The ProblemThe Problem• Half the world’s people must burn wood or Half the world’s people must burn wood or

dried dung to cook their food.dried dung to cook their food.• Nearly 1.2 billion people, a fifth of the world’s Nearly 1.2 billion people, a fifth of the world’s

population, do not have access to clean population, do not have access to clean drinking water.drinking water.

• Over 1 million children die yearly because of Over 1 million children die yearly because of un-boiled drinking water.un-boiled drinking water.

• Wood cut for cooking purposes contributes to Wood cut for cooking purposes contributes to the 16 million hectares of forest destroyed the 16 million hectares of forest destroyed annually.annually.

• Half the world’s population is exposed to Half the world’s population is exposed to indoor air pollution, mainly the result of indoor air pollution, mainly the result of burning solid fuels for cooking and heating.burning solid fuels for cooking and heating.

““I’d put my money on the sun and solar I’d put my money on the sun and solar energy. What a source of power! I hope energy. What a source of power! I hope

we don’t have to wait ‘til oil and coal we don’t have to wait ‘til oil and coal run out before we tackle that.”run out before we tackle that.”

Thomas Thomas EdisonEdison

OverviewOverview

• Types of cookersTypes of cookers• Principles of solar cooker designPrinciples of solar cooker design• Retained heat cookingRetained heat cooking• Cooking guidelinesCooking guidelines• Teaching ideasTeaching ideas• ExamplesExamples• Additional information and Additional information and

resourcesresources

Types of solar ovensTypes of solar ovens

• Box CookerBox Cooker

• Panel CookerPanel Cooker

• Solar Funnel CookerSolar Funnel Cooker

• Parabolic Cooker Parabolic Cooker - not - not recommendedrecommended

Box cookerBox cooker

• Among easiest and most popular to build and useAmong easiest and most popular to build and use• Lid of a cardboard box reflects light onto pots Lid of a cardboard box reflects light onto pots

under glassunder glass• Advantage of slow, even cooking of large Advantage of slow, even cooking of large

quantities of foodquantities of food

Panel CookerPanel Cooker

• Sunlight is reflected off of multiple panels Sunlight is reflected off of multiple panels onto a pot under a glass lid or in a bagonto a pot under a glass lid or in a bag

• Can be built quickly and at low costCan be built quickly and at low cost• Many different varietiesMany different varieties

Solar Funnel CookerSolar Funnel Cooker

• Safe, inexpensive and easy to useSafe, inexpensive and easy to use• Concentrates sunlight into a dark pot in a plastic Concentrates sunlight into a dark pot in a plastic

bagbag• Combines best of parabolic and box cookersCombines best of parabolic and box cookers• Anyone can make oneAnyone can make one

Parabolic CookerParabolic Cooker

• Highly focused light and high temperaturesHighly focused light and high temperatures• Cooks nearly as fast as a conventional ovenCooks nearly as fast as a conventional oven• Costly and complicated to make and use – Costly and complicated to make and use –

have to turn frequently to follow the sunhave to turn frequently to follow the sun• Potentially hazardous-not recommendedPotentially hazardous-not recommended

The basic principles - The basic principles - C.A.R.E.S.C.A.R.E.S.

•CCollect the lightollect the light

•AAbsorb the lightbsorb the light

•RRetain the heatetain the heat

•EEase and Efficiencyase and Efficiency

•SSafetyafety

C: Collect the LightC: Collect the Light

• Collect the sunlight using reflectors with Collect the sunlight using reflectors with an approximately 400 square inch an approximately 400 square inch opening (20x20)opening (20x20)

• Easy way to measure: the minimum Easy way to measure: the minimum opening of the cooker needs to be the opening of the cooker needs to be the diameter of an adult’s armdiameter of an adult’s arm

• Reflective surface materials include: Reflective surface materials include: aluminum, Mylar, aluminized Mylar of aluminum, Mylar, aluminized Mylar of any thickness, aluminum or chromium any thickness, aluminum or chromium paint (Note: mirror like reflectors can paint (Note: mirror like reflectors can lead to eye damage)lead to eye damage)

A: Absorb the lightA: Absorb the light

• Absorb the light – paint the pot Absorb the light – paint the pot matte black or another dark color to matte black or another dark color to absorb the heatabsorb the heat

