Solar cooking

Why isn’t it yet global?

Jeremy MacClancyOxford Brookes University

It is one of the simplest modes of cooking known: exploitingand concentrating the rays of the sun to cook food. Forenvironmentalists and those wishing to improve the lot of theimpoverished, solar cooking appears to tick almost every box

they can think up. Given all this, and the fact that in recentdecades solar cooking has been increasingly promotedthroughout the warm corners of the globe, working solar ovensshould now be found in millions of homesteads, villages, townsand cities. But they are not. Why not?

The aim of this paper is to answer that question, and tosuggest ways to ameliorate the present condition.

A little history

It is possible to argue that solar cooking is an ancientpractice. Certainly, exploiting the heat of the sun to dryfoods, especially meat, is a widespread and very long-established mode of presentation: for example, the preparationof beef jerky in much of sub-Saharan Africa.1 In the West,however, much of the present-day impetus to the promotion ofsolar cooking derives from experiments made in California inthe postwar decades by independent-minded individuals. Theirefforts and those who have been inspired by them have led tothe development of various organizations dedicated to thepromotion of solar cooking throughout the world, e.g. SolarCookers International (SCI). Various international NGOs havetaken their lessons on board and strive to advance the use ofsolar ovens throughout the impoverished parts of tropicalregions. This California-based initiative has also led to thepublication of a variety of solar cuisine cookbooks, thoughadmittedly all of these are aimed mostly at a Euro-Americanmarket.2

It has been argued that in China the use of light-collecting and focussing devices can be dated back toantiquity and that some providers of cooked meats wereexploiting solar cookers in the late nineteenth century. Thepresent efforts of the Chinese Government, however, date fromthe 1980s when its Ministry of Agriculture began to promoteits use. China has now the largest solar cooker programmes inthe world.3

Key principles, common cookers

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The principles which underpin solar cooking are simple. First, solar cooking reveals a beneficial dimension to the greenhouse

effect. Rays from the sun fall on Earth, they are absorbed intomatter and so converted into infra-red radiation. If thisradiation tries to leave the Earth, it is reflected off theatmosphere surrounding the planet. When this reflectedradiation returns to Earth, it is again absorbed into matter,so increasing the temperature of the matter.

This effect is exploited in solar cooking, by envelopingthe cooking pot in a transparent plastic bag, covering it witha glass bowl, or placing it in a glass-topped box. The potacts as the Earth, and the covering as the atmosphere. Inother words, reflected radiation is bounced back from thecover onto the pot, so raising its temperature.

Second, opaque materials absorb heat. Light-coloured or shinyobjects reflect, and thus do not absorb, most of the lightwhich falls on them. Opaque objects, especially black ones,reflect very little light. Instead they absorb much more of itthan shiny objects do.

Third, reflected rays intensify the heating effect. Reflectors placedaround or inside the pot’s covering can boost the amount ofrays which fall directly onto the pot.

The two most common types of solar cookers are panel andbox ovens. Panel ones are made of a series of interconnectingpanels, each covered with a reflective surface, which form thebase and sides. The food to be cooked is put in a large,sealed plastic bag, or placed in a pot, which is positioned inthe centre of the oven.

The aim of a box oven is to create a cooking space byplacing an open cardboard box inside another, larger one; thegap in between is filled with an insulating material, e.g.crumpled newspaper. The base of the inner box is paintedblack, and its sides covered with a reflective surface, e.g.aluminium foil. The lid, a piece of framed glass, has anadjustable reflective surface attached to one of its sides.

Advantages of solar cooking

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Sunlight is free. That is the central benefit of solarcooking. Sunlight is an unlimited source of costless energythat we can exploit at any time whenever the sky is clear. Forimpoverished peoples, this is key.

Solar cooking is, moreover, an efficient mode ofgenerating heat. A recent project in China, the world’sgreatest national user of solar ovens, calculated that atraditional coal-fired stove has a thermal efficiency ofc.15%, while that of a solar cooker was more than four timeshigher, c.65%. Their studies suggested that the daily cookingand water heating needs of an average rural family would bemet by about four hours of solar cooking per day.4

Solar cooking also demands very little effort, above allfor women and children, who in many parts of the world arecharged with collecting firewood. In deforested or lightlyforested areas, collecting combustible material can takehours, every day. And, as areas become progressivelydeforested, the amount of time spent collecting firewood canonly go on rising. In 1999, it was estimated that about twobillion people around the globe were suffering from fuelwoodshortages.5 In rural areas of Tibet, there are so few treesthat locals rely on dried yak dung. Collecting dung, at timesfrom distant pastures, and then carrying it up a mountainsideto dry are regarded as women’s work. But these tasks are solaborious that one charity estimates that women spend c. 35hours per week on them. According to the charity’s website,local women are very well aware the beneficial differencesolar ovens could make to fundamental aspects of their lives.6

