Residue conversion, wood

Several firms have developed systems for specialized application such as agricultural residue conversion, wood residue conversion and municipal solid waste disposal. Most of these systems have capacities of less than 50 GJ/h of product gas, i.e., 80-90 oven dried tons per day (ODT/D) of feedstock. Larger systems gasifying more than 100 ODT/D of wood are similar in design to gasifiers developed prior to 1950. 

Second-generation biofuel technologies make use of a much wider range of biomass feedstock (e.g., forest residues, biomass waste, wood, woodchips, grasses and short rotation crops, etc.) for the production of ethanol biofuels based on the fermentation of lignocellulosic material, while other routes include thermo-chemical processes such as biomass gasification followed by a transformation from gas to liquid (e.g., synthesis) to obtain synthetic fuels similar to diesel. The conversion processes for these routes have been available for decades, but none of them have yet reached a high scale commercial level. 

Forest residues typically refer to those parts of trees such as treetops, branches, small-diameter wood, stumps and dead wood as well as undergrowth and low-value species. The conversion of wood to biofuels and biochemicals has long been a goal of the forest products industry. Forest residues alone count for some 50% of the total forest biomass and are currently left in the forest to rot (Demirbas, 2001). 

This paper is concerned with the potential for production of liquid fuels from biomass in Canada. To this end, the availability and cost of wood wastes, surplus roundwood, bush residues, energy plantation trees, and municipal solid wastes (mostly cellulosic) are assessed and promising thermal, chemical and biochemical conversion processes reviewed. 

Cost. Bat telle Columbus ( 5) recently estimated the 1980 cost of readying timber residue, cull and dead trees for fuel conversion in the state of Vermont. The analysis considered procurement (stumping), harvesting, chipping and transportation over 40 kilometres, but omitted fertilization costs. Based on green wood (45% moisture, 10.9 GJ/green tonne), the wood cost was estimated as 16.40/green tonne. 

This type of process can theoretigally be used to treat any gaseous, liquid or solid feed. In practice, however, it is reserved for the conversion of the cheapest raw materials such as hea 7 hydrocarbons (especially fuel oilX and possibly, in the future, petroleum residues (asphalts), coal and biomass (wood). In this case, moreover, the conversion is usually called "gasification. ... 

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