Solar Cooking

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Solar Cooking

• Quinton Stowell
• Product Development Manager
• Nordson UV Ltd

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Overview of sessions

• 1. Theory of Solar Energy/Cooking
• 2. Solar v Wood/gas
• 3. Design features of Solar Cookers
• 4. Case Study in Peru
• 5. Successful initiatives
• 6. Practical session

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Who am I? Nordson UV?
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Links with Peru

• Peru Childrens Trust
• Shantytown in Peru

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Why is Solar Cooking Important?

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

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Energy from the Sun?

• Solar Constant 1367 W/m2
• Clear sunny day 83 1134 W/m2
• Engineers 1kW/m2

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Energy from the Sun?
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Theory behind Solar Energy

• Low grade energy
• Collect/retain..
• Box type cooker
• Magnification..
• Parabolic cooker

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Parabolic and Box Cookers
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Wood/Gas V Solar
Wood 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
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Wood/Gas V Solar
Wood 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.
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Parabolic Design Features

• Size of reflector
• Reflectivity of reflector
• Accuracy of reflector
• Emmisivity of cooking vessel

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Energy Calculations

• Area 1 m2
• Power 700 Watts
• 1 litre of water 7 to 8 minutes
• Temperature at focus
• 420 deg C. (small black thermocouple)

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Box Cooker Design Features

• Greenhouse principle
• Area of collection
• Transmission of glass/plastic
• Emissivity of cooking vessel
• Insulation of box
• WAPI (Water Pasteurisation Indicator)

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SUNSTOVE Design

• Low cost enclosure
• Sloped side walls, scrap Aluminium
• Fibreglass insulation
• Clear glass/plastic cover
• 80 100 deg C
• 10,000 in SA India

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Parabolic v Box Cooker
Parabolic 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
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Parabolic v Box Cooker
Parabolic 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)
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Trip to Peru

• 10 teenagers
• 30 of materials
• Woodwork
• Cardboard
• Metalwork
• Fun time

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How did it go?

• Workshops
• Language!
• New skills
• Too small!
• Too big!
• Rainy season
• Years later.

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What makes an Initiative Successful?

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

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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.

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Scheffler Design

• Community Kitchen - India

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Refugee Camp - CooKit
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What makes an Initiative Successful?

• Marketing contacts with organisations
• Existing charities
• NGOs sustainable development
• Government initiatives
• Demonstrators evangelists
• Local entrepreneurs
• Empowering the right people

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Useful information

• www.sunspot.org.uk
• www.peruchildrenstrust.org.uk
• www.sungravity.com
• www.solarcooking.org
• www.itdg.org (Practical Action)
• www.sunspot.org.uk/ewb

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Making your Solar Cooker

• Split into groups
• 2 hours
• Safety

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Inner and outer sheets

• Mark out according to the drawing
• Cut with a pair of sharp scissors
• Fold with a block of wood.

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Make wooden frame and fit outer
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Fit insulation then inner panel
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Paint base plate and fit acrylic cover