A combination of the mentioned glass vessel with a thin tube coil allows relevant biomass production rates at laboratory research scale.
 Though closed systems have better productivity compared to open systems due to the advantages mentioned, they still need to be improved to make them suitable for production
of low price commodities as cell density remains low due to several limiting factors.
Since the geometry of the reactor integrates one or more down chambers that transport the culture from the top area around to the bottom area, the culture is constantly homogeneously
supplied with the photosynthesis-relevant factors, thus achieving a high productivity.
Plates with different technical design are mounted to form a small layer of culture suspension, which provides an optimized light supply.
The rising of the air bubbles in the specially shaped plate reactor creates a homogeneous mixing of the culture and, on the one hand, a very long residence time of the CO2-air
mixture and thus a very good CO2 input (degree of utilization) into the culture.
 All modern photobioreactors have tried to balance between a thin layer of culture suspension, optimized light application, low pumping energy consumption, capital expenditure
and microbial purity.
This new procedure reduces by a factor of up to one hundred the amount of liquid needed for operation compared to the current technology, which cultivates algae in suspensions.
On the other hand, the homogeneous mixing ensures a very good light input of the grow-light LEDs usually installed on both sides of the system and thus a very high utilization
of the light energy.
 The accumulation of photosynthetic oxygen with growth of microalgae in photobioreactors is also believed to be a significant limiting factor; however, it has been recently
shown with the help of kinetic models that dissolved oxygen levels as high as 400% air saturation are not inhibitory when cell density is high enough to attenuate light at later stages of microalgal cultures.
Using open technologies also result in losses of water due to evaporation into the atmosphere.
The combination of turbulence and the closed concept should allow a clean operation and a high operational availability.
A photobioreactor (PBR) refers to any cultivation system designed for growing photoautotrophic organisms using artificial light sources or solar light to facilitate photosynthesis.
 This type is quite common in laboratory scale, but it has never been established in bigger scale, due to its limited vessel size.
However, they offer an insufficient control of reaction conditions due to their reliance on environmental light supply and carbon dioxide, as well as possible contamination
from other microorganisms.
The biomass production can be done at a high quality level and the high biomass concentration at the end of the production allows energy efficient downstream processing.
Raceway ponds are still commonly used in industry due to their low operational cost in comparison to closed PBRs.
Simultaneously, a larger light quantity can be exploited in order to improve photoconversion efficiency.
 Many different systems have been tested, but only a few approaches were able to perform at an industrial scale.
meandering flow designs or bottom gassed systems have been realized and shown good output results.
A dedicated location is not crucial, similar to other closed systems, and therefore non-arable land is suitable as well.
This has a positive impact on the necessary energy input and reduces material costs at the same time.
[‘1. Yuvraj; Ambarish Sharan Vidyarthi; Jeeoot Singh (2016). “Enhancement of Chlorella vulgaris cell density: Shake flask and bench-top photobioreactor studies to identify and control limiting factors”. Korean Journal of Chemical Engineering. 33 (8):
2396–2405. doi:10.1007/s11814-016-0087-5. S2CID 99110136.
2. ^ Benner, Philipp; Meier, Lisa; Pfeffer, Annika; Krüger, Konstantin; Oropeza Vargas, José Enrique; Weuster-Botz, Dirk (May 2022). “Lab-scale photobioreactor systems: principles, applications,
and scalability”. Bioprocess and Biosystems Engineering. 45 (5): 791–813. doi:10.1007/s00449-022-02711-1. ISSN 1615-7591. PMC 9033726. PMID 35303143.
3. ^ Wasanasathian, Attaya; Peng, Ching-An (2007-01-01), Yang, Shang-Tian (ed.), “Chapter 19 –
Algal Photobioreactor for Production of Lutein and Zeaxanthin”, Bioprocessing for Value-Added Products from Renewable Resources, Amsterdam: Elsevier, pp. 491–505, doi:10.1016/b978-044452114-9/50020-7, ISBN 978-0-444-52114-9, retrieved 2022-05-21
Lane. G. (2013). Up To Speed On: Algae Biofuels. Vol. 1. Smashwords. pp. 1–9. ISBN 9781301351961.
