DIY thermal storage refrigerator
 

Thermal Energy Storage Project: Icebox - YouTube
Presumably, that idea can be extended to make a freezer by adding propylene glycol or similar to the water. With a sufficiently big insulated container, it could even be scaled up for HVAC use.

I like the possibilities of the project, I see it as very useful for off grid use etc.
The system could be modified for a warmer temperature refrigerator as well, witch subsequently would slow the melt.

my thought is to have a a heavily insulated main box that stays sealed, surrounding a smaller insulated box with a removable insulated top mount door.

The premise is the main insulated thermal storage box (which should be 12" rigid or spray foam encompassed) would ever so slowly soak its cold into the the center insulated refrigerator box.

Pretty much just like the demo only with 12" of insulation for slower draw and refrigerator temp.

I like the idea of cold storage as well as heat storage. The guy definitely needs more insulation though. :)

I've always wanted to do something like that for an A/C system, that way I could take advantage of the time of use power billing option, and only make cold at night when it is cheap...not sure how much ice I would need to cool my house for 12 hours though...

If you know how much energy it currently takes to cool your house for 12 hours during the day you could calculate the amount of ice you would need. Distributing that "coolth" may be a bigger problem than calculating how much of it you need.