Hydrogen bioreactor

Hydrogen production by algae on a laboratory scale

A hydrogen bioreactor is a bioreactor in which the biological production of hydrogen gas takes place. The production of hydrogen gas can take place in various ways. In this way, algae can generate hydrogen under certain conditions . In the late 1990s, this changed behavior of algae when there was a lack of sulfur was discovered. The algae stop producing oxygen and produce the hydrogen gas. Another possibility is the construction of a hydrogen bioreactor based on bacteria . There is the possibility of establishing a two-stage system in which thermophilic bacteria and cyanobacteria are used.

A technology of this kind is interesting insofar as the biohydrogen produced in this way can be used as a climate-neutral energy carrier. For example, an algae farm the size of Texas could produce enough hydrogen to meet the world's energy needs. Hydrogen production from a 25,000 square kilometer farm could replace all of the US gasoline consumption. This is less than a tenth of the area of soy production in the USA (as of 2006).

history

The German biochemist Felix Hoppe-Seyler provided the first evidence that microorganisms can form hydrogen at the end of the 19th century. Most bacteria and fungi produce hydrogen gas in connection with fermentation processes. In 1939, the German-born biochemist discovered hans gaffron in green algae the ability to temporarily produce hydrogen. Until then, it had been assumed that only prokaryotic organisms had this capability. However, he was unable to clarify the background to this process. At the beginning of the 1970s, the connection between hydrogen metabolism and photosynthesis could be demonstrated, but it would take almost another 30 years before the full potential of unicellular green algae for the production of H2 could be demonstrated

Around 1990, Anastasios Melis , a researcher at the University of California at Berkeley, observed that a lack of sulfur in the alga Chlamydomonas reinhardtii caused a change in the photosynthesis process , which in turn underlies the hydrogen production described by Gaffron.

In order to be used in power generation, however, it is necessary to make hydrogen production more efficient (or more economical). In 2006, researchers from the Universities of Bielefeld and Queensland succeeded in genetically modifying the alga Chlamydomonas reinhardtii so that it can produce up to five times more hydrogen than the wild type .

Further research deals with the genus Scenedesmus Obliquus, which also has hydrogenases for hydrogen production by means of photosynthesis .

Procedure

The Institute for Bio- and Food Technology at the Karlsruhe Institute of Technology names the species Chlamydomonas reinhardtii as a possibility for hydrogen production by microalgae . For this purpose, the algae must be in an anaerobic environment in which there is a shortage of sulfur.

Problems in planning a bioreactor

• Impairment of photosynthetic hydrogen production through the creation of an electrochemical potential
• By competitive inhibition of the production of hydrogen by carbon dioxide hindered.
• A bicarbonate compound is required for efficient photosynthesis .
• Elimination of electrons
• The efficiency is very low. The normal energy efficiency (conversion of sunlight into hydrogen) must reach at least 7 to 10 percent in order to be economical. In their natural form, however, the algae only reach 0.1%.

One tries to solve these problems with the help of biotechnology.

In addition, the construction of the bioreactor is a problem to be solved, among other things with regard to the light requirement.

examination

2006: A prototype of a bioreactor is built at the University of Karlsruhe , which holds 500–1000 liters of algae substrate.

literature

Ingo Rechenberg : Photobiological hydrogen production in the Sahara . Workshop Bionics and Evolution Technology Volume 2, Frommann-Holzboog, Stuttgart 1994, ISBN 3-7728-1643-6

See also

• Biohydrogen
• Hydrogen economy

Web links

• Tasios Melis: Maximizing Light Utilization Efficiency and Hydrogen Production in Microalgal Cultures . In: DOE Hydrogen Program. University of California, Berkeley, Annual Report 2007 (PDF file; 330 kB), English, accessed April 8, 2011.
• Report in ARCHE ONLINE
• Wired-Mutant Algae Is Hydrogen Factory
• FAO
• Maximizing Light Utilization Efficiency and Hydrogen Production in Microalgal Cultures (PDF file; 367 kB)
• NREL reports
• Scientific report on cost analysis (PDF file; 678 kB)
• CYCLIC PHOTOBIOLOGICAL ALGAL H2-PRODUCTION , Proceedings of the 2001 DOE Hydrogen Program Review (PDF file; 146 kB), English, accessed on April 8, 2011.
• US Department of Energy, Washington : Collection of articles on the keyword H2-production, English, accessed on April 8, 2011.

Individual evidence

1. ^ Newscientist.com: Growing hydrogen for the cars of tomorrow (February 25, 2006).
2. ↑ Röbbe Wünschiers: Biological "electrolysis" by microalgae Uppsala University Dept. Physiol. Botany Uppsala Sweden
3. ↑ Hoppe-Seyler, F. (1887) in Zeitschrift für Physikalische Chemie 11: 561-568
4. ↑ Peter H. Homann: Hydrogen metabolism of green algae: discovery and early research - a tribute to Hans Gaffron and his coworkers. In: Govindjee, JT Beatty, H. Gest and JF Allen (Eds.): Discoveries in Photosynthesis. In the series: Advances in Photosynthesis and Respiration, Vol. 20. Springer-Verlag, pp. 119 ff., ISBN 978-1-4020-3323-0 . Chapter online
5. ↑ H. Gaffron, Reduction of Carbon Dioxide with Molecular Hydrogen in Green Algæ Nature 1939, 3614, 204-205.
6. ↑ T. Stuart, H. Gaffron, Plant Physiology 1972, 6, 136-140.
7. ↑ Ulf-Peter Apfel and Sven Timo Stripp: Hydrogen production based on the model of nature GIT Labor-Fachzeitschrift 06/18 June 4, 2018
8. ↑ Scenedesmus Obliquus - an Overview on ScienceDirect
9. ↑ ^{a b} KIT: Hydrogen Production with Microalgae , accessed on September 15, 2014.