The Eco-Friendly Solar Cooker is intended to provide an inexpensive, eco-friendly means of cooking pieces of meat and other small food items in poorer parts of the world, where extremely dirty fuels are often used to cook meals. It requires no fuel, no electricity, and produces no pollution. It is designed to be very low in cost and have components which are very easy to replace or repair.
The Cooker is made in the form of an octagon 1.0 meter in diameter (Figure 1). Cardboard structural elements support a curved surface composed of paperboard. Sheets of highly reflective Mylar cover the paperboard. Thin metal tubes support a coffee can at the solar focus. Inside this can is the cooking zone – the space where the Sun’s radiant energy is most concentrated. A second can resides below, which serves to collect grease. A grease channel guides the run-off to this grease can. Finally, a hinged plate in the front and a support bar underneath allow the Cooker to be positioned directly facing the Sun (Figure 2). All operation is manual.
The Cooker is to be assembled from pre-fabricated elements in the form of a kit. The kit includes the cardboard structural elements; paperboard surface; Mylar reflector sheets; three brass tubes; metal grease channel; a hinge; the support rod; a roll of solder, and glue. The user supplies the two metal coffee cans, and two wooden boards for the positioning plate. (A flame torch is required for soldering, but this item may be borrowed. Aluminum foil may replace the Mylar.) Such a kit could be mass-produced for as little as USD $50.
In space, some 1360 Watts of radiant power passes through each square meter of area incident to the Sun. Under clear skies, the atmosphere filters this down to about 1000 Watts at ground level. The Cooker has an area of 0.785 m^2. The intercepted power is therefore 1000 Watts / m^2 x 0.785 m^2 or 785 Watts.
The Mylar material has a reflectivity of at least 80%. However, some of the reflected rays will miss the cooking zone. Assuming that 80% of the reflected power enters properly, the total estimated power available for cooking is 0.8 x 0.8 x 785 = 502 Watts. The Cooker will therefore concentrate 500 Watts into a 5-inch (12.5 cm) diameter area. This power density (4.1 Watts/cm^2) is 41 times the incident power density of the Sun at ground-level (0.1 W/cm^2). This should be sufficient to cook a typical meat-patty within a few minutes.
Assembly & Operation
A single person should be able to assemble the unit within three hours. The unit is aimed at the Sun. The food item is held by tongs and held above the cooking can. The food should be turned to prevent burning. Collected grease should be discarded when the collecting can is full.