Every year, nearly three million people die of illnesses caused by exposure to household air pollution. Every day, billions fulfill their daily energy needs for cooking family meals, heating water, processing food for livestock, and warming the house over inefficient open fires that emit health-damaging pollutants.
Solving this global health crisis has not proved easy. More efficient stove technologies and greater access to clean fuels have made inroads, but have not yet completely replaced traditional practices of using solid fuels. Greater understanding of the relationships between solid-fuel users, their daily needs, and the technology and fuels available to them is vital to the design of sustainable solutions.
Figure 3 from the published study. Household fuel use (kg year−1) for the average home in each elevation, distributed across fuel designations. The width of bands connecting designation nodes is proportional to the quantity of fuel flowing to the right. Colors differentiate fuel used in a single season. Note that bands for individual seasons (colors) may be discontinuous after the stove nodes, which is done to minimize band overlap.
A new study from CACHE post-doctoral researcher Nick Lam and collaborators at the Center for Rural Technology in Nepal (CRT-N) and the Berkeley Air Monitoring Group is contributing to that understanding by delving into the total energy needs of rural families in Western Nepal and the social interplay between those needs and the technologies and fuel sources required to meet them.
During four seasons over one year, the team visited more than 100 households to measure fuel consumption across different stoves in each home. With an emphasis on human behavior and needs instead of just technology, they also recorded the types of activities a stove was used for to understand the connection between energy needs and the ways they were met. The result is an outline of fuel consumption over time, by device used to meet the needs, and by tasks accomplished — a guide to which energy services contribute most to household air pollution exposure.
Some of the study’s findings were expected. Family meal preparation required more fuel than any other single activity on average over the year, so the international community’s focus on cleaner cooking technologies seems justified. People used more fuel in the cold winter months than they did in other seasons of the year.
A closer look at the data showed a more complicated story. Space heating did not account for as much of the increased fuel use in winter as one might expect. Instead, charcoal left over from the main cooking fire was distributed around the home in metal pans to take care of space heating, adding very little to total fuel consumption.
Other activities that increase with cold weather were the real drivers of elevated fuel consumption in the winter. Non-meal activities like water heating and preparation of animal food accounted for about one quarter of annual energy consumption. Such tasks happened mostly on stoves other than the main one used in meal preparation. So, an improved stove optimized and marketed for cooking may do little to eliminate emissions from these non-cooking activities.
“People use what’s most appropriate for the services they need,” said Tami Bond, CACHE researcher and an investigator on the study. “If the stove promoted doesn’t provide that service, it’s not surprising that people keep using technologies that do.”
For example, the supplemental stoves used by families in this study accommodated larger pots than their main cooking stoves, and it was used for a range of tasks throughout the year.
An alternative reflecting only cooking needs of the main stove couldn’t be expected to fully displace the larger supplemental stoves, and so they would stay in use. Even limited use of traditional devices (more than 10-20% of total cooking time) can lead to unsafe levels of exposure.
“If we had measured only the main stove’s fuel use, and assumed that any use of that stove was cooking related, these interesting behaviors would not have shown up in the results,” Lam said. “I think it points to the necessity of combining fuel assessments and questionnaires to gain insight into the full spectrum of energy needs in a home — all the factors driving consumption patterns and behavior changes.”
“Everyone is agreed that transitions to cleaner household energy practices will have significant welfare benefits,” he said. “The problem is that most of the models we rely on to predict those benefits and guide strategies to realize those benefits aren’t reflecting all the nuances. They assume 100% adoption, yet we know that’s not the case in the real world.”
“Social scientists have been emphasizing the importance of the link between household energy needs and technology for decades. Multidisciplinary approaches like the one used in this study in Nepal are a step toward getting the right information to address the problem.”
Full text of the paper, “Seasonal fuel consumption, stoves, and end-uses in rural households of the far-western development region of Nepal,” can be found at http://iopscience.iop.org/article/10.1088/1748-9326/aa98cc.
