moving ahead with solar cookers

8/9/2019 Moving Ahead With Solar Cookers

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Moving Ahead withSolar Cookers

Acceptance and Introduction to the Market

Deutsche Gesellschaft frTechnische Zusammenarbeit (GTZ) GmbHGerman Technical Cooperation


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Imprint

Published by:Deutsche Gesellschaftfr Technische Zusammenarbeit(GTZ) GmbHGerman Technical CooperationDag-Hammarskjld-Weg 1 565760 Eschborn, German yTelephone +49-6196-79-1266Telefax +49-6196-79-6320Internet: http://www.gtz.de

For:Sustainable Energy SystemsDivision 44 - Environmental Management,Water, Energy and Transport

Edited b y:Cornelia Schichtel

Text:Hanna Bergler, Eberhard Biermann,

Dr. Michael Grupp, Maria Owen-Jones,Richard Palmer

Graphic design:Andreas Funke, 61476 Kronberg/Ts., Germany

Pictorial matter:Hanna Bergler: pp 18 19 26 27 28 29 31 32


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Contents

Foreword ........................................................................................................................

Preface ............................................................................................................................

1. Introduction ..............................................................................................................

2. The Fuelwood Problem ..........................................................................................

3. Introducing New Household Technologies........................................................

4. Cooking Traditions..................................................................................................4.1 A Rural Family in Tamil Nadu , India ................................................................4.2 An Affluent Family in Kaolak, Senegal ............................................................4.3 A Typical Family in Qu etzaltenango, Guatemala ............................................

5. Cooking Profiles......................................................................................................

6. Solar Cookers Somewhere Between Utopia and Reality ..............................

7. The Technical Side of Solar Cooking..................................................................

8. Solar Cookers in Practice A Comparative Field Test in South Africa ......8.1 The Field Test ....................................................................................................8.2 Regard ing Accep tance ........................................................................................8.3 Profitability and Economic Aspects ..................................................................8.4 Case Examples for the Use of Solar Cookers ..................................................

9. Macroeconomic Impacts ......................................................................................

10. Outlook: Solar Cookers now on the Market ....................................................

11. Outlook: What Still Needs to be Done?..............................................................

12. Outlook: On the Potentials of Solar Cooking ..................................................


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optimistic abou

cooker technolto finding suchabout socio-ecocreation and allveloped rural ain your endeavdisseminate thithe rural commimpact on their

SENTI L. THOChief Director: Renewable EneDepartment of South Africa

Foreword

South Africa is a country

endowed with abundant energyresources, none more so thanthe Sun. The irony of the situati-on is that this plentiful resourceremains almost completelyunused, while another equallyplentiful resource which is usedextensively - coal - has consider-able negative impact upon our

environment.

Firewood forms the main energysource in the rural domestic sector butthere are signs that it is becoming scarce.

Throughout Africa deforestation is in-creasingly placing a burden upon womenwho are responsible for collecting this

fuel as they forage further and furtherfrom their homes.

While solar power technologies aresteadily being developed and promotedfor use in developing countries such asSouth Africa, these have hitherto beenonly available for low load applications

such as photovoltaic systems. Some solardevice was still lacking to fill the gap forcooking needs.

Therefore when solar cookers began tobe promoted in South Africa, the Depart-ment of Minerals and Energy was the


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It is fascinating to cook food using only

direct solar power, which is inexhaustible,clean and free. While this shop reportintroduces the approach to and initialfindings of a solar cooker project, it ishoped that the reader will experience theintrigue of those involved in the project.

Many inventors and developers have beenbusy designing numerous imaginative

devices with which to capture the sunfor cooking. Their contribution is laudableand we are grateful to them for theirpioneering spirit and personal commitment.

In arriving at their places of use in low-income areas of tropical countries, solarcookers have followed many differentpaths. However, they have not evolved

into commercially viable products that"sell" themselves. Only in Tibet, at extremealtitudes, where there is no wood andwhere dried dung and sod are the mostvaluable - indeed, the only sources ofdomestic energy, are solar cookers repor-ted to be used extensively. Most otherattempts to get solar cookers successfully

established on a large scale have endedup as case studies for future projectarcheologists.

But still the technology offers good op-portunities particularly against thebackdrop of the steadily worsening fuel-

Preface

The Federal German Ministry

for Economic Cooperation andDevelopment undertook to joinforces with the Federal GermanMinistry for Education and Re-search in a systematic shakedownof available solar cookers withregard to performance and con-venience of operation. First, atechnical test was conducted in

Almera, Spain; then, GTZ andits South African partner, theDepartment for Minerals andEnergy, investigated the cookers' atance in a developing country by wa field test.

