The Parabolic Earthen Solar Cooker is a low cost and low environmental impact design envisioned by Bart Orlando for use by the poor in refugee camps and in villages of non-industrialized nations. The design is simple; a large parabolicly shaped hole in the ground lined with reflective materials such as salvaged pieces of broken glass mirrors, reflective can lids or with funding, approximately 50 one foot diameter mirror finished aluminum food serving plates collected each day by 10 a.m. and used to line the hole (earthen solar cooker).
Sunlight is concentrated to the base of the hole where 10 one gallon black containers of water can be boiled per hour and used for drinking or food preparation. A 210cm(7ft) diameter hole, 150cm(5ft) deep cooks 38 liters(10 US gal) of rice/hr from 11 a.m. to 3 p.m. on an 30°C(85°F) summer day in south central Oregon. Cooking/water boiling containers are accessed via steps carved into the side of the hole. The plates are redistributed with servings of the solar cooked food. When cleaned, the reflective plates can be used as person grooming mirrors until collected the next morning for solar cooking again. The plates rest upon salvaged nails pressed into the sides of the hole. Each plate would be be less than half the diameter of the larger aluminum sheet metal mirrors shown in the image above. This will enable the final reflective surface lining the sides of the hole to conform better to its parabolic curvature, thus making possible a more tightly focused concentration of reflected sunlight near the vertex.
Given a large enough diameter parabolic hole and smaller diameter mirrors it may even prove to be an effective solar barbecue pit; vegetarian being my preference. Doubling the radius of the hole increases the power of the Earthen Solar Cooker by a factor of four. An Earthen Solar reflector the size of an amphitheater might be capable of casting bronze.
above text from http://www.appropedia.org
- See Bart Orlando.