Solar cooking works, from sunny Brazil to Seattle
Ashton Vital explains alternative box-cooker designs. Credit: Eric Scigliano
Northwest Public Radio’s enterprising Tom Banse was working on a collaborative project on wood smoke in this region when he came upon a much bigger story — a global one. The effects of wood stoves here are just a puff of, well, smoke compared to the ills suffered, and perpetrated, by up to 3 billion people around the world who depend on biomass — wood, charcoal, dung, and the like — to cook their food. Smoky, inefficient cookfires such as the classic “three rock” arrangement cause tens of millions of respiratory ailments and some 1.5 million deaths each year, more than malaria.
The soot they produce is a potent greenhouse agent in itself, and if it falls on snow — say, Himalayan glaciers or arctic icepack — it reduces the snow’s albedo, making it absorb more heat and melt faster, a proverbial feedback loop. And gathering or buying firewood consumes an enormous share of many power people’s time and income. It’s a main cause of deforestation, degrading habitat, triggering erosion, and further contributing to global warming — another feedback loop.
Banse found that a growing movement is attempting to remedy this situation by replacing those dirty cookfires with clean, efficient stoves that consume less fuel and produce much, much less smoke and illness. And that the Northwest is home to a “burgeoning cluster of lifesaving stove designers” — at least four of them, anyway.
The clean-stove movement has indeed come into its own recently, with an outpouring of media and official attention. Last year, the United Nations Foundation, together with the U.S., German, and Norwegian governments and others, launched the most ambitious initiative yet, the Global Alliance for Clean Cookstoves; Secretary of State Hillary Clinton, who got attuned to the issue when she traveled as First Lady and saw poor people staggering under heaps of firewood, was a main instigator. It proposes not merely to send clean stoves around the world, but to insinuate them so thoroughly into local economies and customs that people from Kampala to Kathmandu will keep manufacturing and buying them on their own.
But valuable and impressive as all this is, it’s not the full story, nor a perfect solution to the cookfire conundrum. A fire-free alternative, variously described as a “solar cooker” or “solar oven,” can not only reduce but eliminate toxic smoke, costly fuel, and their attendant ills. Solar cookers can be assembled from everyday, even scrap, materials for less than the target cost ($10) of clean-burning stoves.
Clean stoves stand to dirty cookfires as Priuses and Fiestas do to smoky old gas guzzlers. But solar cookers are like bicycles — except they don’t entail anything like the exertion and loss of capacity and functionality that come with switching from a car to a bike.
Solar cookers are an idea that’s been hiding in plain sight for a very long time — and Seattle is a hotbed for them too. In 2009 the Financial Times awarded its $75,000 FT Climate Challenge award for “the most innovative and scalable solution to the effects of climate change” to the Kyoto Box, a cheap cooker made out of an insulated cardboard box lined with tinfoil and black paint, with a clear acrylic cover to catch the heat (a beneficial application of the greenhouse effect). It was a ringing endorsement of the idea of solar cooking, and of the appeal of super-cheap, simple design; I felt the same way the first time I saw a similar box cooker in action, in Brazil a few months before the FT contest. But it also seems a gesture of astonishing naiveté by a sophisticated newspaper, a bit of clever brand appropriation, and an indication of the widespread ignorance of solar cooking.
According to various promoters and practitioners of such cookery, the idea goes back to the 18th or 19th century. Box cookers like the Kyoto have been around for decades. “We laughed at that [prize choice],” says AmyJo Mattheis, executive director of the California-based nonprofit Solar Cookers International. “His cooker doesn’t even work!” Indeed, a promotional video of the original cardboard model suggests it wouldn’t: It had heat-absorbent black where it should have had reflective foil. A new model, apparently developed with that $75,000 prize, is made of sturdier polystyrene, with reflective lining.
A range of designs have been devised to capture and concentrate the sun’s rays for cooking. (Wikipedia shows others.) Inclined lids and plywood make the simple box more efficient and sturdier. Open boxes, foiled or mirrored across their entire inner surfaces — some ingeniously shaped, fanning out like card hands — bounce the rays onto a blackened pot, bagged in heat-resistant plastic for greenhouse value. Parabolic designs, some homemade and some exquisitely engineered, concentrate the rays even more intently. The slickest, naturally, seem to be from Germany, or to be made using a German design in Kenya.
These can get hot enough to sear a crunchy crust onto a casserole or roast, if desired — or to burn it, if neglected. The glass-topped and plastic-bagged versions, by contrast, self-regulate to guard against burning: When water inside boils, it steams up the cover, blocking the rays and cooling the contents. The temperature stays just over 200 degrees Fahrenheit.
Last year I salvaged a parabolic antenna Direct TV had left behind, thinking to make a cooker out of it but wondering if it was too small. Now Joann Kerr, a graphic designer, cofounder of Sustainable Northeast Seattle, and coordinator of perhaps this town’s widest-reaching solar-cooking effort, tells me it’s been done. It works.
Kerr and the Sustainable Northeast group got the solar cooking bug about three years ago. They discovered that one of their neighbors, Tom Sponheim, had been doing it for some 20 years, and had even served as Solar Cookers International’s webmaster. “Tom will take his solar cooker out in March and use it into November if it’s still sunny,” Kerr says admiringly. I couldn’t reach Sponheim for this story, but he presents a fan-like, clamshell-shaped cooker, made from a cardboard box and tinfoil and designed by a Malaysian “origami master,” in this video. He says it takes about an hour to assemble, maybe two the first time, and will “bake bread in Seattle in Feburary.”
