Environmental Engineering Reference
In-Depth Information
BioResource
Biological
Thermochemical
Anaerobic
Digestion
Fermen-
tation
Metabolic
Processing
Gasification
High Pressure
Aqueous
Pyrolysis
CH
3
CH
2
OH/CO
2
Severe
H
2
/CO
CH
4
/CO
2
CH
4
/CO
2
CH
1.4
O
6
CH
4
/CO
2
Synthesis
Bio-shift
CH
3
OH/CO
2
Reforming
shift
Reforming
shift
Reforming
shift
Reforming
shift
Pyrolysis
Photo-
biology
Shift
Reforming
shift
H
2
/CO
2
H
2
/CO
2
H
2
/CO
2
H
2
/CO
2
H
2
/CO
2
H
2
/CO
2
H
2
/CO
2
H
2
/C
H
2
/O
2
H
2
/C
FIGURE 4.1
Pathways from biomass-to-hydrogen.
Source
: Reproduced with permission from
Milne [3].
TABLE 4.1 Comparison of Hydrogen Yields Are Obtained by Use of Three
Different Processes
Hydrogen Energy Contents/
Biomass Energy Content
Processes
Hydrogen Yield (wt%)
12.6
91
Pyrolysis
+
catalytic reforming
11.5
83
Gasification
+
shift reaction
17.1
124
Biomass
+
steam
+
except heat
(theoretical maximum)
Source
: Reproduced with permission from Wang et al. [6].
An example of oil palm shell compared with physic nut waste is listed in
Table 4.2 [9].
Biological hydrogen production processes are found to be more environ-
mentally friendly and less energy demanding compared with thermochemical
and electrochemical processes [10]. Researchers have started to investigate
hydrogen production with anaerobic bacteria since 1980s [11]. Biological
production of hydrogen (biohydrogen) as a byproduct of microorganism
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