Whitney Steed, Erin Hamson, and Jeff Lord with Dr. Matt Jones, Mechanical Engineering
Introduction
Statistics report that approximately three billion people in the world prepare their meals using solid fuels1. The incomplete combustion that comes from burning these solid fuels creates harmful fumes and particulate matter that damage human health. Our goal was to create standard methods to measure progress towards cleaner stove emissions, focusing on cookstoves in Peru. These consistent testing procedures will allow designers to assess the impact of design changes on cookstoves by using them to measure the combustion efficiency of biomass cookstoves and to measure the indoor air quality in homes where biomass cookstoves are used.
Numerous research projects at BYU involving cookstoves previously had no effective methods to measure emissions. With our research, these groups now have a way to accurately track their progress towards cleaner stoves and therefore optimize their research. Field tests were conducted when we traveled to Peru in the spring of 2013 as part of the Global Engineering Outreach (GEO) program that is sponsored by the Ira A. Fulton College of Engineering and Technology.
Methodology
Our project began by researching the current methods of measuring emissions and fuel consumption including the water boiling test, controlled cooking test, and kitchen performance test. Our goal was to maintain the accuracy of these testing methods while eliminating expensive equipment, intensive set up, and strict control of variables in the tests. Concurrently, we began rebuilding a mobile cookstove testing unit that is safe and convenient for researchers to use. Through the redesign of this testing unit, we were able to integrate newly aquired equipment from Aprovecho, a leading cookstove developer, which aided in obtaining accurate results.
Once the testing unit had been built and new equipment integrated, we began testing. Three instruments were used to measure carbon monoxide and particulate matter including an expensive and large but accurate instrument called a PEMS, a smaller but still expensive IAP meter, and small less expensive CO monitors. By using all three, we could compare results and see whether differences in accuracy were significant. We set out to control three variables; wood placement, size of wood, and type of wood. The fire is designed to look and perform like a typical fire in rural Peru. We began by measuring the weight of the wood, weight of water in the pots on the stove, and the filter paper placed in the PEMS. After allowing the fire to burn for a certain amount of time, each of these was weighed again. A calculation spreadsheet was then used to calculate particulate matter and carbon dioxide from the fire and at various times during the burning of the fire.
We worked throughout the school year to develop less expensive yet very effective and consistent methods of analysis for cookstoves. When we arrived in the village of Matinga in May 2013, we were able to test various stoves for particulate matter and carbon monoxide. Our primary purpose in Matinga was to collect preliminary data to create a baseline for future cookstove research at BYU pertaining to Peru. This included observing as many types of stoves and cooking methods as possible. In addition to this, we used the IAP meter and the CO monitors to collect carbon monoxide and particulate matter data for five different meals.
Results
Our specific goals were to (i) optimize currently available lab space and equipment, (ii) use available instruments to develop a repeatable test, and (iii) apply the test to analyzing cookstoves in Peru. We were successful in achieving all three of these goals.
After many ideas and design iterations, we designed and built a new testing unit. The new testing unit integrated numerous design features that increased both testing effectiveness and accuracy. Design features such as a large metal hood above the fire and a box with a trap door beneath the fire were specifically catered to our testing methods and equipment, which made for better results. Also, the cinder block and brick walls surrounding the fire kept out the wind and other elements that affected results. The stove itself inside the unit was made to look and perform like a stove in Peru and can be switched out to test new designs. The new cart base and handle made it easy to transport the testing unit outside where tests could be performed.
As discussed in methodology, we created standard testing procedures for testing cookstoves using our testing cart unit and equipment. After performing numerous tests using these procedures, it was found that the testing method was repeatable. In addition to being repeatable, the tests took less time and energy than current testing methods. We wrote a manual on how to carry out these standard procedures as well as how to analyze data collected so future research will be consistent with ours. BYU cookstove research now has a standard and repeatable way to measure particulate matter and therefore quantifiably track progress of new cookstove designs.
After we created a standard procedure with our equipment that yielded accurate and repeatable results, we needed to find a way to make a more inexpensive and adaptable way of gaining accurate results in the field. We measured and documented six different stoves inlcuding their physical measurements and immediate surroundings (such as position in house and proximity to doors or windows). In documenting cooking styles we focused on getting physical measurements of the fuel used, observed how the fuel was fed into the fire, and talked with the cooks about cooking habits and what changes they would be willing to make. We used three CO monitors and an IAP (indoor air pollution) meter to measure both CO and particulate matter. The result of this was accurate and specific qualitative and quantitative information on current Peruvian cookstoves.
Discussion
Ability to measure increases in fuel efficiency and air quality attributed to improved biomass cookstoves is essential in designing and implementing improved cookstoves. Our research has greatly contributed to solving the challenge of determining whether the increase in fuel efficiency and improved air quality of newly designed cookstoves is accurately measured in both the lab and field tests. The testing unit we designed is able to integrate new stove designs as well as other changes to cookstoves such as airflow to the fire. It is a longterm and versatile solution for cookstove testing at BYU.
There are many challenges with designing new cookstoves besides their ability to improve air quality and combustion. Part of our research in Peru included making careful documentation of stoves currently in use in order to determine social and technical constraints to minimize the risk of cultural issues with new designs. We also obtained information on how, when, what, for how long, etc. Peruvian people cook. This will allow designers to determine whether a stove will meet the people’s needs. There is more to stove design than minimizing the amount of particulate matter released.
In summary, we feel that our development of a testing facility and methods at BYU as well as our implementation of analysis and immense cookstove observations in Peru will make a significant difference in the direction of cookstove research and will be imperative for future cookstove design. Knowing cultural restraints, current empirical data, and overall cooking style directly from Peru will immensely benefit all future cookstove research at BYU.
Conclusion
In the past, GEO and other NGOs have implemented many new stove designs in Peru and we have now created a quantifiable way to evaluate their success in reducing fuel and emissions. We have obtained baseline results from current cooking stoves in both the lab and in the field that will allow future cookstove developers to compare and contrast results from their new stove designs to these foundational results. This will be done using standard and repeatable procedures that we have developed and documented. Comparing new designs to traditional cookstoves in the field and then comparing this to lab results will yield new insight for future research and eventually lead to the improvement of human health around the world.