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Cooking in rural Africa
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adam2
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PostPosted: Fri Mar 08, 2013 1:08 pm    Post subject: Cooking in rural Africa Reply with quote

My neighbours in London are from Ghana and keep in regular touch with friends and family back home.

In the last year or two there has been significant interest in PV powered electric cooking in rural areas.
The accepted wisdom is that PV is not viable for cooking, and this is no doubt true if a full size electric cooker that uses 10 KW or more is being considered.

LPG and kersosene are readily available but very expensive, having trebled in price over the last couple of years.
PV modules have recently halved in price.
High efficiency electric cooking appliances are becoming affordable.
Most of Africa has plentiful sunlight.

Many rural households already have a small battery charging PV system for lighting and a radio set. The more affluent have larger systems that also power a TV and a fridge.
In many cases it is worth expanding an existing system so as to supply an electric slow cooking pot, or even a microwave oven or an induction cooking ring.
An additional 200 or 250 Wp module can supply a slow cooking pot for much of the day, or a microwave oven or induction cooking ring for a couple of hours a day.
The main problem has been the unreliability of cheap chinese power inverters, and the high price of good reliable inverters.

There would seem to be a market for mass produced microwave ovens, slow cookers, and induction cookers for 12 volt input. These do in fact exist, but are very expensive and not readily available.
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PostPosted: Fri Mar 08, 2013 1:11 pm    Post subject: Re: Cooking in rural Africa Reply with quote

adam2 wrote:
There would seem to be a market for mass produced microwave ovens, slow cookers, and induction cookers for 12 volt input. These do in fact exist, but are very expensive and not readily available.


A friend said, "Impossible!" when I said you could cook using a 12 volt system (I said it was not ideal but definitely possible).

What's the best available options, adam2?
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adam2
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PostPosted: Fri Mar 08, 2013 2:18 pm    Post subject: Reply with quote

Depends on what you wish to cook of course.
For cheaper cuts of meat and many roots or pulses, prolonged slow cooking is usually best and for this purpose an electric slow cooking pot is ideal. The loading varies from about 40 watts up to about 150 watts and is easily supplied from PV.

For quicker cooking or reheating, both microwaves ovens and induction cookers are useful, these need 1,000 watts or more but usually for a fairly short time.
If frying or boiling on an induction cooker, full power is only needed fairly briefly and can then be reduced to a few hundred watts.
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kenneal - lagger
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PostPosted: Fri Mar 08, 2013 3:33 pm    Post subject: Reply with quote

They would be better off cooking direct using a solar cooker. They could make one themselves or buy one for a lot less than the cost of enough pv to power an electric cooker.
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Little John



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PostPosted: Fri Mar 08, 2013 4:21 pm    Post subject: Re: Cooking in rural Africa Reply with quote

emordnilap wrote:
adam2 wrote:
There would seem to be a market for mass produced microwave ovens, slow cookers, and induction cookers for 12 volt input. These do in fact exist, but are very expensive and not readily available.


A friend said, "Impossible!" when I said you could cook using a 12 volt system (I said it was not ideal but definitely possible).

What's the best available options, adam2?
I would have thought cooking with 12 volts would be definitely do-able and certainly very safe due to the high amps-low volts. I would have thought I could even lash up a "kettle" with my AC welder pretty easy by connecting my positive and negative terminals onto a panfull of water. The pan would act as a resister and heat up, in turn heating the water up.

The problem with doing the same with a 12v battery is that there would be no limiter to the amps and the battery would get very hot (and dangerous) very quickly, I would have thought.

So, thinking about it, my idea only works with an ac transformer (with amp limiting shunts in it) pumping out low volts/high amps.
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Catweazle



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PostPosted: Sat Mar 09, 2013 8:37 pm    Post subject: Reply with quote

The slow cookers I have seen have very poor insulation, usually a large area glass top. A properly insulated "strawbox" type cooker could work well on very little power, and of course if the ingredients were added in the morning it could do useful work in daylight hours and keep the cooked food warm until evening with no requirement for complicated energy storage.

I feel a project coming on, possibly with a 12v panel and a glow plug from a small diesel engine as a heater.
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adam2
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PostPosted: Sat Mar 09, 2013 9:32 pm    Post subject: Reply with quote

Catweazle wrote:
The slow cookers I have seen have very poor insulation, usually a large area glass top. A properly insulated "strawbox" type cooker could work well on very little power, and of course if the ingredients were added in the morning it could do useful work in daylight hours and keep the cooked food warm until evening with no requirement for complicated energy storage.

I feel a project coming on, possibly with a 12v panel and a glow plug from a small diesel engine as a heater.


