A Refrigerator that Runs Without Electricity | Hacker News Reader

A Refrigerator that Runs Without Electricity

celsias.com

147 pointsstretchwithme60 comments

Not a new concept, see:

http://en.wikipedia.org/wiki/Pot-in-pot_refrigerator

and

http://en.wikipedia.org/wiki/Absorption_refrigerator

the first article you link (pot-in-pot) credits the same inventor as OP's article. In other words, while there may be historical evidence that the technique was used millenia ago, both articles credit the same man for re-introducing the principle in 1995.

It's also similar to old Australian meat keepers. Australia was, historically, one of the world leaders at refrigeration development.

It's also a common sight to see canvas water bags hanging from the front of a 4WD in Australia. The bag is porous causing some of the water to evaporate slowly as you drive. Hey presto, beautiful cold water when stop to take a break.

also known as the Coolgardie Safe http://en.wikipedia.org/wiki/Coolgardie_safe

Also see IcyBall [1], a type of gas absorption refrigerator that was used in the 1920's and 1930's.

[1] http://en.wikipedia.org/wiki/Icy_Ball

This only works in dry climates, no?

In humid, tropical climates this will not work.

MotherEarth had an article on building a solar-powered freezer that uses ammonia gas. Use that to make ice, and then use the ice in an ice-box like storage device.

http://www.scribd.com/doc/6599651/How-to-Build-a-Solar-Icema...

Yeah, clay is easier to find than the other materials, but the ammonia freezer does work without any moving parts.

My grandparents lived, until the early '90s, on a farm with no running water, no plumbing and no electricity. Lighting was provided by kerosene lanterns hanging in each room, and they had a number (three, from memory) of kerosene powered fridges for keeping things cold.

My google-fu is failing me this evening, and this is about the best I can come up with http://www.earthgarden.com.au/kerosene.html

IIRC, natural gas -- or propane -- powered refrigerators are not all that uncommon, either. This pre-supposes more infrastructure, but it's still not electricity.

Propane refrigerators are extremely common in the RV/camper world, likely because most of them already have a propane tank for cooking.

I just read a fascinating book, Gaviotas (http://www.worldcat.org/search?q=isbn%3A1890132284), that describes an attempted reverse-engineering of the same thing (back in the 80s).

This was hot on the heels of the 1970s energy crisis and the solar technology boom; I wonder in what ways the drive to innovate appropriate technology has changed since then.

Actually I'd think refrigeration would be a more effective use of solar power than electrical generation. Refrigeration works by compressing/condensing/evaporating a refrigerant. Compressing a gas is the same thing as heating it, so it makes sense. Only problem with ammonia is that it's quite dangerous if inhaled, but it's commonly used in commercial/industrial refrigeration.

The ammonia would be in a closed loop system.

By only freezing water to make ice and to keep an icebox cool (the icebox and where you freeze the water are two seperate physical locations), you reduce the risk of any ammonia related injury or contamination.

You would just have a bunch of 1 gallon jugs of water you freeze and swap out between the icebox and the freezer).

Like the olds days!

http://en.wikipedia.org/wiki/Icebox

Maybe you could put it in yet another container with a dessicant to draw the moisture?

No, I know Hawai'ians who use an ammonia freezer.

Can you elaborate on that? I am curious what the setup is?

Greeks used a twin pot system to cool (or keep cool?) their wine. They would have a psykter ("cooler") and a krater. The psykter is filled with water or ice and floated in the krater holding the wine.

It's been long known that wet terracota on a windy day keeps the insides cool.

http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:19... page also describes a double walled amphora where the space was filled with water, no mention of external glazing (or its lack). These are apparently known as psykter amphora, http://books.google.co.uk/books?id=L-DYdyXXMy8C&lpg=PA22.... Such amphora are known since 6th Century BC.

A technology that I haven't seen mentioned yet is the thermoacoustic generator. http://en.wikipedia.org/wiki/Thermoacoustic_hot_air_engine These are basically a resonator driven by a heat differential. Very simple, no moving parts. With the proper arrangements you can get out heat for cooking (obviously), refrigeration, or with a piezoelectric module, electricity. They're still more or less experimental, but very cool nonetheless.

A friend from Albuquerque, New Mexico was just telling us about swamp coolers which are commonly used instead of AC to cool homes, and works on the same principle.

I'd never heard of it before.

I used one of those in college. I lived in an un-air-conditioned apartment in Denver, and during the summer it could easily get over 90 degrees inside. The swamp cooler would bring the temperature down to about 75 (so long as I closed the blinds). Also, one of my friends had a whole-house swamp cooler, mounted like an air-conditioner on the roof of his home. They work beautifully in dry climates.

