Woody biomass

Several studies estimate the potential of available virgin and waste biomass as energy resources (Table 4) (10). In Table 4, the projected potential of the recoverable materials is about 25% of the theoretical maximum woody biomass is about 70% of the total recoverable potential. These estimates of biomass energy potential are based on existing, sustainable biomass production and do not iaclude new, dedicated biomass energy plantations that might be developed. 

Another biofuel of importance is wood. The Forest Service, which is part of USDA, administers national forest lands for the sale of wood for wood fuel. Besides determining the quantity of wood fuel to bring to market by collecting and analyzing statistics on woody biomass supply and use, the Forest Sendee sponsors forest biomass energy-related research in conjunction tvitli federal and state agencies, as well as universities. 

The burning of slash following deforestation, whether intentional or unintentional, results in far greater direct and indirect losses of nutrients than deforestation alone. This is particularly true in many tropical forests where only a small fraction (if any) of the aboveground biomass is removed prior to burning. Carbon losses from slash fires in the tropical dry forest were 4-5 fold greater than C losses from wood export (Table IV) (55). Slash fires in tropical dry forests resulted in N losses of 428-500 kg ha whereas fuel wood export of the relatively N-poor coarse woody debris amounted to approximately 41 kg N ha" Losses of P increase with increasing fire severity. P losses of 10-77 kg ha" as a result of severe fires is not uncommon (Table TV) (53, 58, 60). 

Zeolite-bentonite hybrid catalysts for the pyrolysis of woody biomass... 

Pyrolysis is the decomposition of organic material due to the influence of heat. By performing controlled pyrolysis the woody biomass can be converted into high value added products, namely bio oil, formed in addition to char and gases. 

The highly oxygenated bio oil can be de-oxygenated, and thereby upgraded, over acidic zeolite catalysts through the formation of mainly water at low temperatures and C02 and CO at higher temperatures [1-3], Successful catalytic pyrolysis of woody biomass over Beta zeolites has been performed in a fluidized bed reactor in [4]. A drawback in the use of pure zeolitic materials has been the mechanical strength of the pelletized zeolite particles in the fluidized bed. 

The objective of this work is to synthesize and characterize zeolite-bentonite hybrid catalysts and perform test reactions in the pyrolysis of woody biomass in a dual-fluidized bed reactor. The aim is to produce catalytic materials which have good mechanical strength and are still able to de-oxygenate the pyrolysis oil. 

This could be a result of dealumination of the catalysts in the presence of water formed in the thermal pyrolysis of woody biomass. 

The BioTherm process of the company Dynamotive (Vancouver, Canada). The process is based on a stationary FB and the largest plant processes about 100 t/day of biomass. This unit is situated in Ontario (Canada) and its feedstock is woody waste. In this application, the obtained bio-oil is converted into electricity using an Orenda gas turbine (2.5 MWe). 

Hanaoka, T. Yoshida, T. Fujimoto, S. Kamei, K. Flarada, M. Suzuki, Y. Flatano, FI. Yokoyama, S.-Y. Minowa, T., Flydrogen production from woody biomass by steam gasification using a C02 sorbent. Biomass and Bioenergy 2005,28,63-68. 

Sime, R. Kuehni, J. D Souza, L. Elizondo, E. Biollaz, S., The redox process for producing hydrogen from woody biomass. International Journal of Hydrogen Energy 2003, 28, 491-498. 

Gas Techn. Inst. Woody biomass MHV Fuel gas. svnsras 3.6-12 479 816 Oxygen/ 816... 

Thermal Process Studsvik (TPS) (Studsvik Eneriteknik AB) Woody biomass LHV Fuel gas, duel fuel engine, gas turbine, boiler/furnace/ kiln fuel 13-78 (upper limit commercial) 14.7... 

The next generation of biofuel processes should differ from the first in (a) utilizing the whole plant as a feedstock and (b) the use of non-food perennial crops (woody biomass and tall grasses) and lignocellulosic residues and wastes (woodchips from forest thinning and harvest residues, surplus straw from agriculture). 

The effect of heating rate on evolution of volatiles is most clearly evidenced in the case of woody biomass, which has been shown to have a volatile yield of greater than 90% when small particles are rapidly heated to 1200°C and to have a volatile yield of only 65% when large particles are slowly heated to 500°C in the commercial charcoal-making process. 

Table 1.3 The distribution of above-ground woody biomass by region (FAO, 2001)...

The growth of woody biomass in one year s annual increment represents the quantity of material that can be harvested without affecting the productive capacity of the forest in subsequent years. The gross annual increment (GAI) is the yearly increase in woody biomass, whereas the net annual increment (NAI) is the GAI adjusted for natural losses such as fire, insect damage and so on. The NAI is often referred to as the allowable cut . In boreal and temperate zones, the removal of woody biomass is lower than the NAI, and thus these forests are presently acting as net sinks for carbon dioxide (Figure 1.6). If all of the NAI was harvested, then the forests would no longer act as sinks for CO2, but would be in balance with the atmosphere. 

The basic structure of all wood and woody biomass consists of cellnlose, hemicelluloses, lignin and extractives. Their relative composition is shown in Table 2.4. Softwoods and hardwoods differ greatly in wood stmctnie and composition. Hardwoods contain a greater fraction of vessels and parenchyma cells. Hardwoods have a higher proportion of cellulose, hemicelluloses and extractives than softwoods, but softwoods have a higher proportion of lignin. Hardwoods ate denser than softwoods. 

Industrial saccharifications of woody biomass 20 U/g cellulose 600 U/g cellulose... 

Woody plants can synthesize anywhere from 15-30% of all biomass as lignin. Hence, equivalent amounts of phenylalanine are required at some point, i.e., during lignin formation, large amounts of ammonia are recycled as a consequence of PAL activity. While plants have no serious problems in obtaining glucose as a carbon source, supplied abundantly through photosynthesis,... 

---