User behavior, influence factors, and impacts on real-world pollutant emissions from the household heating stoves in rural China.

Household heating stoves are commonly used for heating in rural China during winter and are responsible for a large portion of the particulate matter in the atmosphere. Pollutant emissions from household stoves are influenced by user behaviors in actual use, in addition to purely technological reasons (i.e., type and age of appliance) and installation conditions (i.e., the natural draft of chimney system). The variability in user behavior is one of the reasons for uncertainty in household emission inventories. In this study, household stove user behaviors, including ignition frequency, heating with or without cooking, smoldering duration, and fuel-adding times, were investigated through face-to-face surveys in Shanxi province, north China. The survey of user behaviors showed that the majority of the RHS users (81.3%) and approximately half of the WHS users (49.4%) used their stoves for both cooking and heating, whereas the remaining users used their stoves just for heating. Approximately 80% of surveyed households (97.4% for water heating stove and 68.7% for radiant heating stove) kept the stoves smoldering at night, whereas the remaining users ignited their stoves every day. The highest frequency of smoldering duration and highest frequency of fuel-adding operation were 8-9 h and 4-7 times, respectively. Principal component analysis showed that stove type, permanent population, and annual income are the potential influencing factors of user behavior. The smoldering duration was positively related to indoor air pollutant concentrations and fuel-adding times had a significant impact on outdoor PM2.5 emission factors. The results from this research will be beneficial for understanding the cause of fluctuation in emissions and designing heating appliances for real-life operations.

In-use emissions and usage trend of pellet heating stoves in rural Yangxin, Shandong Province.

The use of coal in Chinese households for winter heating emits harmful pollutants that severely affect indoor air quality and climate. Therefore, China has made efforts to transition into clean heating using improved heating stoves and biomass pellets. Although the economic and policy implications of such demonstration projects have been extensively investigated, little has been done to understand the real-world performance and adoption trends of such stoves. This study measured in-use emissions from nine different pellet stoves used for heating among 52 rural households in Yangxin, Shandong Province. The temperature of the stove chimney of 21 households was monitored and 56 households were surveyed to explore the stove use trend. The particulate and gaseous emission concentrations for most of the stoves exceeded the limits specified in the Chinese national standard. The measured fuel energy-based emission factors (mean ± standard deviation) for CO2, CO, NOx, and PM2.5 were 103 ± 3, 1.41 ± 1.19, 0.336 ± 0.237, and 0.146 ± 0.108 g/MJ, respectively. Between January to February, the average daily heating duration was 8.71 h, and the sustained use of heating stoves was seen among over 85% of the households. On average, the households used their heating stoves for 3.28 months and the estimated annual pellets consumption for a household was 2.7 tons. Besides inherent variabilities associated with user habits, the stove's design-related shortcomings and low-grade pellets hindered the performance and effectiveness of pellet stoves. This study provides insights into opportunities and challenges for the promotion of cleaner fuels and heating technologies. Furthermore, it will provide information on emissions from rural residential sources to build the emission inventory and inform policymaking for successful stove promotion programs.