PORTABLE COOKING WITH NATURE( THEME : EFFICIENT ENERGY COOKING )

1.0 ABSTRACT

The sun showers us with energy equal to all the earth's fossil fuels in just a few

days. With the depletion of fossil fuels, the world has to turn to alternative

renewable energy sources.

Solar energy is one of the renewable energy resources that can fulfill the energy

needs for mankind. Unlike non-renewable fuels, such as fossil fuels which

produce many side effects like pollution, acid rain and global warming, solar

energy is clean, sustainable and environment friendly.

Solar cooking is one way of using the resource of the sun which is given freely. A

solar cooker is a device which uses sunlight as its energy source. Because they

use no fuel and they cost nothing to run, humanitarian organizations are

promoting their use worldwide to help slow deforestation and desertification,

caused by using wood as fuel for cooking. Solar cookers are clean, convenient,

non-polluting and easy on the environment. And, for millions of people living in

arid, fuel-scarce regions of the world, solar cookers can literally save lives.

2.0 OBJECTIVES OF THIS PROJECT

i. To create awareness among the general public that solar energy is

an alternative to fossil fuels

ii. To promote solar energy as a renewable, sustainable, clean and

environmentally friendly fuel

iii. To introduce solar cooking as cost-free way of using the resource of

the sun

3.0 INTRODUCTION AND PROBLEM STATEMENT

3.1 Introduction

Students experiment with a virtual solar cooker to discover what types of

materials will be best for use in constructing a solar cooker. Students then apply

their knowledge to building and testing a solar cooker of their own invention. In an

extension, students investigate how these principles can be used as sustainable

energy sources for homes through passive solar heating.

Students will know that

Incident sunlight is reflected, transmitted, and absorbed when it falls upon

a surface.

A solar cooker is a solar collector; it “collects” and traps the sun’s energy,

creating heat.

Solar cookers require three (3) components: glazing, insulation and

reflectors.

Heat can be transferred through 3 types of method : (i) radiation,

(ii) conduction and (iii) convection.

There are limitations to how we can maximize solar energy depending

upon our geographic location.

3.2 Problem statement

What types of materials will be best for use in constructing a solar cooker?

4.0 SCIENTIFIC THEORY

4.1 Principles

The basic principles of our solar cooker are:

Concentrating sunlight: Reflective mirrors are arranged in a parabolic

shape to concentrate light and heat from the sun into a small cooking

area, making the energy more concentrated and therefore more potent.

Converting light to heat: A black pot is used to absorb almost all of the

sun's light and turn it into heat, substantially improving the effectiveness of

the cooker.

Trapping heat: Isolating the air inside the cooker from the air outside the

cooker makes an important difference. Using a clear solid, like a plastic

bag which allow light to enter, but once the light is absorbed and converted

to heat, the plastic bag will trap the heat inside. A transparent heat trap

around the dark pot lets in sunlight, but keeps in the heat.

Plastic Sheet: Uses plastic sheets to assure that liquids do not seep

through into the oven. Also to prevent staining of the underlying sheet in

the oven.

Alone, each of these strategies for heating something with the sun is fairly

ineffective, but by using all three of these strategies in combination we can

increase temperatures sufficiently for cooking.

5.0 RESULTS OF EXPERIMENT

5.1 Materials

Zinc Box , Mirror , glass, copper container, river stone, old newspaper, magnifier, spray, and retort stand.

5.2 Assembly

The solar cooker is assembled as shown in the picture.

5.3 Procedure To Use:

1. A bright sunny day in a big field is chosen.

2. The pot is filled with water

3. The pot is put into a plastic bag and sealed.

4. The mirror and the pot are positioned so that the sunlight is focused

on the pot.

5. The initial and final temperature are recorded and the result is

tabulated.

