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Roof Garden Baking - Hot Off the Grid

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  • Mark Gagliardi
    For Beth Terry, roof gardeners, & others copy into your browser this whole string: http://www.sfgate.com/cgi-bin/article.cgi?
    Message 1 of 2 , Aug 6, 2007
      For Beth Terry, roof gardeners, & others

      copy into your browser this whole string:

      Hot off the grid
      Solar ovens utilize nature's rays for energy-efficient, everyday
      cooking -- even in foggy San Francisco

      Tara Duggan, Chronicle Staff Writer
      Wednesday, July 11, 2007

      Global warming. Dwindling energy resources. Deforestation and
      pollution, natural disasters and power outages.
      These are just some of the things to worry about in today's world.
      Yet a small but growing group of advocates says a simple tool exists
      that can help address them: the solar oven.
      Sun-heated ovens are nothing new. The idea has been around for
      centuries, and people of a certain age may remember using ragtag
      cardboard-and-foil contraptions to bake carrot-lentil loaf back in
      their hippie days. But with today's new versions that produce results
      comparable to conventional ovens, solar ovens are poised to move into
      the mainstream.
      "For people who are interested in being carbon-neutral or being
      green, the idea of using something like a Sun Oven is very
      appealing," says Paul Munsen, president of Sun Ovens International,
      based in Elburn, Ill. He expects to sell 5,700 ovens in the United
      States this year, up from around 1,000 in 2004.
      Lynn Langford of Ross purchased a Sun Oven a year ago and uses it to
      prepare dishes such as baby beet salad with walnuts and feta. Instead
      of boiling the beets on her stove and toasting walnuts in her oven,
      she places the beets in a dark pot, wraps the nuts in parchment paper
      and tucks both into the oven to cook in her sunny backyard.
      "When you care about not heating up the whole planet, it's a fun and
      easy way to do it," says Langford, who says her electricity bills
      dropped by 30 percent in the first month of using her solar oven
      about three times a week.
      Solar ovens alone will not solve the energy crisis. A typical family
      of four consumes about 500 kilowatt-hours per year using an electric
      range and oven combination, which adds up to only around $65 a year
      on Bay Area utility bills. Still, it's a start.
      "People look into installing solar panels or a solar water heater,
      and it's a sticker shock when they start to think about that initial
      investment," says Munsen. "Then they look at a $260 oven and it's a
      lot more immediate."
      Munsen's company focuses primarily on getting solar ovens into the
      developing world, as does Sacramento organization Solar Cookers
      International, which promotes their use for impoverished people who
      lack access to cooking fuel (see "A tool for the developing world,"
      this page).
      The ovens work best in sunny climates like California's Central
      Valley and the American Southwest, but even those who live in cooler
      parts of the Bay Area also can take advantage of them on sunny or
      mostly sunny days year round, and on camping or boating trips.
      Some people purchase them in the event that a major earthquake or
      hurricane -- not to mention terrorist attack -- wipes out power for
      days, or weeks. Solar cookers provide additional energy savings to
      those who use air-conditioning, because the air conditioner doesn't
      have to fight the heat produced by an indoor oven.
      "We bought our house in Sonora, and it's so hot and I thought, 'I
      have to have one of those sun ovens,' says Sharon South, who recently
      moved from San Jose to Tuolumne County. "Because in the summer, who
      wants to turn the oven on?"
      This spring, South started using her solar oven about three times a
      week and plans to buy a second one so she and her husband can cook
      more dishes at once when they have guests.
      Solar cookers like the Sun Oven can maintain temperatures of 350
      degrees or higher and start around $230. Less-insulated and simpler
      versions such as one called the CooKit cost about $32 and cook food
      in the low to mid 200 degrees -- hot enough to boil water, which is
      all you need for most cooking.
      Most solar ovens rely on the greenhouse effect. The Sun Oven, for
      example, consists of a well-insulated box with a glass lid and four
      reflective panels that direct sunlight into the box. As the sunlight
      is absorbed by the oven's black interior and any dark-colored dishes
      place inside, it converts into heat, which is trapped inside by the
      glass lid. (For more on how solar ovens work, see graphic, F5)
      There are disadvantages. Solar ovens don't work on super-foggy or
      rainy days. They also can't be used with recipes that require high
      heat or lots of stirring; heat escapes each time you open the oven or
      lid, adding another 15 minutes of cooking time. On the other hand,
      the ovens can't burn food because there aren't any hot spots.
      Solar cooking typically takes two to three times as long as
      conventional cooking. But once you get used to the relaxed rhythm, it
      can be easy and convenient, kind of like using a Crock-Pot. If your
      backyard has sunlight all day, you can place a one-dish meal inside
      the oven in the morning, position it toward where the sun is at its
      height in the middle of the day, and come home from work to a fully
      cooked, warm dinner.
      "Someone who likes precise cooking might be frustrated with these
      ovens," says Langford, a mother of twin preschool-age boys. But,
      partly because she works at home as a consultant, she says, "I'm not
      concerned with how long it takes. I see it as a different kind of
      The Food section purchased a Sun Oven and conducted a range of tests
      on the roof of our often-sunny South of Market office, with
      surprisingly good results.
      We found it perfect for low-and-slow cooking, such as a whole-grain
      rice pilaf. It also did a lovely job baking up corn bread and peach
      and blackberry cobbler, and cooked up sweet and tender baby beets and
      skewered shrimp.
      It took us awhile to get the hang of the oven, and our results were
      better after we learned more about sun patterns. Box cookers like the
      Sun Oven are most effective when adjusted about once an hour so the
      glass top is always perpendicular to the sun's rays.
      "What it is with the solar oven is you start to develop an intuitive
      sense. It's a little closer to nature," says Don Larson, assistant
      manager at Common Ground, a nonprofit organic garden supply and
      education center in Palo Alto, where he teaches classes on solar
      cooking and building solar ovens. "You notice, for example, if it's
      windy you leave it in 15 minutes longer."
      Common Ground sells about eight solar ovens a month during spring and
      summer. At their San Jose home, Larson, his wife, Susan, and their
      two children have three homemade solar ovens. Larson first got
      interested in solar energy when visiting a technology expo as a
      junior high student. He went home and built a model solar heater out
      of a cigar box and has been hooked ever since.
      "It's a very positive form of environmentalism," says Larson. "You're
      not out there protesting and marching. I'd rather be taking action,
      and this is a very social form of it. Everyone congregates around
      Still, Larson insists that the primary reason he uses solar ovens is
      even simpler: "How it tastes when you get it all done."

