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Energy from microalgae

Alternative energy sources are increasingly gaining in importance. Several teams of researchers, including scientists from the University of Karlsruhe, are using different strategies to increase hydrogen production in algae. These might then become environment-friendly, low-cost suppliers of energy.

The “Biological hydrogen production in microalgae” project integrates four groups of researchers, including the group of Prof. Dr. Michael Hippler from the Institute of Biochemistry and Plant Biotechnology in Münster, researchers from the Max Planck Institute of Molecular Plant Physiology in Golm (Potsdam, Germany), the University of Karlsruhe (TH) and researchers of the University of Bielefeld who are coordinating the project. The project is funded by the German Federal Ministry of Education and Research with a total of 1.8 million euros in funding.

Hydrogen is regarded as an environmentally-friendly energy source of the future, for example in the car industry. However this is only true if hydrogen can be produced using environmentally-friendly methods. That is why the researchers have plans to turn unicellular green algae (Chlamydomonas reinhardtii) into industrially suitable hydrogen suppliers that produce hydrogen without negative consequences for the environment. Under certain conditions, for example oxygen deprivation or adaptation to sulphur deficiency, the tiny algae produce hydrogen when exposed to sunlight. However, normal green algae only convert 0.1 of the “light particles” into hydrogen molecules. From an economic point of view, this is not at all sufficient. “If it were possible to increase the rate to seven or ten per cent, then the algal hydrogen production would be of commercial interest,” said Hippler.

Gene technology to increase hydrogen production

Miniature cultivation of algae for research purposes: the microalgae grow in glass flasks in the laboratory (Photo: Peter Grewer)
In order to increase hydrogen production, the researchers are pursuing several different strategies. One strategy focuses on an already existing green algae cell line that carries a genetic modification that results in increased hydrogen production. However, the amount of hydrogen produced is still far from the amount desired.

By comparing this special cell line with “normal” algae, the researchers hope to find out which metabolic pathways cause the observed differences in hydrogen production – which genes are active in the algae and which proteins and metabolic products are generated. “Once we know the exact mechanisms, we hope to genetically modify the cells and obtain new cell generations that are able to produce hydrogen far more efficiently,” explains Hippler. In addition, the researchers are looking for other, previously unknown algal cell lines that also produce higher amounts of hydrogen and contribute to the researchers’ efforts in finding an ideal hydrogen producer.

Another strategy involves the improvement of fermentation facilities, the water tanks in which algae produce hydrogen under defined growth conditions. A major difficulty of this strategy is the illumination of the tanks. In order for the algae to produce hydrogen, they have to be exposed to sufficient light. At present, the algae are grown under artificial light. In order to improve the energy balance, the researchers hope to develop “external reactors” that work with sunlight. The researchers also have plans to increase the size of the tanks. “Our team hopes to scale up from 25-litre to 250-litre fermenters,” said Hippler. The researchers from Karlsruhe are in charge of this technical subproject.

The microalgae project is linked with the work of the international “Solar Biofuels” consortium that hopes to use algae for hydrogen production and for the production of biodiesel and biomethane.

Source: Press release, University of Münster- 7 August 2008
Website address: https://www.biooekonomie-bw.de/en/articles/pm/energy-from-microalgae