Furthermore, a cook does not have to sit and watch overthe stove the whole time, but can leave its contents cookingand get on with other tasks. It can also be argued that inlesser developed areas, whose government wish to develop thefledgling economy, solar cooking can save on the consumptionand transportation of coal, which can then be diverted toother ends.7

Solar cooking is good for your health. Open fires presenta variety of potential risks. The smoke produced can irritatethe lungs and lead to many respiratory disorders. According toWHO estimates, acute respiratory infections is the leadingcause of death among children younger than 5 in the developingworld; 1.6 million are thought to die annually from thiscause, one individual every 20 seconds.8 Smoky fires can result

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in chronic bronchitis, emphysema, and lung cancer; they arealso linked to asthma and tuberculosis. There is also thepotential of damage to the eyes, both from smoke and sparks.Moreover people, especially children, are at risk of harmingthemselves by falling in or onto open fires. The burns theymay receive range from the mild to the gravest. One additionalhealth benefit is suggested in one study in India, where womenstated that solar ovens increased their physical security:‘When collecting wood from remote forests, they face abusefrom forest officials and others’.9 These concerns are evenmore marked in places where female security is low. In refugeecamps in Chad, panel cookers have been used for an extendedperiod, because women, young and old, have been attacked,raped, and in some cases killed when foraging for firewoodoutside the camp.10

Another big plus listed by promoters of solar cooking isthe contribution its widespread use could make to forestallingdeforestation. The global consequences of losing forests arevery real, as is repeatedly stated in the media. Deforestationhas already led to the destruction of about 90% of WesAfrica’s original forests, and threatens food security inseveral African countries. An influential factor in these highrates is the dependence of 90% of the Sub-Saharan populationon wood for heating and cooking.11 Emergencies, such as thesudden creation of large refugee camps, can affect the rate ofdeforestation even more dramatically. For example, during theTigray famine in Ethiopia in the mid-1980s, refugees removedall the accessible trees within a very short time: ‘Tosurvive, fuelwood supplies were brought in both by longcaravans of donkeys from areas controlled by rebels and, sosevere was the situation, by airfreight from Europe’. 12

Solar ovens may also help mitigate climate change becausethey sidestep the harmful consequences of open fires.According to one study in south Asia, 42% of all soot in theatmosphere comes from cooking fires. Over the Indian Ocean,the effect of soot on the climate was ten times greater thanthe effect of greenhouse gases.13

Further, solar ovens may aid in combatting soil erosion.Peoples who traditionally use dried excrement and harvestleft-overs as cooking fuels can, on conversion, to solar ovensuse these farmers’ by-products as fertilizers for theirfields.14

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Solar cookers may be used not just for cooking, but fordrying foods as well. In China, solar ovens are used to dry,among other income-generating fruits, medlars and grapes.15 Oneproblem here is that, in a solar box oven, condensationcollects on the inner surface of the glass. For this reason,those who wish to dry large amounts of food, especially fruitor juicy vegetables such as tomatoes, use solar convectionboxes. Here the box-oven is surmounted at one side by a tiltedchimney: the water vapour rises and condenses in a bulb at thetop of the chimney, away from the drying food.

Solar ovens can also be used to purify water. Therevolutionary effect this could have is highlighted by thenumber of deaths from diarrhoea, cholera, and other water-borne diseases, especially among children, each year inlesser-developed areas. Longterm research by the biologistRobert Metcalf at California State University has shown thatto remove the great majority of pathogens, water does not needto be boiled, but only raised to 60 degrees: an easy aim formost solar ovens. A project, overseen by him, in Kenya wherelocal women used solar boxes to both cook food and pasteruizetheir contaminated water reported ‘a significant decrease indiarrheal diseases as a result’.16 Recent studies demonstratethat solar ovens can also be used for medical wastedisinfection.17 Furthermore, SCI claims that increased use ofsolar cooking may mitigate the AIDS pandemic. It states HIV-positive mothers can reduce the chance of transmitting it totheir babies by using their ovens to pasteurize water to mixwith infant formula.18

At times the potential uses of solar ovens appear almostunlimited. In rural South Africa, solar cookers are even usedfor ironing. Instead of putting a cast iron on top of a fire,which can dirty it and thus clothes, women place them directlyinto their ovens. Further uses for solar ovens include canningand refrigeration.19

Unlike conventional stoves, panel or box solar cookers donot generate high levels of heat. They can thus be made ofcardboard or, more durably, of wood. They are also easy tomake, not requiring any skilled knowledge of carpentry orengineering. In other words, almost any able-bodied personcould make one. Specialists do not need to be hired. Moreover,most forms of these ovens are very cheap to make.

