> cubic meter of sea water will have 1000\*0.036/0.058=620 moles of salt, and it... | Hacker News

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Animats on July 5, 2023 | parent | context | favorite | on: Why is desalination so difficult?

> cubic meter of sea water will have 1000*0.036/0.058=620 moles of salt, and it'll require 2.4MJ of energy to remove the salt in a perfect desalinator. In more common units, 2.4MJ is about 0.75 kWh.

> A thousand liters takes about 3kwh.

So, if those numbers are right, desalination is currently at about 25% of theoretical energy efficiency. Is that correct?

cyberax on July 5, 2023 [–]

I made a small arithmetic mistake at the end, 2.4MJ is about 0.66kWh

But otherwise it's correct, we're at about 20% of the theoretical maximum. The best RO systems are right now working towards 2kWh per cubic meter: https://uh.edu/uh-energy/educational-programs/tieep/content/...

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