Aaron Harrison and Dr. Vincent Wilding, Department of Chemical Engineering
The Uros Islands in Peru, also known as the floating islands on Lake Titicaca, are made from reeds by the inhabitants. These reeds serve not only as shelter, but also as the main cooking fuel for nine months of the year. During the other three months the reeds are too wet to burn, so the islanders use propane to prepare their food. Unfortunately, propane can cost more than 50% of their monthly income which is a financial burden to most families on the islands. Additionally, breathing the smoke from these reeds can increase the islanders’ risk of contracting a respiratory disease. The goal of this project was to reduce the cost of cooking fuel spent by the inhabitants of the Uros Islands in Peru by designing a sustainable method of producing charcoal briquettes from the reeds in Lake Titicaca. Since charcoal burns cleaner than reeds, we also hoped to reduce the amount of harmful smoke the islanders breathe. Finally, we wanted to create an additional source of income for entrepreneurial islanders with this system.
The process of manufacturing charcoal briquettes is well understood and requires four things: a carbon containing agent, (e.g. wood), a kiln, a binding agent, and a press. Initially, the carbon containing agent is loaded into the kiln. Then the carbon agent is burned for a short time, while impurities in the material escape in the smoke. The smoke will change colors after most of the impurities are purged from the carbon agent. The kiln is then sealed which prevents oxygen from entering and allows the carbonization process to occur. Following a cooling period, the chamber is reopened and the carbonized material (charcoal) is removed. This charcoal is then combined with a binding agent (usually starch), compressed into briquette form, and then dried1. The charcoal briquettes can then be stored until they are used.
We tested multiple kiln designs (e.g. orientation, size, material of construction); presses (e.g. material of construction, cost, size); and binders (e.g. yucca, clay). Our final charcoal manufacturing design was based off of the work done at the D-Lab at the Massachusetts Institute of Technology2. It consisted of a metal press, a kiln, and a simple binder. The press was made from hollow metal bar stock, a metal rod, and two metal plates. The metal plates were shaped with a grinder to fit into the bar stock. One of the plates was welded to the metal rod and acted as a piston (see Figure 1). All of this material was accessible as scrap metal from welding shops in the local cities and cost 10 soles ($3.33). The kiln was a 55-gallon oil drum with seven holes in the bottom and a square hole in the top. The total capital cost for the kiln and the press was approximately 65 soles ($22). Lastly, the binder was a mixture of water and grated cassava root, which cost about 4 soles ($1.33).
Nelson Coila Lujana, a leader on the islands, was instrumental in helping us to refine our design to best fit the needs of the people and to help us better understand what resources were available in Peru. We maintained contact with him throughout the project via email and telephone. His insight was critical to the success and final design of the process.
As the crowning event, we shared the charcoal making process with the islanders during the first week of May in 2011. This involved locating the necessary supplies in local shops and markets, as well as locating qualified welders who could construct the press and kiln. We then demonstrated how to burn the reeds and how to press them into briquettes for the President of the islands. Once these briquettes were dry, we successfully cooked a pot of rice for the islanders. On the final day on the islands, over twenty representatives from different islands attended a makeshift engineering fair where we presented the briquetting process and its benefits. We distributed nearly twenty manuals that included the manufacture, safety, and maintenance of the process.
In summary, our goals for the project were to reduce the cost of cooking fuel, to reduce the amount of smoke inhaled, and to create an additional source of income for the islanders. Overall, we feel that we were successful in achieving these goals. The cost of the process was $27, as opposed to $40 per month for propane. Additionally, the briquettes burned almost without smoke because all of the contaminants were released in the kiln. Finally, with the engineering fair, we shared the briquetting system with many people from different areas of the lake and encouraged them to begin their own neighborhood briquetting businesses. The best measure of success was that the islanders expressed how they could best implement this process to improve their lives. For example, one woman mentioned that because the briquettes burn without fire or smoke, they could cook during the day and not scare away tourists, who are their main source of income. Through developing and sharing this technology, this project truly helped to further the mission of the College of Engineering and Technology by “conduct[ing] creative work of consequence that contributes to solving the world’s problems.”3
References
- Emrich, W. (1985). Handbook of Charcoal Making: The Traditional and Industrial Methods. Boston: D. Reiel Publishing Company.
- D-Lab Charcoal Process Copyright © Massachusetts Institute of Technology, http://d-lab.mit.edu (Accessed on October 27, 2010).