Biomass, types availability

Because of the unique character of biomass resource availability, computer modeling requires a more sophisticated approach than that suitable for other types of resources. Unlike other energy sources, biomass is both a renewable and depletable feedstock at the same time. It is renewable oyer long periods and depletable in the short term because of restrictions such as length of the growing season and rate of residue generation. 

Distribution of Carbon. Estimation of the amount of biomass carbon on the earth s surface is a problem in global statistical analysis. Although reasonable projections have been made using the best available data, maps, surveys, and a host of assumptions, the vaHdity of the results is impossible to support with hard data because of the nature of the problem. Nevertheless, such analyses must be performed to assess the feasibiHty of biomass energy systems and the gross types of biomass available for energy appHcations. 

Another factor is the potential economic benefit that may be realized due to possible future environmental regulations from utilizing both waste and virgin biomass as energy resources. Carbon taxes imposed on the use of fossil fuels in the United States to help reduce undesirable automobile and power plant emissions to the atmosphere would provide additional economic incentives to stimulate development of new biomass energy systems. Certain tax credits and subsidies are already available for commercial use of specific types of biomass energy systems (93). 

These applications avoid the major obstacles for using biomass for electricity generation fluctuation in the supply, and the type of biomass available. Seasonal variations and differing quality of feedstock are the biggest barriers to more widespread use. This is especially true for biomass wastes. 

The amount of biomass produced in a habitat— the productivity of the habitat—is determined by the types of plants (some species are more efficient photosynthesizers than others), the intensity and duration of solar radiation, the amount of nutrients available, and climatic factors such as temperature... 

Xylan-type polysaccharides are the main hemicellulose components of secondary cell walls constituting about 20-30% of the biomass of dicotyl plants (hardwoods and herbaceous plants). In some tissues of monocotyl plants (grasses and cereals) xylans occur up to 50% [6j. Xylans are thus available in huge and replenishable amoimts as by-products from forestry, the agriculture, wood, and pulp and paper industries. Nowadays, xylans of some seaweed represent a novel biopolymer resource [4j. The diversity and complexity of xylans suggest that many useful by-products can be potentially produced and, therefore, these polysaccharides are considered as possible biopolymer raw materials for various exploitations. As a renewable resource, xylans are... 

Current reviews on biosorption are related to general approaches90-93 to diverse types of biomass such as microbial biomass, plant wastes, and agro-based waste materials, or to a specific metal.4-94-98 However, a review on metal biosorption using macrophytes biomass is not available. In this chapter, a review on the current knowledge of biosorption using preferentially nonliving biomass from aquatic plants is presented. 

The potential of biomass to make a large contribution towards replacing conventional fuels is constrained by land availability and competition with other end-use sectors. In particular, the potential for oil seeds to generate FAME is limited. Generally, yields of biofuels from purpose-grown crops depend on the species, soil type and climate.22 At a global level, it is estimated that biofuels could substitute up... 

Figure 4 gives an alternative scheme of possible biomass conversion pathways. Depending on the type of available biomasses and the objective products, each biorefinery will implement a different production and conversion scheme. 

Commercial gasifiers are available in a range of sizes and types, and run on a variety of fuels, including wood, charcoal, coconut shells and rice husks. Power output is determined by the economic supply of biomass, which is limited to 80 MW in most regions. The producer gas is affected by various gasification processes from various biomass feedstocks. Table 6.7 shows composition of gaseous products from various biomass fuels by different gasification methods. 

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