5.1 Biomass and Its Utilization

5.1.1 Definition of the Term Biomass

The term biomass has been an important part of legislation enacted by Congress for many decades and has evolved over time, resulting in a vari­ety of differing and sometimes conflicting definitions [1]. These definitions are critical to all parties engaged in the research, development, finance, and application of biomass to produce energy. The term biomass is more gener­ally defined as "different materials of biological origin that can be used as a primary source of energy" [2-5]. Alternately, biomass is defined as "plant materials and animal wastes used especially as a source of fuel" [6]. These biomass definitions contain the generalized statements for the origins of the materials or their intended uses and applications, however, the definitions are not meant to provide sufficient and necessary conditions for certain spe­cific material to be classified, or qualified, as biomass.

Riedy and Stone (2010) explained the evolving nature of biomass defini­tions and analyzed its trend in biomass-related legislation [1]. Based on the common definition that biomass is biologically originated matter that can be converted into energy, more readily conceivable and common examples of biomass include food crops, nonfood crops for energy generation, crop residues, woody materials and by-products, animal waste, and residues of biological fuel-processing operations. Over the past decades, however, the term biomass has grown to encompass algae and algae-processing residues, municipal solid waste (MSW), yard waste, and food waste. The term still remains highly flexible and open to divergent interpretations, including spe­cific inclusions and special exceptions, often based on a number of factors involving technoeconomic considerations, technological advances, and new scientific findings, renewability and sustainability issues, environmental and climate change concerns, ecological issues, strategic directions of local and federal governments, regional economic strengths and weaknesses, and more. Simply put, biomass is a very broad term and encompasses a wide variety of matters. This is why the term biomass itself has been a part of modern legislation promulgated by the U. S. Congress. Legislation can have many purposes: to regulate, to authorize, to provide funds and incentives, to sanction, to grant, to proscribe, to declare, or to restrict. Using a globally generic definition of biomass in specific legislation would be not only grossly insufficient and inappropriate, but also potentially conflicting and contro­versial [1].

This book deals with conversion of biomass into biofuels and bioenergy, generally speaking. For the same reason described above, the individual chapters of this book are subdivided, based on the specific types of bio­mass and their associated transformation technologies, into the technolog­ically categorized topics of corn ethanol, cellulosic ethanol, biodiesel, algae biodiesel, waste-to-energy, biomass pyrolysis and gasification, and so on.

The discussion of biomass definitions lately has centered around the issues involving: (i) the types of forestry products considered eligible biomass sources, (ii) the lands where biomass removal can occur, specifically Federal and Indian lands, and (iii) the kinds and types of waste that qualify as biomass, specifically municipal solid waste and construction and debris (C&D) [1].