Solar Fridge Invented (Again) by UK Student
by Lloyd Alter, Toronto 
on 01. 8.09
Image Ross Parry Agency via Daily Mail
Congratulations to Emily Cummins for building a portable evaporator fridge out of household parts in her grandpa's potting shed. The Daily Mail claims that she has "invented an Amazing Solar Powered Fridge," which would be a terrific thing if it was a) solar powered and b) she invented it.
The Daily Mail's illustration describes it as having a "gap between the inner and outer layer that is filled with sand, wool or soil, that can be soaked with water." they continue and say that "the sun's rays heat this wet material and the water evaporates off."
Right. Putting it in the sun increases evaporation, cooling the interior? I suspect not, but evaporative cooling can be used to make an effective and cheap cooling system for Africa, like Mohammed Bah Abba did ten years ago.
Warren described it earlier:
[Take] two pots, one inside another. Fill the space between the two with moist sand, and you have a most ingenious fridge. (That’s very modern if you live in one of the 90% of villages that don’t have electricity.) The water in the sand naturally migrates towards the outer pot, where it evaporates causing a temperature drop around the inner pot.
It was one of Time Magazine's inventions of the year in 2001 and won a Rolex award. It is made locally and sells for forty cents.
Warren also points us to the Darfur’s Women’s Association for Earthenware Manufacturing, where:
In Al Fashir, the capital of North Darfur, ITDGPractical Action and the Women’s Association for Earthenware Manufacturing have been experimenting with a traditional storage container called a zeer, invented by a teacher called Mohammed Bah Abba.A lidded earthenware pot is fitted inside a larger pot with an insulating layer of sand in between. This sand layer can be kept cool by adding water regularly, thus providing a refrigerated storage space at minimal cost.
The results of these trials were amazing. Carrots, tomatoes and okra could now be kept in good condition for nearly twenty days, whereas previously they would have been unsaleable after two or three.
While evaporative cooling has been around for millenia, according to Rolex:
The city of Qena in Upper Egypt is renowned for its porous-clay cooling vessels – a tradition spanning more than three millennia. In Burkina Faso, the Jula people’s traditional jars are sometimes soaked in water before goods are stored in them, so that they stay cool by evaporation. This single-pot design is similar to the pot-in-pot, but less efficient.
The double wall system is a dramatic improvement. In most of the versions we have seen, the porosity of the clay is an important component; Emily has made her version of a non-porous metal. Perhaps there is something about it that I am missing, that lets it work better in the sun than in the shade.
But every swamp cooler and fridge I ever heard of right back to the Australian Coolgardie Safe worked better in the shade and relied on moving air to increase evaporation rather than sitting in the sun.
Daily Mail via PSFK and EcoFriend
More TreeHugger on Solar Fridges:
Solar Powered Refrigerator Could Bring Health and Energy Savings to Rural India
Follow @TreeHugger on Twitter & get our headlines with @TH_rss!
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Great way to encourage our youth to experiment and problem solve - pubicly rip into their efforts on a blog that they probably look to for inspiration.
My message to Emily: Keep up the good work and continue learning and contirbuting.
LA: You have a point and I have revised the first paragraph; her work is outstanding, and I would not want to discourage her.
"Right. Putting it in the sun increases evaporation, cooling the interior? I suspect not..." Don't be so incredulous. This is the same proven concept as an absorption chiller: a heat source causes phase change that "sucks" the heat out of an adjacent material. The outside material in this case doesn't need to be porous, (there are holes drilled). It just acts as a heat collector.
So a) it is solar powered.
b) she definitely didn't come up with the concept, but hey it seems like a nice little design.
Please, Marines have been using this concept for years. While in Iraq we would take our camelback, or canteen cover, and soak it in water. Wait about 30 minutes and the 100 degree water that was in your camelback becomes nice and cold. It was a life saver when it's 130 degrees outside and all you want is some cold water.
logically, if it does keep contents at 6C then it must be doing more than just self-regulating temperature through evaporative colling of heat from the contents of the 'fridge'. If it gains energy from the sun then the overall (I would put italics here if I knew how) temperature must go up but the evaporation carries heat to the outer edges..I am not a physics graduate but I can believe it. I would have thought a porous material would be better than one with holes drilled in though. The real criticism should be (perhaps is) of the ever-sloppy Daily Mail, sorry Lloyd but I have to say Rob has a point.
One thing I noticed in the description is what temperature her device achieves. The other things I've been reading today state that the older variations are warmer (though that could be directly influenced by the local climate). I mentioned this on Digg earlier today, does anyone know more about that?
The tone of this post and these comments seems mildly condescending. Underlying principles do not need to be new for an invention to be a contribution.
I don't understand why this article is so negative. It may not be earth shattering, but I think it's still a positive contribution.
Energy efficiency is the key to a healthy planet. Emily's overall research and study about the environment ultimately inventing a solar fridge is indeed praiseworthy. You may visit our site for checking out our green topics. I'd appreciate if you can give me some feedback on our site: http://greenbydesign.com. I'd like to hear your opinion/feedback on our green topics.
Thank you,
greenerguy
Emily, very nice bit of handy work this...
@Daily mail
a) It is solar powered
b) No.She din't "invent" it. She just built a more expensive version of an already existing model.
It was invented WAYYYY before we discovered electricity.
Its true,it was a simpler concept. and did not need 2 layers, sand, drilled holes etc.
and if you wanted to cool something else, well, they'd put a smaller jar inside that which was non porous but was a thermal conductor. like a thin brass vessel.
What amuses me is the fact that using this very same concept (evaporative cooling) a Junior grade schoolchild built a solar powered refrigerator when I was doing my undergrad in India. Only, he made the outer pot with his mothers help and used a tin lunch box as the inner container, in a farming village near my college. and came up with the entire concept using his school's science text book prescribed for the junior grades.
Heck, the Persians and Indians used to carry ice/snow around in boxes in the middle of the desert. that was some seriously advanced tech for their time.
you got to admit she does look hot!!!
This is an old idea, yes, but this student is helping introduce it to the West and familiarize Westerners about this ancient method of refrigeration.
Dig a root cellar, duh!
Good job, but like many have said, consept is nothing new. Same consept has been used before to create a low-tech cooled pot - basically a double-walled clay pot with wet sand between layers. Also, it can reduce the core temperature only 10-20 degrees below ambient depending on the relative humidity.
Anyway, still, glad to see people are experimenting with simple tech. I hope to see something similar, that can actually cool the contents below freezing without using PV-solar panels or any moving parts (maybe with heat pipes then?)
Mohammed Bah Abba did it ten years ago.
see http://www.treehugger.com/files/2009/01/student-invents-solar-fridge.php
It was one of Time Magazine's inventions of the year in 2001 and won a Rolex award. It is made locally and sells for forty cents.
@ Richard Newton
Yes, the chief issue to note here is her sexual attractiveness (to men). Sure. Right-o.
SIGH.
She doesn't invent anything new but her success probably comes from her positive and confident attitude, gained with the support of her father to make things since the age of 4.
Communication and self confidence are the keys to get your inventions out there.
Emily keep up the good work,even if she didn't invent the very 1st one at least she's trying it instead of talking about it,and not sitting on her thumbs!