Water Footprint Of Biomass Thermal-Chemical Conversion Technologies Based On Hybrid Life Cycle Assessment

Water is essential for bioenergy production.Characterized as low carbon technology,bioenergy plays a critical role in global energy supply and mitigation of climate change.However,its rapid development inevitably putting pressure on global water resources.Therefore,it is crucial to carefully assess bioenergy technology’s overall impact on scarce water source for a sustainable bioenergy future.In this study,based on 2^nd generation biomass,i.e.,agricultural residues.Three typical thermal-chemical conversion technologies are studied,direct power generation,gasification power generation and pyrolysis polygeneration.By combining Water Footprint Assessment and Tiered Hybrid Life Cycle Assessment,detailed system boundaries,assessment indicators and computing model are built.For the first time,a comprehensive accounting for life cycle water footprint which including biomass feedstock agricultural plantation,biomass feedstock transportation,plant construction facilities and equipment,operation and maintenance and wastewater treatment are made.The results show that pyrolysis polygeneration system has the highest water use efficiency,its life cycle water footprint is 4.62m³/GJ,far lower than direct power generation system（10.74m³/GJ）and gasification power generation system（20.69m³/GJ）.Among the water footprint of different life stages,agricultural plantation accounts the majority part of life cycle water footprint,the proportions are 83.32%,85.89%and 90.26%,respectively.Direct water footprint is the main component of the total water footprint while green water footprint,blue water footprint and grey water footprint take the average proportion for these systems.When compared with water footprint of traditional fossil energy and other 2ⁿdd biomass utilization technologies,biomass thermal-chemical conversion technologies have no advantages compared with fossil energy but more water efficient than the latter.In the last part,scenarios analysis shows different feedstock allocation ratios during agricultural production have striking influence on water use intensity.Other sensitivity analyses indicate that improving system productivity and efficient water-saving management measures have a significant effect on reducing life cycle water footprint.