As far as latitude, the sun just isn't as strong the farther north you go, and in the winter. So you have to cook longer or sometimes assist using other means to finish the food up. But I've heard of people cooking at 55N with a solar oven, so if they can do that then anyone can. _________________ Conservation is conservative
It is not the strongest of the species that survive, nor the most intelligent, but the ones most responsive to change. -- Charles Darwin
Posted: Thu Feb 28, 2008 8:26 pm Post subject: Re: Cooking in the city
mattduke wrote:
Can you tell me about solar ovens?
Do they work at any latitude? Any tips or other alternatives? Thanks.
Hey Mattduke, I know all about solar cooking... Not all solar cookers
will work everywhere, but many will and the most important things are sun and sunglasses.
This is a picture of a commercial solar cooker boiling water in the winter.
I have not bought theirs, but I have made several of my own design
and they work as described. The cooker in this picture uses a simple
curved mirror and acrylic dome to insulate the cooking pot.
http://home.att.net/~cleardomesolar/parabolic.html
Personally I prefer the rocket stove and other small efficient wood
stoves over solar cooking. But it's nice to make bread in a solar
cooker and many solar cookers are like a crock pot, just set it and forget it...
and it's useful to know how to cook when no fuel is available.
One big problem that happens is if a country doesn't have fossil fuel
available for cooking, people pull up every tree, weed and bush and
cook with them. Biofuels at their worst, it's human nature. So solar
cooking is a useful skill for long term survival and of course it could
be useful for cutting down on bakery fuel costs as fuel prices rise,
sterilizing water...
You can find many useful websites on solar cooking.
Quote:
The Solar Funnel Cooker
"...was able to boil water in Utah in the middle of winter!"
Some things to note when building solar cookers:
*Acrylic containers and cheap sheets of Vinyl from walmart work
great instead of glass. In fact I think they are better for most
applications. You could build a rock proof water tank heater by
using fencing and vinyl instead of glass. Vinyl and Acrylic are
surprisingly useful for a lot of things. A box covered with clear vinyl
on one side and a mirror is all it takes to make a solar cooker.
Large nylon "Oven Bags" also work well...
* Adhesive spray works great for applying mirror material.
You can make large mirrors from doors, plywoods, and satellite dishes...
* Glass mirrors are a pain to work with. Tin foil will work, but mylar
is the best. You can get huge sheets of mylar for about $2.00 in the
camping section as an emergency blanket or as gift wrapping for
about the same price.
steam_cannon wrote:
Parabolic Solar Cookers: Mylar, Sticky Spray, old satellite dish, box, vinyl...
Box cooking bread at 350 F
Note, the first picture is a large dish that can be used for winter
solar cooking. Also notice how I hold up my reflectors. I use a board
with two nails in it. One nail goes in the ground and the other nail
goes into the top of whatever is being held up. This design is very
portable, positionable and will work for all large mirrors. Also note
that the mirrors have a board on the bottom and a rope handle
on the back. This is a very portable sturdy design.
Also in the pictures, you can see I am covering cooking pots and pans to
reduce heat loss into the air.
I'm using an acrylic cover in the first picture.
Vinyl on a box in the second picture.
And in the bottom pictures I am using Nylon "oven bags".
Box Cookers
I'm not sure where those pictures are at this moment. They also
work, but my opinion they are not ideal for the winter...
Large Mirrors have many uses...
steam_cannon wrote:
Large Utility Mirrors
Even simpler, you can do a lot of things with large mirrors and they
cost hardly anything! You can point large mirrors on a tent to warm
it up, make a large solar cooker, in theory warm up a side of a
house with yard mirrors, possibly roof mirrors to keep a building
cool, or point it at your neighbor as a joke (hahaha)...
So there are lots of things you can do with large mirrors and they
are very easy to build. As mentioned earlier, you can make them
with camping mylar (or potatochip bags) and sticky spray (or
improvised adhesives), and stick it onto plywood, an old door,
fibercrete, sheetmetal... Whatever you want to make into a large mirror.