For the past three summers Sustainable NE Seattle has hosted cooker-building workshops, using the origami clamshell design. At first, a $3 fee covered the materials; now $15 pays the instructor as well. Kerr estimates 150 to 200 people have attended, and some have gone on to teach their own classes. Perhaps solar cooking will spread the way belly dancing and marimba playing did in past decades.
Each July Sustainable NE Seattle hosts a solar cookout. “People bake bread, cook meat dishes, boil eggs and potatoes,” says Kerr. “It’s surprising how they’ll experiment.” One wrapped foil over various containers lying around the house: a laundry basket, a Rubbermaid plastic bin, etc. “A black pot suspended over them cooked just fine.”
This past July, the Sustainable Northeasterners determined to assemble the largest array of solar cookers ever, anywhere. But the day rose cloudy, and most chickened out. Those who came anyway had a fine afternoon cook-in. If you use a clothesline or otherwise depend on sunshine in Seattle, you learn to have faith in clear afternoons.
Fickle weather, and timid responses to it, represent what may be the biggest obstacle to the widespread adoption of solar cooking despite all its benefits. The high-powered Global Alliance for Clean Cookstoves, in its survey of various cooking technologies, concedes that solar cookers are “truly ‘smokeless’ solutions,” but finds “limits to the technology’s acceptability and viability that have limited large-scale adoption.” Their dependence on the weather, for starters: no cooking at night, or indoors, or, supposedly, on cloudy days.
Then there’s a conceptual hurdle, the natural human resistance to strange, counterintuitive technologies. Solar Cookers International’s AmyJo Mattheis concedes that “it is easier to move from a three-stone fire to an efficient biomass stove” than to a shiny clamshell that cooks without any fire at all. And, the rap goes, people love the (unwholesome) smoky taste that comes with burning wood.
There’s also the trash issue. Cheap cardboard and plastic-bag cookers may not last long, especially in dwellings exposed to the elements and insects. Replacing them may be easy for people living within the industrial salvage loop, but not out in the bush. And that produces waste — worst of all, plastic bags — that’s anathema to the UN agencies, which have opted instead for sturdy clean-burning stoves. (Is that waste anywhere near as bad as toxic smoke and deforestation? Good question.)
When I hear these caveats, I recall the first time I saw solar cooking and tasted its fruits, in Aracaju, the capital of the little state of Sergipe in Northeast Brazil. An old friend, Osirís Ashton Vital, who was then teaching environmental design at the Federal University of Sergipe, invited me over for lunch. I’d long marveled at the range and ingenuity of projects Ashton has conceived, initiated, and, most important, achieved: wind-powered water and closed-loop farming systems for a withering fishing village; a recycled craft and paper-making co-op, lending library, and computer school in another neglected town in the sertão outback; getting rural communities online and equipping them with refurbished surplus computers from São Paolo; inventing a cottage-industry sunflower-seed mill (its only moving part, a recycled computer fan) that lets small farmers break into the lucrative biodiesel business.
On that day, Ashton had something simpler to show: a foam-and-foil-lined computer carton with an old black cookie sheet on the bottom and a glass pane on top. Total cost, not counting salvaged scrap: $5. Just as Ashton and his wife, Claudia Andrade Leão, started fixing lunch, unseasonable clouds rolled across the sky. That slowed our meal but didn’t scuttle it. We had creamy baked plantain in half an hour and roast brisket (a little too done to my taste) in two. What the cooker demanded in patience it repaid in tranquility. We could doze, wander off, forget about it, and that self-regulating steam ensured nothing would burn.
Best of all, the results seemed to taste better for being cooked gratis. I remembered Fast Eddie Felson’s maxim in The Color of Money: “Money won is always sweeter than money earned.”
Ashton, Claudia, and their colleagues knew it wouldn’t be enough to just hand out solar cookers and expect people to adopt them. She and other eco-Betty Crockers were fanning out across the countryside, teaching people how to make and use their own cookers. I hope to get back soon and check the results. Meanwhile, she’s blogging (in Portuguese) on solar cooking and writing a solar cookbook.
Solar Cookers International is launching two similar-sounding efforts in Kenya, in a sugar-plantation camp and a rural slum. Another group is doing the same in Bolivia. Jewish World Watch has taken over from SCI in distributing thousands of solar cookers to refugee camps in Chad. Mattheis says the Indian and Chinese governments are distributing cookers en masse to their hard-pressed, smoke-afflicted rural populations.
But for all this, solar cooking doesn’t get respect from the big donor countries and international organizations. Just because desperate refugees in Chad or subsidized recipients in China use them doesn’t prove the concept, the thinking goes: The countries that need them must be able to manufacture them, and people there must want to buy them and cherish them as their own — the goal of the Clean Cookstoves initiative.
Solar Cookers International tries to meet that standard with a folding CooKit (cardboard and plastic bag) that it makes in both California and (for just $5) Nairobi. SCI claims a CooKit can last two years, though that seems wishful; at some point, the trash issue rears its ugly head. Corrugated plastic board offers a cheap, durable alternative, but it’s unavailable in nearly all of Africa.
And so the search continues for a scalable design that meets all these requirements. Flimsy disposable cookers are clearly a transitional technology on the way to a sunnier culinary future. Clean-burning stoves may be as well.
Meanwhile, from the hardscrabble, sun-blasted Brazilian sertão to richer but less sunny Northeast Seattle, backyard cooks are voting with their briskets and bread. I’ll wait for a little more sun before submitting that parabolic antenna to the great outdoor test kitchen.
This article was changed on Dec. 23, 2011 to correct the spelling of Joann Kerr’s name.