Melting polar caps, rising sea levels, floods and drought catastrophes - the consequences of climate change present a global threat. The main reason for the increase in atmospheric carbon dioxide concentrations is the combustion of fossil energy. But there are ways to reduce the CO2 concentration in the air. Prof. Walter Trösch, head of the Department of Environmental Biotechnology and Biochemical Engineering at the IGB in Stuttgart, is a firm believer in algae when it comes to binding fossil CO2. Working with Dr. Ulrike Schmid-Staiger and Subitec GmbH, Trösch has developed a reactor platform that enables CO2 from flue gas plants to be put to good use. A smart side effect is that the algae produce vitamins, fatty acids, pharmaceutical substances and regenerative energies.

The foil reactor works on the principle of an airlift reactor. The scientists exploit the flash effect, since algae are able to grow even if they are only periodically exposed to strong sunlight. This can be achieved by the targeted conduction of the flow across static mixers. After cooling and condensate separation, the researchers supply the CO2 arising from the combustion of gas as a direct source of CO2 to the photobioreactor without causing algal growth to be impaired. “Our technology not only leads to the reduction of CO2, but also enables us to produce algal biomass under net energy yield,” said Trösch. The reactor (flat plate airlift reactor) is produced inexpensively using thermoformed flat film in the form of two half-shells. Using this twin-sheet technology, Subitec GmbH, a spin-off from the IGB, was able to considerably reduce production costs of the photobioreactor.

“Up until now, algae are rarely used as one of the natural sources of raw materials that have the potential to contribute to solving global food and health problems,” explained the scientist. “Algae produce a broad range of chemical compounds that represent a huge value creation chain for the pharmaceutical and food industries.” For example, natural astaxanthin, a red dye with antioxidative and health-promoting properties, or the omega-3 fatty acid EPA which is essential for human beings. A food-related EPA deficiency is associated with an increased risk of western-style diseases such as cardiac infarction or stroke. Algae can also be used as raw materials for industrial biotechnology or alternative energy supply.