Solar Cooking

Quinton StowellProduct

Development Manager

Nordson UV Ltd

Overview of sessions1. Theory of Solar Energy/Cooking2. Solar –v– Wood/gas3. Design features of Solar Cookers4. Case Study in Peru5. Successful initiatives6. Practical session

Who am I? – Nordson UV?

Links with Peru

Peru Children’s Trust

Shantytown in Peru

Why is Solar Cooking Important?

2,000 million cook with wood (TFL)20-25,000km2 of forest lost/year (UNEP)Contaminated water = 80% illnessesARI (Acute Respiratory Infections)Solar Cooking = no wood & no smoke

Energy from the Sun?

Solar Constant = 1367 W/m2

Clear sunny day = 83% = 1134 W/m2

Engineers= 1kW/m2

Energy from the

Sun?

Theory behind Solar Energy

Low grade energyCollect/retain….. Box type cookerMagnification…..Parabolic cooker

Parabolic and Box Cookers

Wood/Gas – V – SolarWood Burners or Gas Solar Cookers

Disadvantages Advantages

Takes time to collect wood, and is using up natural resources.

Solar energy is free

Smoke filled rooms = ARI (Acute Respiratory Infections)

Smoke free cooking

Wood/Gas – V – SolarWood Burners or Gas Solar Cookers

Advantages Disadvantages

Cook any time. Day/night/cloudy.

Only cook when it is sunny.

Gas is instantaneous and controllable.

Box cookers take time to heat up. Parabolic cookers need frequent adjustment.

Cook summer and winter.

Need to store cooker in rainy season.

Parabolic – Design Features

Size of reflectorReflectivity of reflectorAccuracy of reflectorEmmisivity of cooking vessel

Energy Calculations

Area = 1 m2

Power = 700 Watts1 litre of water = 7 to 8 minutesTemperature at focus = 420 deg C. (small black thermocouple)

Box Cooker – Design Features

Greenhouse principleArea of collectionTransmission of glass/plasticEmissivity of cooking vesselInsulation of boxWAPI (Water Pasteurisation Indicator)

SUNSTOVE ® DesignLow cost enclosureSloped side walls, scrap AluminiumFibreglass insulationClear glass/plastic cover80 – 100 deg C10,000 in SA & India

Parabolic – v – Box CookerParabolic Cooker Box Cooker

Disadvantages Advantages

Needs frequent adjustment

Adjust once an hour.

More likely to be dazzled by reflected light.

Much less reflected light.

Unstable Very stable

Parabolic – v – Box CookerParabolic Cooker Box Cooker

Advantages Disadvantages

Very high temperatures.

Only 80 – 100 deg C.

More like a BBQ or Grill Cooking takes much longer.

Easy to see it cooking quickly.

Not too sure it is working! (WAPI – 65 deg C)

Trip to Peru

10 teenagers£30 of materialsWoodworkCardboardMetalworkFun time

How did it go?WorkshopsLanguage!New skillsToo small!Too big!Rainy seasonYears later….

What makes an Initiative Successful?

Choosing the right design for the right location.Not this one for £750 in Australia!

What makes it successful?Over 4kWhr per m2 per day.e.g. India, China, South Africa.Robust, easy to use.Perform well/efficient.Local materials.Very low cost.

Scheffler DesignCommunity Kitchen

- India

Refugee Camp - CooKit

What makes an Initiative Successful?

Marketing & contacts with organisationsExisting charitiesNGO’s – sustainable development Government initiativesDemonstrators – evangelistsLocal entrepreneurs Empowering the right people

Useful informationwww.sunspot.org.ukwww.peruchildrenstrust.org.ukwww.sungravity.comwww.solarcooking.orgwww.itdg.org (Practical Action)www.sunspot.org.uk/ewb

Making your Solar CookerSplit into groups2 hoursSafety

Inner and outer sheets

Mark out according to the drawingCut with a pair of sharp scissorsFold with a block of wood.

Make wooden frame and fit outer

Fit insulation then inner panel

Paint base plate and fit acrylic cover