5. ^ Jump up to:a b Yuvraj; Ambarish Sharan Vidyarthi; Jeeoot Singh (2016). “Enhancement of Chlorella vulgaris cell density: Shake flask and bench-top
photobioreactor studies to identify and control limiting factors”. Korean Journal of Chemical Engineering. 33 (8): 2396–2405. doi:10.1007/s11814-016-0087-5. S2CID 99110136.
6. ^ Yuvraj; Padmini Padmanabhan (2017). “Technical insight on the requirements
for CO2-saturated growth of microalgae in photobioreactors”. 3 Biotech. 07 (2): 119. doi:10.1007/s13205-017-0778-6. PMC 5451369. PMID 28567633.
7. ^ Yuvraj; Padmini Padmanabhan (2021). “Improvements in Conventional Modeling Practices for Effective
Simulation and Understanding of Microalgal Growth in Photobioreactors: an Experimental Study”. Biotechnology and Bioprocess Engineering. 26 (3): 483–500. doi:10.1007/s12257-020-0293-1. S2CID 235638512.
8. ^ Submariner Project: Photobioreactor design
9. ^ Decker, Eva; Ralf Reski (2008). “Current achievements in the production of complex biopharmaceuticals with moss bioreactors”. Bioprocess and Biosystems Engineering. 31 (1): 3–9. doi:10.1007/s00449-007-0151-y. PMID 17701058. S2CID
10. ^ Oliva, Giuseppina; Ángeles, Roxana; Rodríguez, Elisa; Turiel, Sara; Naddeo, Vincenzo; Zarra, Tiziano; Belgiorno, Vincenzo; Muñoz, Raúl; Lebrero, Raquel (December 2019). “Comparative evaluation of a biotrickling filter and a tubular
photobioreactor for the continuous abatement of toluene”. Journal of Hazardous Materials. 380: 120860. doi:10.1016/j.jhazmat.2019.120860. PMID 31302359. S2CID 196612644.
11. ^ Pulz. O. (2001). “Photobioreactors: production systems for phototrophic
microorganisms”. Applied Microbiology and Biotechnology. 57 (3): 287–293. doi:10.1007/s002530100702. PMID 11759675. S2CID 21308401.
12. ^ Algae Observer: IGV Biotech Presents Novel Algae Screening System
13. ^ F. Cotta, M. Matschke, J. Großmann,
C. Griehl und S. Matthes; “Verfahrenstechnische Aspekte eines flexiblen, tubulären Systems zur Algenproduktion” (Process-related aspects of a flexible, tubular system for algae production); DECHEMA 2011
14. ^ Großmann Ingenieur Consult GmbH: Aufbau
eines Biosolarzentrums in Köthen, 6. März 2011.
15. ^ Handbook of microalgal culture. Vol. 1 (2nd ed.). Blackwell Science Ltd. 2013. ISBN 978-0-470-67389-8.
16. ^ Briegleb, Till (2013-03-25). “IBA Hamburg – Opening, Algaehouse, Worldquartier”.
Art Magazin. Archived from the original on 2013-03-28.
17. ^ Zittelli, Graziella; Liliana Rodolfi; Niccolo Bassi; Natascia Biondi; Mario R. Tredici (2012). “Chapter 7 Photobioreactors for Microalgae Biofuel Production”. In Michael A. Borowitzka,
Navid R. Moheimani (ed.). Algae for Biofuels and Energy. Springer Science & Business Media. pp. 120–121. ISBN 9789400754799.
18. ^ Porous substrate bioreactor
19. ^ Spolaore. P.; et al. (2006). “Commercial Applications of Microalgae” (PDF). Journal
of Bioscience and Bioengineering. 102 (2): 87–96. doi:10.1263/jbb.101.87. PMID 16569602. S2CID 16896655.
Photo credit: https://www.flickr.com/photos/46183897@N00/14244273988/’]