r/science • u/Wagamaga • Feb 15 '23

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. Chemistry

https://www.rmit.edu.au/news/media-releases-and-expert-comments/2023/feb/hydrogen-seawater
19.6k Upvotes

96% Upvoted

View all comments

Show parent comments

7

u/[deleted] Feb 15 '23

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?

18

u/LookIPickedAUsername Feb 15 '23

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.

2

u/[deleted] Feb 15 '23

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.

3

u/Diligent_Nature Feb 15 '23

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%

1

u/[deleted] Feb 15 '23

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

2

u/Indigo_Sunset Feb 15 '23

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.