5.4 Findings

Item QuantityInitial Temperature (o C)

FinalTemperature(o C)

Cooking Time(Mins)

Results

1. Water 500ml 29 o C 47 o C 30 mins

Temperature

Increased by

18 o C

5.5 COSTING

No. Items Cost(RM)1 Zinc Box + Mirror + glass 100.002 Copper container -3 River stone -4 Old newspaper -5 Magnifier -6 Spray 5.007 Retort Stand -

Total 105.00

5.6 TIPS TO INCREASE EFFICIENCY

Dark Cooking Pots

Food is solar cooked in lidded, dark-coloured pots or similar vessels. Thin aluminium pots work best. Stainless steel pots can be used, but choose the lightest and thinnest. Thick and heavy materials absorb heat resulting in a slower cooking process.

Shallow, wide pots are better than tall, narrow ones. Indian pots are the best.

If you don't have dark-coloured pots, you can spray them black (outer surfaces only). Dull, nontoxic latex or blackboard paints are preferred. If oil-based paint is used, "bake" the pot in the sun for several days to get rid of any odour.

Glass jars with lids can be used if painted black. You can place a vertical strip of tape of tape on the jar before painting and then remove the tape, leaving a space to view food while cooking.

Reflective Surfaces

Aluminium foil mounted on cardboard, which makes for a simple, effective reflector.

Aluminized polyester film, if reflective, can be used for panel cookers and as the reflector on top of a box. Do not use inside a box cooker, because it might melt or emit fumes

Mirror, is an alternative but it is heavy and fragile.

Metal sheets made from aluminium or steel are not recommended. The surfaces are not reflective and tend to absorb some radiation, making them less effective.

Metallic paints are not recommended as they are not reflective enough.

5.7 ADVANTAGES AND BENEFITS OF SOLAR COOKING

1. Sunshine is free - reduce our expenditure on fuel.

2. Solar cooking saves precious fuel.

3. Save time. Food can be cooked unattended while you carry out 

other chores.

4. Pots are easy to clean. Food does not stick to the inside and there

is no soot on the outside.

5. A solar cooker is easy to make from a variety of materials.

6. Solar cookers are safe as there is no fire.

7. There is no hazardous smoke that can cause injury to our eyes or

harm our lungs. People allergic to smoke can now enjoy "solarcues" - 

barbecues without the smoke.

8. Most solar cookers cook at 82 - 121 degree celcius, which is ideal 

for retaining nutrients, moisture and flavour and not burning foods.

Wood and gas fire temperatures, by contrast, exceed 260 degree

celcius.

9. Solar cooking is similar to slow cooking. Slow cooking

retains flavour, moisture and nutrients and makes meats tender.

Recent studies indicate that foods cooked at moderate temperatures

may be healthier.

10. Solar cookers are versatile and adaptable. This

simple technology is easily adapted to a wide variety of

construction materials, cooking customs and climates.

11. TheWorld Health Organization estimates 80% of all illness are

spread through contaminated water. In places where there is a

shortage of fuel, water can be pasteurized in solar cookers. This will

help reduce incidences of cholera and other waterborne diseases.

Water that has been heated to 65 degree celcius for a short period of

time is free from microbes including Escherichia coli, Rotaviruses,

Giardia and the Hepatitis A virus. At around 71 degree celcius, milk

and food are pasteurized. Boiling is not required.

MicrobeKilled rapidly

at

Worms, Protozoa cysts (Giardia, Cryptosporidium,

Entamoeba)

55 degree

celcius

Bacteria (V. cholerae, E. coli, Shigella, Salmonella

typhi), Rotavirus

60 degree

celcius

Hepatitis A virus65 degree

celcius

12. Burning traditional fuels such as wood and gas pollutes the air and

contributes to global warming. Solar cookers provide a pollution-free

alternative.

13. Vegetables, fruits and meats cook great without water.

Water tends destroy nutrients.

14. Many foods can be cooked for several hours without

overcooking. This allows food to be placed in the cooker early in the

day and left until mealtime. No monitoring or stirring is

required. ("Absentee cooking")

6.0 CONCLUSION

Conversion to clean energy sources such as solar energy would enable the world

to improve the quality of life throughout the planet Earth, not only for humans, but

also for its flora and fauna as well. Because of the foregoing, there is a need to

develop an ingenious method of solar energy conversion systems and then to

substitute it where applications of fossil fuels are most vulnerable. Therefore,

extensive research and development in solar energy utilization technologies must

be carried out.