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Prospect of Solar Oven to Reduce Fossil Fuel Energy

Consuming In Indonesia

Fatahul Arifin

Staff of Mechanical Engineering

POLITEKNIK NEGERI SRIWIJAYA

Jalan Srijaya Negara, Bukit Besar Palembang 30139

INDONESIA

Email: farifinus@polisriwijaya.ac.id

farifinus@yahoo.com

Abstract

  Indonesia is a country that placed in equator.God bless this country which is shined by sun along year. Sun shine is cheap energy and can beused for cooking. However, this energy is not used maximally, especially for cooking. Many

 people used fossil fuel to cook their meal. They

only believe that fossil fuel is only energy can beused. So, the writer wants to inform to the

  Indonesian, especially to housewives that theycan use alternative energy such as solar energy.  In this paper the writer give information about type of solar oven that can be made with simplematerial and simple form. Moreover, theimportant thing of using solar energy is reducethe fossil fuel energy consuming.

Key words:   solar energy, simple, parabolic,cooker 

1. INTRODUCTION

Our society is always developing from

time to time. Nothing is static, all are change. One

of changing is energy needed. Energy is

considered necessary in all sectors such as

cooking, lighting, running vehicle, etc.

A lot of energy are able to be used such as

wind, water, fossil fuel, bio-mass, bio- gas and

solar energy. However, only a few are used such

as fossil fuel and natural gas. As we know that

 both of these energy is un-renewable. Because of 

that we have to find alternative energy. Indonesia

is placed in equator. God bless this country which

is shined by sun a long year. However, many

 people in this country use shine sun only to dry

the clothing. In this paper the writer wants to

inform that the shine sun can be used as energy,

especially to cooking.

2. BACKGROUND

The sun is a constant source of energy. Each day,

the sun bathes the Earth in unimaginable amounts

of solar energy, most of which comes in the form

of visible light. All over planet Earth, sunlight isthe by far the most important source of energy for 

all living things. Without it, Earth would be

lifeless. Sunlight can be a practical source of 

energy for such everyday jobs as cooking, heating

water, or warming up homes. The challenge is to

find ways to transform sunlight into useable heat.

The most efficient way to use heat from sunlight

transforms sunlight into heat is to shine lots of 

sunlight onto a dark surface. Dark surfaces absorb

most of the visible light that falls upon them, and

reflect very little. Visible light that is absorbed

this way usually causes the dark-colored surfaceto warm up. Of all colors, black is able to absorb

the most light, and produce the most heat.

Most of people are familiar with what happens to

a dark-colored surface when sunlight strikes it, it

will get warm. But without a little help, there is

not enough heat produced to cook foods. To

 produce enough heat for cooking, it is necessary

to shine additional sunlight from a wider area onto

the black surface. This is easy to do with mirrors

or other reflective surfaces, or with glass or plastic

lenses. All the material can be united became the

tool that is called solar oven. 

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3. TYPE OF SOLAR COOKER 

3.1. Simple solar cooker (SSC)

The simple solar cooker is made with

cardboard or triplex and aluminum foil, and oneof reflector (mirror or aluminum foil). Styrofoam

or cloth or newspaper can be used as insulator.

The aluminum foil is used to gather sunlight. The

foil-covered panels of the oven reflect sunlight

into the cooking chamber, which is painted black.

Heat is produced when the concentrated sunlight

is absorbed by the black surface of the cooking

chamber. The heat is contained inside the

chamber with the help of insulation, and a clear 

 plastic oven bag. The size of this SSC design by

the writer is 60 cm length, 40 cm width, 30 cm

height. The maximum temperature is 120o

C in thechamber of the stove.

Figure 1 SSC (Autor)

3.2. Solar Cooking Table (SCT)

The following describes how to make a

solar oven that is proven to work in an inventive

way, cooking from the bottom! On a bright sunny

day, this cooker can reach temperatures in excess

of 350 degrees Fahrenheit. SCT cooks from the bottom, with the help of some easily constructed

solar troughs, 2" rigid foam insulation, and some

home made triple pane glass panels, a little

silicon, some deck screws, and a lot of fun

ingenuity.