Yes, I lived there and we had swamp coolers, aka evaporative coolers. They're adequate, but not as deluxe feeling as refrigerated air.

It's basically a 3 foot wide wheel that spins in a metal box, blowing air. Water is misted through the air that comes through the box, cooling it and making it more humid. This works quite well in a dry place like Abq, but you can imagine what it would be like somewhere like Houston that is already very humid.

AFAIK, evaporative coolers are more energy efficient than AC, as they just power a small pump instead of a compressor.

Yes, they're far less expensive to operate than refrigerated air, since it's pretty much just a fan with a bunch of water.

I lived in Flagstaff, another high altitude dry city. Personally I hated swamp coolers because of the increased humidity and would rather have the dry heat instead.

They used to be very common out here in Arizona - so much so that the daily forecast would often include the temperature your house would be with the evap running.

Yeah. They fail miserably when it gets humid.

If I ever end up there, AC for me!

We Spanish people had been using evaporative cooling since dogs bark.

Botijo(spanish version is more complete): http://en.wikipedia.org/wiki/Botijo

Other methods that people used was making deep holes on the ground( > 30feet 10meters under ground level). Old houses in Madrid have (now sealed) passages and cellars under ground. They were used as pantries(in some cases they had snow with straw that lasted for months, now some are used for winery, but most are closed and owners only realize they exist when they remodelate their homes.

Ammonia cycle refrigerators like the classic Frigidaire of the 1930s operated on a small flame from natural gas, propane, or kerosene. See http://en.wikipedia.org/wiki/Ammonia_Refrigeration for an overview of this and other similar processes. Ammonia is toxic at the levels used for refrigerators and was phased out in home refrigeration units for safety reasons.

You can still buy ammonia-absorption refrigerators today. A quick Google search finds http://www.warehouseappliance.com/propane_gas_refrigerators..... I had one in my Vanagon in 2006. It's certainly true that they're more dangerous than compressor refrigerators.

Presumably you could easily operate a refrigerator like this with a solar concentrator instead of a flame providing the heat.

A thermoacoustic cooler like the one in the SCORE project http://www.score.uk.com/research/default.aspx could also refrigerate using only a heat source, without a source of electricity. (The SCORE stove also produces electricity.) I don't know what the state of the art in this technology is right now.

The developer of this solution won an award for building and distributing this to rural areas in Nigeria - see the cooler working in a video profile here: http://www.youtube.com/watch?v=SsH7dp2MB2c

The guy in the doc "No Impact Man" tried using one of these in NYC and I recall it didn't work too well and he ditched it.

NYC isn't dry enough. This device operates through the evaporation of water. Using a humidity delta to create a temperature delta.

This double pot evaporation system is not new, it's ancient. I can clearly recall seeing antique market photos from the 19th C clearly showing the double pot cooler throughout the middle east. (can't find reference sorry.) It works especially well in hot dry climates where you can have extensive evaporation. It doesn't work in humid or cold climates. What's needed in North America is a return to the root cellar, and external cold sheds or window boxes for climates that fall below freezing. Again this is not new technology, but was widespread in the 19c. (again, it is amazing that I can't find any image references for window box cold storage.)

But won't work where it's humid, right?

Because there would be little or much slower evaporation?

Tomatos can last three weeks in this thing? My electricity-powered fridge can't even do that!

Creative and Intuitive. The same way our body keeps us cool by sweating.

Does this scale? How large can the pot be before you run into problems?

The problem you run into with evap cooling is that you only get the benefit once for a given volume of air. Once you humidify the air you can't humidify that same air again. So its all about how much dry air you can bring in and how quickly you can eliminate the already moist air.

I'd imagine that this pot in pot method wouldn't scale very far. Your cooling a volume but your evaporation rate is governed by surface area.

I think it would scale fairly well, just buy a second set of pots.

The thing I think lost in the discussion is that the solution is not a great one in the general case and thats a given, so what. What it is is a way for lots of very poor people to have a better quality of life. Also they can do it on there own. This just might spark other very good local applications of existing knowledge to existing problems. There is plenty of knowledge out there that would improve the local living conditions, especially if that knowledge is in the hands of people who really know what the local problems are. Hopefully this will lead to other people boot strapping/rediscovering/stealing simple solution to local problems.

To the people who are saying that this would not work in a rain forest, or high humidity in general. A heavy winter coat is useless in the amazon, but I am rather glad to have it in NYC during the winter.

> I think it would scale fairly well, just buy a second set of pots.

He's saying that you couldn't scale the individual size of the pots that much. The ratio of surface-to-volume changes dramatically as the pots get larger (squared-polynomial for surface vs cubed-polynomial for volume).

