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Title
An economic analysis of energy fuels and chemicals from forest biomass
Authors
Thomas C. Browne
Received
May 6, 2011
Published
Volume 45 Issue 7-8 September-October
Keywords
forest biomass, feedstock, biorefinery
Abstract
The forest sector in Canada is rapidly changing, due to shifting markets and increased competition from modern, low-cost mills in tropical countries. The northern hardwood kraft mill, in particular, is endangered. The conversion of these kraft mills to produce energy, fuels and chemicals has been proposed. However, the cost of biomass collection makes large-scale conversion of wood to a single commodity product, such as heat, power or transportation fuels, difficult from an economic perspective. In the petroleum refinery model, a very small amount of petroleum, perhaps as little as 4%, is converted to chemicals, rubbers and plastics and, according to Werpy,1 generating as much as 42% of the value obtained. At the same time, some use must be found for the remaining 96% raw material: 70% is converted to liquid transportation fuels and generates another 43% of the value. The final 26% becomes bunker fuels, home heating oils, asphalts, bitumens and other relatively low-value products, generating a final 15% of the value. Clearly, sales of gasoline and Diesel fuel, while not sufficient on their own to ensure profitability, are critical to the profitability of the whole site. Similarly, heat, power or bio-fuels should not be considered as the best use of the entire biomass supply in a biorefinery: there is a need for biomass-generated side-products to generate relatively large revenues from a relatively small stream. A second issue is one of scale, which derives from the feedstock supply costs. Considering feedstock consumption in terms of the rate at which the energy content is supplied to the plant, even the largest North American pulp mill is small compared to typical petro-chemical refineries or coal-fired generating stations. This is primarily due to increasing feedstock costs as scale increases, which rapidly overshadow the decreasing capital and operating costs. This makes the production of high-value products even more important for the forest biorefinery than the petroleum refinery, as economies of scale will not be available to the same extent for the biorefinery. This report identifies some lower limits on the necessary revenues per ton of wood supplied, leading to an economically successful biorefinery installation, and compares scales and economics of the forest biorefinery to those of the petroleum refinery. The biorefinery concept, where small volumes of high-value products are produced and the residues are converted to heat, power or fuels, is identified as a necessary economic condition for success, given the costs of large-scale biomass collection.
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