Some of the first things that have to take

into consideration before building this oven are

the following; the glass- it should be tempered,

  but standard plate (window) glass will work,

however, our cooker actually got so hot that the

center pane broke due to the extreme heat! The

height of this oven is designed approximatelythree feet. Last and most importantly the size of 

the door is a little bigger than the pan is going to

 put inside.

Table 1. Time to cook using STC

(www. solaroven.com)

No. FoodTime

minuteSky

Condition

Temperature

(oF)

1

Chicken

 breast

w/BBQ

25 -30 Clear sky 225 -250

2Apple

 pie

45 - 60 Clear sky 350

3Browni

es

240 Really

cloudy

200

Figure 2 STC (www.solaroven.com)

3.3. Double-Angled-Twelve-Sided

(DATS) solar cooker

Double-Angled-Twelve-Sided (DATS)

solar cooker employs 24 small reflective panels to

concentrate extra sunlight to compensate for the

heat loss from not using a plastic bag. DATS

cooker design is similar to a deep-focus parabolic

cooker, but instead of using a true parabolic

curve, multiple flat panels concentrate sunlight

onto the cooking pot. Two reflective surface-angles, 45º and 60º, are used so that a bend can be

introduced in between for structural rigidity to

hold the cooker’s shape. This structural rigidity

allows for DATS cooker to be constructed out of 

cardboard material. The DATS cooker, tested in

Shanghai, reached a maximum temperature of 

140ºC (284ºF) inside an empty black cooking pot,

on a clear sunny day with 21ºC (70ºF) ambient air 

temperature and a slight breeze. Eggs became

hard-boiled in 30 minutes and two cups of rice

cooked in 95 minutes. The cooker should be re-

  positioned every 45 minutes or less for better 

efficiency. A simple supporting structure, made

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out of bamboo or wooden sticks, is built-in as an

integral part of DATS cooker to support the

cooking pot at the desired cooking position.

DATS cooker is held rigid by a string, which links

all twelve 45º-panels together at the bottom end.

The string is made taut by twisting in the loose

string loop around a short stick. The tighter the

string is, the better DATS cooker holds its shape.

If needed, a small gage string, tied across two

opposite panels, at 3:00 o’clock and 9:00 o’clock 

 position, can be used to pull in any slack in the

cooker shape due to gravity. By loosening the

string and removing the cooking pot supporting

structure, DATS cooker can be folded up for 

storage or transportation.

Construction

The size of 12 rectangular pieces is 24cm x 61cm

each. Make a straight fold at 24cm distance from

the small end of the panel. Punch a hole in each of 

the two “ears” at the narrow end of the panel, as

shown, and fold the ears away from you.

Figure 3 DATS

(http.//solarcooking.org/plans/DATS.html)

3.4. Butterfly solar cooker (BSC)

BSC is made with 2 plates which is like

wing of butterfly. The reflective square area of the

  butterfly parabolic solar cooker is 1.5 square

meters. The heat output is rated at 800 watts. To

work efficiently, the butterfly design solar cooker 

should be adjusted approximately every 30

minutes to track the sun. This only takes a few

seconds using a convenient screw mechanism.

The butterfly solar cooker's weight of 50 kilos isan advantage because it provides stability in

strong winds.. The butterfly solar cooker has two

cast iron wheels which means it can be moved

easily. The design life of the butterfly solar cooker 

is 20 years. If there is any loss of reflectivity, the

reflective tape can be replaced. The only

limitation on the use of the butterfly solar cooker,

aside from rainy and overcast days, is where

housing is so crowded that there is not sufficient

room for the solar cooker to receive direct sun

light during the day. Most village and rural

housing in east Africa apply this type of solar 

cooker.

