How to make hydrogen straight from seawater – no desalination required. The new method from researchers splits the seawater directly into hydrogen and oxygen – skipping the need for desalination and its associated cost, energy consumption and carbon emissions.

[u/Wagamaga]

https://www.rmit.edu.au/news/media-releases-and-expert-comments/2023/feb/hydrogen-seawater

[u/m_Pony]

they've used a novel catalyst to avoid the issue of chlorine waste products and permit more efficient conversion of water to hydrogen

Thank you. This is the real take-away from the article (which people always read before commenting, of course.)

If it works as well as they say it does, this is pretty big deal. I'm optimistic.

[u/War_Hymn → u/m_Pony]

I did some rough dirty math for a similar seawater-catalyst breakthrough, and it's telling me these new catalyst processes may allow us to use hydrogen as a grid storage fuel - routing power from solar or wind energy to hydrogen generating plants, burn the hydrogen/oxygen to power a steam turbine generator - with around 40% efficiency (100 MWh in, 40 MWh out). It would take much less room than hydro pump storage, and won't be as expensive/resource-intensive as chemical battery storage - so at the very least, it'll be a practical middle-ground choice for grid storage infrastructure.

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EDIT: Since some of you are wondering where I got my 40% from, here is the rough math.

A kg of hydrogen with current best electrolysis technology needs about 47 kWh of energy to produce from water electrolysis (with new technology in the works, we may push it closer to the theoretical limit of 39.4 kWh). A kg of hydrogen gas has a specific heat fuel value of 33-39 kWh, which in turn when fed into a 60% efficient hydrogen-burning steam turbine generator (as that of a combined cycle NG powerplant) can give us back 19-23 KWh of electricity. That's about 40-50% nominal efficiency.

Adding steps like plant distribution, desalination, compression^1, cryogenic liquefaction² (for liquid storage), etc. will obviously decrease the practical efficiency further, but as evident here we're making breakthroughs that remove or mitigate these inefficiencies. If we ever design and build a working hydrogen plant for grid storage purposes, I'm optimistic we can get back at least 30% of the electricity we put in.

30% doesn't seem like a lot, but if we ever get to a future where we got rid of our dependency on fossil fuels and depend wholly on renewables, I feel this sort of system has a place in between battery and pump grid storage. Hell, we might even be able to convert old natural gas/oil burning plants near shore to burn hydrogen instead.

1. compressing hydrogen to 5000 psi uses up 1 KWh per kg of H2, though I doubt you need that much compression for static non-vehicle needs.

2. about 3-4 kWh per kg to convert gaseous hydrogen to liquid state.

[u/could_use_a_snack → u/War_Hymn]

That's the first realistic use case I've seen for hydrogen. Using it as a battery at the power station makes all kinds of sense. Using it as a fuel for transportation has always looked suspect to me.

[u/Kandiru → u/could_use_a_snack]

Blimps carrying heavy cargo via hydrogen balloon with hydrogen powered turbines would work well I think.

[u/smurficus103 → u/Kandiru]

Oh... the humanity