Assessment of the efficiency of improved cooking stoves and their impact in reducing forest degradation and contaminant emissions in Eastern Rwanda

Biomass is a major source of cooking energy in Rwanda. This high dependence on biomass strongly contributes to forest degradation, biodiversity loss, and atmospheric pollution. Shifting from the traditional three-stone stove (TSS) to improved cooking stoves (ICS) is being promoted to reduce wood consumption and air pollutant emissions. This study assessed the emission reduction of adopted ICS and their impact on forest conservation through a combined laboratory and kitchen performance test (KPT).Out of 940 households surveyed in Eastern Province (EP) of Rwanda, 317 used ICS. Among these users, 180 were selected and revisited for an in-depth interview about the adoption process. The four most popular ICSs were selected for evaluating thermal efficiency and emissions of contaminating gases using laboratory test protocol ISO 19867-1. In addition, the avoided wood consumption of improved cooking stoves compared to the TSS was assessed using a KPT in 100 households.The survey findings indicate that 33.7 % of households use only ICS, 23.1 % only TSS, and 56.4 % ICS and TSS combined. The laboratory results show that the Save80 stove had the highest thermal efficiency (45.8 %) followed by Igisubizo (32.8 %), EcoZoom (32.6 %), and Songa (29.6 %). The emission results showed a significant difference in CO2 (carbon dioxide) emissions (p = 0.001) between the ICS models. However, the emissions of PM2.5 (fine particulate matter) and CO (carbon monoxide) of ICS were high compared to the WHO (World Health Organization) guidelines.The KPT results show that using ICS would result in an estimated annual saving of 149,313 tons of firewood corresponding to 0.7 m3 of wood, leading to an annual equivalent reduction of 0.02 ha of forest per household and 7167 ha of forest in the EP. The KPT results show that using ICS reduced CO2 emissions by 0.372 tons per household per year and by 111,088 tons of CO2 in the EP. ICSs have been shown to enhance fuelwood efficiency, leading to reduced forest degradation.