      History of solar cooking
      Ancient Greeks, Romans and Chinese experiment with the use of curved
      mirrors that could be angled toward the sun and cause objects to
      burst into flames, for military purposes.
      16th century. The Dutch, French and English begin widespread use of
      greenhouses, which are heated when sunlight passes through glass and
      becomes trapped inside, to raise tropical plants.
      1767. Swiss scientist Horace de Saussure develops a solar cooker
      using the greenhouse effect, in the form of several glass boxes set
      inside one another and placed on a dark surface.
      19th century. French mathematician Augustin Mouchot uses curved
      mirrors to angle the sun's rays into an insulated box that traps
      1894. A restaurant in China serves solar-cooked food.
      1950s. Maria Telkes of the Massachusetts Institute of Technology
      develops the present-day box solar cooker, an insulated, glass-topped
      box with four reflectors to direct light into the box. The United
      Nations and other agencies begin studying how to bring solar cooking
      to countries where fuel is scarce; early programs do not take off.
      1973. The first solar cooking convention is held in China, where
      solar cooking has become widespread.
      1992. China reports the use of 100,000 solar box cookers.
      Source: solarcooking.org

      A tool for the developing world
      Over 2 billion people, a third of the world's population, rely on
      wood-fueled fires to cook food. Of these people, around 500 million
      frequently encounter fuel shortages yet live in ideal climates for
      solar cooking, says Kevin Porter of Solar Cookers International (SCI)
      in Sacramento.
      Many women, especially refugees, trek miles to obtain cooking fuel,
      and the reliance on wood for fuel has led to deforestation in many
      SCI and other organizations help impoverished communities gain access
      to solar ovens to cook food, pasteurize water and sterilize medical
      equipment. Since 1995, SCI has taught 30,000 families in eastern and
      southern Africa how to use solar ovens and has helped establish solar
      businesses in refugee communities.
      The majority of funding comes from individual donors; to donate or
      learn more, visit solarcookers.org.
      -- Tara Duggan

      Where to find solar ovens
      The following organizations and companies sell solar ovens; some
      offer lots of online resources:
      ClearDome Solar Thermal. (888) 277-7547, Ext. 3427, or
      Common Ground Organic Garden Supply and Education Center. 559 College
      Ave., Palo Alto; (650) 493-6072 or www.commongroundinpaloalto.org.
      Solar Cookers International. (916) 455-4499 or www.solarcookers.org.
      Solar Living Institute/Real Goods. 13771 S. Hwy. 101, Hopland; (707)
      744-2017 or www.solarliving.org.
      Sun Ovens International. (800) 408-7919 or www.sunoven.com.

      --- In ZeroWasteOakland@yahoogroups.com, "Beth Terry" <beth@...>
      > My name is Beth Terry. I just joined this group because I am
      > in ways to reduce the amount of plastic that enters the waste-
      stream, by
      > eliminating unnecessary sources of plastic, re-using plastic items,
      > also recycling the plastic that can be recycled. I am interested to
      > find out what Oakland is doing about plastic curb-side recycling,
      as we
      > recycle way fewer types of plastic than San Francisco.
      > In an effort to educate myself and contribute to the dialogue in the
      > online world, I have created a blog about my personal quest to
      > the plastics in my life. It's at www.fakeplasticfish.com
      > <http://www.fakeplasticfish.com/> . I welcome all to come visit and
      > leave comments/ideas.
      > I also enjoy roof gardening, running, movies, and music. But right
      > my main obsession is plastic ever since I read an article called
      > "Plastic Ocean" that just broke my heart:
      > http://www.bestlifeonline.com/cms/publish/health-
      > turning_into_plastic_are_we_2.shtml
      > <http://www.bestlifeonline.com/cms/publish/health-
      > _turning_into_plastic_are_we_2.shtml>
      > Since I am new to thinking about these kinds of issues, I welcome
      > information that you wish to impart. Feel free to e-mail me
      > Beth
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