Question: What are some good electricity-efficient ways to cool an ice pack down to ~5 degrees C once every 48 hours?
Background: I am in a warm climate and connected to the grid in a US city. I don't freeze anything else regularly.
I think the most efficient method is to share a freezer, e.g. find someone with unused freezer capacity and stick my ice pack in there. But I am interested in other methods as well, and how they compare to the sharing method.
I do have a high-efficiency freezer with 70L capacity. Maybe this would be the most efficient, even with nothing else inside other than the ice pack?
I know there are those portable thermoelectric coolers, but I'm not sure how efficient those would be, or how well they would function at high ambient temperature.
Very similar to this question, only lower capacity: How to get a small volume of freezer capacity with high efficiency and low cost?