Reader

So... this is a fuel-cell-adjacent technology, and as such you need to read announcements like this with a somewhat cynical eye. I have no reason to doubt the science here. It probably works, or certainly is no less likely to fail than any other new technology.

But here's the thing: PEM electrolysis promises to reach hydrogen production efficiencies of... 80% or so, using exotic materials and entirely new chemistries. Regular DC electrical electrolysis (literally the "stick a wire in water to make bubbles" experiment we all did as kids) is starting out around the 65-70% mark. This just isn't that much better.

And doubly so when you realize that the most efficient reconversion of that hydrogen to electricity is going to lose another 20%.

This is better, but it's only incrementally better. 30% cheaper hydrogen would be nice, I guess, but it's not going to change any fundamentals of the energy economy.

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> "And doubly so when you realize that the most efficient reconversion of that hydrogen to electricity is going to lose another 20%."

I think the real value of water-sourced hydrogen is going to be in three fields: synthesis of ammonia (atmospheric N2 + H2 -> NH3), direct reduction of iron ore to sponge iron (FeO + H2 -> Fe), and synthesis of methane and jet fuel (Sabatier and Fischer-Tropsch processes, respectively).

It's important to note, that that methane will be used by the chemical industry and not get burned, it's more efficient to burn H2 directly.

In Germany there's also plans to repurpose gas plants to burn H2 during Dunkelflaute. I'm curious if that will pan out.

But it should be noted, this is how progress usually happens, right? Little incremental gains in efficiency, added together over time.

Although that does make it hard to judge the significance of any one breakthrough.

Yes. But you don't plan on an entirely new organization of the energy economy on the basis of that. To pick other examples: VLSI scaling happened first, then the software industry explosion. Lithium batteries arrived first, then people started developing mobile devices (and eventually cars).

Planning on this great new "hydrogen economy" thing when even the best-case theoretical technologies represent only a mild improvement over what we have isn't responsible punditry, it's just playing "What if George Jetson had a Jetpack?" games.

Hydrogen doesn't suddenly appear to create a new kind of market, like sudden availability of jetpacks would.

Burning remainders of dinosaurs is on the decline. It is frowned upon by many due to CO2, it is not always readily available (see current war), and finally supply is limited. This leads to a decrease of availability, and at continuing demand an increase in price. Unavoidable.

Prduction of electrical power from renewables is the cheapest form available already today. Also, it can scale without any practical limit. Power just isn't always available when needed, with surplus production at other times. Any improvement in storage cost (mainly device cost, much less efficiency) decreases the price of power from storage.

At some point, the price of power from storage will drop below the price of power from fossil fuels. No magic step will be needed, simply increasing/decreasing prices will meet at some point.

> Yes. But you don't plan on an entirely new organization of the energy economy on the basis of that.

These kind of breakthroughs change the economics and composition of the new energy economy. They are not a challenge to the fact that harmful, limited, fossil energy is a very cheap and simple way to run an economy for a century or so.

Just to be clear. The one change everybody is waiting for is excess renewables capacity at peak times, not improvement on storage technologies.

Of course, improvement at storage will always be good. It's just not the bottleneck right now.

So, yeah, the article is great news. And it won't change the electricity paradigm at all. Both at the same time.

> The one change everybody is waiting for is excess renewables capacity at peak times

That's already the case in the northern parts of Germany. On windy days feeding excessive electricity to all neighbors, and still shutting down some wind turbines. The local energy company is planning 320 MW hydrogen production [0].

[0] https://www.ewe.com/de/media-center/pressemitteilungen/2022/...

80% isn't amazing, it's not ideal for an electric car, but it's not terrible either. IMO, to switch to 100% renewables, we're going to need grid-scale batteries, but it might also help if we had a mechanism to achieve seasonal energy storage.

I know hydrogen is hard to store, so I think it would be best if we could somehow use electricity to produce ethanol directly from CO2 and water (is that feasible with reasonable efficiency?). But just imagine if we could, in the summer, we could turn excess solar power into ethanol and stockpile it for the winter. We could also use that fuel to power jet airplanes and cargo ships without using any fossil fuels.

CO2 to hydrocarbon fuels (not ethanol, but methane and potentially liquid hydrocarbons as well) is exactly what Terraform Industries is planning to do.

https://terraformindustries.com/

Do you know what kind of efficiencies they get and how close to practical or not this is?

I’ve always worried about the energy density of batteries. They’re explosive enough as it is, imagine if it was 10x worse. I’ve always hoped that we’d transition to synthetic fuel - fuel like diesel is surprisingly stable and safe.

the batteries explode because of the materials in them, not because of the stored electrical energy. An full lithium battery wouldn't explode much more violently than an empty one.

I fly FPV so I deal with exploding batteries from time to time. Fully charged batteries explode much more violently than discharged batteries which tend to smolder instead. I suspect the additional electric discharge is adding ‘fuel to the fire.’

Interestingly, a discharged lithium ion battery still has electric potential in it, it's just that we stop discharging it after it hits a cutoff voltage to protect the battery's lifespan.

I wonder if a truly 100% discharged battery (down to zero volts) would actually be basically inert, and not even smolder if you poked it.

Lithium Ion batteries do burn much more readily when fully charged than when discharged -- this is because they self-discharge rapidly at elevated temperatures, which provokes an even greater reaction of the materials inside of them. Specifically, if the cathode of NMC/NCA batteries gets hot enough, it will decompose into oxygen and really kick off the graphite + electrolye burning. Discharged batteries are tougher to get to burn since it's harder to heat the cathode to that point externally so oxygen has to come from the environment.

This is not correct and is against basic thermodynamics and conservation of energy. Store a whole bunch of potential energy somewhere and you have an explosive. The more stored energy of any form, the bigger the boom.

Fuel infrastructure burns all the time, though. It's like every month there's a video of some tanker overturned on the highway, or a refinery fire, or a gas explosion. I don't have statistics in front of me but I'm all but certain that lithium batteries as deployed today are safer by pretty much any metric you want to pick.

I’m no expert on this but it certainly seems conceivable that a 30% cost reduction can be the difference between “not profitable” and “profitable”.

In regards to the efficiency argument against hydrogen: Sometimes that is an issue but sometimes it’s just not an issue at all. Fossil fuel efficiency is abominable but they’re still used.

If hydrogen would only halve the amount of usable energy, it would already offset the difference in a perfectly sunny location and one that's often cloudy. The case for wind energy is probably similar.

You can also increase efficiency by using waste heat.

Only if you have something nearby that needs low-grade heat, like warming buildings. Waste heat is a diffuse source of energy that's not worth the infrastructure cost of transporting more than a few miles.

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