International Research 
Journal of 
Environment 
Sc
iences______________________________
_
__
 
ISSN 2319
–
1414
 
Vol. 
2
(
4
), 
44
-
47
, 
April 
(201
3
)
 
 
Int. Res. 
J.
 
Environment 
Sci.
 
 
 
International Science Congress Association
 
 
 
 
  
44
 
Biohydrogen from Algae: Fuel of the Future
 
 
Sharma Shaishav, Singh R
.
N
.
 
and Tripathi Satyendra
 
School of Energy and Environment Studies, Devi Ahilya Vishwavidyalaya, Takshashila Campus, 
Indore, INDIA
 
 
Available online at: 
ww
w.isca.in
 
Received
 
6
th
 
November 
2012
, revised
 
2
7
th
 
December
 
2012
, accepted
 
24
th
 
January
 
201
3
 
 
 
 
Abstract
 
 
Hydrogen holds much promise as a future fuel because of the increase in pollution caused by fossil fuels and continuous 
decrease in the availability
 
of fossil fuels. The biggest drawback of hydrogen is that its production involves fossil fuels thereby 
causing pollution of environment. Biohydrogen produced from algae is not only a clean source of energy but can also be a 
major substitute for the contin
uous depleting gasoline. Third generation biohydrogen from algae have provided solutions to 
drawbacks of first and second generation biofuels up to an extent. This review critically updates different processes availab
le 
for biohydrogen production from alga
e with special emphasis on their merits and demerits. Some approaches to overcome 
existing problems have also been outlined.
 
 
Keywords:
 
Biohydrogen, 
a
lgae, 
b
iophotolysis.
 
 
Introduction
 
Energy is the most important factor for sustaining a civilization 
as 
well as for its development but our dependence on fossil fuels 
as our primary energy source contributes to global climate 
change, environmental degradation and health problems. The 
limited amount of fossil fuels also is a cause of concern
1
. 
Hydrogen (H
2
) o
ffers tremendous potential as a clean, 
renewable energy source. The higher heating value of hydrogen 
is 3042 cals/m
3 
(considering water as a product). In combustion, 
water is the main product, thus, hydrogen is regarded as a clean 
non
-
polluting fuel
2
. Apar
t from being used as a clean fuel, 
Hydrogen has following uses
3,4
.
 
Used for the manufacture of 
ammonia.
 
Used in oil refineries for removal of impurities.
 
Used 
in methanol production
,
 
u
s
ed as a fuel in rocket engines.
 
 
99% of the total hydrogen is produced 
from fossil fuels. 
Catalytic steam reforming of naphtha or natural gas, gasification 
of coal and electrolysis of water are some of the classical 
methods of hydrogen production but these methods are energy 
extensive and affect environment. On the contrary, 
biological 
hydrogen production is particularly useful because they are 
catalyzed by microorganisms in aqueous environment at 
ambient pressure and temperature.
 
 
The interest in large scale production of biohydrogen developed 
when the limited availability of
 
fossil fuels and the pollution 
caused by them started putting a negative impact on the 
sustainability of the world population. The discovery that algae 
can produce hydrogen upon illumination was done 70 years ago 
by Gaffron and coworkers
5
. Hydrogen evolut
ion in algae was 
induced when prior incubation in dark was given to the cells
6,7, 8
. 
A high specific activity enzyme, Hydrogenase was expressed 
due to incubation and catalyzed light mediated hydrogen 
evolution. The monomeric form of the enzyme belongs to t
he 
class of Fe hydrogenase
9,10
 
is encoded in the nucleus of the 
unicellular green algae. However, the mature protein is localized 
and functions in the chloroplast stroma
10
. The absorption of 
light by the photosynthetic apparatus is an essential step for th
e 
production of hydrogen because the absorbed light energy 
oxidizes the water molecules and the released electrons are 
transported to ferredoxin. The ferredoxin transfers the electrons 
to the Fe
-
hydrogenase there by linking it to the electron 
transport cha
in of the chloroplast
11
. The activity of the 
hydrogenase last only for a short span of time (few seconds to 
minutes) because the light dependant oxidation of water leads to 
formation of molecular oxygen which unfortunately is a strong 
inhibitor of the Fe
-
h
ydrogenase
12
. This review critically deals 
with different approaches for biohydrogen production from 
algae, their advantages and drawbacks. Attempts have been 
made to highlight some techniques for improving the current 
drawbacks.  
 
 
General Characters of A
lgae:
 
Green algae and cyanobacteria 
(also called blue
-
green algae) are made up of a large group of 
photosynthetic organisms. Algae are some of the most robust 
organisms on earth, able to grow in a wide range of conditions. 
Algae usually grow in damp places
 
or water bodies and hence 
found both in terrestrial as well as aquatic environments.
 
