Agriculture Reference
In-Depth Information
Table 6.1 Biomass feedstock type and forms matrix for four categories of conversion technology a
Biomass
conversion
technology
Major outputs
and products
Feedstock form
requirements
Preferred feedstock types
Gasiication
Electricity, thermal
energy, hydrogen,
bio-oils, charcoal
Dry feedstock
Coal size particle
distribution
Pyrolysis
Bio-oil, charcoal,
electricity,
thermal energy
Any feedstock
(<10 % moisture content
preferred to assure high
heat transfer rate)
<6-mm particle
(1-2 mm preferred)
Biochemical
ethanol
production
Ethanol, lignin,
electricity,
and heat
Cellulosic/woody biomass
<9.35- to 25.4-mm
particle with
pretreatment, <1 mm
without pretreatment
Chemical
biodiesel
production
Biodiesel, soaps,
and glycerin
Bio-oil from feedstock
gasification or pyrolysis
The same as gasification
and pyrolysis
a Adapted from [ 48 ] and [ 11 ]
operations are discussed with an emphasis on energy requirement. Thirdly, trans-
portation of biomass using truck, rail, water, and pipeline are addressed. Fourthly, a
section is devoted to future directions, which discusses challenges and potential
areas of research. A summary concludes the chapter.
6.2
Types of Feedstock
In a first-generation feedstock such as corn for ethanol production, the form of the
material is essentially unchanged from harvest until milling takes place in the bio-
refinery. The reason is that corn kernels in bulk form comprise a near-ideal granular
material that is gravity flowable with a relatively high bulk density of 720 kg m −3 . In
addition, an expansive transportation system that includes elevators with drying
facilities, roads, railroads, and waterways has been built over the past century. Sugar
cane is mostly harvested in billet form and directly delivered to the sugar mills or
the biorefinery using truck transport without intermediate storage because of the
perishable nature of sucrose. In the processing plant, the material is separated into
juice with a high sugar concentration and a cellulosic bagasse sidestream.
The logistics associated with second-generation biomass feedstock are more
challenging than those of first-generation feedstock. As an example, harvesting of
the high-yielding energy grass Miscanthus giganteus takes place in winter, at which
time the crop consists of bundles of tall thin stems that can be cut and baled using
adapted hay baling equipment (Fig. 6.1 ). Second-generation biomass bales typically
have a density ranging from 105 to 150 kg m −3 , although modern high-compression
balers can achieve a density of up to 230 kg m −3 [ 10 , 11 ]. To put the densities of
 
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