The Chemical Value of Biomass

Central Science Laboratory, Sand Hutton, York, UK 

Despite the general move towards use of fossil hydrocarbon feedstocks, some plant-derived materials have continued to provide economic or technical benefits that ensure they remain the preferred source of raw materials for industry. For example, cotton still accounts for 38% of all textile production due to its airflow- and temperature-regulating capabilities, which are difficult or costly to replicate with man-made fibres. Linseed oil remains a key feedstock in surface coating and linoleum flooring applications. Plant oils are still widely used in the oleochemicals sector, where coconut and palm oils are widely used in detergent 

Introduction to Chemicals from Biomass Edited by James Clark and Fabien Deswarte 2008 John Wiley Sons, Ltd. ISBN 978-0-470-05805-3 

There are a number of economic, environmental and other factors affecting consumer purchasing and industry response to such pressures, and other legislative developments that are prompting reassessment of the opportunities and properties that plant-derived materials can offer. Pressures include  

In addition, developments in biotechnology, chemistry, enzyme and catalysis research, engineering, processing and extraction technologies are opening, and will continue to open up, new routes, pathways and possibilities to exploit plants in an ever-widening fashion and at lower cost to industry. 

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Turley DB. The chemical value of biomass. In Clark J, Deswarte F, editors. Introduction to chemicals from biomass. Chichester John Wiley Sons 2008. 

Turley, D.B. (2008) The chemical value of biomass, in Introduction to Chemicals from Biomass (eds J.H. Clark and F.E.I. Deswarte), John Wiley Sons, Ltd, Chichester, UK, pp. 21-45. 

Using the aforesaid procedure, the RIs for the other biomass (whose product properties are not experimentally studied) have been calculated. The RI values obtained are normalised to obtain NRI as per equation 5 and are presented in Table 2. The values of the maximum rate of devolatilisation is obtained from the actual TGA curves. (These may also be calculated with a high level of accuracy using the chemical analysis of biomass as described in steps (ii) and (iii) in Section 3). The last column indicates the remarks regarding their utilisation or end-product based on the ranking systems suggested. 

Chemical composition, as discussed in the next section, is closely related to the caloric values of biomass, and also affects the efficiency of conversion, particularly when using a biological approach. For example, the presence of phenolics, particularly lignin, presents a major roadblock for enzymatic conversion of polysaccharides to alcohol. The conversion of juvenile biomass has been shown to have a higher moisture content and lower specific gravity than mature wood (47), and may respond more favorably to such a treatment process. The energy conversion of juvenile biomass materials by a thermal or biological methods needs to be explored. 

The economic value of biomass is determined by the revenue from the various products on the market and the production costs (e.g., capital and operation costs) of the various products. In most of the cases products with a relative high market value are associated with high production costs, and vice versa. In addition, also the size of the market is relevant for the economic feasibihty of biorefining. In most of the cases, products with a high market value have a relative small market (e.g., speciality chemicals) and vice versa (e.g., liquid... 

There are many different routes to organic chemicals from biomass because of its high polysaccharide content and reactivity. The practical value of the conversion processes selected for commercial use with biomass will depend strongly on the availabiUty and price of the same chemicals produced from petroleum and natural gas. 

Uncertainties with the availability and suitability of biomass resources for energy production are primarily due to their varying moisture content, and to a lesser degree to their chemical composition and heating value. As the moisture content of biomass increases, the efficiency of thermal conversion process decreases. At some point more energy may have to be expended to dry the biomass than it contains. Uncertainties can be reduced by conducting a detailed chemical and physical analysis of the biomass sources. 

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