Biomass Characteristics

The physical, chemical, and thermodynamic characteristics of biomass resources vary widely. This variation can occur among different samples of what would nominally seem to be the same resource. Also, variations could occur from one region to another, especially for waste products. This wide variation sometimes makes it difficult to identify a typical value to use when designing a gasification plant. 

Biomass Source Heating Value, Btu/Lb Reference Source 

Sewage sludge (biosolids) 8217 Klass, Donald L., Biomass for Renewable Energy, Fuels, and Chemicals, Academic Press, 1998. 

Fruit pulp 3600 Assumed same as bagasse. Bagasse heating value obtained from Klass, Donald L. and G. H. Emert, Fuels from Biomass and Waste, Ann Arbor Science, 1981. 

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The biomass characteristics already described, namely 50% moisture content and heterogeneity, introduce many materials handling problems. The importance of scale should also be noted—the largest biomass processing plants are pulp mills of around 2000 ton/day of product or about 6000 t/day of dry feed stock. In electrical energy terms, the average Canadian pulp mill of 1200 t/day would correspond to an electrical station of 150 MWq (70-85% utilisation) or the production of about 1100... 

Ng HY and Hermanowicz SW. Membrane bioreactor operation at short sobds retention times Performance and biomass characteristics. 

Germain E, Stephenson T, and Pearce P. Biomass characteristics and membrane aeration Toward a better understanding of membrane fouhng in submerged membrane bioreactors (MBRs). Biotechnol Bioeng. 2(X)5 90 316-322. 

Biomass combustion is a complicated process involving drying of solid fuel, pyrolysis and oxidation of pyrolysis gases and carbon. Many modelling studies to describe combustion performance have been based on these three stages (4, 5, 14, IS). In order to further investigate the effects of biomass characteristics on the observed combustion performance, a simple stoichiometric model for wet biomass combustion was employed to describe the overall reaction process (Eqn. 3) 15). An empirical mole of biomass is arbitrarily normalised to one atom of carbon by the formula C H Oj. 

Sonkaria S, Boucher G, Horez-Alvarez J et al. (2004) Evidence for lock and key character in an anti-phosphonate hydrolytic antibody catalytic site augmented by non-reaction centre recognition variation in substrate selectivity between an anti-phosphonate antibody, an anti-phosphate antibody and two hydrolytic enzymes. Biochem J 381 125—130 Sprossler B, Plainer H (1983) Immobilized lactase for processing whey. Food Technol 37 93-96 Stemmer WP (1994) Rapid evolution of a protein in vitro by DNA shuffling. Nature 370 389-391 Sticklen M (2006) Plant genetic engineering to improve biomass characteristics for biofuels. Curr Opin Biotechnol 17(3) 315-319... 

Ng, H. Y, Hermanowicz, S. W. (2005). Membrane bioreactor operation at short solids retention times performance and biomass characteristics. Water Research, 39(6), 981-992. 

Sticklen M. (2006). Plant genetic engineering to improve biomass characteristics for biofuels. Curr Opin Biotechnol, 17, 315-319. 

Stichnothe, H., Azapagic, A., 2009. Bioethanol from waste life cycle estimation of the greenhouse gas saving potential. Resources Conservation and Recycling 53 (11), 624r-630. http / /dx.doi.org/ 10.1016/j.resconrec.2009.04.012. Sticklen, M., 2006. Plant genetic engineering to improve biomass characteristics for biofuels. Current Opinion in... 

The chemical characteristics of biomass vary over a broad range because of the many different types of species. Table 8 compares the typical analyses and energy contents of land- and water-based biomass, ie, wood, grass, kelp, and water hyacinth, and waste biomass, ie, manure, urban refuse, and primary sewage sludge, with those of cellulose, peat, and bituminous coal. Pure cellulose, a representative primary photosynthetic product, has a carbon content of... 

Table 11. Biomass Feedstock Characteristics that Affect Suitability of Conversion Process...

Particle Size Reduction. Changes in the physical characteristics of a biomass feedstock often are requited before it can be used as a fuel. Particle size reduction (qv) is performed to prepare the material for direct fuel use, for fabrication into fuel pellets, or for a conversion process. Particle size of the biomass also is reduced to reduce its storage volume, to transport the material as a slurry or pneumatically, or to faciHtate separation of the components. 

The specific design most appropriate for biomass, waste combustion, and energy recovery depends on the kiads, amounts, and characteristics of the feed the ultimate energy form desired, eg, heat, steam, electric the relationship of the system to other units ia the plant, iadependent or iategrated whether recycling or co-combustion is practiced the disposal method for residues and environmental factors. 

There are many grasses and related plants that can be considered for energy apphcations because they have the desirable characteristics needed for land-based biomass energy systems. 

Ash Characteristics. The elemental ash composition of biomass waste and municipal soHd waste differs dramatically from that of coal (qv). ... 

An alternative method of produciag hydrocarbon fuels from biomass uses oils that are produced ia certaia plant seeds, such as rape seed, sunflowers, or oil palms, or from aquatic plants (see Soybeans and other oilseeds). Certain aquatic plants produce oils that can be extracted and upgraded to produce diesel fuel. The primary processiag requirement is to isolate the hydrocarbon portion of the carbon chain that closely matches diesel fuel and modify its combustion characteristics by chemical processiag. 

The equations that have been developed for design using these pseudo constants are based on steady-state mass balances of the biomass and the waste components around both the reactor of the system and the device used to separate and recycle microorganisms. Thus, the equations that can be derived will be dependent upon the characteristics of the reactor and the separator. It is impossible here to... 

Wang et al.2 and Najafpour et al.3A worked with immobilised microbial cells of Nitrobacer agilis, Saccharomyces cerevisiae and Pseudomonas aeruginosa in gel beads, respectively. They found separately that the cells retained more than 90% of their activity after immobilisation by using specific oxygen uptake rate (SOUR) [mg 02g 1 (dry biomass) h 11 as the biomass activity indicator. Such differences in immobilised biomass and activity between free and immobilised biomass activities depend strongly on the particular characteristics of the microbial systems and their interaction with the support matrix. 

Biomass Redistribution Associated with Deforestation and Fire. The influence of deforestation on biogeochemical cycles is dependent upon a number of factors associated with the unique characteristics of the ecosystem (climate, soils, topography, etc), the quantity of the total nutrient pool stored in aboveground biomass (Table II), and the level of disturbance (i.e. the degree of canopy removal, soil disturbance, and the quantity of wood or other forest products exported from the site). The quantity of biomass consumed by one or more slash fires following deforestation can also dramatically increase nutrient losses, influence post fire plant succession, and hence, postfire biogeochemical cycles. 

Drought is perhaps one of the most complex examples to choose but it illustrates well the possibilities of, and pitfalls to, progress. Drought affects almost every facet of plant function and we are faced with the paradox that yield and evapotranspiration are intimately linked. In general, increases in yield when water supply is limiting are likely to result from characteristics which increase the available water supply, increase water use efficiency or increase biomass allocation to the economically useful plant parts (Pass-ioura, 1986). Additionally, features which maintain cell viability and protect metabolism in water-stressed tissue and allow rapid recovery after dry periods will contribute yield under some circumstances. 

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