Biomass conversion processes

The need to meet environmental regulations can affect processing costs. Undesirable air emissions may have to be eliminated and Hquid effluents and soHd residues treated and disposed of by incineration or/and landfilling. It is possible for biomass conversion processes that utilize waste feedstocks to combine waste disposal and treatment with energy and/or biofuel production so that credits can be taken for negative feedstock costs and tipping or receiving fees. 

S. S. Sofer and O. R. Zaborsky, eds.. Biomass Conversion Processes for Energy andFuels, Plenum Press, New York, 1981, 420 pp. 

The data discussed above can easily be used to develop a crude figure for the cost of biomass conversion processes. It suffices to consider the feed cost, for the appropriate feed and conversion efficiency (Fig. 2.12), the appropriate capital charge (Fig. 2.11) and add a contribution of —1/3 of the capital charge for fixed cost, to account for various additional costs such as labor, maintenance, etc. The manufacturing cost is not far from the sum of these three contributions. 

Figure 2.13 did not include all the biomass conversion processes discussed above. It only considered those that produce transportation fuels. The processes that convert bio-feedstock into biocrude or electricity could not be included because their products have a different value than the transportation fuels. Such a comparison can be attempted by displaying the total manufacturing cost of biobased products in a graph that shows typical relationships between the price of crude and that its derivatives, i.e., of fuel oil, transportation fuel and electricity. This has been done in Fig. 2.14 for the lignocellulose conversion processes. 

Biomass conversion processes are still expensive today, being competitive at crude oil prices between 50 and 100 bbl-1. Lignocellulose might be a fairly cheap feedstock, cheaper than crude oil. However, its conversion requires large... 

The chapters of this book have been selected to provide an introduction to the catalytic issues of biomass conversion processes. The introductory chapters make clear the political decisions, especially in the EU, that drive biomass conversion technology, its prospects compared with other options for renewable energy, and the main technological options for conversion of biomass into secondary energy carriers. 

High-temperature processes, based on pyrolysis, gasification or combustion of biomass are the preferred conversion routes for non-food competing biomass conversion processes to secondary energy. 

Mclnemey Ml, Bryant MR. 1981. Basic principles of bioconversions in anaerobic digestion and methanogenesis. In Sofer SS, Zaborsky OR, editors. Biomass conversion processes for energy and fuels. New York Plenum, p 277-96. 

Demirbas, A. 2001. Biomass resource facilities and biomass conversion processing for fuel and chemicals. Energy Convers Manage 42 1357-1378. 

A biorefinery is a facility that integrates biomass conversion processes and eqtrip-ment to produce fuels, power, and value-added chemicals from biomass. Biorefinery is the co-production of a spectram of bio-based products and energy from biomass. The biorefinery concept is analogous to today s crude oil refinery. Biorefinery is a relatively new term referring to the conversion of biomass feedstock into a host of valuable chemicals and energy with minimal waste and emissions. 

Demirbas, A. 1998. Yields of oil products from thermochemical biomass conversion processes. Energy Convers Manage 39 685-690. 

Commodity Chemicals acetic acid, acetone, butanol, ethanol, many other products from biomass conversion processes. 

The main characteristics of a biomass conversion process are illustrated in Figure 13.21. The biomass feedstock, together with added water, is pumped and heated to a temperature and pressure not too different from water s critical point. The conversion process taking place at these conditions results in a transport fuel-type product, that... 

The fossil load factor is an important issue and its origin so evident and often unavoidable that we asked ourselves the question what the consequences are when this factor is reduced to zero. Whenever, in a biomass conversion process, a fossil fuel contribution was spotted, we replaced this contribution by one from biomass origin. For example, the process may require electricity, which is supplied by a nearby coal-fed power station. Then this amount of electricity was thought to be generated by a power station fed by biomass. Or the process may require heat or chemicals and again biomass is the raw material from which these requirements were met. Dr. Feng Wei made such an analysis for a process where a diesel-type product was obtained from wood chips as a feedstock. His work has been discussed as an example at the end of Chapter 13. 

FIGURE 9 Biomass conversion processes. [Reprinted with permission from Probstein, R. F., and Hicks, R. E. (1990). Synthetic Fuels, pH Press, Cambridge, MA.]... 

As illustrated in Fig. 33.14, biomass feedstocks can vary widely in the number of constituents and the concentration of each constituent. In biomass conversion processes, up to 20 constituents may need to be monitored to characterize the conversion of feedstock into a desired product or products. Standard wet chemical methods for the chemical characterization of biomass feedstocks and biomass-derived materials have been validated through the International Energy Agency and are available from the American Society for Testing and... 

Compositional variability can have a significant impact on biomass conversion process economics. The large effect (i.e., at least 0.30/gal ethanol) of observed compositional diversity on process economics is shown in Fig. 33.19 and is primarily due to the fact that the maximum theoretical product yield is proportional to feedstock carbohydrate content (Fig. 33.20).131 Yield is the major economic driver for the technoeconomic model used to assess the economic impact of composition on minimum product selling price,130 as can be seen from the data in Fig. 33.21. 

Milne, T. A., Brennan, A. H., and Glenn, B. H., Sourcebook of Methods of Analysis for Biomass and Biomass Conversion Processes. Elsevier Science New York, 1990 p. 341. 

The simple act of burning biomass to obtain heat, and often light, is one of the oldest biomass conversion processes known to mankind. The basic stoichoimetric equation for the combustion of wood, represented by the empirical formula of cellulose, (CsHjOsln, is illustrated by... 

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