Solar Box Cooker

In this activity, People build a solar box cooker from simple materials. The solar cooker represents a simple technology that is beginning to be used in less developed countries. Many countries depend heavily on wood for cooking.

 

This dependence is creating a serious deforestation problem. In some areas, women and children must spend several hours each day searching for fuel wood. Solar cookers could help improve these people’s lives and reduce the rate of deforestation.

 

Process

1. Glue foil on the cardboard. Dilute the water-based glue in a bowl, so that it will last a long time and you can brush-apply it. Glue foil completely over: (a) the inside and outside of the smaller box (cut off the fl aps), (b) the inside of the larger box, (c) the inside and outside of the larger box’s fl aps, and (d) one side of the flat cardboard piece.

2. Add bottom supports and insulation. Cut out 4 cm squares from the discarded smaller box flaps. Glue them on top of each other to form eight pillars 2 – 3 cm high. Glue these pillars inside the bottom of the bigger box to support the inner box. Tear up newspaper sheets in fourths and crumple each piece into a lemon-sized ball. Cover the bottom of the bigger box with these balls.

3. Add inner box and side insulation. Place smaller box inside the larger box. Stuff more newspaper balls between sides of boxes.

4. Cut the flaps of the outer box so that they fi t in the inner box. Cut them so that they can be folded over, covering the top space between the boxes as well as the inner wall of the inner box (see diagram). Fold the flaps over and glue them.

5. Put the black tray in the box. Paint it black if it isn’t already. Use nontoxic paint.

6. Make the lid. Take the fl at cardboard piece and center it, foil facing down, on top of the box. Fold down what sticks over the edges of the large box. You need to make four cuts in the cardboard to do this. Then, glue the folded edges of the lid together (not to the box). Make sure the lid fits snugly on the box.

7. Glue the glass to the lid. Cut 3 sides of a rectangle in the lid. This rectangle should be slightly smaller than the glass. Turn the lid over and glue the glass, around its edges, to the inside of the lid. Press it fl at until theglue dries. If you use plastic wrap, stretch it out around the rectangular opening and tape in around the sides.

8. Make a prop. Bend up the cut-out rectangle in the lid so that it can reflect sunlight into the cooker. Attach a stick with string to the corner of the reflector and the side of the lid. If it is windy, you may want a prop on both sides. You are now finished with your solar box cooker and are ready to cook!

 

Solar Box Cooker/ Guidelines for cooking food:

1. Put your food in covered black pots in the solar box cooker with the lid on.

2. Aim the box so the shiny side of the lid reflector faces where the sun will be in late morning (lunch) or early afternoon (supper). Tie the prop to hold the lid reflector where it shines the most sunlight into the box. Warning: Temperatures inside the cooker can reach 275 degrees Fahrenheit. Do not leave cooker unattended in a place where it could be disturbed by other students.

3. Food cooks better:

• on a warm, sunny day in late spring, summer, or early fall,

• if you put it toward the back of the box,

• if you adjust the cooker often so that its shadow lies directly behind it,

• if you divide the food up into small pots.

1. You need not stir the food while it is cooking. If you open the box during cooking, be careful of the high temperatures inside.

2. Most importantly, put the food in early, and don’t worry about overcooking—solar cookers seldom overcook. Cooking times for recommended foods are:

• one to two hours for rice, fruit, above-ground vegetables, pretzels,

• three to four hours for potatoes, root vegetables, some beans (including lentils), most bread,

• five to eight hours for most dried beans.