eli5: Why is it so difficult to desalinate sea water to solve water issues?
In: 1972
Not difficult at all. For the easiest method, all you have to do is steam the water and catch the droplets. The issue is energy.
[A person, on global average, spends 3800 liters of water a day](https://www.theworldcounts.com/challenges/planet-earth/freshwater/how-much-water-do-i-use-a-day/story). Yes, you read that right, it’s not a typo. And no, it’s not only from your daily shower. 90% of it is spent indirectly through agriculture and other products we buy.
Now imagine having to boil 3800 liters of water PR PERSON every day. You quickly see that this isn’t sustainable on any scale.
So boiling is out of the question, what other options do we have? Reverse osmosis is another simple one in theory. For the ELI5 explanation: You push the water through a membrane so fine that larger molecules like salt and other particulates are filtered out. It uses a lot less energy than boiling, so why don’t we just use this? It’s mostly down to cost and maintenance. It still requires huge pumps that are still quite energy expensive, and the membranes needs to be swapped often due to clogging up of bio and organic material. It’s likely the path forward, but we’re not quite there yet to make it properly cost effective.
There are places that have integrated desalination plants, especially some popular tourist islands, but it is done with the knowledge that it’s a money drain.
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