Designing lighter weight, energy efficient cook stoves with materials available in Malawi, AfricaEPA Grant Number: SU836955
Title: Designing lighter weight, energy efficient cook stoves with materials available in Malawi, Africa
Investigators: Ekegren, Ken
Institution: North Central State College
EPA Project Officer: Keating, Terry
Project Period: February 1, 2017 through January 31, 2019
Project Amount: $71,060
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2016) Recipients Lists
Research Category: P3 Challenge Area - Energy , P3 Awards , Sustainability
A vast majority of villagers in Malawi, Africa, use wood or charcoal as their main source of cooking fuel. The villagers almost exclusively build "3 stone fires" which are inefficient and smoky. For the past several years, a team from Malawi Orphan Care Project has been helping the villagers build rocket stoves to improve their method of cooking and reduce the impact on their natural resources. The rocket stoves are being manufactured by local bucket makers working with local pottery makers, using local materials. The purpose of this grant project is to improve the design of the rocket stoves to allow the villagers to sell them competitively. The two main problems with the previous design are cost and weight of the final product.
The general design of rocket stoves with their encapsulating heat shield around the cook pot reduces the amount of wood required to make a meal considerably. Currently, the villagers are using heavy mortar as the insulation filler between the clay tile fire box and the metal exterior. This makes the rocket stove too heavy to transport to and from the market place. It typically requires the stove maker to assemble the stove at a villager's home, minimizing its marketability.
The purpose of this grant project is to find a suitable replacement for the heavy mortar that provides the same insulation properties, but allows for easy transport. The project would meet all three aspects of the grant. It would provide a more efficient stove to enable the villagers to use less firewood; it would provide local villagers a product to sell as a business; and it would ultimately help the environment through the reduction in emissions and reduction of the impact on their natural resources.
To accomplish these goals, a team of students and instructor traveled to Malawi, Africa, in January 2016, to research the various materials available to the local people, improve on the design and manufacturing process using the local tools and local labor, and finalize a conceptual design to meet these goals. Due to the extreme poverty and small locality that the villagers exist in, the use of local materials is mandatory. For the business to flourish, the material transportation costs and requirements must be kept at a minimum. Malawi is one of the poorest countries in the world, and can be seen by virtue of this kind of example. Students in the Mechanical Engineering Technology program at NCSC worked under the direction of their professor, Ken Ekegren, and established a project plan that provided multiple solutions prior to traveling to Malawi. The team stayed in Malawi for two weeks, gathered local information and worked with local tradesmen to understand fully the manufacturing process and materials available. Improvements in the manufacturing process and materials were researched while in Malawi, with further research and development as needed upon returning to Ohio.
NCSC partnered with two organizations: Malawi Orphan Care Project, Inc., located in Mansfield, Ohio; and Kanyenyeva Orphan Care Ministry, headquartered in the capital city of Lilongwe, Malawi.
With the success of building lighter weight stoves with a more efficient and simpler method of manufacturing, an expansion of this project is proposed. While in Malawi, we met with directors from similar organizations in Kenya, Tanzania and Uganda. There is a need to expand the knowledge we have gained to these areas where three-stone fires are still the standard method of cooking. In addition to expanding this methodology to other communities, another practical application is to use the heat from the fire to generate electricity using a thermoelectric generator. While there are companies that already build these types of systems, there has not been a design that has been adapted to fit into typical rocket stoves like the ones now produced in Malawi. The second part of our Phase II proposal is to design and build thermoelectric generators that can be manufactured using local materials in Malawi. The electronic components will still need to be manufactured elsewhere, but will be attached to the generator in country. Phase II will include the prototyping, testing and development of a robust generator that can be built in Malawi using simple, local materials (square steel tubing and flat steel bar), and will also include research and development of an inexpensive electronic package to convert the voltage output from the generator to standard USB five-volt output.
Although villagers in these African countries are still using basic biomass fires and cook stoves, many of them have cell phones and LED rechargeable lights that need electricity - something that is typically miles away. Most villagers have to walk to a local market and leave their phone or battery for a number of hours, pay for the charge and often have their batteries stolen. A thermoelectric generator as proposed would provide sufficient power to charge a phone or an LED light without this inconvenience.
Phase II would enable a team of students to develop the thermoelectric generator and electronic circuitry necessary, build prototypes, test and then teach how to manufacture in the aforementioned African countries at the partner organizations. The project would include a month long trip to Africa, spending approximately one week in each of the four countries of Malawi, Kenya, Tanzania and Uganda. Based on our experience in Phase I, a week in each country would allow the team to work with the bucket makers, clay workers and welders (for the generator hardware) and provide training in the importance and efficiency of using rocket stoves with thermoelectric generators. A team of 3 to 4 students plus instructor would be capable of achieving these goals.
The students found that the manufacturing process used by the bucket maker is as efficient as practical in the Malawian village environment. Although we presented sheet metal hand tools and an antique style metal break (bender), the traditional method of hammer and rail to form sheet metal locking crimps is still the most practical. The sheet metal hand tools for making crimps were received with thanks, and may eventually be adopted, but with minimal increase in efficiency. However, the students are in the process of building a modified "grooving" machine that may replace the method of creating a flat flange around the bottom of the bucket. The bucket maker had a hand crank groover to strengthen the integrity of the bucket, and the students are building a similar machine that will create the 90-degree flange at the bottom of the bucket that could replace the hand hammering process.
The students produced three different designs of rocket stoves for the local villagers to build and assess. The designs incorporated both changes in insulation that fills the stove, as well as a change in methodology in building the stoves. Based on feedback from Shadreck Chikoti, Director of Kanyenyeva Orphan Care Ministries, one of the new stove designs was determined to be the best alternative to the previous design. The preferable stove uses a combination of clay and peanut shells for insulation, and is manufactured using a replaceable wood core in lieu of fired clay tiles that formed the wood chamber and flue. This new design both reduced the weight of the stove and reduced the labor to manufacture. The elimination of the pre-fired clay tiles removed a labor intensive aspect where tiles were formed (one day), dried (two days) and then fired (one day plus cost of wood). Although the tile manufacturer's labor was reduced, she still participated both in labor and knowledge of clay and shell mixtures in the final product.
We were unable to weigh the final product in Malawi, therefore only subjective opinions were available, but the stoves were indeed much lighter than the previously built ones. Approximate weight reduction based on mortar versus clay/peanut shell density indicates a reduction from the original mortar stoves at 40 lbs. to a new weight of 25 lbs. While the weight reduction was received by the villagers as a major improvement, further market analysis of current stoves in Malawi indicated that these stoves are still too expensive for the typical Malawian to purchase.
The objectives of this project were met to a certain extent. The new design is definitely lighter than the previous stoves, enough that villagers could transport the new stoves by carrying them on their heads -a task too difficult with the mortar insulated stoves. The new design also improved the manufacturing time and cost by eliminating the need for the pre-made clay tiles and the additional labor required to cut them to size, tie them in place and secure them while packing the insulation into the stove. The newly designed grooving machine that will create a 90-degree lip on the bottom of the bucket during manufacturing will also reduce labor costs. The bucket maker indicated that the newly designed stove would last longer and be more efficient than the current all-clay lined stoves on the market today. However, with Malawi being one of the poorest nations on Earth, the local populace cannot generate enough cash to buy a prod uct that will last longer and be more efficient than the local clay stoves, even though they would save money in the long run. The reduction in material and reduced labor costs will allow Malawi Orphan Care Project (MOCP) to underwrite a larger number of stoves to be built with the same amount of donated money. MOCP regularly donates money for stove production to enable more local villagers to improve their standard of living by using these stoves instead of three stone fires.