1.0. Introduction 4044 2.0. Biomass Chemistry and Growth Rates 4047 2.1. Lignocellulose and Starch-Based Plants 4047 2.2. Triglyceride-Producing Plants 4049 2.3. Algae 4050 2.4. Terpenes and Rubber-Producing Plants 4052 3.0. Biomass Gasification 4052 3.1. Gasification Chemistry 4052 3.2. Gasification Reactors 4054 3.3. Supercritical Gasification 4054 3.4. Solar Gasification 4055 3.5. Gas Conditioning 4055 4.0. Syn-Gas Utilization 4056 4.1. Hydrogen Production by Water−Gas Shift Reaction 4056

/pdf/synthesis-of-transportation-fuels-from-biomass-chemistry-3sckhzoqoz.pdf

Synthesis of transportation fuels from biomass: chemistry, catalysts, and engineering.

https://faculty.washington.edu/renatab/courses/PSE490/downloads/pretreatment.pdf

Features of promising technologies for pretreatment of lignocellulosic biomass.

Fundamental features of microbial cellulose utilization are examined at successively higher levels of aggregation encompassing the structure and composition of cellulosic biomass, taxonomic diversity, cellulase enzyme systems, molecular biology of cellulase enzymes, physiology of cellulolytic microorganisms, ecological aspects of cellulase-degrading communities, and rate-limiting factors in nature. The methodological basis for studying microbial cellulose utilization is considered relative to quantification of cells and enzymes in the presence of solid substrates as well as apparatus and analysis for cellulose-grown continuous cultures. Quantitative description of cellulose hydrolysis is addressed with respect to adsorption of cellulase enzymes, rates of enzymatic hydrolysis, bioenergetics of microbial cellulose utilization, kinetics of microbial cellulose utilization, and contrasting features compared to soluble substrate kinetics. A biological perspective on processing cellulosic biomass is presented, including features of pretreated substrates and alternative process configurations. Organism development is considered for "consolidated bioprocessing" (CBP), in which the production of cellulolytic enzymes, hydrolysis of biomass, and fermentation of resulting sugars to desired products occur in one step. Two organism development strategies for CBP are examined: (i) improve product yield and tolerance in microorganisms able to utilize cellulose, or (ii) express a heterologous system for cellulose hydrolysis and utilization in microorganisms that exhibit high product yield and tolerance. A concluding discussion identifies unresolved issues pertaining to microbial cellulose utilization, suggests approaches by which such issues might be resolved, and contrasts a microbially oriented cellulose hydrolysis paradigm to the more conventional enzymatically oriented paradigm in both fundamental and applied contexts.

/pdf/microbial-cellulose-utilization-fundamentals-and-4yec12qx1c.pdf

Microbial cellulose utilization: fundamentals and biotechnology.

Pretreatments to enhance the digestibility of lignocellulosic biomass

Pretreatment technologies for an efficient bioethanol production process based on enzymatic hydrolysis: A review

Biomass feedstocks, including corn- and potato-starch gels, wood sawdust suspended in a cornstarch gel, and potato wastes, were delivered to three different tubular flow reactors by means of a “cement” pump. When rapidly heated to temperatures above 650 °C at pressures above the critical pressure of water (22 MPa), the organic content of these feedstocks vaporized. A packed bed of carbon within the reactor catalyzed the gasification of these organic vapors in the water; consequently, the water effluent of the reactor was clean. The gas was composed of hydrogen, carbon dioxide, methane, carbon monoxide, and traces of ethane. Its composition was strongly influenced by the peak temperature of the reactor and the condition of the reactor's wall. Extraordinary yields (>2 L/g) of gas with a high content of hydrogen (57 mol %) were realized at the highest temperatures employed in this work. Irrespective of the reactor geometry and method of heating, all three reactors plugged after 1−2 h of use with feedstocks t...

Biomass Gasification in Supercritical Water

A comparison of liquid hot water and steam pretreatments of sugar cane bagasse for bioconversion to ethanol

Previous work has shown that very high yields of charcoal are obtained when pyrolysis of the biomass feedstock is conducted at elevated pressure in a closed vessel, wherein the pyrolytic vapors are held captive and in contact with the solid products of pyrolysis In this paper, we show that, for some biomass species, the yield of carbon produced by this process effectively attains the theoretical value predicted to exist when thermochemical equilibrium is realized Various agricultural wastes (eg, kukui nut, macadamia nut, and pecan shells) and tropical species (eg, eucalyptus, leucaena, and bamboo) offer higher yields of carbon than the hardwoods traditionally employed by industry in the US and Europe Moreover, the yields of carbon from oat and rice hulls and from sunflower seed hulls are nearly as high as the yields of carbon from hardwoods There is a correlation between the yield of carbon and the acid-insoluble lignin content of the feed Charcoal briquettes made from agricultural wastes and lump charcoal from tropical species are promising sources of renewable carbon for use in the smelting of metal ores

Attainment of the Theoretical Yield of Carbon from Biomass

Sugar-cane bagasse and leaves (10−15 g oven-dry basis) were fractionated without size reduction by a rapid (45 s to 4 min), immersed percolation using only hot (190−230 °C), compressed (P > Psat), liquid water (0.6−1.2 kg). Over 50% of the biomass could be solubilized. All of the hemicellulose, together with much of the acid-insoluble lignin in the bagasse (>60%), was solubilized, while less than 10% of the cellulose entered the liquid phase. Moreover, recovery of the hemicellulose as monomeric sugars (after a mild posthydrolysis) exceeded 80%. Less than 5% of the hemicellulose was converted to furfural. Percolation beyond that needed to immerse the biomass in hot liquid water did not result in increased solubilization. The yield of lignocellulosic residue was also not sensitive to the form of the sugar cane used (bagasse or leaves) or its moisture content (8−50%). Commercial applications for this fractionation process include the pretreatment of lignocellulosics for bioconversion to ethanol and the produ...

Fractionation of sugar cane with hot, compressed, liquid water

Dried, milled corn fiber (0.2−0.5 kg) was fractionated by treatment with either hot liquid water (3−4 kg) at low solids loadings (5−10%) or steam (0.1−0.4 kg) at high solids loadings (>50%) at 210−220 °C for 2 min, using the same novel process equipment. Pentosan recovery and inhibition of yeast fermentation were evaluated and compared. In addition, the reactivity of pretreated fiber with respect to enzymatic hydrolysis was evaluated using a simultaneous saccharification and fermentation (SSF) system consisting of β-glucosidase-supplemented Trichoderma reesei cellulase together with fermentation by Saccharomyces cerevisiae. Greater solubilization was achieved at 215 °C with hot liquid water at 5% solids loading than with steam at 70% solids loading (54% solubilization vs 37%). The lignocellulosic residue from this hot liquid water fractionation was enriched in glucan. Conversely, the steam fractionation caused no significant change in the fraction of glucan in the residue, relative to the feed material. I...

Stephen Glen Allen

Papers

Biomass Gasification in Supercritical Water

A comparison of liquid hot water and steam pretreatments of sugar cane bagasse for bioconversion to ethanol

Attainment of the Theoretical Yield of Carbon from Biomass

Fractionation of sugar cane with hot, compressed, liquid water

A Comparison between Hot Liquid Water and Steam Fractionation of Corn Fiber