Modifying open fires with rock beds or grates is a low-cost way to reduce impacts.
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Rock beds and/or grates can be implemented where cleaner options are unavailable.
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Rock beds or grates to open fires reduce wood use up to 58% in lab tests.
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Rock beds and/or grates reduce CO and PM emissions by 51–84% in lab tests.
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Rock beds and/or grates reduce wood consumption up to 45% in actual cooking.
Abstract
In this study, we use water boiling tests (WBTs), controlled cooking tests (CCTs) and in-home kitchen performance tests (KPTs) to analyze changes in fuel consumption and emissions resulting from low-cost modifications to traditional open fires. The modifications consist of adding rock-beds, ceramic grates or metal grates to open fires. In both traditional and modified stoves, cooking pots are supported over the fire using iron bars, which is a common practice in rural Vietnamese households. The modifications increase airflow through the combustion zone and improve combustion efficiency. The rocks and grate also decrease the distance between the fire and cooking pot, improving heat transfer. These low-cost modifications improve stove performance in many categories: 38–58% reduction in wood consumption and 51–84% reduction in emissions measured in WBTs; 34–37% reduction in wood consumption during simulated cooking with CCTs; and 31–45% reductions in per capita wood consumption measured during KPTs. Grates performed better than rock-beds in nearly all tests. Surveys implemented in parallel with KPTs indicated favorable user perceptions of all low-cost options. The modifications result in lower fuelwood consumption and emissions, resulting in social and environmental benefits, but they are unlikely reduce health impacts, which many policies and programs now prioritize. Nevertheless, there are numerous situations in which these options may be appropriate. In remote, rural or otherwise marginalized communities, clean cooking options may be inaccessible for the foreseeable future. Low-cost modifications like rock beds and grates, which require minimal training and changes in cooking habits, could reduce the impacts of open fires. Similarly, in places where clean cooking options are accessible, but stove “stacking” with open fires persists, these options could present a cost-effective way to achieve a “cleaner stack”.