I believe that someone in Ghana is already experimenting along somwhat similar lines.
Placing a large aluminium cooking pot in an insulated enclosure, and covering it with an insulated lid is relatively easy.
The problem is in finding or making a suitable heating element. This ideally needs to be switchable between say 250 watts or more for heating from cold and perhaps about 50 watts or less for keeping a large insulated pot just below boiling point.
So far the best that has been achieved is to bring the pot to the boil on a gas ring (the high cost of this fuel being of less importance for brief use) and then place the pot into a wooden box lined with fibre glass and with a heating element in the bottom.
The home made heating elements have not been a complete success and work is ongoing.
A physicly small element wont work as it tends to burn the food in one place rather than keeping the whole pot simmering.
I suspect that a higher voltage is the way forward, for example a standard 240 volt 2.4KW cooker ring if connected to 48 volts would use about 100 watts.
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Little John



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PostPosted: Sat Mar 09, 2013 10:26 pm    Post subject: Reply with quote

Fewer people. We need fewer people.

Then all of this marginal-gain engineering becomes unnecessary.

So, people are trying to develop a cooker that runs on little more than snot and fresh air, just so an unsustainable population can continue to live unsustainably for a little while longer to be able to have a few more kids down the line in order to make the problem even worse. What the hell for? What then? Try and squeeze another minute gain out of the technology whilst not dealing with the real problem?

Fewer people. We need fewer bloody people.
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kenneal - lagger
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PostPosted: Sat Mar 09, 2013 11:39 pm    Post subject: Reply with quote

You can sell them a new gadget, Steve, and make a bit of money. A solar cooker made out of a bit of tin foil and a cardboard box hasn't got as much play value in it for big boys who want to play with their toys. After all, where's the fun in just leaving it out in the hot African sun all day to cook on its own? Where's the engineering in that? What would the men do while the women got on with the cooking?
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adam2
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PostPosted: Mon May 13, 2013 11:03 am    Post subject: Reply with quote

Update time.

The favoured option seems to a 12 volt electric slow cooker, these appliances being available increasingly cheaply.
Most are rather small though for a family.

The loading is typicly about 7 to 10 amps, which is readily produced from a largish PV module and suitable battery.

I see a market here for an improved 12 volt electric slow cooker.
Larger than most existing units, probably about 3 L capacity.
Insulated to reduce energy use.
Switchable between say 250 watts/20 amps for quickish heating up and say 60 watts for prolonged simmering.
The inner pot should ideally be stainless steel both against breakage, and to permit of quick initial boiling on a gas ring.
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RenewableCandy



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PostPosted: Mon May 13, 2013 12:47 pm    Post subject: Reply with quote

I remember being astonished to find that Africa is a lot less densely populated than Europe (including E. Europe). There really is enough land there, to grow enough stuff. The trick is to stop cutting the trees down. Cooking with anything that isn't wood is going to be a huge help.

As for what the fellas can do, here's a chap who built his own wind turbine! (this is an olde article and I'm sure he's gone on to greater wind turbines since).
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adam2
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PostPosted: Mon May 13, 2013 1:21 pm    Post subject: Reply with quote

Yes, many pictures of Africa feature crowded cities and refugee camps, but in fact the average population density is fairly low.

My neighbours friends and family are very up to date and allways looking for new ideas.
Recent inovations have included large ferro-cement tanks for rainwater storage, a fairly large scale PV installation, and experiments in growing different crops. "English beans" have been a great success, I think that these are what we call broad beans. The people eat the beans and the rest of the plant is eaten by goats.

Electric cooking finds much favour whenever available as it is easily done indoors away from the heat of the sun.
Cooking with firewood is VERY last century with either LPG or electricity preffered, not so much to preserve trees but because wood is regarded as old fashioned.
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RenewableCandy



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PostPosted: Mon May 13, 2013 1:24 pm    Post subject: Reply with quote

Quote:
"English beans" have been a great success
Aren't beans great Very Happy ?
Got PV. Got Water. Got Beans. Sorted!
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woodburner



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PostPosted: Mon May 13, 2013 9:57 pm    Post subject: Reply with quote

stevecook172001 wrote:
Fewer people. We need fewer people.

Then all of this marginal-gain engineering becomes unnecessary.

So, people are trying to develop a cooker that runs on little more than snot and fresh air, just so an unsustainable population can continue to live unsustainably for a little while longer to be able to have a few more kids down the line in order to make the problem even worse. What the hell for? What then? Try and squeeze another minute gain out of the technology whilst not dealing with the real problem?

Fewer people. We need fewer bloody people.


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clv101
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PostPosted: Mon May 13, 2013 10:29 pm    Post subject: Reply with quote

The population growth problem is virtually solved. Most of the increase for the next couple of decades isn't due to high, unsustainable birth rates. Instead it's due to the high survival rate of girls born a couple of decades earlier now having their own children. The world fertility rate has fallen from 2.8 in 2000 to 2.5 today. The global replacement rate (where growth tends to zero) is 2.33. We're going to get there soon!

The main thing driving future growth is that the age distribution hasn't yet reached equilibrium. It's a population lag effect, not high birth rates today.
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