Having concluded the first phase osolar cooker test, the subject of thi

report, the b asic acceptance p robleand the issue of appropriate condifor use may be regarded as undersIn the right context, solar cookers acceptance by low-income commuas an option for cooking and bakinTherefore, further investigations wifocus on local manufacture, comm

dissemination, and reducing the coproduction. The decisive factors going dissemination and use will be pmarily of an economic nature, e.g.purchase price and the local availaof services and small loans. Such ctions can be influenced. With Germ


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1. Introduction

In many emerging countries, it is be-

coming increasingly difficult to secureenergy for cooking. In areas where fuel-wood is the traditional source of energy,particularly in the more arid regions ofthe African Continent, many peoplesuffer from depleting wood resources.Intensive deforestation and erosion causeirreversible environmental damage. Thisis compounded by high population growth.

Cooking with fossil fuels coal, gas andkerosene (in South Africa known as par-affin) - carries a high price. It is expensiveboth directly to the user and indirectly,to the national economy as a result ofcurrency drain and/or subsidization. Thesecurity of supply is also often question-able. This is worrying as the quality of

life deteriorates and there are negativeeffects on local economies.

Most notably in areas with ample sun-shine, i.e. with high levels of insolation,cooking with solar energy can help allevi-

ate such problems. Unfortunately,

solar cooker projects in developingcountries have tended to achieve omodest results. The following is stiunclear:

s Will solar cooking remain a nichphenomenon in the field of devement assistance, and if so, then w

s Is it possible to commercially

disseminate solar cookers, makinthem available to broader sectionthe population on a sustainable b

To find an answer, the GovernmenGermany and South Africa are prov

joint support to a solar cooker pilogram that includes a comparative ftest under real-life conditions. This

a prolonged period of proof testinthe users themselves. This publicatdeals primarily with the empirical rthat have been gleaned from that pprogram to date.


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Around the world, fuelwood is a leading

source of energy. Fuelwood accounts for15 - 18 % of global primary energy con-sumption more than nuclear energyand hydropower combined [FAO, 1998a].

Each year, some 2 billion tons of woodare "energetically utilized" (read: burned)

[FAO, 1998b], mainly for cookingpurposes.

This has had myriad consequen-ces, from polluted air in people'skitchens, and the respiratoryailments it can cause, to deterio-ration of the earth's entire atmos-phere. Other effects include suchlocal environmental damage as

deforestation, erosion and the increasing

scarcity of wood, as manifested by rising

prices and the

gathering fuelw2 billion peoplsuffering from

Fortunately, feasumption of fueminate in globabeen confirmeddead wood that

by deforestationforests to obtaior commercial the housing condustry. Neverthbe devastating. case examples:

s A total, broad

a seldom occ

2. The Fuelwood Problem

Fuelwood accountsfor 15 18 % ofglobal energy con-sumption morethan nuclear energyand hydropowercombined.


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example, there is no wood to be found

across large swathes of land. Peopleare forced to buy high-priced firewoodhauled in from the eastern forests. Yakdung and sod are therefore used asfuel, causing irreparable damage in theform of erosion.

s Relative scarcity on a broad scale ismuch more frequent. In Tamil Nadu,

India, for example, felling trees is apunishable offence. Trees are sovalued that where they grow alongavenues, they are numbered. Even so,goat herds can be seen climbing uphigh trees and chopping off leafybranches. The goats eat the leaves,and the stripped branches are takenalong as fuelwood.

s Local scarcity is common. It oftenoccurs around towns and villageswhere wood is an important fuel.Large refugee camps can also producebroadening zones of deforestation. InMakalle, Tigray (Ethiopia), for example,during the famine of the mid-1980s,

all the trees were removed within a

very short time. To survive, fuelw

supplies were brought in both bcaravans of donkeys from areascontrolled by rebels and, sosevere was the situation, byairfreight from Europe.

s Scarcity due to interdictionsand regulations is also quitecommon. In South Africa, the

owners of some forested propertforbidden people to gather fuelwthere and have stressed the pobrandishing firearms.

All these forms of fuelwood scarcitfoster, to different degrees, the intrduction of new cooking technologishould be noted here that the gath

of fuelwood does not count amongprimary causes of deforestation. Thnotion that our planet's forests are literally burned down for the cookneeds of poor rural folk in developcountries is incorrect. Reality is a lmore complex than that.


