Lignocellulose-Biorefinery: Ethanol-Focused

Abstract

The development prospects of the world markets for petroleum and other liquid fuels are diverse and partly contradictory. However, comprehensive changes for the energy supply of the future are essential. Notwithstanding the fact that there are still very large deposits of energy resources from a geological point of view, the finite nature of conventional oil reserves is indisputable. To reduce our dependence on oil, the EU, the USA, and other major economic zones rely on energy diversification. For this purpose, alternative materials and technologies are being sought, and is most obvious in the transport sector. The objective is to progressively replace fossil fuels with renewable and more sustainable fuels. In this respect, biofuels have a pre-eminent position in terms of their capability of blending with fossil fuels and being usable in existing cars without substantial modification. Ethanol can be considered as the primary renewable liquid fuel. In this chapter enzymes, micro-organisms, and processes for ethanol production based on renewable resources are described.

Enzymatic processing of lignocellulosic biomass: principles, recent advances and perspectives

“…Among these, wet oxidation [307], hydrothermal pretreatment [270], steam explosion [44,275], dilute acid treatment [252], ammonia fiber expansion (AFEX) [16], sulfite pulping [301,377] and methods based on the use of ionic liquids and organic solvents [398] are the major technologies that have been used at demonstration or industrial scale over the past years. The choice of pretreatment depends on the type of feedstock as well as on the spectrum of desired end products [95,301]. Hydrothermal pretreatment as well as AFEX and ammonium recycle percolation (ARP) technologies cause cellulose decrystallization, some hydrolysis of hemicellulose as well as lignin removal [18] and are primarily used for grass-type biomass (corn stover, switch grass), while steam explosion and alkaline and sulfite pulping can also be used for woody biomass (e.g., poplar and spruce).…”

Discovery of hyperstable carbohydrate‐active enzymes through metagenomics of extreme environments

“…Family GH5 enzymes are retaining enzymes that follow a classical Koshland double-displacement mechanism and present a glutamic acid and a glutamate as catalytic residues [80,81]. Structurally, GH5 enzymes show a classical (a/b) 8 TIM barrel fold. The GH5 enzymes from Archaea mainly belong to subfamilies 1 and 19 (GH5_1 and GH5_19, respectively) in the CAZy classification; GH5_Pool2 is a member of subfamily GH5_19 in which only the bacterial b-mannosidase from Thermotoga thermarum was characterized [82].…”

“…In fact, nonedible lignocellulosic feedstocks (energy crops) constitute a virtually unlimited and convenient alternative to starchy materials (food crops) . This realization led to second‐generation biorefineries which, producing biofuel and bioplastic precursors from lignocellulose biomass rather than starch, may represent a solution to the food vs fuel problem .…”

Construction of advanced producers of first- and second-generation ethanol in Saccharomyces cerevisiae and selected species of non-conventional yeasts (Scheffersomyces stipitis, Ogataea polymorpha)

“…2G ethanol can utilize a range of different types of lignocellulosic substrates. Currently, a limited amount of 2G ethanol is produced at several pilot and demonstration plants around the world; however, due to higher cost of the large-scale ethanol production from lignocellulosics, it is not yet commercially feasible [40,109,135].…”