# Potable water: desalination vs. condensation

**URL:** <https://boards.straightdope.com/t/potable-water-desalination-vs-condensation/948440>\
**Category:** Factual Questions\
**Created:** [August 11, 2021, 11:23am UTC](https://boards.straightdope.com/t/potable-water-desalination-vs-condensation/948440 "2021-08-11T11:23:01Z")\
**Posts on this page:** 3\
**Page:** 2

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**Author:** ![DMC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dmc/32/18049_2.png) [@DMC](https://boards.straightdope.com/u/DMC)\
**Post date:** [August 12, 2021, 10:12am UTC](https://boards.straightdope.com/t/potable-water-desalination-vs-condensation/948440/21 "2021-08-12T10:12:25Z")

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I read that as 10,000 RO for a cubic meter, which when scaled down to produce a single liter (apples to apples) would indeed end up at 10 as stated.

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**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\
**Post date:** [August 24, 2021, 5:34pm UTC](https://boards.straightdope.com/t/potable-water-desalination-vs-condensation/948440/22 "2021-08-24T17:34:58Z")

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The thing with multi-effect evaporators is that they can use low pressure steam to evaporate water. I’m more accustomed to them in industrial rather than marine environments but basically after you’ve used your steam to spin your turbines to generate electricity you’ve got a lot of low pressure steam that is essentially free. It’s well worth the capital expenditure to use it in a multi-effect evaporator. In the pulp mill recovery process you can evaporate a 5 tons of water for every ton of steam used in a six effect evaporator, so they’re energy efficient, although capital expensive.

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**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\
**Post date:** [August 25, 2021, 9:45am UTC](https://boards.straightdope.com/t/potable-water-desalination-vs-condensation/948440/23 "2021-08-25T09:45:39Z")

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It’s possible to condense water out of the air without any energy input. You have to use special hygroscopic materials. Here’s an example where the material is an aerogel made of polymers plus a metal-organic framework. It doesn’t need any energy input although it works better when exposed to the sun.

> **[Sponge-like aerogel turns airborne vapor into drinkable water](https://newatlas.com/materials/sponge-aerogel-vapor-drinkable-water/)**
>
> Water security is a significant problem and pulling it out of the air, as fanciful as that may sound, is shaping as a potential part of the solution. A team from the National University of Singapore (NUS) has put forward a promising example of this...

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