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3. Introducing New Household Techn

History shows that the introduction of

new technologies can be both time-consuming and tedious. Back when coalwas first being introduced as a substitutefor wood in cooking, people receivedfree coal to overcome their distrust. Thatdid not work at first, because the era'swood-burning stoves were unsuitablefor burning coal, and many people suc-cumbed to carbon monoxide poisoning

as a result. Subsequent conversions toelectricity and gas were less dramatic but

just as wearisome. Even microwave ovens,which have been on the marketfor some 20 years now, are stillin their introductory phase.

Nor are introductory processesirreversible. During and after

World War II, many peoplerelied on their "fireless cookers"(an insulated box in whichalready hot food remains hotenough to continue cooking).

Even though such cookers required nosupervision while they kept the foodwarm with no danger of scorching, anddespite the fact that they saved theirusers lots of energy, especially when

long cooking p

they eventually

The following obe made:

s No new technitself, simply environmenta

s The users muis the right dsocial contexthe new tech

s The users mugetting help ior otherwise)

s "All-or-nothingarding new are the excepTechnologicabe looked upcooking optioexpected to pof compariso

New technologiesdo not just estab-lish themselvessimply because

they are economi-cal, environment-ally sound or prac-tical.


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"outdoor cooking is frowned upon

only thing that all cooking traditionin common is that they are all diffeConsider the following case examp

Generalization would be out of place

here. For example, it would not be fullycorrect to flatly state that "Africans eattheir warm meal at supper time", or that

4. Cooking Traditions

The Rajagopalan family in Tamil Nadu livesin a hut with a thatched roof and reed-mat walls in Kizhmeni, a little village in

Tamil Nadu. The six-member family(parents, grandfather, three children)draw income from a small plot of croplandthat Mr. Rajagopalan farms with someoccasional help from his wife.

Most days, Mrs. Rajagopalan cooks twomeals on her chulha, a traditional mudstove installed beside the house. The stovehas two enclosed he arths, i.e., combustion

chambers, that are fueled with wood,dung or rice chaff.

If the family decides to eat breakfast,which often is not the case, they sit downat about 7 a.m. to a meal of cold, slightly

fermented Indian rice that was soakewater overnight. They may also slaktheir thirst with tea or coffee.

Around noon, Mrs. Rajagopalan cooup a batch of curry rice, and the evemeal, which is taken at about 6 p.mmost likely will consist of rice and d(pigeon peas). Each such meal, whictakes about an hour to prepare, alsocludes water or milk to drink. Speciadishes are served on holidays andwhen there are visitors. Once in a w

a chicken enriches the family's diet.The Rajagopalan family is not poor. neighbors, though, who are very necan only afford one meal a day, usuin the evening (acc. to Sodeik, 1991

Mr. and Mrs. Soumar, with their twochildren and five grandchildren, livetogether with their servants and variousvisitors in a prosperous neighborhood inthe city of Kaolack, Senegal. The family'sincome consists of Mr. Soumar's civil

bread. Dinner is served at about 2 pwhen the children arrive homefrom school. Usually, this meal ismade up of ceebujen (rice, fishand vegetables in a sauce),though sometimes white rice with

4.1 A Rural Family in Tamil Nadu, India

4.2 An Affluent Family in Kaolak, Senegal


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In view of all the different cooking tradi-tions, the following must be stressed:

The dissemination of solar

The main aspections and condi"cooking profile

5. Cooking Profiles

4.3 A Typical Family inQuetzaltenango, Guatemala

The Lopez family lives near Quetzaltenangoin Western Guatemala in a hut made ofscrap metal and cardboard. The family ofeight consists of Mr. and Mrs. Lopez, thelatter's parents, and the couple's four child-ren. Mr. Lopez is a construction worker, andhis wife earns a few pesos now and then

doing laundry.

The family's meals are cooked over a woodfire in a three-stone indoor hearth. A neigh-bouring family recently purchased an im-proved stove with an enclosed combustionchamber that will burn sawdust, cardboardand even plastic bags.

