For a minute there I thought I had to get off my couch, when all the while the fact is we don't have to do anything much but keep things afloat for just a few decades more! In fact, we'd best shut up about PO, because if our offspring finds out we knew about it all along, they'll turn and wring our necks come 2036!
If you happen to live in an area that depends on a lot of electricity, and you’re finding electricity to be rather expensive...or would rather wisely eliminate as much of that expense as possible so you could spend your hard earned money on other things, then you need to be looking for ways to reduce or eliminate your electrical use as much as possible. Where can we cut our electric bills?
We’ve all heard of changing our light-bulbs to the new and improved warm fluorescents (no, they no longer turn your skin green). Of course, we can shut off our lights when we’re not in a room, shut off all electrical appliances we aren’t actually using. After all, there’s really no need to have all the lights on in the house, the stereo blazing and the TV on with no sound while we browse the internet. Those kinds of things are easy to see, and cutting back on them does a lot of good. But a large portion of the energy going into a household is actually used for heating and cooling rooms, food and beverages.
Even if you think you’re rich enough to waste your money on electricity, you still need to be concerned about emergency situations when the power companies stop giving you what you need. If you lived through the LA blackouts as I did...then you know what I mean. Believe it or not...there are a number of free and effective ways to nip your electrical cooling bill in the bud while also be prepared for power-outages.
We can consider passive solar cooling and air-conditioning. Please note that we are not talking about the use of photovoltaic solar panels, those are active solar devices. I’m talking about passive solar cooling. A lot of people have trouble imagining that the hot summer sun, can actually cool your house, but it can. The second law of thermodynamics is our best friend, and it works endlessly for free (or at least as long as the sun exists).
Heat rises , and heat will always move toward cooler areas, and if it happens to draw liquid with it, and that liquid evaporates...the inside surface of what just evaporated will be cooler. Solar chimneys, underground cool rooms (the old fashioned cellar), and the zeer pot, are just a few ways that use this to our advantage to help us cut your power needs forever, and for free. After all, isn’t that what we all want? Why should we slave away at work all day and then spend our hard earned money on things that we can get for free?
To the surprise of many , the world’s cheapest refrigerator costs less than $2 dollars to make, uses minimal resources to produce and runs completely without electricity. It’s called a zeer pot, or the pot-in-pot and was developed by Mohammed Bah Abba, who realized that he could put the second law of thermodynamics and transpiration to work for him. The zeer pot, is actually two earthenware pots (I’m assuming they are both unglazed), one pot smaller than the other. The smaller pot is put inside the bigger pot, and the space in-between them is filled with sand. The sand is made wet with water (twice a day) and a wet towel is put on top of the two pots to keep warm air from entering the interior. As water in the sand evaporates through the surface of the outer pot, it carries heat, drawing it away from the inner core, thus cooling the inside of the inner pot which can be filled with soft-drinks, water, fresh fruit, vegetables or even meat. A damp cloth placed on top keeps the inside pot away from hot air. In this way, fresh produce can be kept for long periods of time without the need for electricity, or camping coolers made high embodied energy. Tomatoes and peppers will last for up to three weeks, and African spinach, or rocket, which normally would spoil after just a day in the intense African heat, can and will remain edible for up to twelve days. Eggplants will keep for up to 27 days instead of three. It can even be used for storing sorghum and millets for a long time since it protects from humidity, thus preventing fungi from developing. The zeer will keep water (and other liquid beverages) at about 15 degrees Celsius, and even meat can be kept fresh for long periods.
The new technology is now being used by farmers at the market. Fresh produce is kept inside, with just a couple fresh items displayed on the damp towel resting on top. In this way, most of the produce is kept hidden away from both warm air and insects. In the past, all produce was displayed in the open air, attracting flies resulting in stomach disease such as dysentery. Now food can be kept fresh for longer and kept away from flies...even miles away from electricity or ice.
Although many people are excited about promoting this technology in developing countries, I see greater potential for this technology in the developed western cities, suburbs and countryside.
Instead of having humming , heat producing, electrical, bank-sapping refrigerators and freezers, we could have zeer pots stashed away in cabinets or under sinks (for convenient kitchen access). We could have them placed in, or near the garden, by the back door, out on the porch or balcony...anywhere. We could have them on the truckbeds of roadside vegetable stands, in cross-country delivery vehicles...at the local farmer’s market. We no longer have to make choices about freshness based on expensive camping coolers, refrigerated trucks, ice machines and electrical outlets. We can provide our own endless supply of refrigeration for less than two dollars.
Posted: Wed Dec 26, 2007 1:34 am Post subject: Re: Nigerian method of keeping food cool (Zeer Pots)
I love it totally cool. (Pun intended)
I wonder if ones the size of a fridge.
Imagine how much you could do with something like this and say more advanced materials than a towel and perhaps minimal electricity application. _________________ "Once the game is over, the king and the pawn go back in the same box."
-Italian Proverb
Posted: Wed Dec 26, 2007 3:51 am Post subject: Re: Nigerian method of keeping food cool (Zeer Pots)
pot-in-pot
Yes, they are a very brilliant invention and very easy to make. You can make a pretty good one just wrapping a wet towel around a metal bucket with a drip pan under it. And a wet towel on top as a cover. So if you were running a food stand by the side of the road in the summer, you could make one very easily that way. And it would keep your vegetables from wilting.
