The newer, more efficient, cleaner cookstoves, designed to reduce household air pollution that worsens climate change, have failed to deliver hoped-for benefits in the field, suggests a recent study.
Researchers from the University of British Columbia, University of Washington and elsewhere measured ambient and indoor household air pollution before and after a carbon-finance-approved cookstove intervention in rural India and found that the improvements were less than anticipated.
Actual indoor concentrations measured in the field were only moderately lower for the new stoves than for traditional stoves, according to the paper.
Additionally, 40 percent of families who used a more efficient wood stove as part of the intervention also elected to continue using traditional stoves, which they preferred for making staple dishes such as roti bread. That duplication erased many of the hoped-for efficiency and pollution improvements.
Laboratory studies suggested that the more efficient, cleaner-burning stoves could reduce a family's fuelwood consumption by up to 67 percent, thereby reducing household air pollution and deforestation. In practice, there was no statistically significant difference in fuel consumption between families who used the new stoves and families who continued to cook over open fires or traditional stoves.
Without field-based evaluations, clean cookstove interventions may be pursued under carbon financing programs that fail to realize expected carbon reductions or anticipated health and climate benefits, the study concluded.
"A stove may perform well in the lab, but a critical question is what happens in the real world?" said lead author Ther Wint Aung. "Women who are busy tending crops and cooking meals and caring for children are using stoves in a number of ways in the field that don't match conditions in the lab."
Across all households, average indoor concentrations of particulate matter, an unhealthy component of cooking smoke that can contribute to lung and heart disease, increased after the intervention stoves were introduced, likely because of seasonal weather patterns or food rituals that required more cooking.
The median increase, however, was smaller in homes where families exclusively used intervention stoves - 51 micrograms per cubic meter, compared to 92 micrograms per cubic meter for families who used both intervention and traditional stoves and 139 micrograms per cubic meter for the control group of families who continued cooking on a traditional stove.
"On the one hand, there was less of an increase in some pollution levels and that's a win. But on the other hand, it feels pretty far from a complete solution," said co-author Julian Marshall.
Co-author Michael Brauer noted, "Ultimately households throughout the world will desire the same clean cooking technologies used in high-income countries and in most urban areas: electricity or gas. This study suggests that the interim solution of cleaner biomass stoves remains elusive."
The study is published in June in Environmental Science and Technology.