The AlgaTex feasibility study, funded by the German Federal Ministry of Education and Research under grant 031B1196, ran from 1 October 2021 to 30 September 2022 and was carried out by the Hochschule Niederrhein’s Institute for Textile and Clothing in cooperation with an algae research institute, a fish‑farm/ algae cultivator, and a company that operates large‑volume culture vessels. The project’s aim was to determine whether filamentous freshwater green algae could be cultivated at an economically viable scale and processed into textile fibres, non‑woven fabrics, yarns and knitted structures.

During the exploration phase eight work packages were executed. Five algal groups comprising more than 60 taxa were screened for filamentous morphology, fibre length (> 1 cm), fineness, tensile strength of dried filaments and special properties such as antimicrobial activity. Seven green algae from the Chlorophyta and Streptophyta divisions were selected for detailed study. Three species were ultimately chosen and identified; one already existed as a pure culture. Initial cultivation trials used fish‑waste water in an aquaponic set‑up, but this was replaced by Woods Hole Medium (pH 6) to achieve optimal growth. Light regimes of 18 h light/6 h dark with 50–100 µmol m⁻² s⁻¹, a temperature of 25 °C, and air‑lift mixing were established. In the laboratory the culture volume was scaled to 9 L in plastic tanks, with 24 h illumination using white, fluorescent or LED light. For larger‑scale tests, semi‑closed systems employing intermediate bulk containers (IBC) were used, and open flat‑tank systems (2 × 40 L) were also trialled at 19–21 °C, 14 h light/10 h dark and 250–270 µmol m⁻² s⁻¹. The flat‑tank approach offered high gas exchange and light utilisation but suffered from bacterial and competing micro‑algae contamination, which was mitigated by switching to the semi‑closed IBC system, inoculating with a clean starter culture, and performing regular microscopic monitoring to time harvest.

The project acquired two 160 L aquariums, lighting units, filters, timers and a digital microscope set for in‑situ analysis of fresh biomass. A CO₂ system was omitted. The algae were harvested, dewatered and dried before being processed with conventional textile machinery. From 100 % algal fibres non‑woven fabrics were produced. In blends with other natural fibres, fibre strands were spun on rotor‑spinning machines into yarns, and the first knitted fabric samples were made. Textile testing confirmed that the produced yarns and fabrics met basic mechanical and structural criteria, demonstrating that filamentous green algae can be converted into usable textile products.

Economic assessment and market potential studies were conducted in parallel, and industry partners were identified for a subsequent technical feasibility phase. The collaboration structure involved the algae research institute providing biological expertise and pure cultures, the fish‑farm partner supplying aquaponic infrastructure and waste water, and the cultivation company offering large‑volume vessels and scaling experience. Regular online and in‑person meetings ensured close integration of biological and textile engineering teams. The project’s outcomes confirm that filamentous freshwater green algae can be cultivated under controlled conditions, processed with existing textile technology, and yield 100 % algal non‑woven fabrics and yarns suitable for further textile applications, thereby establishing a foundation for future industrial development.