Posted January 15, 2013 by Craig Mackintosh & filed under Energy Systems, Processing & Food Preservation.

Most of you will be familiar with the pot-in-pot refrigerator by now. Well, today we’ll revisit this concept by taking a look at the ‘MittiCool’ refrigerator, a possible ‘upgrade’ that also uses evaporative cooling through the use of clay, but which looks a little more like the refrigerator you’re more familiar with. And, just like the pot-in-pot refrigerator, the MittiCool uses no electricity.

How does it work? The topmost section holds water, which very slowly drips down the sides. As permaculturists will know, one of many ‘constants’ we can count on and use to advantage is that evaporation cools. As the water evaporates from the porous clay surface, it cools the interior, enabling you to store fruit, vegetables, milk, etc.

There is even a tap on the front of the unit, so it doubles as a water cooler as well.

In the following videos you’ll meet the maker of MittiCool, and learn how it is made from a specific combination of four different types of clay he has found in his local area. The video states that the inside temperature of the MittiCool can be up to 8°C lower than the outside temperature.

This refrigerator will not function everywhere, of course. Evaporative cooling only works well in dry climates. But for those people living in the right conditions, this looks to be a very sensible, low-cost and planet-friendly way to extend the shelf life of your produce.

This use of natural constants in our designs will, I hope, become more commonplace as society finds itself unable to breach the peak energy impasse. Where previously we had energy to spare and so could just design with fossilised sunlight, we will instead be forced to find sustainable alternatives. It reminds me of the urban legend (myth) about NASA spending millions of dollars to create a pen that could write in the vacuum of space, while Russian astronauts simply used a pencil. Although not a true story, it does graphically illustrate how our industrial mindset leads us to overlook simple solutions in favour of ‘being clever’ instead.