• Pots can also be elevated by a wire Pots can also be elevated by a wire base or posts, allowing the bottom of base or posts, allowing the bottom of the pots to collect sunlightthe pots to collect sunlight

R: Retain the HeatR: Retain the Heat

• Retain the heat – hot vessels lose Retain the heat – hot vessels lose their heat to the air quickly so they their heat to the air quickly so they need to be coveredneed to be covered

• Cover with plastic, glass, Plexiglas, Cover with plastic, glass, Plexiglas, or tempered glass or tempered glass

• A tight lid will trap steam and speed A tight lid will trap steam and speed up cooking Ex: Canning jars work up cooking Ex: Canning jars work like inexpensive pressure cookerslike inexpensive pressure cookers

R: Retain the HeatR: Retain the HeatA note on plasticsA note on plastics

• Oven bags are the best way to retain heat. Oven bags are the best way to retain heat. They are sold in most large U.S. grocery They are sold in most large U.S. grocery stores, although they may be hard to find in stores, although they may be hard to find in other places (Reynoldsother places (Reynolds©© bags work well) bags work well)

• If you can’t find oven bags, an alternate If you can’t find oven bags, an alternate solution is transparent High Density solution is transparent High Density Polyethylene bags (HDPE)Polyethylene bags (HDPE)

• Prevent the HDPE bags from touching the Prevent the HDPE bags from touching the pots or jars, as they may meltpots or jars, as they may melt

• Avoid polyethylene – it melts too easilyAvoid polyethylene – it melts too easily• Good plastic may be the most difficult Good plastic may be the most difficult

material to find, and may require extra material to find, and may require extra planning, possibly including importing the planning, possibly including importing the oven bagsoven bags

E: Ease and EfficiencyE: Ease and Efficiency

Ease Ease – simplicity of everyday use– simplicity of everyday use• Funnel and box cookers are the easiest to Funnel and box cookers are the easiest to

use – they don’t have to be turned to follow use – they don’t have to be turned to follow the sunthe sun

EfficiencyEfficiency - how fast the cooker heats food - how fast the cooker heats food • Parabolic cookers focus light to a point (most Parabolic cookers focus light to a point (most

efficient) causing dangerous conditionsefficient) causing dangerous conditions• Funnel cookers focus light across a broader Funnel cookers focus light across a broader

area down the center of the cooker (efficient area down the center of the cooker (efficient but not dangerous)but not dangerous)

S: SafetyS: Safety

•SSafety – Avoid highly focused light afety – Avoid highly focused light such as that in the parabolic cooker. such as that in the parabolic cooker. It can damage eyes and start firesIt can damage eyes and start fires

• Always exercise caution with Always exercise caution with cookers. Sunglasses are useful when cookers. Sunglasses are useful when looking into a cookerlooking into a cooker

• Cooking pots are hot and should be Cooking pots are hot and should be treated as though they were on a treated as though they were on a stove-topstove-top

Remember - C.A.R.E.S.Remember - C.A.R.E.S.

•CCollect the lightollect the light

•AAbsorb the lightbsorb the light

•RRetain the heatetain the heat

•EEase and ase and EfficiencyEfficiency

•SSafetyafety

Retained Heat CookingRetained Heat Cooking

• If sunlight is lost or multiple items need If sunlight is lost or multiple items need to be cooked, there is a solutionto be cooked, there is a solution

• Once the food is heated, quickly transfer Once the food is heated, quickly transfer to either:to either:

- an insulated box or set of towels,- an insulated box or set of towels,

- or an insulated hole in the ground - or an insulated hole in the ground covered covered

with more insulationwith more insulation• The food will continue to cook for hoursThe food will continue to cook for hours

TemperaturesTemperatures

• Sunny Day: heats from 130-145°C (265-Sunny Day: heats from 130-145°C (265-300°F)300°F)

• Cloudy Day: heats from 95-105°C (200-Cloudy Day: heats from 95-105°C (200-220°F)220°F)

• Hot enough to pasteurize water (at Hot enough to pasteurize water (at least 65-70°C for 20 minutes) least 65-70°C for 20 minutes)

• Hot enough to fully cook meats, Hot enough to fully cook meats, breads, grains, vegetables, etc.breads, grains, vegetables, etc.

