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Image:Umbrella_solar_cook_1.jpg|Here Bart and I are splitting bamboo with a knife and a hammer.  It was pretty easy, it required very little force from the hammer.   
Image:Umbrella_solar_cook_1.jpg|Here Bart and I are splitting bamboo with a knife and a hammer.  It was pretty easy, it required very little force from the hammer.   
Image:Umbrella_solar_cooker_bamboo_2.jpg|Splitting bamboo again.  After splitting off a piece, we had to whittle the rest of the length to get it to a desirable strength.
Image:Umbrella_solar_cooker_bamboo_2.jpg|Splitting bamboo again.  After splitting off a piece, we had to whittle the rest of the length to get it to a desirable strength.
Image:Umbrella_solar_cook_saw1.jpg|Here I am sawing the bamboo to fit into the canvas. 
Image:Umbrella_solar_cook_saw2.jpg|Close up of the saw, make sure to wear gloves for safety!
Image:Umbrella_solar_cooker_bamboo_soak.jpg|The bamboo soaked in water for a couple of days to make it more flexible.
Image:Umbrella_solar_cook_bamboo_n_cloth.jpg|It works as a sun umbrella.
Image:Umbrella_solar_cook_bamboo_n_cloth2.jpg|And it works as a shelter
Image:Umbrella_solar_cook_mylar on cardboard.jpg|After the mylar and cardboard were cut, double stick tape was used to hold them together.
Image:Umbrella_solar_cook_mylar on cardboard2.jpg|Since the tape wasn't strong enough by itself, I stapled the edges.
Image:Umbrella_solar_cook_triangle_n_cloth.jpg|Putting the complete mylar/cardboard triangles into the umbrella.
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Revision as of 08:05, 5 May 2008

Template:305inprogress

A bit of Background

The use of a parabolic shape is not a new invention by any means. There has been use throughout history of focusing the sun’s rays for cooking purposes[1]. Today, many are attracted to the idea of cooking with a renewable resource instead of using expensive and pollutant fuels. Furthermore, I hopeful that with the use of parabolic solar cookers, third world countries can decrease mortality that is attributed to contaminated water. This is what I look foreword to as I begin my project building a solar cooker.

What an Opportunity!

I have the opportunity of working with Bart Orlando, who is known throughout Humboldt County and other sectors of the Engineering Community for his inventive ideas with solar and bicycle power. With his help I will be making a solar cooker for Engineering 305, Appropriate Technology. I chose this project, because I was very inspired by geographically appropriate places, being able to sanitize drinking water and cook food with a renewable resource. Furthermore, with simple skills of making a solar cooker, individuals would be empowered to improve their own lives.

It seems that it is difficult to get people to use solar cookers if they don't feel they have a need for it, or are unfamiliar with it. That is why I am interested in making an umbrella solar cooker, which presents the idea of a multi-use solar cooker. It seems that if someone had an umbrella that could be easily transformed into a solar cooker, that person would be more likely to convert it into a solar cooker, than buy a whole new apparatus. It is my hope that the idea of a solar cooking umbrella can help solar cooking technology become more adoptable.

I will be able to gain hands on experience by making my own solar cooker, which I will construct here in Arcata, with materials that I hope to find locally. I am looking foreword to the development of this project, I hope you come back to visit this site to see my progress..

A look at the Literature

Brief History of the Parabolic Solar Cooker

Solar thermal technologies have been evolving for many centuries. The ancient Greeks, Romans, Aztecs and Chinese used parabolic shapes with reflective material as cookers [2]. There has been documentation dating back to around 1650 where German Engineers harnessed the sun for energy [3]. A Frenchman, Augustin Mouchot designed a portable solar cooker for the French troops in Northern Africa in 1877 [4]. Using basic ideas of reflection, the sun’s energy can be concentrated onto a single spot. The parabolic shape enables the energy to reflect to one point. Getting large populations to adopt solar cookers hasn’t been that successful. In the 1950’s there was a lot of development, however it was an unsuccessful industry because there wasn’t a market for solar cookers [3].

Basics of the Parabolic Solar Cooker

The sun beams down a huge amount of energy onto the earth every day, enough in just 40 minutes to replace fossil fuels burnt up in one year in the United States [1]. The difficult task is to actually capture and use that energy. There are three different types of harnessing the sun’s thermal energy that i am most interested in; a parabolic trough, tracking mirror, and a parabolic dish. The parabolic dish, which is what I am focusing on, is very efficient if it remains directed at the sun, because the sun’s rays can focus at one point [1]. The parabolic solar dish can be constructed out of a parabolic shape, which can be a recycled product like a satellite dish. You also need reflective material and a mounted rack at the focal point of the parabola with a dark pot to absorb the energy and cook food [2].