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A further advantage which some have noted is that thefood cooked in a solar cooker is not smoked, allowing peopleto savour the ingredients’ natural flavours. In a solar oven,the only cooked food which might have a bacon-like taste isbacon; nothing else.

Finally, there is a potentially political dimension tosolar cooking. As one Chinese website advocating the use ofsolar ovens reports, solar cooking ‘has promoted thedevelopment of harmonious society in Tibetan areas and isdeeply received by farmers’.20

Disadvantages of solar cooking

The benefits of solar cooking are manifold; and theirpotential for improving the lot of humankind is so great thatit is almost upsetting to have to list its downsides, and theyare legion.

Though solar ovens are cheap to manufacture, they stillhave their costs. To the poorest of this planet, even a smallcost can be too high a price. They may scavenge the card andother materials from rubbish tips or skips but paying for theglass might prove a burden too much. Since solar cooking is anunexpected idea for many, persuading people to invest part oftheir meagre budget in a novel technology is not an easy task.Further, NGO experience shows that people who are given thingstend not to respect them. If one wants people to use and carefor a solar cooker, the lesson is, they usually need to investsomething of their own in it, no matter how paltry thatcontribution might appear to affluent Westerners. On top ofall that, NGOs need to be aware that locals’ ideas ofinvestment may be very different from common Western ones. Forinstance, a Solar Cooking International project in westernKenya found that local women refused to buy ovens on credit asthey did not believe in going into debt. Even though it mightappear to make more sense, according to Western economics, forthem to take advantage of the cookers as soon as possible,they strongly preferred to make a series of small paymentsuntil they had paid for the full price of the cooker, andthen, and only then, accept the coveted item.21

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Solar ovens, unless made of metal, are light. Lightobjects can be moved, particularly by thieves, especially inurban areas. More to the point, their contents can be stoleneven more easily. Thus, though a box oven with a gentlycooking pot might enable its owner to get on with other tasks,that does not necessarily mean that he/she can quit the scene,say, to go tend their kitchen gardens. Panel cookers, however,which can be folded up, can be taken into the fields by womenwho have to work there during the day.

Quitting the scene for an extended period is alsodifficult because the earth moves round the sun. Unless acarefully positioned solar oven is moved periodically, sayevery hour or so, the sun’s rays will not strike the glass orthe reflector directly. The consequent drop in solarexploitation would be equivalent to turning a conventionaloven down. One possible way to overcome this difficulty is tomake solar ovens with round, rather than flat reflectivesurfaces. According to the physicists who researched this,‘cookers with round surfacts are more symmetrical andtherefore their foci are not as dependent on the position ofthe sun, whereas cookers with flat surfaces have to be pointeddirectly at the sun to achieve maximum effectiveness’.22

As almost any social anthropologist of food can state,the hearth is a central site of most homes. It is where peoplegather to meet, chat and mull over the issues of the day. Itis an opportunity for cooks and their children to relax incompany, while watching the state of the fire and the progressof the food. Solar cooking provides almost none of thesebenefits: there is no excuse for more than one person to stayby the oven. So, very often, they don’t.

A conventional stove or an open fire also provides bothheat and light. In areas without access to electricity,cooking fires may be the only source of nocturnalillumination. The provision of heat is also important, asdeserts or desertified areas, for instance, might be warmduring the day, but can be chilly by light. Moreover, the heatof the flames may keep insects at bay. Again, this ispotentially very important, as the number of insects infestingkitchen areas in tropical areas can easily spiral tounhygienic levels. Solar ovens provide none of these benefits.

Solar cooking is slow cooking. Some users complain thatsolar cooking entails greater planning. A cook cannot decide

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at the last minute what to produce but has to think severalhours ahead, for example what ingredients to include, and hasto start cooking much earlier. This shift in timetable maywell not suit locals’ schedules of what is to be done, when,during the course of a day. For example, in rural Kenya, womenusually buy food for the evening meal from markets, which openat 11am. Those who using a solar oven would have to startcooking by 10am, in effect forcing them to buy produce the daybefore and then having to store it, if they have the space.Also, since solar cooking takes longer, meat has to be cut upinto smaller pieces. But most Kenyans like larger pieces ofmeat, and families who are unable to offer larger pieces toguests may be seen as inhospitable.23

Solar box ovens have to be quite large to accommodate twoat least medium-sized pots. Local cooks report that it can bedifficult to cook two dishes at the same time in a solar oven,if they have different cooking times. In Burkina Faso, forexample, a typical meal has two components (rice, and asauce), which cannot be prepared at the same time.24 Of course,if the oven lid is raised to remove one pot, a finite time isthen necessary to bring the oven up to temperature. In partsof East Africa, it is acceptable for kin and kith to comewithout any forewarning for supper; it is expected ofhouseholds that they cook enough to feed guests who may appearat the last minute. But locals who were given solar ovens inan evaluatory project found that, even though large, they werenot big enough to provide the food necessary for such aparty.25

