Environmental impact assessment of VOC emissions from biomass gasification power generation system based on life cycle analysis

Abstract

The control of volatile organic compounds (VOC) is one of the key challenges in biomass combustion. This study aims to establish a process-based model to assess the life cycle VOC emissions of a biomass gasification power plant in China. In this study, the life cycle assessment (LCA) method was used for the first time to evaluate the direct VOC emissions and indirect VOC emissions from biomass gasification power generation. The whole system consists of three parts: biomass waste feedstock system, gasification power generation system and waste treating system. And waste treatment mainly includes waste water treatment and waste gas treatment. Results show that the life cycle VOC emissions intensity from the biomass gasification power generation process as a whole are calculated as 57.05 g/MWh, without considering the influence of air pollution control devices’ (APCDs). With the implementation of APCDs, this value will be reduced to 7.08 to 22.83 g/MWh, reducing by 12.41 to 40.02 %. In the scenario analysis, APCDs with different combinations of installations are evaluated by applying the practical engineering applications. The scenario of selective catalytic reduction (SCR) and wet electrostatic precipitation (WESP) can achieve the best removal effect, under which VOC emissions intensity can achieve 34.22 g/MWh, and the indirect emissions account for 46.15 % of life cycle VOC emissions, which are mainly from wastewater treatment process. The photochemical ozone generation potential and ozone layer depletion potential from emitted VOC are the two largest in this scenario, accounting for 17.71 % and 8.59 % respectively. If all open burning and indoor combustion of biomass in China can be replaced by the biomass gasification power generation technology, the relevant national VOC emissions reduction potential could reach up to 1.95 Mt/year. Among all the provinces, Heilongjiang, Anhui, Henan, Shandong and Jilin are the five provinces with the highest VOC emissions reduction potential. The influence of key input variables on overall VOC emission is also analyzed in this study. Based on the results, the optimal direction and possible measures to reduce VOC emission are put forward. This study is of great significance for the accurate control of VOC emissions in biomass gasification power generation technology.