Seawater split to produce green hydrogen (opens in new tab)

Between about 2000 and 2010 I kept seeing people say "well actually hydrogen isn't a power source it's a just a storage mechanism", since about 2010 I keep seeing people say "oh we can't possibly get to 100% renewables, storage isn't a solved problem".

And back in the 80s and 90s, the US was regularly making 3.5 GWh hydrogen tanks fly hypersonic while attached to strong enough pumps that it could've powered an entire medium-sized European country for the 500 seconds it took to empty the tank, and they didn't bother to make them reusable.

So yeah, I recon it will be used for heating and power. Not 100% sure because it has competition from batteries, pumped hydro, and a global power grid, but it's certainly viable and the competition will take time.

There’s a number of industrial processes that require higher temperatures than you can easily get from electricity. Replacing that with burning green hydrogen lets you decarbonize them.

Even if you can replace a furnace with an electric one, it may be easier and cheaper to replace a process burning gas with one burning hydrogen.

You can also use the hydrogen as a battery to move electricity into the future (with losses).

It is of course possible that there are better options for all of this other places, or that this process will not scale up well. And hydrogen has a lot of complicated logistics — storage and shipping are harder than larger gases. But a source of cheap green flammable gas has a bunch of potential applications.

Industrial chemistry. Steel making uses coke to reduce ore but could use hydrogen if it was cheap enough. Fertilizer like ammonia (NH3) is produced with those H's coming from methane, releasing carbon.

If it's nearly 100% efficient it becomes a low loss battery. Floating turbines could generate hydrogen in periods of low demand and send to a floating compressor and storage system to be used for energy generation or chemistry or airships, whatever

The country I live in is very small and has no natural resources. We rely on having oil shipped to us. From our point of view replacing oil with hydrogen would be an improvement. Due to various geopolitical and geographic issues relying on electric cables to supply us with power from our neighbors may not be a viable option.

The oxygen byproduct does not figure favorably unless it can more than pay for itself.

Seems like the same amount of electricity will always have more energy than the amount of hydrogen it can be turned into.

Takes theoretically a minimum of 39 kwh of electricity to make 1 kg of H2.

Decently efficient processes still use up 48 kwh so far to make 1 kg of H2 since they are not perfect.

1 kg H2 yields 120 to 140 MJ when burned

or probably the lower of 33 to 39 kwh depending on how you calculate the heat.

Keeping in mind the only way to get 39 kwh back out is if the byproduct oxygen actually consumed none of the electricity during the gas production.[0]

Probably quite a bit lower for domestic heating due to losses out of exhaust flues that are necessary.

Indoor heating using the same electricity will always be more efficient than turning the electricity to hydrogen first.

[0] didn't calculate that far myself to be sure.

Your line of reasoning is the one I always take on these sorts of things. If it takes X input energy to make energy saving Y, if Y is not significantly more efficient than X, it's probably a net loss.

A lot of green stuff ends up being much less cheap/green if one looks at the total cost and environmental impact of the thing over its lifetime (including efficiency loss over time, mineral extraction, labor, electrical source, etc).

Energy has always been an expense people want to minimize. There's not a ton of low hanging fruit here.

Someone else mentioned ammonia, steel, and similar industrial chemistry applications, but another use case is transportation. I think regular ground transportation is going to mostly be battery electric eventually, but it's not really practical now to use batteries in planes except for narrow use cases. (Hydrogen has issues too, but they're probably not quite as difficult to solve.)

Ships also might use hydrogen as a fuel, if we can't find a better low-carbon alternative.

If something is nearly 100% efficient, how can anything else be significantly more cost effective?

Zepelins and rockets?

The paper is being widely discussed everywhere. I didn't get it (paywalled), but it seems the high efficiency claim means that way more than 95% of the electrical current goes into electrolysis.

Overall, the most important thing is that this thing is cheap. Everything else you read around just means it's equal or not much worse than the usual electrodes.

