Seawater electrolysis ignites new hope for affordable green hydrogen

FT article references https://www.chemistryworld.com/news/water-splitting-device-s..., which is free and references the actual paper at https://www.nature.com/articles/s41586-022-05379-5

or the DOI https://doi.org/10.1038/s41586-022-05379-5

There is no fresh watter at sea wind generator fields.

Yes, exactly this. These membranes will foul and need replacing. I don’t see why anyone would use this over freshwater. There’s plenty of freshwater available in many places. It literally runs into the ocean. You just don’t build one of these plants in the desert. It might be interesting in niche cases - desert countries where they're already producing water via desalination. But those countries tend to produce energy from fossil fuels anyway, and it's less effective to burn fossil fuels to split water than it is to just split methane to begin with. Maybe in the far future.

Even fresh water needs to be filtered before running it through the electrolysis. But yes, part of the problem with electrolysis is the power cost compared to current "blue" hydrogen, which is decarbonated natural gas. Some of the better places to get electricity though have been places with little fresh water, so being able use saltwater instead helps with this idea.

Given how cheap PV is, I think the limit is "we'd rather not actually try to keep it as moleculer hydrogen, how do we add carbon or nitrogen to it?"

Yeah, this is something of a problem; it makes the capital cost quite high, which in turn makes it less useful for intermittency and less cost-effective as a means of energy storage.

Solar is Fusion .. and already available in direct light, indirect wind, and totals some 173,000 terawatts continuously reaching earth, or some 10,000x current total energy use.

Usable Earth based Fusion is still quite some time away, meanwhile the immediate issue of mitigating fossil fuel byproducts is pressing.

Economics is more complicated than is X possible. We can make and store antimatter, but all those sci-fi applications that need significant quantities are still dozens of orders of magnitude outside our reach.

It's not fusion we need, it's cheap non polluting energy.

Fusion _might_ become that cheap non polluting source, but right now we don't know. What we do know is: renewables are cheap right now.

Now applied to hydrogen, we can even say that hydrogen production can perfectly adapt to the intermittency of renewables. But I'm of the opinion that we need to decarbonate our grids further before we start looking into using renewables for h2 production.

We don't want to just hang everything on "Once we harness fusion". We gotta act now, not in 100 years.

How are you going to turn that fusion based heat into electricity?

Coal and nuclear are uncompetitive simply from the cost of the steam side. Today you can just about give a steam plant free energy and it still makes a loss.

Solar or wind does not have this limitation. CCGT gas plants gets around it by having a turbine giving raw mechanical power and then utilizing the same awful steam side to get the last percentage points of efficiency at a much smaller required scale.

Unless you can step around the steam turbine I am not so positive on fusions future outside of incredibly small niches.

It would suffice to dissolve oxygen in river water on its way out. All the dead zones are at river outlets.

The hydrogen freed would need to be sequestered to burn later, because hydrogen is insoluble in water, and is a 200x greenhouse gas (when counting secondary effects).

There will be a hell of a lot of spare oxygen available to dissolve in water and flush to rivers, after we start producing green hydrogen.

But just bubbling regular air through should suffice to saturate it, no electrolysis needed. A big perforated plate, with water running over it and air pushed under, does the job without fuss.

It's absolutely impossible to deplete a significant, or even an insignificant portion of the world ocean.

To get a feel or it, it's useful to think in terms of cubic kilometers. A cubic kilometer of water weighs a billion tons (1 GT). The world consumes every year something of the order of 10 GT of fossil fuel (about 5 GT of coal and 5GT of petroleum and natural gas). Hydrogen has a higher energy density than fossil fuels (by a factor of 2 or 3). But only 10% of the water by weight is hydrogen. So, to get one GT of hydrogen you need to electrolize about 10 cubic kilometers of water. Let's say you want to fully replace all the fossil fuels with hydrogen, and then have room for further growth. 10 GT of hydrogen/year will be more than enough regardless how you project that growth. That would be 100 cubic kilometers per year, or 10000 cubic kilometers per century.

The volume of the world's oceans is 1.3 billion cubic kilometers. You just used less than 0.001% of that.

But actually you didn't. Because all the hydrogen you've produced and then burned to generate electricity ends up as water vapors, which after a bit of travel in the atmosphere become clouds, then rain, then end up right back in the oceans.

Store it in old oil tankers for future dispersal in polar oceans when salinity drops from glacial melting, potentially disrupting things like the Gulf Stream?

- ed "North Atlantic thermocline" is what I meant! I originally wrote "North Atlantic endocrine" before realising that was entirely wrong, and after wracking my brain went with 'gulf stream'. I need more tea.

Sell it as some sort of high-end version of regular salt at Whole Foods?

I doubt it, much less a problem than with desalination, volume wise.

It's simply left in the sea and washed away by the current. Presumably that results in a local salinification, which might limit the safe scale.

I think I saw this somewhere else earlier, and one of the ideas listed was: don't use seawater, use other wastewater, like mining leachate, or similar. This gets rid of the water in it, making it more concentrated, and gives a useful product. The more concentrated heavy metal contaminated waste would then potentially be used as feed stock for extraction.

Or if you're using seawater, and have a convenient large area nearby, just make sea salt from it.

With some of it, we can make those fancy new sodium-sulfur batteries.

Are you then gonna complain that att articles are AI written crap because noone is paying writers?

Maybe if we had conpetent, well paid journalisms we would not be in the shit we are now

> On the other hand, is there a service that charges per read?

There are services like this, https://launch.blendle.com/ for example. I have an account from a long time ago and it seems to still be working, but it hasn't really changed in 5 years and it looks like they never got out of beta, so I'm not sure if there's any ongoing effort there.

Someone posted the paywall-bypassing archive link two hours before you commented.

You can install a web browser add-on called, 'Bypass Paywalls Clean'. It transparently bypasses FT and over 400 other media paywalls.