Preserving perishable items without a fridge?

We have a problem. We are searching for a way to preserve food without
the use of a refrigerator (Our solution needs to be energy efficienti i.e. consume less energy than a standard fridge). We do not have access to the traditional ways of preserving food
(like drying, putting food under salt, alchool, ethyl, or any other
chemical substance that is going to alter the food itself).

Can you help us?

We basically need to find:

• a way to safely preserve perishable food
• that keeps the nutritional characteristic of the food itself unaltered
• that more energy saving than the best refrigerator available on the market
• not involving:
⁃ drying
⁃ vacuuming
⁃ putting under salt, alcohol, ethyl or oil
⁃ smoking
⁃ marinating
⁃ chemicals
⁃ preservatives


We were wondering wether there is any technique, from transplant practices for example, that might be applicable to our issue.

Thank you.