Take the salt, heat it, run current through it. Sodium vapor comes out. Not exactly "easy", but self-contained. From an environmental point of view sodium is a

Take the salt, heat it, run current through it. Sodium vapor comes out. Not exactly "easy", but self-contained. From an environmental point of view sodium is absolutely brilliant compared to lithium. Everyone with access to sea water can produce almost 400 g of sodium from 1kg of common table salt. No lithium mining needed. More info: https://en.m.wikipedia.org/wiki/Downs_cell https://en.m.wikipedia.org/wiki/Downs_cell