Life Cycle Assessments of Waste-Based Biorefineries—A Critical Review

Abstract

In recent years advanced biorefineries based on organic residues and waste have gained increased attention for their potential to obviate first-generation biorefineries environmental burdens. During the conceptual design phase of an advanced biorefinery the role of Life Cycle Assessment (LCA) is crucial for providing information on its environmental performances, better solutions, preferable process setup, more suitable feedstock, trade-off, and so on. This review focuses on advanced biorefineries LCAs in order to accomplish a synthesis of the state of the art from the methodological point of view. Some main methodological issues have been analyzed and discussed on 24 LCAs. Attention has been drawn to functional units, system boundaries, inventory data collection, allocation methods and multifunctionality management approach. Results show different approaches and solutions to the analyzed aspects but some clear addresses can be pointed out. It has been observed that LCA of biorefineries can be classified in three different types in base on focal aim, and then functional units are consequentially defined. A large variability has been observed regarding system boundaries even if “cradle-to-gate” appears the most common. Inventories are mainly based on secondary data due to the very innovative features of the analyzed technologies. No general consensus has been observed concerning allocation of environmental impact between co-products.