Realistically, unless you are storing something which generates its own heat, the only thing affected would be the amount of time to lower the internal temperature to equilibrium, at which point the added thermal inertia of everything in the pot would help keep things at temperature. With a system like this, what you're fighting is the thermal exchange with the surrounding air, which is of the same magnitude as the vapor exchange (both are a squared-polynomial).

(Anybody with a less hand-wavy understanding of thermodynamics, feel free to step in!)

I knew that, I was trying to say "So What" in a more polite way. My point was this is better then what was available before. It is a real improvement in the peoples lives who use it: more fresh food consumed, food costs go down and probably less food poisoning by trying to stretch one more day from what we have bought for dinner. It is cheap enough to be purchased and simple enough to be maintained by untrained people. This is a solid step in the better direction.

About the size of a Google or Facebook data centre.

I imagine it scales fairly well, though perhaps with some modifications. Historically, the purpose of a cellar was that it was cool underground storage for food to get you through the winter months. My recollection is that some cultures also buried large clay pots in the ground to store grain. I am trying to look for supporting links. So far, this is the best I have come up with:

http://www.cd3wd.com/cd3wd_40/vita/grnstor3/en/grnstor3.htm

Edit: This (link below) appears to be a good source on historical methods of food storage, including underground and pottery storage.

http://bioconservation.co.uk/Documents/FGO-all3209.pdf

That sounds perfect for camping in the southwest US during warmer months.

Anyone know the typical internal temperature?

Possibly a differential proportional to both the outside temperature and the difference of humidity? I'd love some links to the physics behind this system.

Rather I would find radiative cooling cool.

Anyone do this at Burning Man?

Unlikely. There is massive use of evaporative cooling techniques (We cool our domes with a pair of Essick 3301 coolers) - but the preponderance of (A) Electricity, and (B) ice at BRC would make it unlikely that anyone would futz around with this technology to cool food instead of air, particularly as all you would be doing is preventing food from spoiling, not particularly cooling it that much.

I've often wondering if the critical ingredient that makes BM so popular (they won't even sell tickets at the gate this year they are so oversubscribed - might even sell out for the first time) - is that they sell ice at a number of distribution points on the Playa.

Far more likely they put that energy into figuring out how to evaporate / dispose of their grey water.

People at BM unwilling to futz around? Huh? Isn't that the point?

I might try it out this year. One of the things that most appeals to me about BRC is the game of maximizing utility whilst minimizing resource consumption. The playa is incredibly dry and seems a perfect environment for this system. Yeah, you can buy ice for your cooler chest, but where's the challenge in that?

10 or 12 years ago, I saw a guy who built a hay bale structure with an evaporative cooler at Burning Man. It was the first time I'd seen one in real life, and it worked really well (it was a hot, dry year...not all of them are).

See Also: Chotukool in India. Example of large conglomerate making products for the base of the pyramid and succeeding: http://www.gizmag.com/refridgerator-rural-india-chotukool/13...

And Mitticool - this one is similar to the nigerian one in that it uses evaporative cooling. http://www.sankalpindia.net/drupal/know-india/mitticool-cool...

I'm somehow very doubtful that this works effectively. If it is so effective, then why is it so rare? Probably it keeps the goods somewhat cool, but not particularly cool.

It's not as cold or as convenient as a standard plug-in refrigerator. If you're living in an area with access to HN, congratulations, you have electricity, which eliminates the need for something like this in your area unless you're really trying to save on energy. Another contributing effect is probably that not everybody understands the concept of this design. Much of the world is under-educated, with limited access to knowledge like this.

The operating principle isn't rare. We use swamp coolers here in Arizona all the time. But I wouldn't use them to store food.

There are a number of limitations to them. The maximum cooling you'll get is 20F less than ambient, and that is entirely dependent upon humidity. So these only work in places that are extremely dry (yet also have plentiful water to run these coolers).

With the "pot in pot" method I wonder how they circulate air. You need a fairly constant supply of dry air for evap cooling to work. I'd imagine a porous exterior pot (think whiffle ball) filled with a spongelike material.

> The maximum cooling you'll get is 20F less than ambient, and that is entirely dependent upon humidity.

Any idea about the specific physics here? I'd love to see some equations to help explain this system (and the swamp coolers we use here in rural CA too).

Equations: http://en.wikipedia.org/wiki/Wet-bulb_temperature#Temperatur...

Ka-zaa!

It is so rare because it is pretty useless, inefficiently and there is no need for it in the proposed regions. People there desiccate their food or use spices like chili to make sure it stays esculent for a longer time, They don't have much water, so in my opinion it is pretty stupid to waste it for food if they have much better ways to conserve.

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