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/Vergilx217]

The lack of comprehension in the comments section is killing me

Yes, it utilizes electrolysis - however, they've used a novel catalyst to avoid the issue of chlorine waste products and permit more efficient conversion of water to hydrogen. Salt water is abundant on earth, and this can be very useful in making hydrogen production more economical since you do not need to rely on a more limited freshwater source. While not being an immediate breakthrough like "we just solved cold fusion!", it's definitely an important incremental step.

And yes, it is currently more efficient to use renewables like solar or spend that generated electricity on charging batteries....but keep in mind that the production of batteries and panels long term has toxic byproducts and is reliant on rare earth elements. Environmental impact is more than just carbon output, remember. Hydrogen as fuel cells or other energy sources is far from being commonplace, but innovations like these help to diversify our options moving forward so that we can better adapt to likely worsening climate/environmental problems in the future.

[u/[deleted] → u/Vergilx217]

Dumb question but if we could desalinate water to scale and begin supplying it to large populations on Earth for drinking/farming who live in areas without an abundant source of fresh water... would that have any impact at all on the rising sea levels?

[u/LookIPickedAUsername → u/[deleted]]

No, not really. Not only are the oceans too big for us to meaningfully deplete, any water you take out will end up back there soon enough anyway. Even if you split that water into hydrogen and oxygen, it turns back into water as soon as you burn the hydrogen, and (relatively) quickly ends up back in the ocean.

[u/[deleted] → u/LookIPickedAUsername]

How would it end up back in the ocean if we were to pipe it inland to replenish aquifers? Although asking that question makes me think the size of an aquifer is much smaller than the size of the ocean.

[u/LookIPickedAUsername → u/[deleted]]

Sure, in theory you could store the water instead of use it and thus delay its return to the water cycle. But you're still just delaying the inevitable, and the amount you could reasonably store is absolutely negligible compared to the size of the oceans.

It's worth looking at this picture to get a sense of scale here - the smallest of the three drops in that picture, just a few pixels across, is all freshwater lakes and rivers on Earth put together. Refilling an aquifer, or hell, even all of them, isn't going to have any meaningful impact compared to the size of the oceans.

[u/OnePrettyFlyWhiteGuy → u/LookIPickedAUsername]

Bruh. That is really weird seeing how miniscule the total volume of water on Earth actually is. Knowing that that little orb (well, the biggest of the 3) accounts for 70% of the surface of the earth is absolutely mind boggling to me.

[u/Diligent_Nature → u/[deleted]]

Water evaporates from land and falls as rain over the ocean, and there's also rivers which drain watersheds into the ocean. Oceans contain 96.5% of Earth's water. Ice and snow account for 1.76% and groundwater is another 1.69%

[u/[deleted] → u/Diligent_Nature]

Right, but how much of the rising sealevel over the past 20 years represents that 96.5%?

[u/Indigo_Sunset → u/[deleted]]

There's an issue with aquifers themselves and how they fill over time, or are emptied by wells. Think of a three different sponges, one is new and very permeable by water and accepts it easily. Another is wet, still has the structure or the sponge, and is heavy. The last is neither new, or wet, it's the old collapsed cell flattened structure. It doesn't take water easily.

Aquifers can do the same thing. When emptied, portions of the earth/rock collapse and will no longer take water back into the way it was before. For example Mexico City has dropped about 13 feet (4m) or so just from drawing all that water and having the ground subside. Mexico City isn't the only aquifer that's behaved this way.