Abstract:
Agricultural systems produce vast amounts of crop residues (CR) as by-products. More than
200 billion tonnes per year of CR are produced worldwide. They are mostly used as animal feed or
disposed of by incorporation into soil for fertility purposes and by burning. Traditional CR management
practices have environmental and techno-economic implications. Crop residues are an excellent
bioresource, with multiple untapped applications. There is a significant lack of knowledge about
commercializing the conversion of CR into value-added products in a sustainable way. A biorefinery
concept is an important option that can transform CR into useful products. This paper reviews the
potential state-of-the-art options for valorization of CR into multiple product streams. The paper
focuses on 13 products. These are biogas, bioethanol, biobutanol, biohydrogen, biomethanol, pyrolytic
products, enzymes, bioactive compounds, animal feed, mushroom, single-cell protein, organic acids, and
biocomposites. The product streams can be divided into three categories: biofuels, animal feed and food,
and phytochemicals. Biofuel production is the most promising strategy for the valorization of CR at
large-scale biorefineries. Anaerobic digestion and fermentation are preferred to thermochemical
conversions because they are cost effective and have improved conversion efficiency. © 2021 Society of
Chemical Industry and John Wiley & Sons, Ltd
