Photobioreactors:
Design and Performance with Respect to
Energy Input
Light
Otto Pulz and Karl Scheibenbogen
IGV Institut fiir Getreideverarbeitung, Arthur Scheunert-Allee 40-41,
14558 Bergholz/Rehbriicke, Germany
1 Introduction .............................................
124
2 Short Review of History ......................................
124
3 Influence of Light on Microalgae ................................
127
3.1 Photosynthetic Efficiency ...................................
127
3.2 Qualitative Light Requirements of Phototrophic Microorganisms ...........
128
3.3 Quantitative Light Requirements of Microalgae .....................
128
3.4 Effects of Changing Light Conditions on Algal Growth .................
130
3.5 Utilization of Light-Source Energy .............................
131
4 Problems of Cultivating Phototrophic Microorganisms ...................
132
5 Cultivation Techniques ......................................
133
5.1 Open Cultivation Systems ..................................
133
5.2 Closed and Semi-Closed Outdoor Photobioreactors ...................
135
5.2.1 Tubular Photobioreactors ...............................
136
5.2.2 Plate Type Reactors ..................................
138
5.3 Experimental Photobioreactors ...............................
139
5.3.1 Laboratory-Scale Reactors ..............................
!39
5.3.2 Fibre Optic Reactors ..................................
141
5.3.3 Immobilized Cell Systems and Hydrogen Production ...............
143
5.4 General Aspects of Phototrophic Mass Cultivation ...................
144
6 Conclusion ..............................................
147
7 References ..............................................
148
Photosynthesis is the most important natural process for the neogenesis of biological material. More
than 40 000 species of oligocellular algae constitute a unique biochemical fund in the plant world. As
the energy supply to the phototrophic microorganisms is transported via photons and as the physics
of light distribution is a technical challenge, the technique of biomass production of single cell algae
as against heterotrophic organisms is in a stage of intensive development. In contrast to area
intensive open pond technology, space saving closed cultivation systems could be gradually established in the market of industrial photobioreactors. The present review surveys outdoor cultivation
systems and indoor photobioreactors with respect to their light utilization and productivity. To
evaluate reactor performance independently of their design and location, growth yields were
recalculated from published data. It became obvious that closed systems may out-perform raceway
ponds by about 300%, which represents productivities over 100 g dry algal biomass per m 2 per day.
Thus, economic aspects for the cultivation of phototrophs, even in moderate climates, are better
satisfied, but microalgal biotechnology is still of minor importance because of high biomass
production costs. Considering indoor systems with internal illumination arrangements, the growth
potential can be increased by a further 100%. Due to the high technical expenses, this technology
will be confined to the production of high value products, e.g. pharmaceuticals. Consequently, very
defined axenic cultivitation has to be guaranteed by all means available.
Advances in Biochemical Engineering/
Biotechnology, Vol. 59
Managing Editor: T. Seheper
9 Springer-Verlag Berlin Heidelberg 1998
Design and Performance with Respect to
Energy Input
Light
Otto Pulz and Karl Scheibenbogen
IGV Institut fiir Getreideverarbeitung, Arthur Scheunert-Allee 40-41,
14558 Bergholz/Rehbriicke, Germany
1 Introduction .............................................
124
2 Short Review of History ......................................
124
3 Influence of Light on Microalgae ................................
127
3.1 Photosynthetic Efficiency ...................................
127
3.2 Qualitative Light Requirements of Phototrophic Microorganisms ...........
128
3.3 Quantitative Light Requirements of Microalgae .....................
128
3.4 Effects of Changing Light Conditions on Algal Growth .................
130
3.5 Utilization of Light-Source Energy .............................
131
4 Problems of Cultivating Phototrophic Microorganisms ...................
132
5 Cultivation Techniques ......................................
133
5.1 Open Cultivation Systems ..................................
133
5.2 Closed and Semi-Closed Outdoor Photobioreactors ...................
135
5.2.1 Tubular Photobioreactors ...............................
136
5.2.2 Plate Type Reactors ..................................
138
5.3 Experimental Photobioreactors ...............................
139
5.3.1 Laboratory-Scale Reactors ..............................
!39
5.3.2 Fibre Optic Reactors ..................................
141
5.3.3 Immobilized Cell Systems and Hydrogen Production ...............
143
5.4 General Aspects of Phototrophic Mass Cultivation ...................
144
6 Conclusion ..............................................
147
7 References ..............................................
148
Photosynthesis is the most important natural process for the neogenesis of biological material. More
than 40 000 species of oligocellular algae constitute a unique biochemical fund in the plant world. As
the energy supply to the phototrophic microorganisms is transported via photons and as the physics
of light distribution is a technical challenge, the technique of biomass production of single cell algae
as against heterotrophic organisms is in a stage of intensive development. In contrast to area
intensive open pond technology, space saving closed cultivation systems could be gradually established in the market of industrial photobioreactors. The present review surveys outdoor cultivation
systems and indoor photobioreactors with respect to their light utilization and productivity. To
evaluate reactor performance independently of their design and location, growth yields were
recalculated from published data. It became obvious that closed systems may out-perform raceway
ponds by about 300%, which represents productivities over 100 g dry algal biomass per m 2 per day.
Thus, economic aspects for the cultivation of phototrophs, even in moderate climates, are better
satisfied, but microalgal biotechnology is still of minor importance because of high biomass
production costs. Considering indoor systems with internal illumination arrangements, the growth
potential can be increased by a further 100%. Due to the high technical expenses, this technology
will be confined to the production of high value products, e.g. pharmaceuticals. Consequently, very
defined axenic cultivitation has to be guaranteed by all means available.
Advances in Biochemical Engineering/
Biotechnology, Vol. 59
Managing Editor: T. Seheper
9 Springer-Verlag Berlin Heidelberg 1998