Electricity Free Refrigeration – A Summer Experiment?

Hey, you there – ASIC student. At the beginning of this term, you were probably thinking, “Now, what do I need thermodynamics for? How will thermodynamics help me, or save a life, or end poverty? C’mon science, cough up the fucking goods already!”

Well, I hear you loud and clear – so, I bring you this:

The pot-in-pot system! It’s actually quite ingenious:

  • Step 1: make two earthen pots, one slightly larger than the other
  • Step 2: place the smaller pot inside the bigger pot
  • Step 3: fill the space between the two pots with wet sand
  • Step 4: place food inside, cover with damp cloth or lid
  • Step 5: laugh your way to the food bank, you clever bastard!

So, how does it work? Well, in hot, arid regions like Nigeria (the home country of the inventor, Mohammed Bah Abba), food spoilage is a major problem. As soon as your pick the fruit off the tree, you’re swatting flies away. Luckily, in comes thermodynamics to save the day: when water evaporates, it takes energy to change from a liquid to a gas. Therefore, when the water entrained in the sand evaporates near the outside of the larger pot (earthen pots are porous to air exchange), the inside pot cools down, and a simple fridge is made!

Old fridges suck for many reasons – they use nasty refrigerants and a tonne of energy to keep your food cold. Unfortunately, my apartment’s fridge is at least 10-15 years old. Therefore, as an experiment in reducing my personal carbon emissions, I will determine if such a system is feasible for Vancouver summers.

My plan: buy three small, earthen pots and determine how much longer a green pepper will last inside the single pot compared with the pot-in-pot invention. Pictures will be taken, daily(ish) temperatures will be recorded, and food will be eaten.

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Dave Semeniuk spends hours locked up in his office, thinking about the role the oceans play in controlling global climate, and unique ways of studying it. He'd also like to shamelessly plug his art practice: davidsemeniuk.com

5 Responses to “Electricity Free Refrigeration – A Summer Experiment?”

  1. Kerrie

    “laughing all the way to the food bank”

    I love it!!

  2. Rob

    I came across an instructable for a project similar to this a while ago:
    http://www.instructables.com/id/Make-an-Evaporative-Terra-Cotta-Beer-Chiller/

    The creator noted that “The only catch is (as I found out) that it requires a low dewpoint.” I suspect in Vancouver’s humid climate it may not work well.

    It’s also worth noting that during the 2/3 of the year when you’re heating your home anyway, eliminating your fridge will not reduce your energy consumption. You’ll simply consume more energy for home heating. If you heat with natural gas replacing that inefficient old fridge may actually increase your carbon footprint since in BC electricity has much lower carbon emissions associated with it than natural gas.

  3. Vivian

    Restaurants should switch to this soon! Haha… I can imagine champagne being chilled in vats like this. Very Egyptian. Can’t wait to see your peppers!

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