Algae are very easily satisfied, and they multiply extremely fast. All they need to grow is light, water and carbon dioxide - plus a little phosphate, nitrate and minerals. During photosynthesis they produce a variety of color pigments and vitamins, essential fatty acids and amino acids, even antibiotics and pharmaceutical agents. "Many of these substances which could previously only be produced by chemical means could also be obtained from algae," explains Jörg Degen, a biologist at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart. The red color pigment astaxanthin, for example, used in red lipsticks by the cosmetics industry. If the environmental conditions affecting a particular kind of algae known as haematococcus pluvialis change - through a superabundance of mineral salts in their water, or excessively intense sunlight - the algae synthesize this color pigment by themselves. But algae are also suited as a health food, as well as a supplier of products for the chemical and pharmaceutical industries. In the longer term, researchers also envisage the possibility of obtaining environmentally compatible motor fuels such as methanol or bio-diesel from these useful micro-organisms.

Attempts to cultivate these tiny organisms in large numbers have
always foundered in the past because of the difficulty inherent in large-scale plant of providing the algae with the optimum amount of light. This will soon change with the new photo-bioreactor of the IGB. "To enable every single algae cell to rise to the reactor surface for a short period and thus be exposed to light," explains Professor Walter Trösch of the IGB, "the glass reactor consists of flat bubble columns with a constant flow of bubbles of air". It is quite sufficient for the algae only to be exposed to the light for fractions of a second - the so-called "flashing-light effect". In this way, algae cultures of great density can be provided with sufficient light. The new method gives a substantially higher yield per unit of area than other means of cultivation. Scientists at the IGB are now working on further improving the input of light and the efficiency with which it is applied. The vision of an environmentally compatible and commercially attractive sea-water-based large-scale production of microalgae is thus becoming a genuine proposition.