supplementary pigments. Their photosynthesis differs significantly from that of
plants in that they only have one photochemical reaction center, and water
decomposition through photosynthesis does not occur. Organic matter (typically
organic acids) and sulfur compounds are used as electron donors instead of water.
The ability of photosynthetic bacteria to produce hydrogen when exposed to
sunlight was first discovered in 1949. Since then, much research has been conducted on the hydrogen formation mechanism, the relevant enzymes, and hydrogen
production.
To produce hydrogen, photosynthetic bacteria must be in anaerobic conditions
with sunlight and a nitrogen source. For sunlight exposure, intense light with
illuminance of 5000–20,000 lx (at the container surface) is used. The resulting gas
is over 90% hydrogen, with the remainder consisting of carbon dioxide.
To produce hydrogen from unexploited marine resources and marine biomass
with the highest efficiency using photosynthetic bacteria, it is better to use the
bacteria to convert sea-grown biomass into hydrogen while still in seawater.
Freshwater photosynthetic bacteria cannot grow or produce hydrogen in seawater.
Marine photosynthetic bacteria are reported to have significantly higher hydrogen
production capabilities than traditional forms of freshwater bacteria. With
farther-ranging explorations in the future, marine bacteria with even better hydrogen production capabilities may be found.
Stability with respect to oxygen can be improved through a technique that
involves fixing the bacterial body with a high molecular weight gel supporter. This
allows for greater ease of isolation and enables reuse and serial usage of bacteria
bodies, increasing the efficiency of hydrogen production over the long term. In
terms of applied research, hydrogen has reportedly been produced from the products of marine blue-green algae decomposed with acids or bases after being grown
in a biosolar reactor. This research has drawn attention for showing the potential to
establish hydrogen production systems using marine biomass and photosynthetic
bacteria.
Hydrogen production from marine biomass using photosynthetic bacteria has not
yet reached the commercialization stage. In light of future energy supply needs and
environmental issues, however, such systems are the focus of high hopes, and
commercialization technology will certainly be developed before long. The chief
goal in commercializing hydrogen production using photosynthetic bacteria lies in
increasing the bacteria’s hydrogen production capabilities.
In the future, as new high-performing photosynthetic bacteria are explored and
metabolically controlled, and research advancements in the area of marine
biotechnology (such as molecular breeding and cell engineering techniques) allow
for the development of photosynthetic bacteria with superior hydrogen production
capabilities, systems will hopefully be commercialized for the production of
hydrogen from marine biomass (Beer et al. 2009).
9.4 Biohydrogen Production
315
plants in that they only have one photochemical reaction center, and water
decomposition through photosynthesis does not occur. Organic matter (typically
organic acids) and sulfur compounds are used as electron donors instead of water.
The ability of photosynthetic bacteria to produce hydrogen when exposed to
sunlight was first discovered in 1949. Since then, much research has been conducted on the hydrogen formation mechanism, the relevant enzymes, and hydrogen
production.
To produce hydrogen, photosynthetic bacteria must be in anaerobic conditions
with sunlight and a nitrogen source. For sunlight exposure, intense light with
illuminance of 5000–20,000 lx (at the container surface) is used. The resulting gas
is over 90% hydrogen, with the remainder consisting of carbon dioxide.
To produce hydrogen from unexploited marine resources and marine biomass
with the highest efficiency using photosynthetic bacteria, it is better to use the
bacteria to convert sea-grown biomass into hydrogen while still in seawater.
Freshwater photosynthetic bacteria cannot grow or produce hydrogen in seawater.
Marine photosynthetic bacteria are reported to have significantly higher hydrogen
production capabilities than traditional forms of freshwater bacteria. With
farther-ranging explorations in the future, marine bacteria with even better hydrogen production capabilities may be found.
Stability with respect to oxygen can be improved through a technique that
involves fixing the bacterial body with a high molecular weight gel supporter. This
allows for greater ease of isolation and enables reuse and serial usage of bacteria
bodies, increasing the efficiency of hydrogen production over the long term. In
terms of applied research, hydrogen has reportedly been produced from the products of marine blue-green algae decomposed with acids or bases after being grown
in a biosolar reactor. This research has drawn attention for showing the potential to
establish hydrogen production systems using marine biomass and photosynthetic
bacteria.
Hydrogen production from marine biomass using photosynthetic bacteria has not
yet reached the commercialization stage. In light of future energy supply needs and
environmental issues, however, such systems are the focus of high hopes, and
commercialization technology will certainly be developed before long. The chief
goal in commercializing hydrogen production using photosynthetic bacteria lies in
increasing the bacteria’s hydrogen production capabilities.
In the future, as new high-performing photosynthetic bacteria are explored and
metabolically controlled, and research advancements in the area of marine
biotechnology (such as molecular breeding and cell engineering techniques) allow
for the development of photosynthetic bacteria with superior hydrogen production
capabilities, systems will hopefully be commercialized for the production of
hydrogen from marine biomass (Beer et al. 2009).
9.4 Biohydrogen Production
315