Algae 
lack the various structures that characterize land plants, such as 
phyllids (leaves) and rhizoids in nonvascular plants, or leaves, 
roots, and other organs that are
 
found in tracheophytes (vascular 
plants). Its uniqueness that separates them from other 
microorganisms is due to presence of chlorophyll and having 
photosynthetic ability in a single algal cell, therefore allowing 
easy operation for biomass generation and
 
effective genetic and 
metabolic research in a much shorter time period than 
conventional plants. Well defined nucleus, a cell wall, 
chloroplast containing chlorophyll and other pigments, 
pyrenoid, a dense region containing starch granules on its 
surface, 
stigma, and flagella are the major components of green 
algae
13
. 
 
International Research 
Journal of 
Environment 
Sciences_
______________
_________________________
______ 
ISSN 2319
–
1414
 
Vol. 
2
(
4
), 
44
-
47
, 
April 
(201
3
)
 
     
Int. Res. 
J.
 
Environment 
Sci.
 
  
 
International Science Congress Association
 
 
45
 
Biohydrogen production from Algae: 
Production of hydrogen 
biologically is mainly the domain of microalgae and bacteria. 
Many microbial species of these groups consisting of different 
taxonomi
c and physiological types are involved in hydrogen 
metabolism
3
. Table 1 summarizes different processes of 
hydrogen production from Algae, general reactions and their 
advantages: 
 
 
Direct Biophotolysis: 
This involves the dissociation of water 
molecules unde
r sunlight in the presence of microalgae. 
Microalgae possesses the genetic, enzymatic, metabolic and 
electron transport machinery to photo produce hydrogen gas. 
Biophotolysis is an inherently attractive process since solar 
energy is used to convert a readi
ly available substrate, water to 
oxygen and hydrogen as shown in 
f
igure
-
1.
 
 
 
The overall general reaction of biophotolysis can be described 
as: 
 
2H
2
O + light = 2H
2
+ O
2
 
 
The well
-
known H
2
-
producing green algae, 
Chlamydomonas 
reinhardtii
, under anaerobic con
ditions, can either generate H
2
 
or use H
2
 
as an electron donor
10
. The generated hydrogen ions 
are converted into hydrogen gas in the medium with electrons 
(donated by reduced ferredoxin) by hydrogenase enzyme 
present in the cells. Light energy absorbed by 
photosystem II 
(PSII) generates electrons which are transferred to ferredoxin 
using light energy absorbed by photosystem I (PSI). This 
enzyme is very sensitive to O
2
. Hydrogenase activity has also 
been observed in other green algae like 
Scenedesmus obliquu
s, 
Chlorococcum littorale, Platymonas subcordiformis
 
and 
Chlorella fusca.
 
On the other hand, there are several green algae 
types that do not have hydrogenase activity such as 
Dunaliella 
salina 
and
 
Chlorella vulgaris
15
.
 
 
Indirect Biophotolysis: 
Cyanobacter
ia (also known as blue 
green algae) are a large and diverse group of photoautotrophic 
microorganisms, which can evolve hydrogen by indirect 
biophotolysis. The general reaction for hydrogen formation 
from water by cyanobacteria can be represented by followi
ng 
reactions:
 
 
12H
2
O +6CO2+ light energy = C
6
H
12
O
6
 
+ 6O
2
 
C
6
H
12
O
6
 
+ 12H
2
O + light energy = 12H
2
 
+ 6CO
 
 
Photosystem II utilizes the energy of sunlight in photosynthesis 
to extract electrons from water molecules. Electrons released 
upon the oxidation of water
 
are transported to the Fe
-
S protein 
in ferredoxin on the reducing side of photosystem I. 
The 
hydrogenase in the stroma of the algal chloroplast accepts 
electrons from reduced ferredoxin and donates them to two 
protons to generate one H
2
 
molecule. For phot
obiological 
hydrogen production, cyanobacteria have been adjudged as one 
of the ideal candidates since they can grow in air (N
2
 
and CO
2
), 
water and mineral salts with light as the energy source
16
. The 
cultivation of cyanobacteria in nitrate free media unde
r air and 
CO
2
, followed by incubation in light under argon and CO
2 
atmosphere has rapidly become standard, since it results in 
immediate hydrogen production. Localization of nitrogenase in 
heterocysts provides an oxygen free environment and the ability 
of 
heterocystous cyanobacteria to fix nitrogen in air
17
.
 
 
 
 
Figure
-
1
 
Mechanism of Biophotolysis
 
 
Table
-
1
 
Different biohydrogen production processes from Algae and their advantages
 
S.No.
 
Process
 
Reactions
 
Advantages
 
1.
 
Direct Biophotolysis
 
2H
2
O + light = 2
H
2
+ O
2
 
Can produce H
2
 
directly from water and 
sunlight. Solar conversion energy 
increased by 10 folds as compared to 
trees.
 
2.
 
