Pollutant reduction analysis of a comprehensive utilization model of straw: A case study ofHenan, China

Abstract

Abstract As a traditional agricultural country, China’s biomass energy sources account for a significant proportion of national energy consumption. Henan Province, a major agricultural province in China, produces a large amount of agroforestry biomass with the straw as the primary type every year. Due to the technological backward in rural areas, there are frequent agroforestry biomass direct burning activities (both open and residential), which not only wastes biomass resources but also produces large quantities of unorganized emissions of air pollutants that have adverse impacts on human health and air quality. In this study, the environmental impact of open burning of straw plus residential combustion of straw and firewood in Henan Province during the 2016 crop harvest period was investigated by emission inventories method and the numerical simulation by source-orientated air quality model system. The results showed that the monthly average of primary particulate matter emissions contribution from open burning of straw and residential combustion of straw and firewood in Henan province accounted for about 2.24% and 1.61% of the total amount of primary particulate matter generated by pollutant emission sources in Henan Province during the crop harvest period, respectively. A control scenario was designed based on national and local policies and regulations, in which straws used for cooking in rural areas were uniformly replaced by biogas, and straw burned in the open field in farmland was replaced in proportion to biomass briquette fuel. This control scenario leaded to significant reduction in emission intensities of SO2, PM2.5, PM10, CO, NO2 and VOCs throughout the year. Air quality results showed that in control scenarios, it was effective in reducing atmospheric particulate matter concentrations, while the impacts on SO2, CO, NO2, NH3, and O3 were negligible. The results of this study provided scientific guidance for the relevant biomass energy policy and related emission reduction strategies in Henan Province.