Also, terracotta or home made low fired pottery in a campfire will work well as they are porous and allow water to pass though. Like the pottery we made Nars... You can also try it wrapping a towel around a soda can.
Eggplants, for example, stayed fresh for 27 days instead of three, and tomatoes and peppers lasted for three weeks or more. African spinach, which usually spoils after a day, remained edible after 12 days in the pot-in-pot.
This is a somewhat disturbing thought. Occasionally someone mentions that the US wastes half of the food they consume, but what about the rest of the world? We waste lots of food, this is true. But also we don't lose lots of our food because we have efficient refrigeration. That is to say, if our power grid becomes less reliable our food losses may increase dramatically and become more like other parts of the world.
But also on the other side of the coin, with a little technology like this, other parts of the world where electricity is not available and farm production is marginal, these areas will see greater production and labor savings due to this invention. Just some thoughts, but that note about common losses like spinach crops should make you think about how much food the rest of the world loses...
Posted: Wed Dec 26, 2007 3:52 am Post subject: Re: Nigerian method of keeping food cool (Zeer Pots)
Concerned wrote:
Imagine how much you could do with something like this and say more advanced materials than a towel and perhaps minimal electricity application.
As great and simple as evaporative coolers are, they are very limited in how much more efficient they can become. The full sized terracotta device shown in the article works pretty close to the maximum efficiency that sort of device can achieve. Regarding minimal electricity, putting a fan on it would speed up the rate at which it cools down, but it would still not get any cooler then a maximum coolness, it would just cool to that limit faster. So a fan would do very little to improve this technology.
wiki wrote:
Swamp Cooler
A typical residential 'swamp cooler' in good working order should cool air to within 3°C - 4°C (6°F - 8°F) of the wet-bulb temperature."
Performance
Some rough examples clarify this relationship.
* At 32°C (90°F) and 15% relative humidity, air may be cooled to nearly 16°C (60°F). The dew point for these conditions is 2°C (~36°F).
* At 32°C (90°F) and 50% relative humidity, air may be cooled to about 24°C (75°F). The dew point for these conditions is 20°C (~68°F).
* At 40°C (105°F) and 15% relative humidity, air may be cooled to nearly 21°C (70°F). The dew point for these conditions is 8°C (~47°F).
Evaporative "swamp coolers" only cool so much, but a fan will increase the amount of air they can cool. So for a house with a little "swamp cooler" it makes sense to use a fan to push air though faster. But with a pot in a pot refrigerator, a fan wouldn't be needed since the sides of the refrigerator offer sufficient surface area to cool the inside of the pot. But even if a fan was used, remember it wouldn't get any cooler then a swamp cooler could cool. So this technology will never be any good for making ice cream. It can only cool a few degrees, which under the right conditions makes a big difference.
Last edited by steam_cannon on Wed Dec 26, 2007 4:12 am; edited 1 time in total
Posted: Wed Dec 26, 2007 4:01 am Post subject: Re: Nigerian method of keeping food cool (Zeer Pots)
Loki wrote:
That's pretty cool. Yet another reason I want to learn ceramics
I suggest simply learning native pit firing. It doesn't require a kiln, just a fire. It can be a fun activity on camping trips, making things from local clay or as a parlor trick when visiting someone. It only takes a few hours (for me) and you can make all sorts of ceramics for home use and gifts this way; pipes, statues, buttons beads, dice. And it's useful for making water filters and evaporative refrigerators.
It's entertaining and depending on the future, it may be a very useful skill to know.
Joined: Aug 27, 2004 Posts: 162 Location: missouri
Posted: Mon Dec 31, 2007 9:35 pm Post subject: Re: Nigerian method of keeping food cool (Zeer Pots)
I've heard of a similar way to cool a room--moisten a sheet and hang it in the window, and as the sheet dries, the evaporation cools the room. I'm assuming this thing works the same way. Just one problem--it wouldn't work here in Missouri in the summertime because it's so hot and humid that sheets won't hardly dry on the line. It's neat though, and I may play around with it in other seasons.
Posted: Mon Dec 31, 2007 10:03 pm Post subject: Re: Nigerian method of keeping food cool (Zeer Pots)
Quote:
But also on the other side of the coin, with a little technology like this, other parts of the world where electricity is not available and farm production is marginal, these areas will see greater production and labor savings due to this invention. Just some thoughts, but that note about common losses like spinach crops should make you think about how much food the rest of the world loses...
I doubt it (the amount that the 3rd world loses) is much. Consider the fact that they probably know that it will be inedible in a day or so or however long depending on the food. Therefore, they will most likely take that information into account and either eat or sell it before it becomes useless.
Is there any ancient way of making ice? Would that be possible with this or any other type of electricity-free device? _________________ I want to put out the fires of Hell, and burn down the rewards of Paradise. They block the way to God. I do not want to worship from fear of punishment or for the promise of reward, but simply for the love of God. - Rabia
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