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Making a Better Solar Cooker
New submitter jank1887 writes "Back in 2010, the aid organization Climate Healers gave a number of solar-powered cookstoves to rural Indian villages. The stoves were rejected by the communities, mainly because they were useless when they were wanted most: for the evening meal sometimes after the sun goes down, and for breakfast before the sun has risen. Following this, the group issued a challenge to EngineeringForChange. Details of the challenge include the need to provide 1kW of heat at about 200C for two hours in both early morning and late evening, and the users should be able to cook indoors, while sitting. A number of groups, mainly at U.S. and Indian engineering institutions, accepted the challenge, and developed potential solutions. Now, almost a year later, the ten finalist designs have been selected. The actual papers have been posted to the E4C challenge workspace. The goals of most of the designs are to keep the technology simple, although there are a few exceptions, and many include sand-, oil-, and salt-based concentrated thermal storage. Many reports include some level of discussion on the social and economic considerations, barriers to acceptance and sustainability, and how to overcome initial resistance to adoption."
Solar panel, a bunch of lead-acid batteries and a George Foreman grill and they're good to go.
Damn right too, McDonald's hamburgers are horrible. People living rural lifestyles like this are used to eating real meat instead of processed crap.
If these villages can afford to be picky as to when they eat
Perhaps the problem is they can't afford to be picky when they eat. Ever consider they might need to be working during daylight hours.
There are actually government subsidies on kerosene in place in India specifically to prevent deforestation. The kerosene stoves are actually quite safe, efficient, clean burning and relatively inexpensive (by developed nation standards). Now before you start with the "OMG fossil fuels BAD!!!", remember that the grid-connected electric ranges that are so popular here in the USA are running on varying percentages of power derived from nasty, dirty coal - with the added bonus of generation and transmission losses. Since we're talking about a point-of-use fuel, these "third world" kerosene stoves are actually a pretty green solution. Perhaps instead of providing these people with pie-in-the-sky solar stoves that we wouldn't even use ourselves, we should offer good old kerosene stoves and maybe take a closer look at our own wastefulness.
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DRM is like antifreeze, to the MPAA/RIAA it's sweet, to the consumers it's poison.
Reading the article, the first contender came with a proposal to give them efficient wood stoves first, to displace the open fires they're currently using. Doesn't imply that they have gas.
Of course, it makes me want to point out that a modern high efficiency wood stove might sufficiently solve the problem to the point that it renders the solar stove unnecessary. Wood is a renewable resource, they apparently have sufficient quantities of it, and from what I remember, ye old wood stoves were ~10x as efficient as open pit fires at heating and cooking, and modern high efficiency ones are ~50% more efficient than the ye old varieties.
So you're lookng at using 1/15th the wood. At which point you have to convince people that using the solar stove is more convienient/valuable than dealing with the much smaller amount of wood the solid fueled stove needs. Well, don't forget cleaning requirements.
Let's see, stove rating areas:
The more you get, the better the product.
I don't read AC A human right
Doh... Of course you're correct, and I'm mostly thinking of my micro-production at home. Of course, back in the day you had the village baker, the average family didn't bake their own bread. What I get for trying to be among the first to post. ;)
I should have stated a concern more for how easy it is to control the temperature of the stove - keeping it reliable is more important than the exact temperature, and many older ovens were large enough that if you wanted hot you used the back of the fire/oven, if you wanted lower temperature you kept it nearer the front.
As for the outdoor brick/mud oven - if it's solar powered you need something to control the damper, and if you're using stored heat you need a way to moderate the heat from extremely sunny/hot days, while still keeping it hot enough on rainy days.
Supplimental heat from a fire, or like in the one case it's 'add water here, get steam there', so if you have some sort of steam limiter, you have temperature control.
I don't read AC A human right
I wrote the article for Engineering for Change and I'm so glad to see this discussion on Slashdot. I've been a fan reading the daily email for a while now. It's interesting to see that, in a just a few comment strings, some of you came to the same conclusions about the best ways to introduce new technologies that it has taken maybe decades for people who are educated in development issues to reach. Also, your discussion of better solutions other than solar (efficient wood stoves) and better materials (why olive oil?) is the same kind of thing that the community at Engineering for Change struggles with. Our members find different answers that sometimes conflict, and often a solution depends a lot on the place where you use it. So, a universally perfect cook stove might not exist. Just a few thoughts. Thanks again! Rob
There are some real idiots on Slashdot who can't think outside the box that is their mothers basement.