Most solar ovens are only good for certain kinds ofcooking, above all baking. This does not suit many peoples,who prefer much faster modes of producing food, above allfrying. On top of that, some have signalled their distaste forthe result; they don’t like the change in the consistency andtexture of the food cooked. In rural Kenya, for example,people are used to smooth, porridge-like cooked staples, anddo not appreciate the more solid, cake-like version whichemerges from solar ovens. Also, some Kenyans complained thatsolar-cooked food lacked the smoky taste they had become soused to.26

By definition, solar cooking is dependent on the state ofthe sky; i.e. it is completely and permanently reliant on theweather, over which no cook has any control. This factor might

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be almost irrelevant in tropical areas with almost rainlessseasons. Elsewhere, it means that solar cooking isfundamentally unpredictable, in ways that conventional ovensare not. This subjection to meterological vagaries may notperturb those with access to alternative modes of cooking butcan prove a fatal weakness for people whose timetables forcethem to choose early in the day whether to cook with the sunor go gather firewood.

Local forms of domesticity may be another reason why insome cultures, it might be difficult for some to adapt to thisunavoidable unpredictability. In Burkina Faso, many mothersemploy housemaids. Since they want to finish their jobquickly, they find solar cooking too slow and too subject tothe vagaries of climate.27 Researchers in Kenya found that ifthe evening meal ‘is not hot and ready to be served to the manof the house when he wants it, it may lead to domesticabuse’.28 According to a Solar Cooking International surveyinto cultural constraints on solar cooking, some men in partsof Africa were afraid ‘the cookers would provide women time tobe idle’, while in a Central American study, men beat theirwives to discourage them against solar cooking, because theyfelt threatened by the female liberties the new ovens enabled:getting out of the house, meeting with other women, andlearning new skills. This statement may help us understand whysome local women state they prefer working with a cooking firein a hot, smoky kitchen, because the heat and smoke keep theirmen away and so provide them with a space of their own.29

One way to overcome some of these problems is to employsolar cooking not as an exclusive alternative to conventionalcooking, but as a common supplement to it. The trouble here isthat solar ovens can be quite bulky: for how many people,especially in slum areas, have sufficient space for two kindsof oven? Even if a family’s courtyard is not too crowded, theymay still have to consider that ‘neighbours may besuspicious’ of this new technology.30 In areas of East Africa,many eat about 8pm, yet optimal solar cooking ends about fourhours earlier. To keep the pot warm, a cook needs then to putit in a haybox or something similar. Locals surveyed in onesolar-promotion study asked what was the logic of having twocooking devices (the solar oven and the box) when the same jobcould be done by just one device, such as a stove or openfire.31

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For those who have not been trained in the Western-derived laws of physics, and who may well have local modes ofinterpreting physical phenomena, solar cooking can appearmysteriously, or even diabolically different. Severalpromoters of solar ovens in lesser-developed countries havereported that locals may repeatedly ask, ‘Where is the flamehidden?’ Some locals claim that the promoters are trying todeceive them, or that the ovens rely on ‘evil spirits’,‘witchcraft’, or ‘black magic’. To put those statements intotheir appropriate context, one promoter stated that a Westernengineer spent time with them arguing that solar ovens couldnot work, until confronted with the cooked evidence. In someparts of Kenya, there is the further potential obstacle thatlocals believe an enemy who passes by their homestead may give‘the evil eye’ to unguarded food.32

Some NGO workers and government employees who have triedto promote solar cooking have learnt that they have to acceptthat, for its successful exploitation by villagers, a long,culturally very sensitive, time-consuming (and thus expensive)period of training is necessary. Their experience shows thatif this is skimped, the chances of sustained use of solarovens diminish dramatically. Some have learnt, for instance,that local men may not value the saving that solar ovens canmake because they do not consider the time women and childrenspend collecting firewood as work, or at least as laboriouswork. It is just what their wives and off-spring are expectedto do. Thus, experienced workers in this field continue toemphasize that, for a solar cooker project to work, they mustwork in a collaborative manner with locals.33 The concerns,interests, and desires of the locals have all to be taken intoaccount, and be seen being taken into account, if the projectis to have any chance of success. Locals have to feel that, insome sense, they ‘own’ the project and that it addresses theirneeds. Moreover many promotional projects do not givesufficient attention to the potential, future production ofsolar cookers. They do not take the commercial dimensions oftheir manufacture into account. But if solar cooking is tobecome established and continue in an area, mechanisms need tobe put into place to enable the local production and repair ofcheap, robust ovens.34

Some people may be so impoverished that they do not worrytoo much about the proclaimed social or environmental benefits