The Lopez family eats breakfast between 6and 7 a.m. usually a meal of beans andmeat plus cornmeal patties, and, sometimescornbread with a cup of coffee. Dinner iseaten between noon and 1 p.m. and nor-

mally consists vegetables or bwith atole (a thother cool, homThe evening m6 and 7 p.m., ieggs and beans

bananas, and cabout an hour tto cook dinnersupper. Most dfried and heateAlvarado Mrid


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GTZ-DME SOLAR COOKER FIELDTEST SOUTH AFRICA

Location

Typical housing

Income

Size of family

Main diet

Cooking techniques

Preparation techniques

Beginning of cooking

End of cooking

Meal times

Existing cooking equipment

Cooking area

Number of cooking pots

Fuel

(purchased/gathered)

Fuel costs

Climate

Suitable place for a solar cooker

Families interested in

acquiring a solar cooker

(e.g. on a credit system)

ONSEEPKANS (Northern Cape), a five-mile-long town comprisin

three settlements (Melkbosrand, Viljoensdraai, Sending), 50 km f

Pofadder. Surroundings: green belt on the Oranje, with some farm

but otherwise semi-desert (very stony)

Thatched houses with corrugated sheetmetal roofs, often fencedwith an occasional vegetable garden

Average monthly income of R 650 (c. 100 US$) with most families

earning between R 250 (40 US$) and R 500 (80 US$) per month

1 - 14 (2)

Porridge, soft porridge, rice, vegetables, meat, tripe and other inn

and head, legumes, fish, bread, incl. "rusks", spaghetti, soup, maca

potatoes, tea, eggs, milk (1)

Boiling, frying, baking, simmering, steaming (1 and 2)

Mincing, soaking (legumes/pulses), stirring

(e.g. for porridge dishes, which require vigorous stirring);rice added to cold water (1)

Between 6 a.m. and 10 a.m.; noon: between 10 a.m. and 1 p.m.

and between 4 p.m. and 8 p.m. (2)

Between 7 a.m. and 11 a.m.; noon: between 11 a.m. and 2 p.m.

and between 6 p.m. and 9 p.m. (2)

Between 7 a.m. and 11 a.m.; between 12 a.m. and 2 p.m.;

and between 7 p.m. and 9 p.m. 2)

Mainly woodstoves or three-stone hearths, some gas cookers an

a few kerosene cookers; some families have more than one cook

facility, e.g. a woodstove and a gas cooker (2)Mainly indoors or under cover (incl. open fires),

but rarely outdoors (1)

Often two pots with a capacity of 5 to 8 liters (1)

Mainly wood (mostly of it gathered along the river, but some purchas

some paraffin and gas (1 and 2)

1 l kerosene = 1 R; 9 kg bottle of gas = 38 R;

1 bundle of wood (ca. 15 kg) = 7 R (2)

Very sunny October through March; partially cloudy and windy in

April and May; partly sunny with some light rain in June and July

very sunny and windy, with little rain, in August; sunny, with someclouds and wind, in September (2)

Close to the kitchen, for fear of food theft or damage to the

cooker (1)

Yes (1)

2

Cooking Profiles Families (State: January 1997)


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6. Solar Cookers Somewhere Betweeand Reality

There is something fascinating aboutsolar cookers: Anyone who has everwatched a pot of water being boiled"just" by the sun is sure to have beenvery impressed.

Likewise, the principle behind solarcooking is as fascinating as it issimple: rays of sun, bundled ornot, are converted to heat and

conducted into the cooking pot.

The causal connection behindthe use of solar cookers is evenmore fascinating: areas markedby drought and poverty are where

the sun shines at its brightest, providingan inexhaustible supply of clean energyfor cooking.

It is no wonder, then, that solar cookersare a very popular subject of discussion,not only in tropical places where the sunstands high in the sky. The Americanorganization "Solar Cookers International"has identified 653 organizations and indi-viduals in 70 different countries who areactively involved in solar cooking.

The range is broad, extending fromgrass-roots Non-GovernmentalOrganizations (NGOs) that help ruralusers build their own cookers to associ-ations that propagate and disseminate

tries have met wMost such endethe following s

s Stipulation ousually by anthe intention nation

s External definwithout syste

acceptances Import or loc

of a short sercomplete guiunsuitable ma

s Free distributtarget group,familiarizatioits peculiariti

s Inadequate ss Project termi

impacts on th

As a rule, as soended, most usof a few enthuscookers regular

Few projects arted, usually dueThis makes it dsuccess was onla systematic ex

Anyone who hasever watched a pot

of water being boiled"just" by the sun issure to have beenvery impressed.


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The other two questions are the suof a pilot project in South Africa(DME/GTZ, 1997) that is being impmented by GTZ and the South AfriDepartment of Minerals and Energ(DME) on behalf of the German anSouth African governments.

An answer to the first question wasfound in 1994 by way of a comparativetechnical solar cooker test conducted byECSCR with the support of the FederalGerman Ministry for Education, Science,Research and Technology (BMBF)[ECSCR, 1994]; cf. page 16 (Table 2).


