Most ways to purify saltwater take up a lot of energy, but simply running seawater through a thin, heated slice of porous wood can render it fresh and drinkable
Source:
https://www.newscientist.com/article/2212346-a-super-thin-slice-of-wood-can-be-used-to-turn-saltwater-drinkable/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home