The need for energy and fuels is one of the common threads throughout history and is related to almost everything that man does or wishes to do. Energy, in its many useful forms, is a basic element that influences and limits our standard of living and technological progress. It is clearly an essential support system for all of us. In the twentieth century, the subject did not receive much attention until well into the middle of the century, that is, the fossil fuel era, and then usually only in crisis situations of one kind or another. Until we were confronted with energy and fuel shortages that affected our daily lives, most of us assumed that the petroleum, natural gas, and electric power industries would exist forever. A bountiful supply of energy in whatever forms needed was taken for granted.

An energy corollary to the economic law of supply and demand gradually evolved. In the early 1970s, the law’s first derivative might legitimately have been called the law of energy availability and cost. The oil marketing policies of the Organization of Petroleum Exporting Countries initiated the so-called First Oil Shock in 1973-1974 and changed, probably forever, the international oil markets and the energy policies of most industrialized nations. Oil prices increased dramatically, seemingly overnight. Markets were disrupted and short­ages developed. Crash programs to develop alternatives to petroleum-based fuels began in earnest in many parts of the world. Many of these programs continue today.

Intensive research programs were started to develop renewable energy re­sources such as active and passive solar energy, photovoltaic, wind, and ocean power systems, and biomass—the only indigenous renewable energy resource capable of displacing large amounts of solid, liquid, and gaseous fossil fuels. As a widely dispersed, naturally occurring carbon resource, biomass was a logical choice as a raw material for the production of a broad range of fossil

fuel substitutes. Environmental issues such as air quality and global climate change that many believe are related to fossil fuel consumption also began to come to the fore. The world appeared ready to resurrect biomass as a major indigenous energy resource for industrialized nations, as it had been up to the end of the nineteenth century. It now appears that biomass energy will displace increasingly larger amounts of fossil fuels as time passes.

This book addresses biomass energy technologies and the development of virgin and waste biomass as renewable, indigenous, energy resources for the production of heat, steam, and electric power, as well as solid, liquid, and gaseous fuels that are suitable as substitutes for fossil fuels and their refined products. Biomass is defined as nonfossil, energy-containing forms of carbon and includes all land — and water-based vegetation and such materials as munici­pal solid wastes, forestry and agricultural residues, municipal biosolids, and some industrial wastes. In other words, biomass is all nonfossil organic materi­als that have an intrinsic chemical energy content. The history, status, and future expectations of biomass research, development, and deployment efforts are examined from the standpoint of the role of biomass in our global and national energy economy, the impact of biomass energy use on the environ­ment, its potential to replace fossil fuels, and the commercial systems already in place. The development of advanced technology and improved biomass growth and conversion processes and environmental issues are also discussed. One chapter is also devoted to organic commodity chemicals from biomass.

Because of the special organization of most chapters, this book should serve as an introduction to the subject for the student and professional who wish to become knowledgeable about the production and consumption of biomass energy and its potential long-range impact. This book is also useful for energy professionals interested in some of the technical details of and references for specific biomass energy applications. One special feature of the book that will become apparent to the reader is that it is multidisciplinary in content and treatment of the subject matter, because many scientific and engineering disci­plines are directly or indirectly involved in the development of biomass energy. For example, the biological gasification of biomass is described in terms of its microbiology and biochemistry, but the practical use of this information for the design and operation of combined waste disposal—methane production processes for feedstocks such as municipal solid waste is also discussed. An­other example of the multidisciplinary nature of the book is the treatment given to biomass production. The study and selection of special strains of hybrid trees for use as biomass resources, as well as the advanced agricultural practices used for growth and harvesting in short-rotation biomass plantations, are discussed. An important feature of this book is the effort to discuss barriers that hinder biomass energy utilization and what must be done to overcome them. An example of one of the barriers is net energy production. Given that the prime objective of a biomass energy system is to replace fossil fuels in a specific application, the system cannot effectively attain this objective if the net energy output available for market is less than the total of nonrenewable energy inputs required to operate the system.

Throughout this book, the International System of Units, or le Systeme International d’Unites (SI), is used. SI is a modern metrication system of mea­surement consisting of coherent base and derived units and is used by many scientists, engineers, and energy specialists. Most major technical associations and publishers require that SI be used in their publications. Because of the United States’ position as the world’s largest energy-consuming country, com­monly used U. S. energy units, several of which are somewhat unusual, such as quads of energy (1 X 1015 Btu/quad) and barrels of oil equivalent (BOE), and their conversion factors are presented in Appendix A along with the definitions and conversion factors for SI units. This makes it possible for the reader who is familiar only with U. S. units to readily convert them to SI units and to convert the SI units used in the text to common U. S. units. In the text, common U. S. units are sometimes cited in parentheses after the SI units for clarification.