Wood burning has some nasty side effects. First off, wood isn't all that efficient for burning, meaning you need a lot of it. Neither can you turn it on/off as you want, meaning you waste a lot of energy. Consider a gas grill to a coal one. The coals needs to first burn up, then glow and finally cool down. The gas grill is hot in an instant and the moment you stop using it, you can turn of the supply of fuel.
The second problem is that wood is not a renawable resource if you use it up to fast. Trees only grow so fast and it is VERY easy to use them up faster then they can regrow. Land is also expensive and often owned by someone. You can't just go around collecting wood from anywhere and the more people there are, the more this is true. Removing trees even if you intend to replace them also causes climate change. Don't believe this? The rain forest causes most of its own rain, trees evaporate a hell of a lot of water but also capture a lot of it again, it is a complex system that can easily turn forest to desert if upset. See the expanding Sahara as an example.
Then there is another issue, collecting wood is a labor intensive task, often falling down to the women. Gathering it means they can't go to school, can't do anything else. It also forces them to go outside their village, in Africa especially this opens them to attack. Not every area in the world is safe to go outside. One of the reasons for putting wells inside villages is pricesly this, to protect the women and stop them to having to spent every waking hour collecting basic resources.
The solar stove is a good idea. There is just one snag. Those making the decisions ain't the ones who would benefit from it. The mentioned problems of cooking outside sunlight hours are trivial to solve by adjusting how you eat. But the ones in charge don't want to do that, the old ways suit them just fine. They can afford to send their women out to collect wood, and if they get attacked, they are just killed to spare the family shame. Never underestimate the evilness of a village elder.
Change will come but it will come slowly, just as it did in our own history. It isn't so long ago we cooked on wood and coal and suffered from it. Research the clean air act of Britain. You would be suprised how recent it is.
Take it slow with this solar cooker, don't get the adults or old people involved at all, show the kids at school. Those girls will one day have to buy their own stove and if they have learned they can cook at least some percentage of their food without having to spend a fortune on fuel, some might just do it when they got the chance.
Similar things happened in our own history, the bicycle was a huge liberator. While the proper women thought they were indecent, lots of young women took them as it allowed them to take jobs far further from home and thus increase the earning capacity of their family. If you get payed by the hour, any hour not spend travelling means more money and the further your range, the more options you have.
These things go faster then you might think but slower then you might wish. The solution for the solar cooker is already known and used. Hot stones. Heat a stone, it retains the heat for long enough to continue cooking after the fire has gone out (sun has gone down). And people adjusted to this. Just takes time for the old to be replaced by the young.
MMO Quests are like orgasms:
You may solo them, I prefer them in a group.
I would think you think you're being clever or well informed, but I regularly cook things in my Sous Vide machine at the FINAL temperature I want them to be. With this method you cannot overcook your food, it will hold at temperature and in most cases not degrade the texture of the dish if something comes up and you wait 30 minutes to pull it out of the water bath. Some high end restaurants use this method to keep popular foods just shy of done, when an order comes in they give them a quick sear in a pan and put them on a plate.
A lot of the 300-400 degree cooking methods are too-efficient transmission directly from the pan through the meat so when the center is 170 and safe to eat, the outside is 240+ and either beef jerky or charcoal. Likewise air is a poor heat conductor so it takes hours in an oven for the center of the meat to reach 160, see every Thankgiving turkey ever.
With Sous Vide you never overcook and the moisture in the food isn't driven out by the cooking process.
So I'll see your Newton's Law and raise you Fourier's Law
"Writing about sous vide led Myhrvold to think more deeply about how heat moves through different media (which is why Modernist Cuisine may well be the only cookbook ever published with a long disquisition on Fourierâ(TM)s law, the equation for calculating heat transfer)."
http://www.wired.com/magazine/2011/02/ff_myhrvold/all/1