A zeer pot is an evaporative cooler used in rural Africa and the Middle East to keep vegetables fresh. They consist of two terra cotta pots, one nested inside the other, with the gap between them filled with wet sand. The sand serves as a thermal mass that helps keep the pot cold once it has cooled down, and acts as a wick to spread the moisture up the walls of the pot. When placed in a shaded, breezy location, the evaporation of water off the outer surface chills the pot. If you have a good breeze, or a fan powered by a solar panel blowing the pot, the pot can get quite cold. Imagine that chill you get when you step out of a pool when the wind is blowing. Now imagine that wet wind chill going on all day. That’s what the pot feels with a constant breeze.
Unless the air is very dry and the pot is exposed to a constant breeze, they generally do not become as cold as a refrigerator, but they will keep vegetables fresh for a couple of weeks. If you do have cool dry air and a constant stiff breeze, the interior of a zeer pot can chill down to around 40˚F.
Think of it as an open-cycle refrigerator. Conventional refrigerators evaporate a refrigerant in a closed circuit to absorb heat from their interiors, then compress the refrigerant vapor in the coils in back to condense it and to expel heat. The zeer pot simply uses water as its refrigerant, and leaves the condensation to nature.
Zeer pots were re-discovered and popularized in the early 2000s by the Nigerian teacher Mohammed Bah Abba. By manufacturing and mass distributing zeer pots to the poor, he was able to bring refrigeration to tens of thousands of impoverished farmers and home makers, enabling them to extend the usable life of their produce from days to weeks. For his efforts Bah Abba was awarded the Rolex Award for bringing life-changing technology to people in need.
In the under-developed parts of Africa and the Middle East, zeer pots use custom made pots prepared by local potters. Here in the developed world, we need to settle for pre-made pots from the hardware store. There are some drawbacks, but also some advantages afforded by these limitations, as you will see.
There are other zeer pot instructables out there, but this one is optimized for practicality. If the capacity is too small, the cooling capacity too low, or if it an eyesore or is annoying to use nobody would want to use it. This zeer pot uses a large glass pot lid, has an interior basket divider, and sits on a rolling cart. It even has a layer of decorative pebbles over the sand to make it look pretty. The terra cotta pot legs hold the pot off the rolling cart with enough clearance to let the bottom surface contribute to evaporation; this adds about 10%-15% more evaporative surface. The inner pot is bolted down so that it doesn’t float up when you charge the pot with water. Nearly everything I used in this project was purchased at a hardware store, and it can be made in a few hours, plus a day to let the sealants cure.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.
Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.
Join us every Wednesday night at 8pm ET for Ask an Engineer!
Maker Business — To make it through a tough business cycle, layoffs should be a last resort
Wearables — Make it pink!
Electronics — SMT Tip – Stop moving around!
Python for Microcontrollers — Python on Microcontrollers Newsletter: PyCon US, Mother’s Day, KiCad and more! #Python #Adafruit #CircuitPython @micropython @ThePSF
Adafruit IoT Monthly — IoT Pool Monitor, Edge AI, and more!
Microsoft MakeCode — MakeCode Arcade Spring Update
EYE on NPI — Maxim’s Himalaya uSLIC Step-Down Power Module #EyeOnNPI @maximintegrated @digikey
New Products – Adafruit Industries – Makers, hackers, artists, designers and engineers! — New Products 5/12/2021 Featuring Adafruit Rotary Trinkey – USB
No comments yet.
Sorry, the comment form is closed at this time.