Despite the rapid growth in technological advancements, biomass is still widely used all over the world for cooking and heating purposes mainly due to its renewable nature and wide availability. About 75% of rural households in Nepal still rely on solid fuel for cooking. The traditional design consumes more fuel and due to incomplete combustion, produce high levels of indoor air pollution (IAP) by the formation of poisonous carbon monoxide (CO) gas and other various suspended particles in the smoke. The airflow and insulation are poor, resulting lower efficiency in the range of 15 – 20%. To address these problems, the Alternative Energy Promotion Center (AEPC), a governmental agency in Nepal had introduced improved cooking stoves (ICS) in rural areas of Nepal through different Biomass Energy Support Programme. As of 2017, almost 1.2 million ICS models namely Mud ICS, Metallic ICS, Institutional ICS, and Rocket Stoves have been installed in different parts of Nepal. Based on their design, thermal efficiency ranged from 20 – 32% as tested by the Renewable Energy Test Station (RETS). ICS have reduced particulate matter ( PM2.5 and CO emission on average by 60% and 80 % compared to TCS but their concentrations still exceed indoor air quality standards for Nepal set high power PM≤ 168 mg/MJ, low power PM ≤ 2 mg/MJ, high power CO ≤ 9 g/MJ and low power CO ≤ 0.1 g/MJ. Further, indoor emission has been reduced with the help of chimneys but the emission of visible smoke from chimneys causes outdoor environmental pollution. There is only primary combustion in these stoves having no air control mechanism. The Rocket stove was designed for secondary combustion but still lacks proper airflow control. Further, there won’t be complete combustion due to insufficient temperature in the chamber and inappropriate amount of fuel-air ratio.
The Hilly and Himalayan region of Nepal have both cooking and heating as a basic requirement with biomass as dominant fuel source. The project is work on the research, development and commercialization of a low-cost metallic tier-3 combustion stove based on the requirements of the community and the required standards which is also easy to operate. Through a sequence of design modification, the project aims to address the current problem of thermal efficiency and air pollution from TCS and ICSs.