First-generation ethanol plants were designed based on corn (maize grain), a dense, stable, storable and shippable commodity-type product with multiple applications. With these properties, corn was used as a feedstock for large-scale biorefineries without any challenges for a considerable length of time to allow its usage to grow exponentially. In the second-generation biofuels, the feedstocks used are low-cost carbon resources such as crop and forest residues and municipal solid waste. These materials are not dense; they have irregular size and shape, variable moisture, and are not readily storable and shippable. When the industry tested these feedstocks for biofuel production, they faced flowability, storage, transportation, and conversion issues. One way to overcome feeding, handling, transportation, and variable moisture challenges is to densify the biomass. The densification systems such as pellet mill and briquette press are commonly used to produce densified products. The densified products have uniform size, shape, and higher density. Also, the densified products are aerobically stable as they have the moisture of less than 10 % (w.b.).This book's focus is to understand how the densification process variables, biomass types and their blends, mechanical preprocessing, and thermal and chemical pretreatment methods impact the quality of the densified products produced for biofuel production.

Engineering the physical, chemical, and energy properties of lignocellulosic biomass is important to produce high-quality consistent feedstocks with reduced variability for biofuels production. The emphasis of this book will be the beneficial impacts that mechanical, chemical, and thermal preprocessing methods can have on lignocellulosic biomass quality attributes or specifications for solid and liquid biofuels and biopower production technologies. "Preprocessing" refers to treatments that can occur at a distance from conversion and result in an intermediate with added value, with improved conversion performance and efficiency. This book explores the effects of mechanical, chemical, and thermal preprocessing methods on lignocellulosic biomass physical properties and chemical composition and their suitability for biofuels production. For example, biomass mechanical preprocessing methods like size reduction (which impacts the particle size and distribution) and densification (density and size and shape) are important for feedstocks to meet the quality requirements for both biochemical and thermochemical conversion methods like enzymatic conversion, gasification, and pyrolysis process. Thermal preprocessing methods like drying, deep drying, torrefaction, steam explosion, hydrothermal carbonization, and hydrothermal liquefaction effect feedstock's proximate, ultimate and energy property, making biomass suitable for both solid and liquid fuel production. Chemical preprocessing which includes washing, leaching, acid, alkali, and ammonia fiber explosion that can enable biochemical composition, such as modification of lignin and hemicellulose, and impacts the enzymatic conversion application for liquid fuels production. This book also explores the integration of these preprocessing technologies to achieve desired lignocellulosic biomass quality attributes for biofuels production.

This monograph discusses the various biomass feedstocks currently available for biofuels production, and mechanical preprocessing technologies to reduce the feedstock variability for biofuels applications. Variability in the properties of biomass-in terms of moisture, particle size distribution, and low-density-results in storage, transportation, handling, and feeding issues. Currently, biorefineries face serious particle bridging issues, uneven discharge, jamming of equipment, and transportation problems. These issues must be solved in order for smooth operations to be possible. Mechanical preprocessing technologies, such as size reduction, densification, and moisture management using drying and dewatering, can help to overcome these issues. Many densification systems exist that will assist in converting low-density biomass to a high-density commodity type feedstock. In 6 chapters, the impact of densification process variables, such as temperature, pressure, moisture, etc., on biomass particle agglomeration, the quality of the densified products, and the overall energy consumption of the process are discussed, as are the various compression models for powders that can be used for biomass particles agglomeration behavior and optimization of the densification process using statistical and evolutionary methods. The suitability of these densified products for biochemical and thermochemical conversion pathways is also discussed, as well as the various international standards (CEN and ISO) they must adhere to. The author has worked on biomass preprocessing at Idaho National Laboratory for the last ten years. He is the principal investigator for the U.S. Department of Energy Bioenergy Technologies Office-funded "Biomass Size Reduction and Densification" project. He has developed preprocessing technologies to reduce cost and improve quality. The author has published many papers and books focused on biomass preprocessing and pretreatments. Biomass process engineers and biorefinery managers can benefit from this book. Students in chemical, mechanical, biological, and environmental engineering can also use the book to understand preprocessing technologies, which greatly assist in improving the biomass critical material attributes. The book can help policymakers and energy systems planners to understand the biomass properties limitations and technologies to overcome the same.

Engineering the physical, chemical, and energy properties of lignocellulosic biomass is important to produce high-quality consistent feedstocks with reduced variability for biofuels production. The emphasis of this book will be the beneficial impacts that mechanical, chemical, and thermal preprocessing methods can have on lignocellulosic biomass quality attributes or specifications for solid and liquid biofuels and biopower production technologies. "Preprocessing" refers to treatments that can occur at a distance from conversion and result in an intermediate with added value, with improved conversion performance and efficiency. This book explores the effects of mechanical, chemical, and thermal preprocessing methods on lignocellulosic biomass physical properties and chemical composition and their suitability for biofuels production. For example, biomass mechanical preprocessing methods like size reduction (which impacts the particle size and distribution) and densification (density and size and shape) are important for feedstocks to meet the quality requirements for both biochemical and thermochemical conversion methods like enzymatic conversion, gasification, and pyrolysis process. Thermal preprocessing methods like drying, deep drying, torrefaction, steam explosion, hydrothermal carbonization, and hydrothermal liquefaction effect feedstock's proximate, ultimate and energy property, making biomass suitable for both solid and liquid fuel production. Chemical preprocessing which includes washing, leaching, acid, alkali, and ammonia fiber explosion that can enable biochemical composition, such as modification of lignin and hemicellulose, and impacts the enzymatic conversion application for liquid fuels production. This book also explores the integration of these preprocessing technologies to achieve desired lignocellulosic biomass quality attributes for biofuels production.