[...]... who are interested in biofuels Second, it may be used as a textbook to teach biofuel technologies to science and engineering students who want to contribute to the development and implementation of processes for production of these important renewable energy sources In this book, readers will find the fundamental concepts of important biofuels and the current state-of-theart technology for their production... portion becomes reduced as it accepts the electrons from the oxidized portion However, in most bioprocessing industries, the term fermentation has come to mean any bioconversion process The biological processing of organic substrates to biofuel compounds will often entail an anaerobic process, since common biofuels (i.e., ethanol, hydrogen, and methane) are reduced endproducts that are formed by fermentation... and when energyefficient processing is employed One advantage of microbial conversion processes over chemical processes is that microbes are 3 Copyright © 2008 by The McGraw-Hill Companies, Inc Click here for terms of use 4 The Basics able to select their substrate among a complex mixture of compounds, minimizing the need for isolation and purification of substrate prior to processing This can translate... used for biofuels Chapters 5, 6, and 7 cover the microbial process descriptions and systems design and engineering analysis needed for ethanol, biodiesel, and biohydrogen production Chapter 8 covers microbial fuel cells, novel biological reactors used to generate electricity through microbial activity Finally, Chap 9 provides an overview of the bioproduction of methane To what extent will biofuels. .. development continue to improve the efficiency of biofuel production processes, economic feasibility will continue to improve Biofuel production is best evaluated in the context of a biorefinery (Fig 1.1) In a biorefinery, agricultural feedstocks and by-products are processed through a series of biological, chemical, and physical processes to recover biofuels, biomaterials, nutraceuticals, polymers, and specialty... ultimately the sun, as solar energy is captured and stored as organic compounds through photosynthetic processes Certain biofuels, such as oils produced by plants and algae, are direct products of photosynthesis These oils can be used directly as fuel or chemically transesterified to biodiesel Other biofuels such as ethanol and methane are produced as organic substrates are fermented by microbes under... expected to limit further increases in production of these biofuels4 by 2020, unless more promising sources such as algal oils for biodiesel and cellulosic biomass sources for ethanol become prevalent Biomass feedstocks, including dedicated crops and agricultural and forestry by-products, can be converted into usable fuel by biological processing, thermal processing, and direct oil extraction In general, biomass... combusted, is offset by the carbon absorbed as the biomass is grown.22 Second, bioconversion processes in general do not produce hazardous compounds, and if toxic solvents and chemicals are avoided in the processing stages, then fewer environmental pollutants are produced Third, biomass production and microbial conversion processes can be developed and used in a more distributed manner, avoiding the need for... biodiesel.26 1.8 Book Overview This book focuses on the biological processes that convert biomass feedstocks to fuels such as ethanol or hydrogen and those that capture/convert solar energy directly into fuels The basic biochemical pathways for production of biofuels are reviewed in Chap 2 for a complete understanding of these bioconversion processes Chapter 3 provides an in-depth review of microbial modeling... renewable energy Biofuels are just one source, but a very important one Biofuels can be defined as fuels that are derived from biological sources Among them, methane produced by anaerobic digestion has been used by the human race for hundreds, if not thousands, of years More recently, ethanol produced from sugarand starch-based feedstocks has become another important biofuel Other biofuels such as .