Biomass pyrolysis oils were produced from stored biomass feedstocks by
rapid pyrolysis in a fluidized bed reactor. The feedstocks used for t
hese studies were switchgrass, corn stover, and hybrid poplar. The woo
dy and herbaceous feedstocks were stored in chip piles and bales, resp
ectively, unprotected in an open field for 6 months. At the end of the
storage period, biomass samples were taken from the interior of bales
and the centers of chip piles for pyrolysis studies. The materials we
re ground to pass -20/+80 mesh and dried to less than 10% moisture con
tent before pyrolyzing in the fluidized bed reactor. Pyrolysis was con
ducted at 500 degrees C and with less than 0.4 s apparent vapor reside
nce time. Total liquid yields were as high as 66% for the hybrid popla
r and as low as 58% for the corn stover. Moisture content of the oils
was between 10 and 13%. Gas and char/ash yields were 10-15% and 12-22%
, respectively. The char/ash yields were feedstock dependent, but stor
age influence was significant for only the corn stover feedstock. Gas
and liquid yields were not influenced by storage time. The oils were h
ighly oxygenated and had higher heating values (HHV) of 23-24 MJ/kg th
at decreased slightly with storage time for all the feedstocks except
the switchgrass. The oils, as currently produced, are high in ash and
alkali metals. Ultimately, they may be upgraded and used as boiler and
turbine fuels.