I read it as with exactly the same number of joules of electricity as the enthalpy of formation of the water they electrolyze (not sure about the terminology, it's been a while since I took chemistry). Basically the electricity supplies exactly enough energy to pop off the hydrogens.

I'd wondered the same, but even with that question hanging I think the outcome of being able to electrolyse sea water directly was interesting.

Seems like a good first step in desalination.

Hydrogen is a terribly dangerous thing to keep around for fuel. I've been in garages where fuel cell vehicles were being developed alongside EVs. They had hydrogen detectors and alarms. In case of leaks, evacuate. It has a very wide range of concentration where it will not just burn but explode. You don't want this in your neighbors garage.

Don't know about the rest, but the salt can probably just stay dissolved. Their feedstock is cheap, costing a bit of pump electricity at worse, so I assume they can turn just a little bit of it into gas and toss the rest overboard.

>And what happened with the last five promoted articles for new electrolyzers?

I get the sentiment, and it’s one that comes up across a lot of cleantech articles. I think it feels like this because early stage stuff is often published by academics, but the next steps (where the technology ultimately dies or goes to market) are usually shrouded in NDAs and corporate secrecy.

I've always wondered how they prevent all the salts from reacting. Or what they do with side products.

If you run electricity through salty water, you tend to get a whole bunch of interesting chemistry happening.

There are products you can buy that perform electrolysis on water with a small bit of salt to make bleach (sodium hypochlorite).

If you bung in a shitload of salt, you eventually get sodium chlorate, or perchlorate forming, depending on the amount of amps you chuck in.

You also get chlorine coming off, etc...

You can kinda limit or control this with membranes, but with seawater you have a fuckload of side reactions that are going to happen.

The article contradicts your point but justifies itself by just handwaving over it:

> So called green hydrogen has its own problems. Yes, it is technically possible to use renewably-produced electricity to electrolyse water, to make hydrogen – but you need a huge amount of electricity to produce a small amount of hydrogen.

If we can improve the efficiency of electrolysis production of hydrogen, then I don't see how it's greenwashing if it's possible to produce hydrogen without carbon.

Millions of tons of hydrogen will be necessary for fertilizer production and other industrial processes for the foreseeable future. If this hydrogen is produced using electricity from no carbon sources, what would your objections be? What do oil companies have to do with hydrogen not derived from any of their products?

I'd say overall that hydrogen is an attractive proposition because once you have the infra for it, you can substitute whatever color of hydrogen you want. The trick will be making sure we can easily replace gray hydrogen in the future for green.

Well, the proper color for anything hydrogen is "shadow" because all mass market placement of "hydrogen" is the oil industry trying to delay the onset of EVs and alternative energy.

Don't get me wrong, there is legitimate scientific aspects to green/blue/black classification, but those don't matter, because what is being discussed here is in the fantasy land of news media. Anything "green" or "blue" in hydrogen is something far off in the future and they will use fossil fuels in the "short" run. Almost like, it is an "aspirational" green power source. Green, as in, someday theoretically it can be green.

For SPECIFIC industrial use cases, I welcome hydrogen as a possible step off of fossil fuels, you know, someday. Fertilizer, steel, etc. And I like the discussion of reusing existing natural gas turbines and other equipment but... anyway, don't get your hopes up.

They tipped their hand with the "100%" figure. Hey guys, look, we violated the basic laws of thermodynamics! That's why the reporting on hydrogen is so hair-pulling, everything is smoke and mirrors and obfuscation and fake numbers and miracle technologies, so even where there is legitimate potential and uses, I completely distrust it.

I mean, I have to go to goddamn reddit to get a discussion of the "100%" figure:

https://www.reddit.com/r/science/comments/10rvo8x/comment/j6...

100% is for Faradaic efficiency.

"Faradaic efficiency only looks at the efficiency of charge transfer and is not the same as the energy conversion efficiency. The latter is usually meant when speaking of "efficiency" of hydrogen production and it will likely still be ~60% for this new process.

Fucking ridiculous.

TLDR The title is highly misleading."

Fuck your latest "magic hydrogen technology" of the day.

So are there strange quarks?