Mohammed Bah Abba is something of a local hero in the arid plains of northern Nigeria. He is credited with transforming the lives of subsistence farmers, invigorating the local pottery industry and releasing women from the burden of daily treks to the vegetable market. Bah Abba is not, however, a radical social reformer but an inventor, and the invention that has cut the local mustard so convincingly is his "pot-in-pot", or the powerless fridge. The pot-in-pot works by evaporative cooling. One large clay pot is placed inside another with a boundary layer of sand between the two. Tender crops are packed into the inner pot and covered, then water is poured into the sand. The water slowly evaporates, drawing the heat from the contents of the pot and keeping the vegetables fresh for days.Similar cooling devices have been used by the Amish in America, and in the outback of Australia all using the same principle.However there's a drawback, these systems only work well in climates with a low humidity.

Our challenge is to find something that will work well in our humid NZ climates.We made a large cabinet based on the idea of evaporative cooling, but placed it on the shady side where it was the most practical for us to access, and dripped water onto it.  It was more a water cooled safe. This worked well most of the year, but struggled in the summer, when we most needed it.  We got around this by putting 5 litres of ice in it each day (from our freezer).  Next time we'll try putting it directly in the sun, to see what difference it makes.In the meantime we'd love to hear from others with any other ideas.