An electricity-free terracotta fridge
Chill your veg and dairy products without drawing a single watt...
A fridge uses around a third of the electricity in the average kitchen. Although it doesn’t use much at a time it’s always on. Most things don’t actually need refrigerating, but milk and its substitutes do, and purchased vegetables last much longer when chilled.
This simple design for a power-free fridge is much used in Africa. It works on the principle that wherever water evaporates there’s a local drop in temperature.
Take two big terracotta plant pots, one with around 8cm wider diameter than the other. Place the smaller inside the larger and fill the space in between them with sand, so that the tops of the pots are level. Wet the sand and keep it wet. A lid is needed. Until we can find a suitable one with a handle we use an old dinner plate. A tray below to catch surplus water is useful, and an old saucer placed upside down in the bottom makes sure that the things in the bottom of the storage space don’t accidentally get wet.
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simple and easy to make
Such a simple idea and so easy to make. This would be useful for camping rather than buying an expensive and bulky gas fridge.
Effective in our cooler climate?
It's a great design that works well in hotter climes, though the ones I've seen to date in Britain (Landmatters for instance) suggests that we might not have enough heat (ironically) for there to be sufficient evaporation to cool this well. I'd be interested to hear more about the effectiveness of this design in our cool temperate climates through the year (since July 2010?) & in different sites (in the sun for increased evaporation or in the shade for less heat?).
terracotta fridges in the UK
I tried one for a while back in 2006 - like Aranya said, it was not hot enough to cause evaporation to make it work. Also I have a suspicion that industrially-made flower pots on sale in garden centres are too dense for water to evaporate through them and this would be a bit of a killer too.
Commercial Pots
@bobirving - its not usually the density so much as the surface - if the surface (which is usually almost burnished) is sanded back, most pots work fine.
Happily, this is a great technology for hot Western Australia.
Harry
Peactree Permaculture
http://www.ptpc.com.au
Thank you very much for
Thank you very much for sharing this simple solution for fridging. I was trying to use my small studio an maximize the permaculture use and production of it. Little by little and thanks by you and other sources Im getting better ideas.
Im glad the world and earth can enjoy the benefits of your publications.
Terra cotta fridge
In cooler climate, keep it in the shade but put in a wind drift.
Terra Cotta Fridge.
Does the lid need to fit over the two pots or just the centre pot?
This gives me a construction system idea
This gives me some interesting construction ideas for a kind of siding for brick and cinder block homes. I envision a kind of modular panel system with composite hangers and standoffs and terracotta panels. The retrofit system will have sand poured between the terracotta panels and the cinder block or brick exterior wall. I think a 2 inch standoff would be enough for this to work. The install kit would include a soaker hose system or a kind of drip irrigation system at the top of the panels and moisture sensors at the bottom of the panels. These would control the flow of water into the sand core. There would be filters that would allow some water flow through the panel system so that it would not become moldy. I think this system would lower the cost of cooling a house in a hot climate by about 70% if my crude calculations are correct. It would be very cheap to operate and not that expensive to build out with new or retrofit construction. The limitation is that it would require a very water safe skin on the house. I think brick or cinder block or concrete walls will work best. Of course the siding would be complemented by a terracotta/sand/water roof cooling system of the same type.