Cleaner household coal combustion and emissions performance of a semi-continuous cookstove

Abstract

Traditional cookstoves in developing regions exhibit low thermal efficiency and elevated emissions, contributing to environmental and health concerns. This study experimentally investigates an enhanced cross-draft semi-continuous cookstove within the South African context. The stove incorporates a grate-shaking mechanism designed to prevent ash accumulation and maintain airflow during combustion. Four types of South African bituminous coal (A, B, C, and D) were evaluated under high and low-power operating conditions to assess thermal performance and emission characteristics. The results indicate that high-power conditions produced greater firepower and cooking power, whereas low-power operation yielded higher thermal efficiency for selected coal types. Type A exhibited the highest emissions of CO 2 , CO, and PM, while Type D showed comparatively lower emissions. SO 2 and NOx emissions increased under high-power conditions, consistent with temperature-dependent sulphur and nitrogen reaction pathways. Notably, the overall PM emissions of 6.8–13.5 g/kg were substantially lower than values reported in the literature for comparable coal-based cookstoves. Temperature stratification between the hopper and combustion chamber influenced overall stove performance, with sustained thermal stability observed during semi-continuous operation. The grate-shaking mechanism was necessary to maintain combustion stability by mitigating ash accumulation and ensuring consistent airflow through the fuel bed. Compared to traditional cookstoves, the proposed design demonstrates reduced emissions and sustained combustion performance. These findings contribute to the advancement of cleaner coal combustion technologies and energy-efficient household cooking solutions in coal-dependent regions. • Improved cross-draft cookstove designed for cleaner coal combustion • •Thermal efficiency and emissions tested with four South African coals • •Type D coal showed lowest CO 2 and highest thermal efficiency under LP • •Type A coal had a PM emission factor of 0.4 g/kg, below reported values • •Grate shake mechanism improved airflow and sustained combustion