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of solar cooking. Their top priority is everyday survival.35

Quite simply, they wish to get through to the next day, andall other possible considerations are secondary to that. Thisunderstandable priority given to the short-term means thatanything which gives higher value to the longer term isrejected as an unaffordable luxury, for others to enjoyperhaps, but not for them. A study in the Sudan suggested thatlocals ‘did not care about the effects of cutting trees andburning traditional biomass on the environment’; what theycared about was the cost of purchased wood and solar cookingmainly interested them because it helped relieve domesticbudgets.36 In other areas, locals may value modernity over theenvironment. They would rather be trendy though treeless, thanforested hillbillies. For example, the commentator on oneproject in Lesotho came to realize that ‘concern for theenvironment is a post-industrial concern. . . The Basotho arenot going to start caring about saving trees until they canstop caring about getting telephone poles erected leading totheir homes’.37

People may also admit that they are very concerned abouttheir own state of well-being and wish to stay as healthy aspossible. But, again, that concern can be couched in veryshort-term language which sidelines any thought about theincremental effect of quotidian phenomena such as smoke.38

Further, as will already be obvious from some of theabove, solar box cooking usually does not suit those who go towork in the fields or herd cattle in the countryside duringthe day. Agricultural workers could take a panel cooker intothe fields but not if they have to follow a herd. Neither typesuits commuters, who work in towns during the week and returnto their home villages at the weekend.39 Muslims would not usea solar oven during Ramadan, which takes up a twelfth of everyyear. In areas of Africa, where polygamy is practised, peoplelive in large family units, and cooking is only carried outonce a day, most solar cookers are physically too small tocook the main meal.40Members of all these groups can onlyaccommodate it within their usual routine with various degreesof difficulty.

It has also to be stated that the contribution solarcooking can make to the forestalling of deforestation is easyto exaggerate. Even though fuelwood constitutes up to 18% ofglobal energy consumption, i.e. more than nuclear energy and

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hydropower put together, the gathering of firewood is, in mostareas, not a major cause of deforestation. Outside ofemergencies, firewood-gatherers tend to collect twigs andbroken branches.41 In these areas, logging is usually the maincause of deforestation.

Indeed one researcher in development studies in BurkinaFaso has acutely argued that, in environmentalist terms, thepromotion of solar ovens has been mistargeted. Those in ruralareas consume relatively little wood as they only cook once a

1 See e.g. http://www.fsis.usda.gov/factsheets/jerky_and_food_safety/index.asp. Accessed 21 x 20122 E.g. Gurley 1993; Koflak 1995; Anderson 2006; Yaffe 2007. On the historyof solar cooking, see Butti & Perlin 19803 The history of solar cooking in China, www.solarcooking.wikia.com/wiki/China. Accessed 10 ii 20104 ‘China: news and recent developments March 2009’, www. Solarcooking.wikia.com/wiki/China,Accessed 10 ii 20105 Bergler et al 1999: 96 Tso 2008: 14--157 Xiaofur 2009: 68 Knudson 2006; Diamond 20089 McGilligan 2006: 610 http://www.solarcookers.org/programs/iridimi.html. Accessed 21 x 201211 Tropical Deforestation Rates in Africa. (www.mongabay.com/rates_africa.htm). Raphael Mweninguwe. "Massive deforestation threatens food security". http://www.newsfromafrica.org/newsfromafrica/articles/art_9607.html. Agyei, Yvonne. Deforestation in Sub-Saharan Africa. African Technology Forum, Volume 8, Number 1. All accessed 21 x 201212 Bergler et al 1999: 913 ‘Addressing climate change with solar cookers’, Addressing global issues. http://solarcookers.org/programs/advocacy_packet.pdf. Accessed 10 ii 201014 Garzón et al 200615 On solar dryers, see Fodor 2006. On Chinese developments, Xiaofu 2009: 616 Metcalf 2006; n.d.17 ‘China: news and recent developments March 2009’, www. Solarcooking.wikia.com/wiki/China,Accessed 10 ii 201018 ‘Solar cookers and the HIV/AIDS pandemic’, Addressing global issues. http://solarcookers.org/programs/advocacy_packet.pdf. Accessed 10 ii 201019 For canning, see Anon n.d. For refrigeration, see McMahon n.d.20 Xiaofu 2009: 521 Coyle n.d.22 Dormio and Jones 2002: 1223 Baptista et al 2003: 28--9

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day and manage to find enough for their needs within theirlocale. Further, for their fires, they often use corn ormillet stalks instead of wood. In contrast, people living intowns have partly shifted to European food habits, whichentails lighting a fire three times a day. They use more wood,and larger pieces, which has usually to be bought. They alsouse a lot more charcoal than villagers, and the charcoalnormally available contains only about 11% of the originalwood energy. In other words, the culinary style andgeographical location of townspeople means that they rely on amuch greater amount of wood, and of a more difficult toreplace kind than their rural counterparts. On this line ofargument, promoters of solar ovens should be concentratingtheir efforts on urban sites, not rural ones.42

Upsides and downsides to parabolas and heat-storing stoves

To overcome several of these obstacles to greater use of solarcooking, some of its promoters now advance the cause ofparabolic cookers.