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Power spectrum

s The biggest of all known cookersholds enough for between 800 and1000 helpings while the smallest

excerpt of ECWhile the moboil water in

7. The Technical Side of Solar Cookin

Figure 1: Types ofsolar cooker

Box cookers

are insulated boxes with a glasstop, often with a directionallyadjustable reflective lid, de-signed to surround a cookingpot. Box cookers exploit bothdirect and diffuse solar radiati-on. They require little interven-tion by the user and are cha-racterized by widely divergentthermal performance.

Concentrator cookers

concentrate direct insolationon a cooking pot. They arequite e fficient but requirethe user's attention forkeeping them aligned withthe sun and maintaininggood performance.

Co

areoftcola cthevicdirhobu

Within the scope of two studies (GTZ,1991 and GTZ, 1998) a total of 168different solar cookers were catalogued.Many of them were prototypes or hand-crafted small-lot products, and some ofthem proved useless in practice. Despitethe global scale of the studies, it may beassumed that some models were over-looked and, hence, not counted. Of the

168 different soGTZ, the most for 95 models, lowed by 51 kiand 22 collectoBasically, howecookers fits intthree categories


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8. Solar Cookers in Practice A Comparative Field Test in South Africa

8.1 The Field Test

The goal at the outset was to findanswers to the following questions:s Why aren't solar cookers in more

widespread use?s What kind of technical problems, if

any, do today's solar cookers pose?s Can traditional dishes be prepared at

the right time with solar cookers?

s Is the use of solar cookers acceptablefor the users?

s Are potential users interested in solarcooking, and what kind of cookers dothey favor?

s Are solar cookers economical?s Is there a market for them, and, if so,

how can it be reached?

Test areas

Since 1996, within the scope of a pilotprogram, GTZ and DME have been con-ducting a comparative field test in thedry, northwestern part of South Africa.Five potential test areas were investigated

in advance, and 200 families were inter-viewed. The following three test areaswere then selected on the basis of cook-ing profiles and a range of socioecon-omic parameters:

s Onseepkans is representative of small

Field-tested solar cooker mode

Also on the basis of the pertinent coprofiles, seven different solar cookmodels were selected for testing: f


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served as the control group. Each familyused one type of cooker over twomonths' time before switching to thenext model. Users and non-users alikefilled out on-the-spot questionnaires and

were interviewed by the teams sociol-

necessary changfound to requircookers were dof the test than time the users hand ordered orcookers.

8.2 Regarding

Intensive monitby the families individual bits the end-of-test areas over a pertaken. Analysis

s on average, tat least once

s the families wall solar cook

The average fasolar cooking onot completelytions, but mere

Solar cookers wfrequently usedwith wood (opecoal-burning stowith wood). Thcookers that opelectricity. TheULOG in Pniel


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Figure 3 is the corresponding frequency-of-use diagram for the control groupwithout solar cookers.

The study of institutional acceptance

of solar cookers (in schools and kinder-gartens) has not yet been concluded. Thepreliminary results read as follows:

s Major incentives for the use of solarcookers include highly motivated

cooks, opportunity for managempersonnel to reduce fuel-specificexpend itures, and added incentivcooks who use solar cookers;

s Important reasons for not using cookers include their safety deficlack of budgetary control by thecooks, and supervision by externorganizations.

SunStove in PnielSK14 in Barkly West


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8.3 Profitability and EconomicAspects

The average family's monthly expenditureson fuel for cooking purposes amount tothe equivalent of 8 US$. Table 3 lists thefuel-specific expenditures for all threelocations.

Table 4 reflects the average monthlysavings for the various locations.

During the solar cooker test period, theaverage family with a solar cooker saved38 % on fuel (i.e., 33 % on kerosene, 57 %on gas and 36 % on wood). In absoluteterms, the test users saved nearly 60 tonsof wood, over 2 tons of gas and morethan 2000 liters of kerosene in the courseof the test year. The families in Huhudi,

where most fuel has to be bought insteadof gathered, saved the most, while thosein Onseepkans, where gathered wood isa major source of energy, saved the least.Savings in the Pniel area, where a mixtureof purchased and gathered fuel is used,

The average patakes to pay bafuel savings) is depends on thecooker in questestimated meanthe four most a

cookers, priced in combinationtice of purchasappliances on cand 24 monthlyinterest.

