Is biomass energy really clean? An environmental life-cycle perspective on biomass-based electricity generation in China

A bottom-up approach combined with national and provincial statistical data was used to evaluate the potential environmental effects of electricity generation scenarios based on five mature biomasses in China. Coal-based electricity generation technology was used as control. Uncertainty analysis was conducted to confirm and add credibility to this study. The electricity generation capacities of municipal solid waste, sewage sludge, and corn straw account for approximately 0.86%, 0.085%, and 8.18%, respectively, of electricity generated in China in 2012. The estimated national environmental burden caused by biomass-based electricity generation was mainly observed in eastern China, which can be attributed to the relatively high population density and economic levels of this region. For each biomass-based scenario, the key factors that contribute to the overall environmental burden include direct emissions of nitrogen oxides, phosphorus, mercury, and particulate matter. In addition, carbon dioxide pollution generated from methane incineration, road transport, and electricity consumption play a dominant role in the overall environmental burden. The environmental benefits of biomass mainly vary depending on the technologies applied and their electricity generation efficiency. Compared with the corn straw scenario, coal-based electricity generation technology yields strong environmental benefits in most key categories with the exception of climate change and human toxicity. Accordingly, biomass is not unconditionally cleaner than fossil fuel. The utilization and popularization of biomass-based electricity generation technologies must be systematically and scientifically evaluated to avoid secondary pollution generation and pollutant transformation.