especially high. The search for a higher-yield bacterium for hydrogen production
from algal biomass has led to the discovery of a new bacterium with a yield of
2.5 mol-H 2 /mol-mannitol, producing hydrogen at a rate of 1.1L-H 2 L-culture
−1 h
−1
(Borines et al. 2011).
In addition to having a higher yield and hydrogen generation rate than E.
aerogenes, the new bacterium has a hydrogen generation rate roughly equal to that
of the HN001 strain. A simultaneous search for a bacterium to generate hydrogen
from another chief algae component, alginic acid, similarly led to the discovery of a
different new bacterium with a yield of 0.7 mol-H 2 /mol-alginic acid. This bacterium
can be used to produce around 31 N m
3 of hydrogen from 1 ton of wet kelp
according to the following calculations:
Hydrogen production from mannitol
¼ ðmoles of mannitol in wet kelpÞ Â ðhydrogen yieldÞ
¼ ð1000 kg/ton wet kelpÞ Â 8:0% Ä 0:182 kg=molÞ Â ð2:5 mol-H 2 =molÞ
¼ 1099 mol-H 2 =ton-wet kelp
¼ 24:6 Nm
3
-H 2 =ton-wet kelp
Hydrogen production from alginic acid
¼ ð1000 kg=ton-wet kelp  7:0% Ä 0:176 kg=molÞ Â ð0:7 mol-H 2 =molÞ
¼ 278 mol-H 2 =ton-wet kelp
¼ 6:2 Nm
3
-H 2 =ton-wet kelp
Hydrogen production from kelp
¼ ðHydrogen production from mannitolÞ þ ðHydrogen production from alginic acidÞ
¼ 24:6 Nm
3 -H 2 =ton-wet kelp þ 6:2 Nm
3 -H 2 =ton-wet kelp
¼ 30:8 Nm
3 -H 2 =ton-wet kelp
Electricity production from kelp
¼ 30:8 Nm
3
-H 2 =ton-wet kelp  1:7 kWh=m
3
-H 2
¼ 52:4 kWh=ton-wet kelp
This comes out to 52 kWh in electricity (at a fuel cell efficiency of 48% and
1.7 kWH/m
3 -H 2 ), or the same amount of energy found in 31 L of gasoline, the fuel
used in cars.
By using free sources of algae (such as kelp and sea mustard waste or drifting
sea lettuce), this capability becomes economically feasible at an electricity rate of
around 0.27$ per kWh. Because large-scale energy production with farmed algae
will require additional fuel costs, new bacteria with higher yields will need to be
found (Tanisho 2011).
9.4 Biohydrogen Production
327
from algal biomass has led to the discovery of a new bacterium with a yield of
2.5 mol-H 2 /mol-mannitol, producing hydrogen at a rate of 1.1L-H 2 L-culture
−1 h
−1
(Borines et al. 2011).
In addition to having a higher yield and hydrogen generation rate than E.
aerogenes, the new bacterium has a hydrogen generation rate roughly equal to that
of the HN001 strain. A simultaneous search for a bacterium to generate hydrogen
from another chief algae component, alginic acid, similarly led to the discovery of a
different new bacterium with a yield of 0.7 mol-H 2 /mol-alginic acid. This bacterium
can be used to produce around 31 N m
3 of hydrogen from 1 ton of wet kelp
according to the following calculations:
Hydrogen production from mannitol
¼ ðmoles of mannitol in wet kelpÞ Â ðhydrogen yieldÞ
¼ ð1000 kg/ton wet kelpÞ Â 8:0% Ä 0:182 kg=molÞ Â ð2:5 mol-H 2 =molÞ
¼ 1099 mol-H 2 =ton-wet kelp
¼ 24:6 Nm
3
-H 2 =ton-wet kelp
Hydrogen production from alginic acid
¼ ð1000 kg=ton-wet kelp  7:0% Ä 0:176 kg=molÞ Â ð0:7 mol-H 2 =molÞ
¼ 278 mol-H 2 =ton-wet kelp
¼ 6:2 Nm
3
-H 2 =ton-wet kelp
Hydrogen production from kelp
¼ ðHydrogen production from mannitolÞ þ ðHydrogen production from alginic acidÞ
¼ 24:6 Nm
3 -H 2 =ton-wet kelp þ 6:2 Nm
3 -H 2 =ton-wet kelp
¼ 30:8 Nm
3 -H 2 =ton-wet kelp
Electricity production from kelp
¼ 30:8 Nm
3
-H 2 =ton-wet kelp  1:7 kWh=m
3
-H 2
¼ 52:4 kWh=ton-wet kelp
This comes out to 52 kWh in electricity (at a fuel cell efficiency of 48% and
1.7 kWH/m
3 -H 2 ), or the same amount of energy found in 31 L of gasoline, the fuel
used in cars.
By using free sources of algae (such as kelp and sea mustard waste or drifting
sea lettuce), this capability becomes economically feasible at an electricity rate of
around 0.27$ per kWh. Because large-scale energy production with farmed algae
will require additional fuel costs, new bacteria with higher yields will need to be
found (Tanisho 2011).
9.4 Biohydrogen Production
327