Advantages

There are many advantages to the parabolic solar cooker, like the ability to cook without fuel, eliminating smoke and pollutants while cooking. Furthermore the sun’s rays can be used anywhere where then sun is, even if there is a small amount of cloud cover. Also, the ambient temperature is not an issue, because it is possible to cook with the sun even if it is a cold day, just as long as it is sunny [3].

Concerns

There are a few minor setbacks or concerns with the solar cooker; for example it is a slow way to cook; it is unfamiliar to many people, variability of sunshine, wind, and lack of durability depending on the structure [3].

Examples of Solar Cookers

There are multiple types of solar cookers. They all have the same goal of channeling solar energy, but they are a little bit different. Following are three possible designs.

Solar Box
The solar box is a solar cooker that utilizes the greenhouse effect to cook food. Inside the constructed solar box there are reflective materials to reflect the energy and also glass on the top of the box to trap the solar energy inside. This method works well in very sunny situations, and is safe because it is an enclosed instrument. A disadvantage is that it doesn't reflect to a point, like parabolic cookers [3].
Solar Dish
The solar dish is a parabolic shape that reflects the sun energy to a single point. This is advantageous because the structure of the parabola allows the sun to be very intense at one point. The bigger the structure is, the more sun energy it can absorb. Also, it is better if the parabola is deep to protect from the wind. Sometimes if the dish is really big, it can be difficult to transport.
Solar Umbrella
The solar umbrella is similar to the solar dish; however it tends to have a more conical shape. Therefore the sun energy focuses on a line, rather than a point. This is a disadvantage because the sun energy is more dispersed, unless one was cooking a long line of hotdogs. An advantage of the solar umbrella is its transportability.

My Personal Criteria

  • Performance- The ability for the cooker to reach 160 degrees and to cook food quickly. 8
  • Safety- The cooker should not blind or cause food sickness. 10
  • Cost- Monetary spending. 5
  • Durability- The length of time or elements it can withstand. 4
  • Transportability- The ability to bring the cooker to places by one person with little packaging. 7.5
  • Location- Where the materials are found and where structure is built. 7
  • Versatile- The other ways this cooker could be useful (shelter, umbrella). 7
  • Ease of Operation- The ease at which this cooker can be used. 8


each criteria is weighted on a scale of 1- 10

Materials

for a parabolic solar dish or umbrella
When constructing a parabilic solar cooker, you can be very creative with the materials. In regards to reducing the materials embedded energy, it’s great to find local and recycled products to construct this. There are some very essential items that will make your cooker work well. It is important to have durable reflective material and a pot in the middle that is black to absorb the reflected energy. However you go about it, the dish needs to have a parabolic shape. And most importantly, sunglasses need to always be worn to protect the eyes from getting burnt [2].

Umbrella Materials and Budget

Material Source Cost
Cloth for Umbrella Donated $0
Roll of Mylar Donated $0
10 ft Bamboo Rod Nursery $10
Scrap Tire Adventures Edge $5
String/ Shoelace Recycling Center/ Thrift Store $5
PVC Pipe and Screw Attachments Ace Hardware $15
Pyrex Containers Thrift Store $10
Straps/ Wooden Stand Craft Store/ Thrift Store $10
Total $60
Why use Bamboo?


ref: ftp://ftp.fao.org/docrep/fao/010/a1243e/a1243e02.pdf

Proposed time line

Job Week
Brainstorm Week 4-6
Design Week 7-9
Collect All Materials Week 10
Finish Construction/ and Paper Week 12
Testing Week 13-14

Design and Construction

Discussion and Reflection

(things to do differently)

Bibliography

  1. 1.0 1.1 1.2 Johansson T B. H Kelly, A Reddy, R Williams. L Burnham Ed. 1993. Renewable Energy: Sources for Fuels and Electricity. Covelo CA: Island Press.
  2. 2.0 2.1 2.2 Cite error: Invalid <ref> tag; no text was provided for refs named CCAT
  3. 3.0 3.1 3.2 3.3 3.4 Halacy, Beth and Dan. 1992. Cooking with the Sun. Lafayette CA: Morning Sun Press.
  4. Butti, Ken, and John Perlin. 1980. A Golden Thread: 2500 Years of Solar Architecture and Technology. New York: Van Nostrand Reinhold Company.
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