The development of an energy efficient electric Mitad for baking injeras in Ethiopia

摘要

Preparation of Injera, the cultural staple bread food item in Ethiopia, is known for its intensive energy consuming cooking. Baking this food item in the traditional three stone stoves, with an efficiency of 5–15%, consumes huge amounts of firewood and causes consequent problems like deforestation, global warming and household air pollution. Electrical injera stoves (mitads) are a sound alternative in Ethiopia because of the relatively wide availability of electricity (hydropower). However, these electrical Mitad have designs dating back to the 1960's and are highly inefficient as well and are overloading the electricity grid. Consequently, a research and design project called ‘Magic Mitad’ was initiated to develop an energy-efficient electric injera mitad. Starting with the introduction of a new type of fuel-efficient baking plate a range of research and design experiments were initiated to further optimize the energy-efficiency as well as the baking quality of the Magic Mitad. In the first experiment the ‘start-up energy’ of different baking plates was tested in order to identify and select the most energy efficient one. During the next experiment, the chosen type of baking plate was used for baking injeras to study the heat distribution. A uniform heat distribution is key to produce high quality injeras. From the result obtained it was concluded that a different type of heating element was needed. Ten types of alternative heating elements were selected of which four were tested in a lab-setting. Ribbon wire heating element was selected, and optimized in its lay-out. Finally, the prototypes were tested in Addis Ababa on quality performance and energy-efficiency compared to electrical clay mitads. The outcomes were successful in the sense of quality and increased efficiency by 30%.