Water use of a biomass direct-combustion power generation system in China: A combination of life cycle assessment and water footprint analysis

Biomass combustion for power generation plays an important role in achieving 1.5 degrees C climate target and fulfilling global energy demand, while putting pressure on global water resources. Confronted with severe water shortage, it is imperative to understand its comprehensive impact on water resource. Recently remarkable advances of life cycle assessment and water footprint analysis have been witnessed in this field. Based on a review of the two methods' history, we propose a combination evaluation framework and define an associated indicators set to integrate both methods' advantages. By methods integration, direct and indirect water use are combined with the green, blue, and gray water footprint to describe the water use in detail. Furthermore, the life cycle water footprint of a typical biomass direct-combustion power generation system in China is evaluated based on the combined method. Results show the system life cycle water use is 11.71 L/MJ, while agricultural plantation accounts for the major part (84.61%). In addition, direct green water footprint is the largest component (46.54%), while direct and indirect blue water footprints account for 36.59% and 1.74%, respectively; indirect gray water footprint is 1.771 L/MJ. In terms of water use intensity, the direct-combustion power generation is lower than bio-oil power generation, but far more than solar photovoltaic and wind power. Sensitivity analysis suggests that improving power generation efficiency, straw collection coefficient and cultivating high water-efficient crops can evidently contribute to alleviating water stress conditions for bioenergy production.