24 Krämer n.d.: 1025 Baptista et al 2003: 3026 Baptista et al 2003: 1727 Hermann-Sanou 200628 Baptista et al.2003: 2929 Coyle 200630 Hermann-Sanou 200631 Baptista et a. 2003: 3032 Baptista et al. 2003: 29; Coyle n.d.; Krämer n.d.: 9. See for a further example of solar scepticism, this time by a highly regarded Scots missionary in Ecuador, Cuvi 200633 E.g. Kammen and Lankford 199034 Onyango-Oloo 200635 For a Kenyan example, see Baptista et al 2003: 1236 Rizing & Croxford 200637 Grundy 1995: 438 For a Kenyan example, see Baptista et al 2003: 1339 Baptista et al 2003: 2440 Hermann-Sanou 200641 Bergler et al 1999: 8--942 Krämer n.d.

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The distinctive property of a parabola is that all rayswhich land on its inner surface are reflected back through asingle focal point. So a reflective parabolic dish, with acolumn holding a pot at the focal point, will concentrate allthe reflected sunlight onto the pot. This overcomes theproblem of time: a parabolic solar concentrator will, underordinary sunlight conditions, bring a pot of one litre of tapwater to the boil in approximately seven minutes. Further,these cookers are often made of metal or concrete covered withmirrored tiles. This makes them so heavy that they can only bemoved by the strongest winds, or the strongest thieves. Aproject in Somalia found that these were the only kind ofsolar cookers acceptable to locals, because their cookingspeed was comparable to that of charcoal.43 Since these solarconcentrators generate higher temperatures than box ovens theycan be exploited for a greater variety of cooking styles, e.g.steaming, blanching, roasting and frying. Suitably adapted,they can also be used on a large scale by food-processingplants, (for the production of potato chips, jaggery, ormarmalade), textile manufacturers, bakeries, and for theincineration of waste.44 In 1998 Wolfgang Scheffler, inventorof the popular, eponymous solar concentrator, beganexperimenting with solar cremation.45

At first these cookers seem like a godsend to those whowish to assist impoverished others and reverse deforestation.But every technology, no matter how great its advantages, hasits disadvantages. First, parabolic cookers need to be finelyadjusted to the position of the sun. Unless they are shiftedevery thirty minutes or so, they fail to catch the maximalamount of the sun’s rays.

Second, the concentration at the focal point may be sofine that the food in the point may cook very rapidly, whilefood on the inner periphery of the pot can receive much lessreflected sunlight and so heat up much more slowly. In somefinely-made parabolic cookers, this unevenness of cookingwithin the pot can lead to the food in its centre burning.

Third, the concentration of the sunlight around a singlefocal point brings with it the threat of momentary blindnessif a cook points their face too close to it: remember Galileo.

43 Lindsay 200644 Chandak et al 2006; Gadhia & Gadhia 2006; Pulfer 200645 Scheffler n.d.

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Those who use parabolic cookers are thus very strongly advisedto wear sunglasses. According to one report from Burkina Faso,some parabola uses have complained ‘that they cause burns anddazzling. . . and, since, some have been abandoned’.46

One way to overcome these threats of ocular damage,scorching skin and burning food is to split the parabola intotwo dishes. Varieties of this ‘butterfly’ parabolic solar ovenare now promoted by NGOs throughout the globe. A recentalternative is the solar cooking table, where a low-placedparabolic dish focuses the heat onto the underside of acooking surface.47

Among the most recent innovations is one which seeks toovercome a common problem: many families need cooked foodabove all at the beginning and end of the day, when the sun isweak or absent. In 2011, after the failure of a project oftheirs in India Climate Healers, an international developmenttechnology organization, issued a design challenge for thecreation of a solar oven which could cook food for morning andevening meals. I.e. it had to store the energy generated foruse later. So far the best responses have been imaginative,impressive, and highly suggestive.48 The problem is that mostrely on expensive and fragile materials. Instead, someadvocate quicklime solar storers: addition of water to calciummonoxide liberates energy; during sunlight hours, solar energydehydrates the resulting hydroxide, returning it to monoxide.Though the benefits of this process have long been known, thepresently proposed quicklime solar ovens are based onparabolas49, with many of the disadvantages listed above.

Why isn’t solar cooking yet global?

