Re: GAS-L: The Mystery of heat variance in biomass

["Dick Glick" <dglickd@pipeline.com>]

Hello Carefreeland and others -

As a starting point on a dry mass basis -- biomass has an ultimate-like
compositional
formula, providing the ratios of the CHO components -- that may be viewed as
an approximation because of variations in the CHO composition of components;
cellulose, hemicellulose and lignin.  Inorganics need to be subtracted to
provide the biomass mass fraction of interest.

A representative component  analysis is found in, for example;
www.mluri.sari.ac.uk/IFRU/thesis/phd_castro.pdf

Cellulose (pure cotton) formula is (C6H10O5)x where x is the number of
monomer units in the polymer -- x is a variable and large.  Hemicellulose is
generally less well defined, but may be represented to a reasonable
approximation by a combination of 5 and 6 carbon sugars as the basic units;
perhaps something like (C11H18O9)x. For lignin, (C10H1603)x -- see;
http://www.agen.ufl.edu/~chyn/age4660/lect/lect_2b/lect_02.htm

The low heat values for cellulose is near 7000 BTU per pound and that for
lignin, closer to 10,000 BTU/pound.  There are estimates, particularly for
biomass used as rumen feeds, of the relative biomass component compositions.

The rest is arithmetic -- if the heat content you requested is to be
obtained.

Best, Dick




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