The test users wwould be willin

cookers. All of more than eithecarry price or thpayments on a

In order to verifusers were givechase their coo and all of the

Indeed, waitingand an indepenmented widesprchase of solar c

Table 3 :

monthly

expenditure

on fuel in US$

Wood

Kerosene

Gas

Electricity

TOTAL

Onseepkans

3

0.5

2

0

5.5

Huhudi

1

3

3

4

11

Pniel

3

2

3

0

8


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8.4 Case Examples for the Use ofSolar Cookers

Mrs. Bontnael, whose husband diedrecently, lives alone in a typical thatchedhut in Onseepkans on the South Africanside of the Namibian border. The Bontnaels'income consisted of Mr. Bontnael's old-agepension, which was relatively high for

people in this area. Their grown childrenlive elsewhere.

Before the solar cooker field test began,Mrs. Bontnael prepared each day's mealson a wood-burning stove. Each month, theBontnaels bought about 45 kg of wood.This is atypical for the region in question,where most fuelwood is gathered.

A breakfast of bread and tea is taken atabout 7.30 a.m. For dinner, at about 1 p.m.,Mrs. Bontnael often cooks up a soup ordried peas. She occasionally adds somepotatoes and chicken, or instead opts forafval (a stew of tripe, various innards andthe head of, say, a goat, with chicken feetand beaks added as "walkies talkies"). Noevening meal is eaten. Mrs. Bontnael also

uses her solar cooker for baking bread

It takes Mrs. Bontnael about a half an hourto prepare breakfast. Right after breakfast shespends about an hour cooking for dinner.

In fond remembrance of her deceased hus-

Johanna Bock together with her threedaughters and her grandchildren, also in a thatched hut, but at the other endOnseepkans. The male members of thisperson family have out-of-town jobs anrarely get a chance to come home. The

family has a gas stove and a coal-burninstove that can also be fueled with woodLike Mrs. Bontnael, the Bock family couamong the few local families who purchwood (approximately 80 kg each monthinstead of gathering it.

The eldest daughter does most of the cing. Breakfast (served at about 7.30 a.mconsists of bread or vetkoek, a kind of f

roll baked a day in advance. Cooking fodinner begins right after breakfast, becatakes about four hours. A typical meal winclude bread or dombis (a sort of dumling), dried peas, lentils and/or some otlegume, or chicken. Preparations for subegin about 5 p.m. and take about an hThe evening meal often comprises tomarice and fish (either canned or caught in

nearby Oranje river). Miss Bock also babread or cake and, on Sundays, servesdessert.

The Bock family also participated in thecooking test. They were very happy witfirst kind of solar cooker they received.


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9. Macroeconomic Impacts

Should solar cookers ever achieve large-scale commercial dissemination, the prob-

able consequences in terms ofthe economic and social impactswere investigated:

s cumulative savings(cf. Table 5),

s less air pollution (both in thekitchen and outdoors)

ands savings on time spent

gathering fuelwood.

Additional impacts could include:

s a reduction in the degree of atmos-

pheric pollution caused by combustionof fossil fuels,

s fewer cases o(among child

s fewer cases oby paraffin ac

The reductionsemissions (carbTable 5) resulticookers were eof the Environm

Development (Gthat solar cookepollution/energymental burdensduction and tracompensated fowithin a very sh

Table 5: Savings on fuel and reductions in CO2 emissions attributable to solar cook

Solar cookers have adistinctly positivepollution/energybalance, i.e., theenvironmental bur-dens resulting fromtheir production andtransport are com-pletely compensatedfor by conservationaleffects within a veryshort time.

Savings on kerosene

Savings on LPG (gas)

Savings on fuelwood

Reduction in CO2 emissions

(all sources of energy, 50% deadwood)

Per Household

30 liters/year

30 kg/year

900 kg/year

approx. 1,000 kg/year


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In all three South African test regions, itwas demonstrated that, under suitable

conditions, solar cookers are accepted byusers. Also demonstrated was the dualfact that it pays to use solar cookers.Furthermore it was shown that potentialusers are generally interested in purchas-ing such cookers.These results, however, still do not guar-antee that solar cookers will meet with

success on the market. This is one of themain prerequisites for their sustainablelarge-scale dissemination.Some partial market achievements can befound:s In India, where more than 100,000 box

cookers have been disseminated at 50 %subsidized prices, the cookers' utiliz-ation rates, durability and performance

have been unsatisfactory (Philip, S.K. etal.). Also, progress has been relativelyslow, i.e., there is still only one cookerin India for each 10,000 people.

s In Tibet, where a similar number ofChinese-made concentrator-type cookershave been sold, market saturation hasalready been reached in some areas(Integration, 1997). The question is