At the university which employs me, I taught a course on theanthropology of food for several years. One of the fundamental46 Devos 200647 Devos 200648 ‘Ten solar cookers that work at night’, https://www.engineeringforchange.org/news/2012/02/04/ten_solar_cookers_that_work_at_night.html. Accessed 21 x 2012 49 Eshetu, Desalegn, and Ramayya 2005

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statements I had to make, and keep on making, was that the waypeople prepared, cooked, and ate their food was central towhat they did and who they thought they were. In other words,a people’s cuisine, with all that entails, is a key componentof their culture, and thus of their cultural identity. Assuch, change will usually come only for extremely good reason.Unless there is a strong case for altering their mode ofcooking, most traditional peoples on this globe resist theintroduction of culinary novelty.50

The study of solar cooking only underlines the validityof that statement. Critical study of case after case showsthat the importation of solar ovens does not produce theresults development workers had expected. One recent surveycame to the conclusion, ‘Decades of efforts to implement andimprove solar cookers for developing countries have not helpedto achieve the breakthrough of this technology’.51 Anotherreport admitted,

With few exceptions, solar cooking has been a disasterthat happens again and again to well-meaning people indeveloped countries. It is such a clean, shiny idea thatfeels like the future until you actually build it. Thenits flaws jump out.52

To take one specific example, from south Asia:

In India, where more than 100,000 box cookers have beendisseminated at 50% subsidized rates, the cookers’utilization rates, durability and performance have beenunsatisfactory (Philips, S.K. et al: 37). Also, progresshas been relatively slow, i.e. there is still only onecooker in India for each 10,000 people.53

As one solar cooking activist summed up, ‘New habits take timeto grow, people tend to be conservative--choosing the knowneven if it is costly’.54 Others have noted that, for many50 MacClancy 199251 Otte 200952 ‘Ten solar cookers that work at night’, https://www.engineeringforchange.org/news/2012/02/04/ten_solar_cookers_that_work_at_night.html. Accessed 21 x 2012 53 Bergler et al 1999: 2354 Owino 2006

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targeted groups, the perceived benefits, such as those listedearlier, were considered insufficient return for the neededchange in behaviour, the often unpredictable results, and thelimits to performance.55 As part of my research for thisarticle, I contacted a broad number of anthropologistcolleagues who had done fieldwork in areas where solar cookingwas viable. Every single one of those contacted who knew ofsolar cooking projects in their fieldsites stated that theintroduced ovens were no longer being used by the time oftheir fieldwork.

The information presented by websites of NGOs dedicatedto the promotion of this technology provides, unfortunately,little evidence to the contrary. For it has to be recognizedthat the great majority of these sites are in effectpromotional vehicles for the NGOs themselves. This is not amoral statement on their self-presentation; the criteria forsuccessful funding effectively obliges many of them to phrasetheir results in the most positive fashion. Indeed, some feelforced to dispute the very terms of evaluation. At a 2006conference, one German NGO admitted, ‘There has to be a hightolerance for what might be termed ‘failure’.56 All too often,the otherwise laudable projects of NGOs are not backed up byindependent, critical studies of subsequent use of the ovensby the locals. As one environmental anthropologist hasconfessed, ‘They use the solar oven when we’re around, but putit away again when we leave’.57

There is one area of the globe where solar cooking hasbeen very successfully adopted by locals: Tibet. Why? Becausethere the scarcity of fuel is so very great, and so clearlyacknowledged by villagers, that locals appear to have littleoption but to embrace the new technology. This one examplesuggests that it is only when people’s backs are up againstthe wall that they will accept using solar cooking without toomuch resistance.

It is, however, dangerous to assume that peoples in limitcases will automatically adopt solar cooking out ofdesperation. Comparative evidence from projects managed bySolar Cookers International suggests that the timespan foradoption of solar cookers in extreme situations such as

55 Grupp et al 200656 Hoedt 200657 Bick, P, quoted in Diamond 2008

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refugee camps is four to five years.58 Work among refugees in Ethiopiaand Kenya demonstrated that lowering the already low price ofsolar boxes did not lead to a significant rise in sales. Evenwhen the boxes were distributed free, not all the encampedadopted solar cooking.59

It is also possible to argue that other parts of westernChina have, like Tibet, successful programmes. But it is nocoincidence that this takeup of the new technology isoccurring in areas where fuel is scarce, people are poor and,perhaps above all, the government at times crushinglyauthoritarian. That last point chimes with evidence from otherseemingly successful implementations of solar cooking. Tofollow this, we must switch from a geographical focus to afunctional one, for some of the largest recent developments ofsolar cooking have been in institutional and industrialcontexts, i.e. army camps, schools, pilgrimage centres, foodprocessing and textile plants.60 Here, solar cooker activistsare not trying to persuade domestic cooks but are assistingmanagers who make executive decisions about the energy supplyof their organizations. By the nature of their business, theyhave to see employees carry out their assigned tasks, and theyhave to think long-term. Often their organization, though itmay be relatively small, is sufficiently large to accommodateboth bulky solar cookers and supplementary devices, whileemployees managing the solar ovens have far less freedom ofchoice than domestic cooks. In other words, almost all thereasons cited by domestic cooks for not switching to solarcooking are inapplicable or far less applicable to thoseoverseeing institutional use of solar cookers. One implicationof this is that solar cooker promoters should be concentratingtheir efforts in this sphere, rather than devoting years ofexpensive involvement trying to cajole reluctant villagers.

