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AReview of Thermo-chemical Energy Conversion Process of Non-edible Seed Cakes
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biodigestion becomes difficult and conversion
efficiency would be reduced. The seed cake was made
up of the seed husk (42%) and kernel (58%) (Abreu,
2009) and seed husk had about 23.91% of lignin
content (Viboon et al., 2007) that could not be
completely converted into biogas in biomethanation
process. The Table 5 stated the composition of
Jatropha seed husk.
Table 5 Composition of Jatropha seed husk (Viboon et al., 2007)
S.N.
Composition
%
1
Cellulose
56.31
2
Hemi cellulose
17.47
3
Lignin
23.91
Thermo chemical conversion process
Thermo chemical
conversion processes like
combustion, pyrolysis and gasification were the best
routes of biomass energy conversion. For agro waste
management thermal processes were the best option
for efficient utilization of energy conversion. Over
biological conversion process the rate of conversion
was fast. The biomass components cellulose,
hemicelluloses and lignin could be used.
Combustion
Combustion was a process used to convert the
chemical energy stored in biomass by burning
biomass in air to provide heat, mechanical power, or
electricity, etc (Bridgwater, 2003). Fuel briquettes of
organic waste materials in compressed form were used
as a development intervention to substitute firewood,
charcoal or solid fuels. At certain circumstances fuel
briquettes could save time, money and reduce
deforestation rates also provided income generating
opportunity (Boston and Kristen, 2011). In the
briquettes making process the addition of binding
material improves cohesive force between the seed
cake particle resulted in better of compaction with low
pressure compaction system (Jongh and Eric, 2010).
Nugroho et al. (2010), Boston and Kristen (2011), and
Janske van Eijck (2010) carried out combustion
studies with Jatropha seed cake briquettes to
determine their feasibility. Boston and Kristen (2011)
made briquettes from jatropha cake by mixing starch
(10% w/w) as a binding material using pressing
machine. In his study he prepared a full set up of
recepies that comprised jatropha cake with cow dung,
corn husks and saw dust and each composition was
tested for combustion. The briquettes made by using
cow dung and corn husks were not able to sustain a
quality burn. Sawdust briquettes burned better than
others with sluggish in maintaining continuous flame.
The increase in diameter of seed cake briquette
resulted in decrease of combustion gas temperature
and not influencing in CO emission significantly.
The combustion of fresh seed cake briquettes resulted
in lot of smoke emission, Janske van Eijck (2010)
suggested turning of the fresh seed cake into charcoal
avoiding the drawback of smoke emission during
burning and also to increase the energy content as the
weight was reduced due to seedcake burning without
oxygen. The charcoal briquettes burned more easily
and smoke emission also was less. Almost 40% in
weight of the seed cake was lost during char coal
briquette making.
Pyrolysis
For best reduction pyrolysis was the most suitable
technique, to convert them into value added products
which could be easier to transport, storage ,handling
and utilizing. Based on the reactor configuration and
operating conditions such as temperature, particle size
and rate of heating, the key products from biomass
pyrolysis could be liquid oil, charcoal, and gases in
different composition (Wunderlich, 1990). The
technique of slow pyrolysis produced large amount of
the solid fuel coke and the fast pyrolysis technique
produced bio oils in high yields of up to 80% in
weight of dry feed (Huber et al., 2006). The addition
of 20% pyrolysis oil maintained the mixtures within
the standards of the diesel exception of the viscosity
of the mixtures (Monique et al., 2011). Monique et al.
(2011), Viboon et al. (2007) and Antony et al. (2010)
extracted pyrolysis oil from Jatropha seed cake and
pongamia seed cake in an inert atmosphere by
supplying heat with different operating condition.
Monique et al. (2011) conducted low temperature
conversion (LTC) process at a temperature of 380
℃
to
420
℃
in an inert atmosphere and evaluated their
products. Pyrolysis oil, pyrolytic char, gas and
aqueous fractions generated were in relative amounts
Jouranal of Energy Bioscience