Algae biotechnology

Photosynthesis is the only bioprocess capable of building biomass using sunlight as an energy source and carbon dioxide as a carbon source. Microalgae are particularly well-suited for a material or energetic utilization of photosynthetically produced biomass, since the unicellular phototrophic organisms can utilize sunlight more efficiently than higher plants. Microalgae produce a variety of basic chemical substances such as polysaccharides, fatty acids, proteins, vitamins, and carotenoids with a high value-added potential for the pharmaceutical, food, feed, agricultural, and cosmetics industries, as well as biofuels and platform chemicals for biopolymers and textiles.

Processes for the production of biomass and valuable substances from microalgae

Fraunhofer IGB develops processes for the tailor-made production of a wide variety of products from microalgae and cyanobacteria in flat-plate airlift reactors. Through targeted process control, functional ingredients can be produced in high concentrations up to the pilot scale. To increase added value from algal biomass, we have investigated methods for extracting various functional compounds from algal biomass, such as carotenoids like fucoxanthin and astaxanthin, the omega-3 fatty acid EPA as a polar glycolipid, proteins and triglycerides for the production of food, feed, cosmetics, agrochemicals, biopolymers, and as feedstocks for bio-based polymers. For this purpose, we also employ new downstream processing technologies, such as the extraction of carotenoids and omega-3 fatty acids, cell disruption using pressure-change technology, and extraction with sub- or supercritical fluids.

Proprietary Flat-Panel Airlift Photobioreactor (FPA-PBR)

With its proprietary Flat-Panel Airlift Photobioreactors (FPA-PBR), Fraunhofer IGB provides a technology for the commercial-scale production of algal biomass with outstanding productivity, product quality, and cost efficiency. The reactors are modularly scalable (low-risk) and can be deployed on-site (robust, automated, remote maintenance) as a drop-in technology. This accelerates the transfer of new products.

Closing material cycles: CO2 and nutrient utilization by microalgae

Microalgal production can also be utilized as a unit operation in biorefineries, based on the principle of bioeconomic value chains, to utilize exhaust CO2 (carbon capture and use) and nutrients from wastewater streams and liquid fermentation residues, thereby closing material cycles through industrial biotechnological processes.

• Screening for microalgae and cyanobacteria with a wide variety of properties and constituents
• Development of photoautotrophic processes from laboratory to pilot scale for microalgae and cyanobacteria in flat plate airlift reactors
• Process optimization to improve productivity and biomass yield also using off-gas CO₂ and liquid fermentation residues
• Development and adaptation of control software for algae production in the field
• Development of processes for the isolation, fractionation and purification of algal constituents with the fullest possible utilization of the various fractions
• Contract production of algae biomass with defined composition on a 100 kg scale

Diese Liste ist ein Auszug aus der Publikationsplattform Fraunhofer-Publica

This list has been generated from the publication platform Fraunhofer-Publica

In order to keep the investment costs as low as possible the assigned bioreactor should both be economically manufactured and to be installed without high expenditure. The "flat-panel airlift photobioreactor" developed at Fraunhofer IGB fulfills these criteria and is suitable therefore for the large-scale cultivation of micro algae.

The operating costs are determined by the productivity of the selected algal species. Therefore, the efficiency of the transformation of solar radiation energy into biomass must be as high as possible. The energetic expenditure for operation of the plant has to be kept small.

With the development of algal cultivation systems and processes therefore the following parameters must be considered:

• Availability of light for the cells (light entry of appropriate intensity and even distribution to all cells)
• Mixing (algal cells are partly very sensitive to shearing forces)
  
• CO₂ supply and discharge of growth-limiting oxygen
• Temperature control.

The processing costs depend on the one hand on the respective product and the purity requirements, on the other hand on the cell density. A high cell densitiy with at the same time high product concentration decreases the processing costs substantially and must be therefore a goal of each reactor development.

Proceeds of algal biomass or their products is determined by their targeted application. High value products, which can be used in cosmetics, pharmacy and nutrition, will faster lead to an economical production than the use of simple algal biomass as feed additive or fertilizers. Coupling of high value and biomass production, whereby first the valuable material is extracted and the remaining biomass additionally can be marketed, is surely the most meaningful use in the sense of ecological and economic sustainability.