Some solar cooker promoters perceive that their effortsmight be better spent beyond the village. They recognize: thatsolar cooking projects need to be properly marketed, withprovision of dependable after sales service; that there needto be far greater links between solar cooking promoters aroundthe globe; that any project with a long-term framework

58 Dennery 2006, where she also states that the same period of time is needed to reach ten percent of target households in settled communities. 59 Owino 200660 Chandak et al 2006; Gadhia & Gadhia 2006; Pulfer 2006

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requires co-ordination between foreign NGOs and localorganizations from the very beginning; enlisting women’sorganizations to participate in this work is essential;ideally host governments should be encouraged to establishpolicy frameworks and initiate or cooperate in promotionalprogrammes.61 Given this assessment of all the work and varietyof tasks necessary for a project to have a chance to besuccessful, it is perhaps unsurprising that solar cookersremain unpopular among development experts.62

Time to help others by helping ourselves?

The initial promise of solar cooking seems so great, and itspotential benefits so broad, that it is at times deeplydisappointing to have to acknowledge the oft-ignored maximthat technologies are all profoundly social in origin. Wecannot expect to be able to simply transfer a technology,however basic or sound it may appear to us, directly intoanother cultural setting. Different advantages anddisadvantages may occur in each new setting to which thesecookers are introduced, and they have all to be taken accountof, in each particular case.

There is, however, one last problem I wish to consider,and that is the image of solar cooking. For many people,though seemingly very poor and with few apparent options,still wish to hang on to their sense of personal dignity, nomatter how constrained that might appear to us, affluentWesterners.

Let me give some examples of what I mean. In ruralLesotho, many who consider buying a solar oven ask themselves,‘What do white people do?’ ‘Is this going to make me seem moreadvanced?’ Would people call them country bumpkins for havingone around the house?63 The Field Projects Director for SolarCookers International confesses that a common local reactionto her presentation of CooKit panel cookers, ‘the first solar

61 Dutta & Datta 2006; Hermann-Sanou 2006; Knudson 2006; Onyango-Oloo 200662 See for example the comments by experts quoted in Krämer 200663 Grundy 1995: 7

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cookers truly affordable to the world’s neediest’, was ‘It isonly cardboard!’ She acknowledges how challenging it can be topromote a simple, useful device if target customers, howeverimpoverished, view it as a product of little prestige or lowstatus.64 According to the founder of Ladakh Project in India,the locals who tend to adopt solar cookers are the moretraditional ones: ‘The young and fashionable won’t use them;there is no glamour in it’. Cookers are not associated withwhat is modern and fashionable. In her opinion, what is neededto change attitudes is for an American soap opera, such asDallas, to include the use of one in an episode.65 Though thatlast point might appear flippant, it is in fact difficult tooveremphasize the potency inserting solar ovens into a popularTV series would have. Perhaps this is, at present and aboveall, where the efforts of solar cooker promoters should beconcentrated.

Some promoters are well aware of how they themselves maybe viewed. As one put it,

Of course, it’s hard for me to make a persuasive argumentfor the solar oven when they know perfectly well that Iuse more fossil-fuel energy in a day than they use in ayear. ‘Do I use a solar oven?’, they ask.66

One way to surmount this problem is to turn preaching intohome practice. In the words of a charitable programmedirector,

I can say from personal experience that the fact that Iuse these technologies myself has gone a long way interms of technology acceptance in the communities weserve. I suspect that this is because they feel that ifsomeone of greater means chooses to make thesetechnologies instead of being relegated to use them (bylack of other options), that there must be some inherentor perceived benefit from their usage.67

In a small effort to follow this best practice, my familyand I made two solar box ovens in our home in southeastern

64 Shakerin 2006: 165 Farwell, E. n.d.66 Bick, P, quoted in Diamond 200867 Diamond 2008

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Spain, and have cooked with them as much as possible. Also wehave striven to explain how they function to whoever visitsand pays an interest. Furthermore, we have lent them to ourrural neighbours in the hope that they might come to see theirvalue and to make their own. For, in sum, how can we hope tochange the habits of other people, if we are not prepared tochange our own?

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Endnotes

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