• Kills disease-causing bacteriaKills disease-causing bacteria

ImpactImpact

• Expect solar ovens to replace 60% of Expect solar ovens to replace 60% of fuel needs in most placesfuel needs in most places

• The other 40% of the time, due to The other 40% of the time, due to inclement weather or special types inclement weather or special types of food, traditional methods can still of food, traditional methods can still be usedbe used

• Doesn’t replace fire as a way to heat Doesn’t replace fire as a way to heat homeshomes

Approximate Cooking Approximate Cooking TimesTimes

• Vegetables: 1.5 hrsVegetables: 1.5 hrs• Rice/wheat: 1.5-2 Rice/wheat: 1.5-2

hrshrs• Beans: 2-3 hrsBeans: 2-3 hrs• Meats: 1-3 hrsMeats: 1-3 hrs• Bread: 1-1.5 hrsBread: 1-1.5 hrs

See Recipe File for See Recipe File for more details and more details and cooking ideascooking ideas

Costs and benefitsCosts and benefits

• Cost: approximately $2/cooker depending Cost: approximately $2/cooker depending on location and availability of materialson location and availability of materials

• Materials include cardboard, aluminum Materials include cardboard, aluminum foil, plastic bag, etc. See Building foil, plastic bag, etc. See Building Instructions for more details and be Instructions for more details and be creativecreative

• BenefitsBenefits– Saves cost of fuel or time spent gathering Saves cost of fuel or time spent gathering

woodwood– Prevents diseases from impure waterPrevents diseases from impure water– Ecologically friendlyEcologically friendly

**Teaching Ideas****Teaching Ideas**

• Give construction seminar Give construction seminar • Can accompany current educational Can accompany current educational

programs such as hygiene, gardening, programs such as hygiene, gardening, or English/literacy or English/literacy

• Takes as little as half a day trainingTakes as little as half a day training• Train a group to teach others--little Train a group to teach others--little

efforts can achieve large impactsefforts can achieve large impacts• Remember: Focus on training and Remember: Focus on training and

sustainability rather than handoutssustainability rather than handouts

Real World ExamplesReal World Examples

• Summer 2003 Summer 2003 Fernando Fernando successfully taught successfully taught solar cooking solar cooking classes in northeast classes in northeast Brazil with Help Brazil with Help InternationalInternational

• Four solar ovens Four solar ovens transform a Chilean transform a Chilean village (see packet)village (see packet)

• Microenterprise Microenterprise case study in packetcase study in packet

Food for ThoughtFood for Thought

• Solar cookers can be a used for Solar cookers can be a used for micro-enterprise and other business micro-enterprise and other business ventures:ventures:– Build and sell cookersBuild and sell cookers– Cook and sell bread or other foodsCook and sell bread or other foods– See packet for examples and See packet for examples and

suggestionssuggestions

• Adapt to local cultures and customs Adapt to local cultures and customs

BE CREATIVE and BE CREATIVE and HAVE FUN!HAVE FUN!

• You can improvise with most of the You can improvise with most of the techniques and materialstechniques and materials

• Remember the basic principles Remember the basic principles (CARES) and you can adjust for the (CARES) and you can adjust for the skills and resources of those who skills and resources of those who will make and use the ovenswill make and use the ovens

Step-by-Step InstructionsStep-by-Step Instructions

– Funnel Cooker Instructions included on Funnel Cooker Instructions included on this CDthis CD

– Box Cooker are at Box Cooker are at http://solarcooking.org/ in both the box in both the box cooker section and with pictures in the cooker section and with pictures in the slide showslide show

– For more construction ideas see For more construction ideas see Alternative Cookers PowerPoint also on Alternative Cookers PowerPoint also on this CDthis CD

Additional ResourcesAdditional Resources

• Recipe File on this CDRecipe File on this CD• Packet of articles also on this CD Packet of articles also on this CD

including including – Background informationBackground information– Case-studiesCase-studies– Ideas for micro-enterprise Ideas for micro-enterprise – Frequently Asked QuestionsFrequently Asked Questions– Contact list of NGOs using solar Contact list of NGOs using solar

technologytechnology

• Comprehensive Internet Site Comprehensive Internet Site www.solarcooking.org

• For questions or feedback contact For questions or feedback contact Dr. Steven Jones at Brigham Young Dr. Steven Jones at Brigham Young UniversityUniversity– Email: stevejones@byu.eduEmail: stevejones@byu.edu– Phone: (801) 422-2749Phone: (801) 422-2749

Additional ResourcesAdditional Resources