A photobioreactor is a bioreactor that uses a light source to cultivate phototrophic microorganisms.  These organisms use photosynthesis to generate biomass from light and carbon dioxide and include plants, mosses , macroalgae, microalgae , cyanobacteria and purple bacteria. Within the context of a photobioreactor, specific conditions are carefully controlled for respective species. Thus, a photobioreactor permits much higher growth rates and purity levels than anywhere in nature or habitats similar to nature. Hypothetically, phototropic biomass could be derived from nutrient-rich wastewater and flue gas carbon dioxide in a photobioreactor.
The first approach for the controlled generation of phototrophic organisms Was and still is a natural open pond or artificial raceway pond. Therein, the culture suspension, which contains all necessary nutrients and carbon dioxide, is pumped around a cycle, being directly illuminated from the sunlight via the liquid’s surface. This construction is the simplest way of production for phototrophic organisms. Aimed at their depth (up to 0.3 m) and the relative reduced average light supply. In addition, the consumption of energy is relatively high. Open space is dense in areas with a dense population, while water is rare in others. Using open technologies causes high losses of water due to evaporation into the atmosphere.
Since the 1950s several approaches have been conducted to develop closed systems, which theoretically provide higher densities of phototrophic organisms and therefore lower demand for water. In addition, closed construction avoids system-related water losses and the risk of contamination through landing water is minimized.  All modern photobioreactors have been tested, optimized for low-cost applications, low-energy consumption, capital expenditure and microbial purity. Many different systems have been tested, but only a few approaches have been able to perform at an industrial scale. 
Redesigned laboratory fermenters
The simplest approach is the redesign of the well-known glass fermenters , which are state of the art in many biotechnological research and production facilities worldwide. The moss reactor for example shows a standard glass vessel, which is externally supplied with light. The existing head nozzles are used for sensor installation and for gas exchange.  This type is quite common in laboratory scale, but it has never been established in larger scale, due to its limited vessel size.
Made from glass or plastic tubes, this photobioreactor type has succeeded within production scale. The tubes are oriented horizontally or vertically and are supplied from a central utilities installation with pumps, sensors, nutrients and CO 2 . Tubular photobioreactors are established worldwide from laboratory to production scale, eg for the production of carotenoid Astaxanthin from the green algae Haematococcus pluvialis or for the production of food supplement from the green algae Chlorella vulgaris. These photobioreactors take advantage of the high purity levels and their efficient outputs. The biomass production can be done at a high quality level and the high biomass concentration at the end of the production allows efficient energy downstream processing. To to to….,,,,,,,,,,,,,,,,,,,,,,,,,,,. 
The advantages of tubular photobioreactors and production scale are also transferred to laboratory scale. Combination of biomass production rates with a thin tube Being controlled by a complex process control system the regulation of the environmental conditions reaches a high level. 
Christmas tree photobioreactor
An alternative approach is shown by a photobioreactor, which is built in a tapered geometry and which carries a helically attached, translucent double hose circuit system.  The result is a layout similar to a Christmas tree. The tubular system is constructed in modules and can theoretically be scaled up to agricultural scale. A dedicated location is not crucial, it is similar to other closed systems, and therefore non-arable land is suitable as well. The material choice should prevent biofouling and ensure high final biomass concentrations. The combination of turbulence and the closed concept should allow a clean operation and a high operational availability. 
Another development approach can be seen with the construction based on plastic or glass plates. Plates with different technical design, which provides an optimized light supply. In addition, the simpler construction compared to tubular reactors allows the use of less expensive plastic materials. From the pool of different concepts, eg, meandering flow designs, or bottom gassed systems have been realized and shown good output results. Some issues are material life time stability or the biofilm forming. Applications at industrial scale are limited by the scalability of platform systems. 
In April 2013, the IBA in Hamburg, Germany, facade, was commissioned. 
This photobioreactor type consists of a flat-shaped basic geometry with peaks and valleys arranged in regular distance. This geometry causes the distribution of incident light over a larger area which corresponds to a dilution effect. This method is also useful for phototrophic cultivation, because most microalgae species react sensitively to high light intensities. Most microalgae experience light saturation already at light intensities, ranging substantially below the maximum daylight intensity of approximately 2000 W / m 2. Simultaneously, a larger light can be exploited in order to improve photoconversion efficiency. The mixing is accomplished by a rotary pump, which causes a cylindrical rotation of the culture broth. In contrast to vertical designs, horizontal reactors contain only thin layers of media with a correspondingly low hydrodynamic pressure. This has a positive impact on the necessary energy input and reduces material costs at the same time.
The development of foil-based photobioreactor types. Inexpensive PVC gold PE foils are mounted to the shape of the gold or silver foil. The pricing ranges of photobioreactor have been enlarged with the foil systems. It has to be kept in mind, that these systems have a limited sustainability of the time. For full scales, the investment for required support systems has been calculated. 
Porous Substrate Bioreactor
Porous Substrate Bioreactor (PSBR), being developed at the University of Cologne, also known as the twin-layer system, uses a nutrient solution of a biosafety vector. . This new procedure reduces the amount of cash needed for operation compared to the current technology, which cultivates algae in suspensions. As such, the PSBR procedure significantly reduces the energy needed while increasing the size of the crop.
The discussion around microalgae and their potentials in carbon dioxide sequestration and biofuel production has caused high pressure on developers and manufacturers of photobioreactors.  Today, none of the systems is capable of producing phototrophic microalgae biomass at a price which is able to compete with crude oil. New approaches test eg dripping methods to produce ultra-thin layers for maximum growth with application of flue gas and waste water. Further on, much research is done around the world and optimized microalgae.
- Algae fuel
- Jump up^ “Photobioreactor – Definition, Glossary, Details – Oilgae” . Glossary . Oilgae . Retrieved 2015-03-10 .
- Jump up^ Lane. G. (2013). “Up To Speed On: Algae Biofuels”. 1 . Smashwords: 1-9. ISBN 9781301351961 .
- Jump up^ Submariner Project:photobioreactor design principles
- Jump up^ 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 .
- Jump up^ Pulz. O. (2001). “Photobioreactors: production systems for phototrophic microorganisms”. Applied Microbiology and Biotechnology . 57 : 287-293. doi : 10.1007 / s002530100702 .
- Jump up^ Algae Observer:Biotech IGV Presents Novel Algae Screening System
- Jump up^ F. Cotta, Mr. Matschke, J. Grossmann, C. Griehl und S. Matthes; “Verfahrenstechnische Aspekte eines flexiblen, tubularen Systems zur Algenproduktion” (Process-related aspects of flexible, tubular system for algae production); DECHEMA 2011
- Jump up^ Großmann Ingenieur Consult GmbH:Aufbau eines Biosolarzentrums in Köthen, 6. März 2011.
- Jump up^ Handbook of microalgal culture . 1 (2nd ed.). Blackwell Science Ltd. 2013. ISBN 978-0-470-67389-8 .
- Jump up^ Briegleb, Till (2013-03-25). “IBA Hamburg – Opening, Algaehouse, Worldquartier” . Art Magazin .
- Jump up^ Zittelli, Graziella; Liliana Rodolfi; Niccolo Bassi; Natascia Biondi; Mario R. Tredici (2012). “Chapter 7 Photobioreactors for Microalgae Biofuel Production”. In Michael Borowitzka, Navid R. Moheimani. Algae for Biofuels and Energy . Springer Science & Business Media. pp. 120-121. ISBN 9789400754799 .
- Jump up^ Spolaore. P .; et al. (2006). “Commercial Applications of Microalgae”. Journal of Bioscience and Bioengineering . 102 : 87-96.