Sugarcane biorefineries: potential opportunities towards shifting from wastes to products

Biorefining involves the sustainable processing of biomass into a spectrum of marketable food and feed in-gredients, bio-based products (chemicals and materials), and bioenergy (biofuels, power, and/or heat). The processing of sugarcane is a successful example of renewable bioenergy being produced on a large industrial scale. As the world largest crop by production quantity, around 1907 millions of tons of sugarcane were globally produced last year. Currently, most of the sugarcane mills produce first generation (1 G) ethanol, sugar, and energy from the burning of bagasse. However, the use of part of the sugarcane bagasse to produce second generation (2 G) ethanol is beginning to move towards an industrial reality. The 2 G ethanol process itself also generates several side-streams, which could be further used to obtain high added-value products. Integrated 1 G-2 G biorefineries, where the whole sugarcane biomass is converted to bioenergy and a suite of bio-based products, can be an attractive investment option for a future scenario of a low-carbon economy. The purpose of this review is to gather together the most recent technologies that have been developed to enable the whole use of feedstocks, byproducts, and side-streams within the sugarcane biorefinery. Possible ways to improve the efficiency of biomass processing are discussed, such as the use of low-cost additives, together with the economic and environmental aspects related to the implementation of a sugarcane biorefinery. Potential applications of sugarcane bagasse and straw to obtain valuable products including enzymes, biofertilizers, nanocellulose and lignin-derived commodities are presented as opportunities to improve the attractiveness of this business model.