Aluminum Foil VS Mylar?
As a side note I'll just mention that Mylar has better reflectivity then
Aluminum Foil. But Aluminum foil may be more durable and less
subject to sun damage. For a really good mirror Mylar is the way to
go. But Foil mirrors work too and may be better for some
applications...
Note for a solar cooker like the one above, an inner tube will offer
better insulation then a tire and vinyl works better then glass...
Also note, if you are thinking of using large mirrors for a solar array,
don't. To amplify your solar array safely, use a large shutter, door
or plywood painted white. That way it will boost light onto your
solar panel evenly reducing the likelihood of damaging your solar
array and you won't get sued by someone for having mirrors on
your roof because they were blinded while driving...
And remember, large mirrors that shine in the directions of cars or
planes can lead to legal troubles, so use your mirrors with care...
steam_cannon wrote:
Waterlens, just a piece of vinyl over the top of a barrel.
These aren't all that great for solar cooking but they are great at burning things,
very safe and you could make ice lenses in the wintertime this
way... hahaha
Joined: Jan 03, 2005 Posts: 1185 Location: western Wisconsin
Posted: Thu Feb 28, 2008 8:34 pm Post subject: Re: Cooking in the city
We have SunOven brand solar cooker, and a homemade one made from cardboard, glass, and aluminum foil. Both work about the same, but the Sunoven is sturdier and more convenient. We cook coffee cakes, cookies, casseroles, and rice dishes, among other things, in them. The Sunoven has a good seal around the glass door, so things in it stay moister than in a regular oven, so they don't overcook and dry out as quickly if you don't get them out right away. There are some other oven designs that will heat hotter or in less sun. The site that Red mentioned is a good place to start to learn more.
However I will admit that box cookers require less fiddling with then big dishes.
And speaking of "bigger is better" a bigger reflector on a box cooker can make
them work pretty well in the winter...
Quote:
Solar cooking at high latitudes
Heavens Flame - Box Cooker
Pavarti - Funnel Cooker
After a while I used the Parvati most, because it needed no turning
for two hours. I made casseroles, cooked potatoes, vegetables
and fish, and even made bread which tasted really good.
Posted: Thu Feb 28, 2008 9:08 pm Post subject: Re: Cooking in the city
WisJim wrote:
We have SunOven brand solar cooker, and a homemade one made from cardboard, glass, and aluminum foil. Both work about the same, but the Sunoven is sturdier and more convenient.
Yeah, sturdiness is important. If you're making something to last and
be used, cardboard should be avoided (at least as a supportive material)...
Posted: Thu Feb 28, 2008 10:59 pm Post subject: Re: Cooking in the city
In northern locations, a larger collector will do the job, more time can help, but the days can be short up north.
Solar cooking needs only equipment, no fuel needs to be gathered/consumed, making it a particularly useful means of cooking. However, the sun can give way to clouds, or your solar cooker may be too small for the size of the meal you wish to prepare. To keep on cooking when the sun goes down, take a look at
If you must consume a fuel, rocket stoves offer excellent bang for the bark. For electrical devices, a small slow cooker/crock pot can operate on as little as 100 watts. As with the solar cooker, Heat Retention Cooking can minimize the amount of fuel/energy required.
Nothing worse than having a pot full of dry beans, an empty stomach, and no way to cook the things.
I've found that having multiple redundant systems gives me options when problems arise. I have a stove that operates on city gas, a 2 burner electric stove top ($60 walmart), a 2 burner coleman camp stove run on propane ($40 walmart), a propane bbq grill, an experimental rocket stove, a propane stove/oven in the camper, a single burner that fits on top of a 1# propane tank, electric slow cooker, microwave, toaster oven, a solar box cooker, a pile of firebrick that will one day be an outdoor bbq, and if that all fails, a fire pit in the back yard can be dug in short order for a campfire.
