The production of so-called advanced bioethanol offers several advantages compared to traditional bioethanol production processes in terms of sustainability criteria. This includes, for instance, the use of nonfood crops or residual biomass as raw material and a higher potential for reducing greenhouse gas emissions. The present review focuses on the recent progress related to the production of advanced bioethanol, (i) highlighting current results from using novel biomass sources such as the organic fraction of municipal solid waste and certain industrial residues (e.g., residues from the paper, food, and beverage industries); (ii) describing new developments in pretreatment technologies for the fractionation and conversion of lignocellulosic biomass, such as the bioextrusion process or the use of novel ionic liquids; (iii) listing the use of new enzyme catalysts and microbial strains during saccharification and fermentation processes. Furthermore, the most promising biorefinery approaches that will contribute to the cost-competitiveness of advanced bioethanol production processes are also discussed, focusing on innovative technologies and applications that can contribute to achieve a more sustainable and effective utilization of all biomass fractions. Special attention is given to integrated strategies such as lignocellulose-based biorefineries for the simultaneous production of bioethanol and other high added value bioproducts.

A new process for the deconstruction of lignocellulosic biomass was evaluated. It combines thermo-mechano-chemical action and the bio-catalytic action of enzymatic hydrolysis in a twin-screw extruder. The process proceeds in three phases all conducted in a twin-screw extruder: an alkaline pretreatment, a neutralization phase and an enzyme impregnation phase during which hemicelluloses and cellulose saccharification begins. Four model feedstocks with high cellulose content have been selected for the study: sweet corn residue (SC), a co-product of industrial corn grain canning; blue agave bagasse (BAB) from the manufacture of tequila; oil palm empty fruit bunch (OPEFB), a residue from palm oil manufacture, and barley straw (BS). They are all agricultural or agro-industrial processing by-products, although their morphological origin, chemical composition and physical structure differ. Their differences in behavior are studied throughout the process, and their cell wall constituents, hemicelluloses, cellulose and lignin, quantified. The enzymatic hydrolysis of the four feedstocks ranged from 8 to 26% of dry matter and reached 26 to 68% of dry matter after alkaline pretreatment depending on the particular biomass. The process allows preparation of high dry matter content (>20%) cellulosic material for saccharification. The continuous treatment allows extraction of a large part of the hemicelluloses (up to 64% for SC), configures cellulose for better accessibility, and initiates cellulose depolymerization by the enzyme cocktail during bioextrusion. This new process is advantageous because it minimizes energy consumption by operating at a low temperature, minimizes water consumption by working at a low liquid/solid ratio and is fast and adaptable to different biomasses