"Are we dealing with a genuine markethere or not? In addition, people thereare practically forced to use solarcookers: there are only few places inthe world where the scarcity of fuel isas extreme, and people are suffering

s All these cookers will be producSouth Africa; two small enterpristhe capacity to manufacture high-solar cookers have been selectedway of competitive bidding.

s Intensive efforts to achieve the retransfer of technology are under the European designers and SouAfrican producers work togetherimprove the solar cookers and p

them for local production. Thermtests designed to compare the loproduced prototypes with the orversions have already been cond(cf. Appendix).

s A pilot batch of 30 of each type cooker is to be distributed duringsecond quarter of 1999. By year'several hundred solar cookers wil

been shipped out by their produand, if all goes according to planminimum of 2,000 solar cookers have been commercially dissemiby the end of the year 2000.

s All possible market mechanisms cookers' sale, financing and user will be tested in the northwesterof South Africa.

s A mobile demonstration unit is beused to assist in disseminating infotion in general and about the four made cookers models in particular

s An intensive multimedia advertiscampaign is to be conducted wit

10. Outlook: Solar Cookers now on the Market


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11. Outlook: What Still Needs to be D

Up to this point, achievements in the fieldof solar cooking and the present range of

ongoing activities, particularly in SouthAfrica, have been discussed. Let us nowconsider the following examples in con-templation of what still needs to be done.

Further reduction in solar cookerpurchase pricesAt the beginning of phase 2 it was already

becoming apparent that people attachmore importance to the cookers purchaseprice than had been previously assumed.Thus, it will be of decisive importancefor the future of solar cookers that theybe mass produced in order to achievelower prices without sacrificing quality.

Bringing products

up to technical maturityAnyone who has taken a close look at theavailable types of solar cooker will havenoticed how close some of them are to theprototype stage. And anyone who has com-pared them with the kind of technicallymature industrial products that are beingturned out in large numbers can have littledoubt that a comparable mass-produced

cooker should have an over-the-counterprice of not more than 30 to 60 US$.

Drawing up recommendationsSomething else that still needs to be doneis to generalize the results and experience

s Solar cookersproducts, user

ance, durablecooker on todsatisfies all o

s Secondly, disuser support standards setdevelopment

s Finally, the p

be conductivefavouring thenologies withcompetition.

Therefore, a coThis implies thes Solar cooker

identify and

promising sos Manufacturer

field of housproduce costcookers for mwill come dosteps are take

s Private sectorfields of comand financingthese producproviding use

s NGOs shoulddistribution m

s National Gov


25/34

Any attempt to precisely predict the futurepotential of solar cooking would be pre-

sumptuous. but even a few simple clueswould be interesting. However, it can beof interest to estimate some magnitudes.

Let us assume that the annual consumptionof fuelwood for cooking, which amountsto 2 billion tons annually at present,could be reduced by five percent throughthe use of solar cookers. This amounts topotential savings on the order of 100 mil-lion tons of fuelwood per annum. In termsof pure magnitude, this is comparable toGermany's entire annual consump tion ofpetrol. While that is still only a fractionof global energy consumption, it is never-theless worthy of serious consideration.

The production capacity required formaking the number of solar cookers toachieve is also noteworthy: it would take100 million solar cookers to achieve thetargeted savings. That would equate tomaximum annual proceeds of severalbillion US$ (assuming saturation of thepotential global market with cookersdesigned to last five years). While the

estimate does not come close to match-ing that of either the motor vehicleindustry or the computer sector, it isnevertheless nothing to be scoffed at.

It is the people involved who make solar

12. Outlook: On the Potentials of Solar Cooking


26/34

ULOG

Type of cooker:

Conventionalbox cooker

with wooden

frame

Appendix:Technical Data of South African Test

Selected Results of the 1994 ECSCR Comparative Solar Cooker Test and 1

Dimensions (cooking pos.):

Number of pots and nom. volume:

Test pot content:

Aperture surface:

Heating time (water):

- cold start (40 - 80C)- cold start (40 - 96C)

- hot start (40 80C)


Max. temperature (oil):

Continuous cooking:

Heat loss with lid open:

66 x 67 x 104 [c

1 removable pot

2.5 l

0.24 m2 (without ref

*94 minutes*takes 120 minutes to re

*66 minutes/**77 minutes/*

*107 minutes

*124C after 130 m

*boils 7.5 l of water i

*cools from 95C to 80


27/34

Selected Results of the 1994 ECSCR Comparative Solar Cooker Test and 1998/99 Tests in South A



