Description of Problem
The current solar oven design, created by last year's team, does not reach sufficiently high temperatures to allow the frying of foods. These solar ovens, which are presently being used in Nicaragua, only reach temperatures between 160 and 180 degrees centigrade (320-350 degrees Fahrenheit). This is a problem because tortillas, which must be fried, are a staple food in the country of Nicaragua. In order to fry tortillas, a minimum temperature of 250 centigrade (480 degrees Fahrenheit) is needed.
Because solar ovens cannot fry these tortillas, they are presently being cooked on wood-burning stoves indoors. Typical Nicaraguan housing does not provide proper ventilation for such methods; this causes harmful particles and toxins (including carbon monoxide) to be dispersed into the air within housing units. If inhaled, these toxins can trigger asthma attacks and in some cases, cause cancer from long-term exposure. According to the Minnesota Pollution Control Agency, breathing air containing wood smoke can also "irritate eyes, lungs, throat and sinuses, reduce lung function (especially in young children), increase severity of existing lung diseases such as asthma, emphysema, pneumonia and bronchitis, increase risks of heart attacks, and trigger headaches and allergies."1
Additionally, the manual labor required to gather and cut wood for the stoves is a large time commitment. The surrounding environment consists mainly of forested areas, which means the Nicaraguans are both depleting their dwindling natural resources and further enabling soil erosion. Since the year 1990, Nicaragua has lost 20.6 percent of its forests. Currently, deforestation is occurring at rate of 1.3 percent annually.2The primary threat to Nicaragua's forests is illegal logging, in part from obtaining wood for stoves.
Therefore, our team is proposing to create an optimal design for a concentrated parabolic cooker to achieve the high temperatures of approximately 250 degrees centigrade needed to cook tortillas and other foods in general. This design must be conscientious of the building materials available in the area and take into account the windy conditions during which it may be used outdoors.
The previous solar oven team designed and built a two-dimensional parabolic concentrated cooker; we have talked with the team's leader, Scott, and discovered that their prototype was not entirely successful. We have decided to pursue a three-dimensional parabolic design this year instead, which will conserve material and allow for a more compact, efficient concentrated cooker.
Task for Semester
1. Research previous studies on concentrated cookers, review past team's reports and findings, and explore other related topics
2. Make a materials list using available resources in Nicaragua
3. Design multiple efficient parabolic solar ovens based on all relevant research and different material options
4. Choose the best design based on "cost-benefit" analysis, efficiency, practicality
5. Build selected solar oven design
6. Test the results of the built oven
- Experiment involves using special artificial lighting equipment to shine parallel light onto the cooker's parabolic surface, and measuring the temperature at the empirical focal point
7. Redesign and rebuild if necessary
- For example, if tortillas do not fry successfully, design changes and further experimentation will occur.
8. If time allows, consider possible implementation methods for next semester
9. Contact with El Groupo Fenix and Las Mujeres Solares de Totagalpa to establish interest in concentrated cooker use in Nicaragua
10. Maintain communication with Tim Bond (the solar oven facilitator) and Scott (last year's parabolic cooker leader) to keep project on track
Criteria
Technical:
The solar oven design should be user-friendly such that the appropriate components may be removed and/or replaced accordingly. In addition, the oven as a whole should be relatively mobile in order to successfully track the path of the sun. Most importantly, the final prototype should be able to meet the temperature requirements for frying foods (250 Centigrade), and be efficient, durable, and practical enough for everyday use.
Social:
The constructed concentrated cooker should provide concrete results that demonstrate its ability to fry food. These results and their implications will be communicated to the proper organizations in Nicaragua, as well as, local restaurant owners who previously expressed curiosity towards solar frying. Communication and feedback on the cooker design/implementation will develop greater interest in eventually introducing concentrated cookers to Nicaragua.
Economic:
Materials in the final design must be available (in terms of location and cost) to residents in Nicaragua. This will increase the ease with which these ovens can be implemented and built. Ideally, the materials needed should be able to be purchased from local Nicaraguan businesses in order to generate revenue for the local economy.
Environmental:
According to Zimmerman's 12 Principles of Green Engineering, materials and energy inputs should be as renewable as possible; the use of a concentrated cooker in favor of a wood-burning stove implements sunlight as an energy source instead of wood.
Items Specifically Outside of Scope
This project is still in design development and interest gathering stages, so the process of actually introducing/integrating this solar cooker into Nicaraguan culture is not going to be considered. In our design, achieving high temperatures is the leading priority. Once this feat is achieved, we will focus our efforts on making the oven wind-resistant. Also, insulation is generally not used in most designs for concentrated cookers. This topic will only be addressed if there is enough time.
Anticipated Critical Theory Issues and Challenges
It may be difficult to successfully introduce and integrate these concentrated parabolic cookers into Nicaraguan culture. Traditionally, women prepare and fry tortillas in the morning around 4:00 a.m., before the sun has risen. The tortillas are then eaten for the rest of the day, packed in lunches for their children and husbands, etc. It would be impractical for a child to make the long walk home from school during the middle of the day, the only time tortillas can be fried by the solar cooker. This is a societal challenge that may not be easy to overcome. Also, the hierarchal implications of giving Nicaraguan women more free time (instead of gathering and cutting wood) may be problematic.
It is always challenging to introduce something new into any given community/society. Many Nicaraguans have become accustomed to the use of the conventional box cookers; a concentrated cooker would require the women to learn new building techniques and implementation methods. The building process would be more intensive, because the parabolic shape of the cooker component demands more precise construction than any of the current box cooker components.
This is not to say that the concentrated solar cookers will not be useful. Restaurants require constant cooking all day, and would therefore be able to make use of this technology. In fact, Groupo Fenix has already confirmed that they are working on the construction of a restaurant that will utilize solar cookers throughout the day. In order for this technology to be practical residentially, the average woman could perhaps refrain from cooking all her tortillas before sunrise, and eventually opt for a more sustainable route instead.
Gantt Chart Timeline
Financial Requirements
1. Online resources requiring viewing fee
2. Material costs
3. Trip to Nicaragua over Spring Break
Since we are still in the research phase of designing a completely new oven, the design and required materials for the concentrated cooker are not yet known. Therefore, we cannot accurately estimate our financial requirements. We predict that our budget will consist of fees from online resources that are needed throughout the semester and material costs. This cost is expected to be less than $100. Next semester, our budget will consist of the annual Nicaragua trip to try and implement our new parabolic solar oven design, should it prove successful. This will be funded individually and is predicted to be around $1500 given additional support from the Bartel's Funding program.