LIFE CYCLE IMPACT ASSESSMENT OF WATER USE : Reviewing methods and their implications in biorefinery system

Abstract: Over the last few years, the scientific debates and discussions between water resource management scholars and the Life Cycle Assessment (LCA) researchers have brought the impacts assessment of water use into more focus. The results of this discourse have led to methodological advances for assessing and evaluating the environmental impacts of freshwater use. The first aim of this study is to critically review these methods, and then to further compare their appropriateness and competencies for the LCA of biorefinery systems. This thesis highlights the inconsistencies among the water-use accounting and impact-assessment methods that have caused incompatibility among biorefinery system LCA results. The main source of divergence in the results is identified as the disharmony between the definitions and assumptions used in inventorying water consumption, as well as the variation in the methods and parameters used for defining the characterizing factors in their impact assessment. All the methods have applied regional characterization factors and developed their impact assessment based on water scarcity. However, none of them has developed the impact assessment pathway relating to the hydrological cycle changes of water, as well as the synergetic impacts resulting from water consumption and pollution. In the literature review, only one case study could be found that quantitatively compared methods and contrasted their results. This implies that there is a need for more of such case studies to identify the uncertainties and strengthen the need for standardization and harmonization.  Last, the methods are evaluated based on their completeness and environmental relatedness; six indicators are developed for measuring this criteria and evaluating the appropriateness of the methods in addressing the important aspects related to water use in biorefinery systems. As a result, the method developed by Boulay et al., (2011) is identified as the candidate for most appropriate method. However, it should be noted that this criterion will not reflect the applicability, scientific robustness, acceptability of their method among researchers and other stakeholders, and other qualitative and quantitative merits of this method. Further research is needed to investigate the other criteria and improve the results.