Chemical processes and reaction by-products involved in the biorefinery concept of biofuel production

Abstract

With an increase in population, the demand for energy and impending depletion of fossil fuels have led to the research and development of sustainable technologies which make use of the naturally available biomass resources. When it comes to energy production, the distinct components and different processing technologies associated with biomass require significant amount of investmentand is costly to perform everyday operations. From a business point of view, only energy generation with the biomass may not be a profitable industry unless some marketable intermediates and chemicals are produced in addition to energy. Since the major components of biomass include cellulose, hemicellulose and lignin, during its processing for energy, it can form valuable by-products that can find applications in pharmaceutical, food and fertilizer industries. When continuous heat is applied to carbohydrates, such as cellulose and hemicelluloses, it dissociates into products having low molecular weight, which can be useful in the production of ethanol, methane and syngas. Similarly, the burning of lignin forms carbonaceous residue which can act as a source for bio-oil and biofuel, as they are the degraded products of biomass obtained from living materials such as plants, grains, vegetable oils, animal-based oils, etc. For that, the technique of biorefinery system can be followed where it consumes biomass as the major processing input and convertsfully into usable end products. The biorefinery system serves as the basic concept by providing sophisticated platform for the co-production of biofuels, value-added chemicals and energy from biomass. The biorefinery concept uses a number of chemical routes where the initial biorenewable feedstock can be useful for the production of solid fuel, or converted into liquid or gaseous forms for the generation of electric power, heat and chemicals. The chief attention on the general processes of chemical conversion of biomass-derived residues from agricultural and forest wastes, self-sufficiently, increases the utilities in daily life, if it is integrated with the biorefinery system. The present chapter basically provides an overview of the biorefinery concept and how it can be useful for the industrial usage of by-products formed during the production processes of biofuels and/or energy. The potentials of biomass residues in today’s world energy demand and the basic chemical reactions involved in the processing of agricultural biomass for biofuel production are deeply discussed. The authors make an attempt to organize this chapter for a variety of readers who are interested in the topic of by-products from biomass technologies, including the students and professionals.