Under The Sun

In the heat of summer, a solar oven saves energy as it cooks food to fill your stomach

August 01, 2007|By Scott Carlson | Scott Carlson,Special to the Sun

A thought occurs to me now and then, when I turn on a burner and watch a ring of blue flame bloom underneath a pot: If I didn't have easy access to gas, electricity or even firewood, how would I feed myself?

There are millions of people around the world who have difficulty getting their hands on cooking fuels like wood or coal, let alone natural gas.

But a growing number of people are cooking with an abundant, clean power source: nuclear fusion -- or, in other words, the sun. This summer, I became one of them. Using some scrap materials and plans I found online, I built a solar oven whose temperature gets up to 240 degrees. It bakes potatoes, roasts vegetables and slow-cooks meat -- all while sitting on my front lawn on a sunny day.

Solar cooking is enjoying attention that it hasn't seen since the energy crisis and environmental awareness of the 1970s. People who are concerned about high fuel costs and climate change have embraced solar cookers as a super-efficient cooking technique. An added benefit: If you are cooking in the sun, you won't heat up your house on what is probably a hot and muggy Maryland day.

And those interested in international humanitarian work see solar cookers as a solution to deforestation, poverty and disease for people in developing countries.

"There are a number of us here and abroad who are trying to spread the word," said Pat McArdle of Arlington, Va. She retired from her job as a diplomat with the State Department last year and has become an evangelist for solar cooking in the developing world.

She had an "epiphany" about solar cooking while working in Afghanistan in 2005. She found landscapes that had been almost completely deforested and saw children who spent their days gathering scrub brush to cook the night's dinner.

She remembered that she had built a solar cooker when she was in the Girl Scouts. On a military base, she built a simple cooker from plans she found online, then brought it to a village. The skeptical locals were amazed when it boiled water. Now she lectures about solar cookers to people in the State Department, the Peace Corps and the U.S. Agency for International Development.

Nonprofit groups like Rotary International and Solar Cookers International, a 20-year-old organization based in Sacramento, Calif., have given solar cookers to people in countries such as Kenya, Ethiopia and Turkey, and recently to Darfur refugees in Chad. Solar-cooking experts estimate that there are about 1.5 million solar cookers in use around the world.

One of the first solar cookers -- a box with a glass top -- was created in 1767 by Horace de Saussure, a Swiss physicist and naturalist. He cooked fruit in it, but he didn't quite understand how it worked, according to an article about his experiments at solarcooking.org.

Today's cookers can be much more complex. There are parabolic cookers, which are large mirrored dishes that concentrate the sun's energy onto a suspended pot. These cookers get extremely hot and can bring water to a boil within a matter of minutes. On the downside, parabolic cookers are fussy and have to be turned constantly to follow the sun.

Others cookers are simple. The HotPot is a black pot inside a small, fold-out, reflective enclosure. Set it out in the sun late in the morning and it will cook all day. Advertisements say HotPots can reach 400 degrees, but people who have used them say that 250 degrees to 300 degrees is probably as hot as they get.

Commercial models abound online. The HotPot sells for about $100. The Sport Solar Oven, a box that holds two pots and is made from recycled plastic, is $150. The Global Sun Oven, which features a built-in thermometer, four reflective panels and a carrying handle, goes for $250.

I'm both cheap and adventurous, so I decided to build my own -- a simple solar box oven. Basically, it's a shallow box inside another shallow box, with a window on top. Insulation fills the cavity between the two boxes, and a reflective panel stands up on the back side of the oven, shining additional light into the box.

Before I started building, I consulted some instructions, tips and diagrams online. The Solar Cooking Archive, run by Solar Cookers International, is an excellent Web site (solarcooking.org), full of information. Then I went shopping. Solar chefs recommend using dark, shallow, thin-walled metal pots, like black Granite Ware. I bought two small Granite Ware pots at Stebbins Anderson in Towson, for $12 each.

I also purchased two cans of high-heat black spray paint, some weather-stripping, two sheets of clear Lexan plastic, a roll of aluminum foil, an oven thermometer and some assorted hardware -- including two L-shaped brackets. The most expensive item was a router bit ($35) that would allow me to cut a groove in a wood frame, where I would lay the Lexan plastic window. To build the boxes, I would use scrap wood and insulation that I had saved from various home-improvement projects.

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