Test pot content:

Aperture surface:


- cold start (40 - 80C)- cold start (40 - 96C)




Continuous cooking:

Heat loss with lid open:

66 x 63 x 38 [cm]

one, two or three removable pots

1.5 l

0.28 m2

*90 minutes*takes 120 minutes to reach 87C

*78 minutes/**62 minutes/

takes 120 minutes to reach 93C/**90 minutes/***76 minutes

*114C after 130 minutes

*boils 3 l of water in a day

*cools from 90C to 80C in 5 min


28/34

REM5

Type of cooker:

Conductive boxcooker




Test pot content:

Aperture surface:Heating time (water):

- cold start (40 - 80C)





88 x 101.5 x 96 [

2 removable pots (5

2.5 l

0.36 m2

(without ref

*48 minutes

* 66 minutes



*147C after 130 m


29/34

Selected Results of the 1994 ECSCR Comparative Solar Cooker Test



Test pot content:







273 x 135 x 110 [cm]

2 non-removable pots (2 x 5 l)

2 x 2.5 l

1 m2

(without reflectors)

46 minutes

54 minutes

26 minutes

39 minutes

*157C after 130 minutes


30/34




Test pot content:







143 x 163 x 125 [

1 removable pot (

6 l

1.54 m2

(reflecto



-

-

*198C after 130 m

SK12/SK98Type of cooker:"Deep Focus"

concentrator


31/34

Selected Results of the 1994 ECSCR Comparative Solar Cooker Test



Test-pot content:







114 x 117 x 179 [cm]

3 removable pots: one 15-l pot and two 2.5-l pots

7.5 l

0.60 m2

(without reflectors)

40 minutes (moderately preheated)

66 minutes

32 minutes

55 minutes

157C after 130 minutes


32/34

Schwarzer 2Type of cooker:Flat platecollector cooker

Selected Results of the 1994 ECSCR Comparative Sola



Test pot content:

Aperture surface:





C

302 x 192 x 175

2 non-removable pots

5 l / 2.5 l

2 m2 (without refle

50 minutes

64 minutes

6 minutes (large pot) / 14 min


33/34

References

s Alvarado Mrida, Carlos Guillermo(1996), El uso posible de cocineros

solares en Guatemala, Informeevaluativo, 1996, VTZ internal

s Bnninger, Silvia (1993), Bericht bermeine Versuche und Abklrungen imZusammenhang mit dem Solarkochervon Synopsis/VTZ in Senegal vom25/10 27/11/1993, VTZ internal

s BMZ aktuell 060, Bonn, January 1996

s DME/GTZ (1997), Solar CookerField Test in South Africa, Phase 1,Volume 1, Main Report, Johannesburg,December 1997

s ECSCR (1994): Second InternationalTechnical Solar Cooker Test, Summaryof Results, Second Edition, Lodve,

June 1994, published in BMZ aktuell060, Bonn

s Environmental Manual (1996),communicated by U. Fritsche

s FAO (1998a): www.fao.org/fo%2A/nwfp/num4/nwn%2D4ec.htm

s FAO (1998b): www.fao.org/fo%2A/

energy/import.htms Fritsche, U. (1998) private

communication

s GTZ (1991): Grupp, M. et al.,New Prospects in Solar Cooking,

for GATE/GTZ, Eschborn, May 1

s GTZ (1996): www.gtz.de

s GTZ (1997): Biermann, E., TechnEvaluation of the Cookers Particiin the Field Test (internal),GTZ, Eschborn

s GTZ (1998): Grupp, M. et al., Ne

Cooker Designs Since 1994 DrGTZ, Eschborn, December 1998,soon to be published

s Integration (1997),Lnderinformation Tibet Schlu(intern) Frankfurt, 1997

s Philip, S.K. et al. (undated), Monand Servicing of Subsidized Sol C

in Gujarat A case Study, SPRERVallabh Vidyanagar, 388120 Indi

s Sodeik, Eva (1991), Akzeptanz telogischer Innovation, Das BeispiSolarkocher in Indien, MagisterarEthno logie, 1991, PhilosophischeFakultt der Albert-Ludwigs-UnivFreiburg/Br.


34/34

Division 44 - Environmental ManagementWater, Energy and Transport

Dag-Hammarskjld-Weg 1- 5P.O. Box 51 8065726 Eschborn, Germany

Telephone ++(49)61 96-79-0Telex 4 07 501-0 gtz dTelefax ++(49)61 96-79-11 15Internet: http://www.gtz.de

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moving ahead with solar cookers

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