I've done homesteading a couple times in my life but during that time I never new about the Crosley Icy Ball. It was manufactured in the early 1900's but plans to make a modern version with a welder are available. I sure wish I had known about this back then because it would have been nice to have "free" refrigeration.

Google "Crosley Icy Ball" and be amazed

Hehe I stumbled across the Crossley Icy Ball when I was googling your other post (as I was painfully tried to wrap my brain around the conept you were discussing lol) come to find you already psoted about it here . This is a very fascinating device though...took me some time to understand the concept though!

Since so many people travel I wonder if a commuter "icy ball" would work, where you set the de-charged icy ball under the hood on your way home from work and it recharges from the engine heat.