Indirect 
Biophotolysis
 
6H
2
O+6CO
2
+light = C
6
H
12
O
6
+6O
2
 
C
6
H
12
O
6
+2H
2
O=4H
2
+2CH
3
COOH+2CO
2
 
2CH
3
COOH+4H
2
O+light = 8H
2
+ 4CO
2
 
Overall Reac
tion:
 
12H
2
O+light = 12H
2
+6O
2
 
Produced by both microalgae
 
and 
cyanobacteria. Can produce H
2
 
from 
water. Cyanobacteria have the ability to 
fix N
2
 
from atmosphere.
 
3.
 
Photo
-
fermentation
 
CH
3
COOH+2H
2
O+light = 4H
2
+ 2CO
2
 
Produced by both Purple bacteria and 
Micr
oalgae. A wide spectral light energy 
can be used by these bacteria.
 
International Research 
Journal of 
Environment 
Sciences_
______________
_________________________
______ 
ISSN 2319
–
1414
 
Vol. 
2
(
4
), 
44
-
47
, 
April 
(201
3
)
 
     
Int. Res. 
J.
 
Environment 
Sci.
 
  
 
International Science Congress Association
 
 
46
 
Table
-
2
 
Major drawbacks associated with these processes and the ways to overcome it
 
Process
 
Major limitations
 
Approaches to overcome
 
Direct Biophotolysis
 
Sensitivity of hydrogenase for 
O
2
.
 
Light conversion efficiency is low.
 
Use of O
2 
absorbers. b) Use of O
2 
tolerant 
hydrogenase. 
 
Genetic manipulation of light gathering antenna.  
Optimization of light input into photobioreactor. 
 
Indirect Biophotolysis
 
Enzyme inhibition by O
2
. 
 
Overall 
low production rate.
 
To achieve O
2
 
tolerant hydrogenase activity by 
classical mutagenesis.
 
Genetic modification to increase levels of 
bidirectional hydrogenase activity.
 
Photo fermentation
 
O
2
 
is a strong inhibitor of 
hydrogenase.
 
Use of O
2 
absorbers. b) U
se of O
2 
tolerant 
hydrogenase. 
 
 
Photo fermentation:
 
The general reaction for photo 
fermentation can be written as:
 
CH
3
COOH+2H
2
O+light = 4H
2
+ 2CO
2
 
 
A number of microalgae have been examined for 
photofermentative hydrogen production. The most promising 
ca
ndidates are 
Rhodopseudomonas capsulate, Rhodobacter 
spheroides 
and 
Rhodospirillum rubrum
18
. The most promising 
of all of the current body of research is the use of 
Rhodobacter
 
spheroides 
immobilized on porous glass.
 
 
 
Major Bottlenecks of these processes:
 
There are certain 
shortcomings associated with these processes which are an 
obstacle in the path of large scale production of biohydrogen 
from algae. Table 2 summarizes the shortcomings of these 
processes as well as the ways to overcome it. The hydrogenas
e 
enzyme responsible for hydrogen production is extremely 
sensitive to O
2
. Therefore, the concurrent production of O
2
 
poses a serious limitation. This is a major drawback associated 
with photolysis. Removing the O
2
 
as it is produced can solve the 
problem t
o a large extent. But this won’t be possible in a large 
scale operation unit. Some other methods to overcome this 
include use of O
2 
absorbers and the use of O
2
 
tolerant 
hydrogenase enzymes. Another promising solution is to develop 
O
2 
tolerant hydrogenase
19
.
 
 
Photobiological technology holds great promise but because of 
the production of oxygen along with hydrogen causes a major 
setback for the technology. The technology must overcome the 
limitation of oxygen sensitivity of the hydrogen evolving 
enzyme syste
ms. Researchers are addressing the issue by 
screening the algae that is more tolerant of oxygen, and by 
creating new genetic forms of algae that can sustain hydrogen 
production in the presence of oxygen
3
.
 
 
Conclusion
 
Hydrogen has tremendous potential to be
come major 
contributor of clean and renewable source of energy. 
Biohydrogen production from algae on commercial scale can be 
useful as it fulfills most of the criteria of a clean and renewable 
source of energy. The processes through which hydrogen is 
produ
ced by algae has its pros and cons both in terms of 
technology and productivity. These processes are yet to be 
 
 
evaluated and modified for productivity and cost of 
commercialization.
 
 
Acknowledgement 
 
The authors wish to acknowledge the financial support received 
from the Madhya Pradesh Biotechnology Council, Bhopal
, MP.
 
 
 
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International Research 
Journal of 
Environment 
Sciences_
______________
_________________________
______ 
ISSN 2319
–
1414
 
Vol. 
2
(
4
), 
44
-
47
, 
April 
(201
3
)
 
     
Int. Res. 
J.
 
Environment 
Sci.
 
  
 
International Science Congress Association
 
 
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