Potentiale zur energetischen Nutzung von Biomasse in der ... - EPFL

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Feedstock components Composition
Composition
(% wt. dry matter basis) (% wt. fresh matter basis)
Cellulose 42.7 % 22.2 %
Hemicellulose 28.7 % 14.9 %
Lignin 27.7 % 14.4 %
Ash 0.9 % 0.5 %
Water - 48.0 %
Total 100.0 % 100.0 %
Table 1 Composition of lignocellulosic feedstock considered for conversion to ethanol.
The production capacity of the plant has been set to 47.5 million liters (Ml) of bioethanol per year in
order to match the production capacity of the plant envisaged in the Alcosuisse project. The ethanol
yield is 157 liters per ton of fresh wood (respectively 301 liters per ton of dry matter). The conversion
efficiency (expressed as the ratio of the amount of ethanol produced to the maximum theoretical
ethanol obtainable given the composition of the feedstock) reaches 69.3%. As suggested by NREL, it
was assumed in the calculations that no sugars other than glucose and xylose were fermented to
ethanol. Conversion data used in the calculation were those quoted by NREL in their first
lignocellulosic biomass to ethanol process design (Wooley et al., 1999).
Economic analysis of the process
One of the main purposes of the present report is to evaluate the potential production cost of
bioethanol from lignocellulosic biomass, with the objective of assessing its potential as a vehicle fuel
on the market. The economic analysis presented in this section is based on the one performed by
NREL (Wooley et al., 1999), adapted to Swiss conditions (ethanol production capacity, price of raw
materials, investments, salaries, etc.). All the costs in the economic analysis are given in Swiss Francs
2002 (CHF 2002 or simply CHF). The following analysis corresponds to the 2010 scenario. In other
words, the bioethanol plant described in the present section would start production in the year 2010.
The process model followed closely the NREL design as reported so thoroughly by them (Wooley et
al., 1999). A spreadsheet model was developed by the LASEN to calculate all material and energy
balances based on specified yields (Figure 4), and operating costs were calculated based on these flow
and energy use rates coupled with available cost information. Then, appropriate rates were used to
size equipment, and equipment costs were calculated based on the NREL information for all of the
steps from feedstock handling and storage to manufacture of ethanol. The power law scale factors
reported by NREL were used to estimate the change in cost of each equipment item with varying
feedstock composition, cellulosic feed rate, yields, and other information. The installation factors
reported by NREL were used to estimate the cost of installed equipment, and their cost factors were
applied to estimate the total cost of capital including warehousing, engineering profit, and so forth.
The spreadsheet was run initially at NREL conditions to insure that the model could duplicate the NREL
results. Then, changes were made in various parameters to reflect the production capacity,
composition of hardwood, yields selected for the process, specific economic parameters, and any
other changes, as noted later.