Comparative assessment of emissions and performance of biomass cookstove technologies relevant to Nepal under controlled laboratory conditions

Abstract

Traditional biomass cooking remains a major source of household air pollution and climate-relevant emissions in South Asia, yet comparable emission data for commonly used cookstove technologies remain limited. This study evaluated the performance and emissions of eight biomass cookstove configurations representing gasifier, rocket, chimney, and traditional stove designs. Laboratory-based Water Boiling Tests (WBT) were conducted in Finland under controlled conditions using a partial-flow dilution system for particle sampling. Emissions were characterized with real-time gas analysers and extensive aerosol measurements, including fine particle mass (PM_2.5), particle number (PN), alveolar-region lung-deposited surface area (ALV-LDSA), organic (OC) and elemental carbon (EC), equivalent black carbon (eBC), and polycyclic aromatic hydrocarbons (PAHs). Emission factors were calculated using WBT, carbon mass balance (CMB), and Finnish emission measurement standard -based methods to assess methodological consistency. The WBT and CMB methods produced largely consistent emission factors, indicating that simple CO₂- and CO-based approaches provide reliable estimates for the main carbonaceous emissions. Stove performance and emissions varied substantially between technologies. The forced-draft gasifier showed the best performance and lowest emissions, whereas the chimney stove exhibited poor performance and high gaseous and particulate emissions, despite being classified as an improved stove. Phase-resolved analysis showed that refuelling periods produced transient emission peaks, especially for fan-assisted stoves. Tests without a cooking pot resulted in 40−96% lower emissions, demonstrating that stove–pot interaction strongly affected combustion conditions and emission formation. These findings underscore the need for integrated evaluation across performance indicators and multiple emission metrics to identify low-emission cooking technologies.