Figure 4 BSC

(http://solarcooking.wikia.com/wiki/Solar_Cookers_ 

International)

3.5. Concentrating cooker (CC)

This model of solar oven produces higher 

temperature (about 400 ºC). However for its

  proper working, it needs mostly the direct

radiation and thus requires some frequent (15-45

minutes) tracking (manual or automatic).

A hot box can work (bake and cook), even under 

some partial sunny climatic conditions, and takes1- 3 hours. Although food cooked slowly is good

from nutritional point of view, for some users it

may not be as tasty and some also like to have

fried food and food cooked in a short time. For 

this a concentrating cooker is used. Here solar 

radiation is received by a reflecting (parabola or 

cylindrical) surface, and is reflected at the focal

 point where the food to be cooked is kept. In

different models, the focal point could be either 

inside or outside the parabola. In addition, the

 parabola can be fixed and the focal point movable

or the focal point can be kept fixed while the parabola is movable.

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Figure 5 CC (http://solarcooking.wikia.com)

4. DISCUSSION

In this part, the writer attempts to explain

the minimum energy needed to boil drinking

water. The formula that is used to calculate the

energy need to boil the water is:

Q = m.c. ∆T …….. (1)

Where:

Q : Heat (energy)

m : (mass) = V. ρ

ρ : density of water = 103 kg/m3 = 1 kg/l

c : specific heat

∆T : temperature change

As we know that human need to drink 2.1 liters to

2.8 liters per day (Suprihatin, Kompas 2004)

The temperature minimum water before boiled is

28 oC, and the boil water is 100oC.

The specific heat of water is1 kcal/kg.oC.

So, minimum energy is needed to boil the water 

for a man/day is:

Q = 2.1 x 1 x 1 x (100-28)

= 151.2 kJ

According data a number of people of Indonesiais 220,953,634. So, we can imagine that the

minimum energy consuming in Indonesia is about

33,408,189,460.8 kJ or 33,408 GJ. If Indonesian

use solar oven is assumed 30 %, so energy from

another sources can be save is about 10022.4 GJ

 per day.

5. CONCLUSION

Principal of all type of solar cooker are

reflecting the sun shine as energy. The good shape

of solar cooker is concentrating cooker. It collects

the sunshine in one spot area that produce higher 

temperature is about 400oC. However, it still need

move to good position to accept sun shine even

manually or automatically. All type of solar 

energy can be applied in Indonesia that is shined

 by sun in a long year.

Actually, solar energy can be used to

cooking. However, solar energy still unfamiliar by

Indonesian, they still used kerosene to cook their 

meal or boil the water. If 30 % Indonesian have

used solar energy as energy for cooking, we can

 be saved fossil fuel is about 3658176 GJ in a year.

 

REFERENCES

Devos X, The Solar Cooking Table,

www.solarcooking.wikia.com, retrieved 20 Juli

2008

Fatahul Arifin, 2008,   Disain dan Prototipe

 Kompor Tenaga Surya Dengan Reflektor Tunggal, Prociding Seminar Nasional

Hasil Penelitian 2008, page 155 – 162,

Bogor, LPPM Universitas Juanda

Giancoli, D, C, 1985, Physics: Principle with

applications, 2nd edition, New Jersey,

Prentice-Hall, Inc

Suprihatini, Dr, Ir, 2004, Kompas, 7 Januari2004,

http://digilib.ampl.or.id/detail/ detail.php?row=9&tp=artikel&ktg=airminum&kd_li

nk=&kode=116, Retrieved 24 Juli 2008

Surya W.P., Rochmin Armando, 2005, Membuat   Kompor Tanpa BBM , Jakarta, Penebar 

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retrieved 18 Juni 2008

………,http://solarcooking.wikia.com/wiki/Solar_ 

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2008

……., http.//id.wikipedia.org/wiki/daftar propinsi

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retrieved 25 Juli 2008