Review of waste biorefinery development towards a circular economy: From the perspective of a life cycle assessment

Nowadays, reducing the environmental impact of biorefinery is a common concern of scholars. life cycle assessment (LCA) is a widely used method to evaluate the environmental impact of biorefinery. Considering the lack of a latest review on the progress and existing problems related to biorefinery based on LCA studies, this paper carried out a systematic review of the evaluation of environmental impact of biorefinery based on LCA, and proposed the development strategies for waste biorefineries by targeting literature on LCA methods. After finding out the imperfections existing in the current researches, the paper then constructed a comprehensive and systematic biorefinery framework with a standard LCA employed as a reference template for following researches. 92 peer-reviewed articles published in Web of Science, Springer and Scopus from 2015 to 2019 with LCA and biorefinery as the keywords were considered. The key findings are as follows: (1) Agricultural waste and industrial residues are the top two feedstocks widely employed, accounting for 32.61% and 29.35% respectively; (2) the primary data is scarce. The foreground data of LCA is 56.52% from the researches of other scholars; (3) the LCA methods are not standardized. 30.26% and 18.42% have unclear system boundaries and functional units; and (4) there is a lack of estimating the influences of various uncontrollable external factors in the biorefinery process. Furthermore, the review highlighted and discussed the defects of biorefineries, a robust LCA template that can be used for evaluating the environmental impact of biorefinery was constructed, taking algae biorefinery as an example.