Life Cycle Assessment On Various Flue Gas Desulfurization Processes In Coal-Based Power Plant

China is the largest contributor of SO2 emission worldwide because China currently consumes approximately half of the world’s coal. To promote national air quality and reduce the precursor of sulfate microscopic particles, the Chinese government has invested immense manpower, materials, and financial resources, efforts at SO2 controlling as well as implemented limits, the strictest in China’s history, on SO2 for thermal power plants in 2014. The required upper limits of SO2 for existing power plants drop from 400 mg/m3 to 200 mg/m3. Complying with this restriction is a huge technical and economic challenge. Wet limestone flue gas desulfurization technology (WFGD), the most mature desulfurization technology used worldwide with approximately 86% of the market share rate, is extensively adopted in China (>90%). However, WFGD technology can generate secondary gypsum particle pollution, carbon dioxide, desulfurization wastewater, and desulfurization gypsum. To avoid the transfer of pollutants and generation of secondary pollutants, a life cycle environmental assessment (LCA) of flue gas desulfurization technologies that are commonly used in China was conducted in this study.LCA is an internationally standardized method to systematically and scientifically assess the environmental effects associated with all stages of a product, including all activities from the beginning until the final phase. This paper compared the environmental effects of various desulfurization technologies in coal-based power plant via LCA. The results obtained in this study will be helpful to the improvement of life cycle inventory database for flue gas desulfurization and promote the decision making on considering the technological transformation in desulfurization industries.In this study, life cycle impact assessment (LCIA) is assessed by using the ReCiPe method, which is the latest and commonly used LCIA approach worldwide. The main step of this research includes life cycle inventories, LCIA analysis, key factors identification, sensitivity analysis, and uncertainty analysis. Results showed that the environmental impact generated from climate change, terrestrial acidification, human toxicity, photochemical oxidant formation, the formation of particulate matter, and fossil depletion were the main contributor to the overall environmental burden for each desulfurization technology. The key processes that contributed to each key category were ammonia production, electricity generation, and energy (i.e., steam and electricity) production in the ammonia, limestone, and active coke scenarios, respectively. For the ammonia scenario, the electricity process was the dominant contributor in climate change, terrestrial acidification, human toxicity, photochemical oxidant formation and fossil depletion. For limestone scenario, wastewater disposal process was a dominant contributor in most categories, except for particulate matter formation. Direct air emissions from the desulfurization stage played the most significant role in particulate matter formation for both ammonia and limestone scenarios. Additional categories dominated by direct emissions included climate change for the limestone scenario.The substances that significantly contribute to climate change are methane and carbon dioxide emissions in the air, whereas nitrogen oxides and sulfur dioxide are the most critical contributors to terrestrial acidification, photochemical oxidant formation, and particulate matter formation categories. Another dominant substance in the particulatematter formation category is the direct fly dust emission from the stages of desulfurization or active coke producing. Heavy metal emissions adversely affect human health. Similarly, the use of coal during ammonia production, desulfurization, and active coke production processes in the non-renewable energy category are the highest contributors.Additionally, to confirm and add credibility to the study, sensitivity and uncertainty analysis was conducted. Results proved that the ReCiPe method is reliable, as far as the current research is concerned. Moreover, WFGD and ammonia-based FGD have larger potential environmental impact than active coke-based FGD. If active coke-based FGD technology is used instead of WFGD technology in China, approximately 66% of the overall environmental benefit can be obtained.