One of my favorite cooking devices was an Electrocution Cooker used back in college in the dorm to cook hot dogs. 2 forks, some electrical tape, and the cord from a broken toaster. Separate the wires in the cord, strip off an inch or two to expose the wire, taping one wire to each fork, stab the forks into each end of the hot dog, put the hot dog on a plate, plug it in, and DON'T TOUCH THE HOT DOG until you unplug it. Cooking time, about a minute. _________________ If you want a picture of the future, imagine a boot stamping on a human face--for ever."
-George Orwell, 1984
Posted: Fri Feb 29, 2008 2:19 pm Post subject: Re: Cooking in the city
Thanks for the great responses everyone.
kpeavey wrote:
One of my favorite cooking devices was an Electrocution Cooker used back in college in the dorm to cook hot dogs. 2 forks, some electrical tape, and the cord from a broken toaster. Separate the wires in the cord, strip off an inch or two to expose the wire, taping one wire to each fork, stab the forks into each end of the hot dog, put the hot dog on a plate, plug it in, and DON'T TOUCH THE HOT DOG until you unplug it. Cooking time, about a minute.
Joined: Jan 03, 2005 Posts: 1185 Location: western Wisconsin
Posted: Sun Mar 02, 2008 10:01 pm Post subject: Re: Cooking in the city
We have baked yeast breads in the Sunoven brand cooker, but we only do it if we are around to keep an eye on it, and if it is really sunny and stays sunny. If it clouds up around the time you put the bread pans in the oven, it doesn't bake fast enough and the dough keeps rising, filling the entire oven with a mass of sticky messy dough. I would get a solar oven that was a bit hotter than a Sunoven if I was going to depend on it to make bread regularly. It does work fine, however, for quick rising or baking powder breads or bisquits, cakes, etc.
Posted: Wed Mar 05, 2008 7:16 am Post subject: Re: Cooking in the city
Mattduke, no, solar ovens do not work at any latitude. They do not work at all in winter at Scandinavian latitudes, above the 54th parallel. In Stockholm, 59th parallel, the sun rises only 9 degrees above the horizon at midday at the winter solstice, and it is usually cloudy. Thus totally impossible from Nov-Feb.
I built a simple solar cooker by cardboard, aluminum foil, and a glass cover. Admittedly, the design was primitive and could be improved, but hardly more than doubled. In a sunny day in June-July, I managed to cook an omelette, and some weird-consistency rice another day. You need a day with dependable sunshine, which is a minority of days here, although they exist. (And such summer days - a rare treat for us - we tend to have better plans than sitting a around the house adjusting a solar cooker) Shading trees are no good either - and remember, the shadow moves.
My solar cooker was pretty good in making hot water though, always a good thing to have in a summer cottage without heating or electricity where I built it - although on sunny summer days, hot water for doing dishes can easily be produced by placing the dishwater tub in the sun. Our baths are taken in the Baltic on such days. - So, most useful when the need was low.
It was also useful for reheating already cooked food. Not bad.
In August, the sun is already lower and the efficiency less. The shadows of the trees are longer too. Hardly any chance of real cooking at my cottage.
Since it was made of cardboard, it could not be left out over night, with dew and constant chances of rain. Bulky and a fragile glass-pane, not that easy to move and find a place indoor for, either. But a sturdier thing that can be left outside all summer, and is easy to fold and store has certain potential.
Luckily, there is always lots of wood around in most places in Scandinavia.
I am a firm believer in solar cooking in dry locations at low latitudes. Plenty of those on Earth. Cool, wet, high latitudes means limited potential.
Posted: Wed Mar 05, 2008 6:01 pm Post subject: Re: Cooking in the city
I have a homemade solar cooker that I'm itching to try out this summer. Right now, though, it's usually raining (it is Oregon, of course it's raining, lol).
I am also going to buy a good cast iron charcoal grill and see what I can do with "found" wood - cast off wood from within town. Like pallets, old fences etc that folks just want to dump. It will be an interesting experiment to see if I can cook for free!
I would love, though, to be able to build a cob bread oven, but I don't own land to build one on and the landlord said no way!
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