Maybe I am overthinking it, but if you can take food and drop it into a box, and that will keep it fresh for 2 weeks instead of 24 hours, that seems to be a survival advantage.

RV fridges, or other absoprtion fridges can be used with almost any heat source, including the sun. Having a labor free way to keep food fresh seems like a major edge.

Having drinks that are cold in the summer, or a cold rag for a child with a fever.


Can you fake it? Sure, wrap a glass in a cloth, soak it with alcohol, and you can get it to make ice, but that is a long nasty process, and your booze is gone......