Multi-criteria decision analysis of agri-food waste as a feedstock for biopolymer production

The use of renewable resources is becoming increasingly important if we are to address the negative impacts of petroleum-based polymers. Utilising renewable resources, such as agri-food wastes (AFWs), for biopolymer production offers the advantages of lower dependence on fossil fuels, resource recovery (generating added value), and waste management. AFWs are generated as by-products or residues at every stage of the food supply chain: harvest, processing, and post-consumption. AFWs are a significant societal challenge but their full potential as renewable resources remain unexploited. Hence, this study aimed to identify feedstocks that can provide a continuous supply of raw materials for the manufacture of biopolymers. Harvest and process wastes from major crops were assessed using information from published reports and government departments over the period 2013-2017. The analysis was based on criteria focusing on the availability, characteristics, and market value of the identified AFWs. The analysis was conducted for the crops: wheat, barley, oats, rapeseed, sugar beet, carrots, and onions. Total AFW production in the UK over the reference period was estimated at 15 Mt dry matter/yr, to which wheat is the major contributor (≈7 Mt). The results show that harvest residues, e.g., straw, have medium to high theoretical availability and competing uses, whereas processing residues, e.g., onion peels, have low theoretical availability and cost but are well suited for biopolymer production. These findings provide valuable information about resources that will enable potential investors to conduct studies to accurately assess the practicality of valorising AFWs into biopolymers.