Abstract As photosynthetic microorganisms with carbon-fixing ability, algae can potentially be exploited for sustainable production of biomass, food, fuels, and chemicals. However, their substantial water demand has hindered the widespread application of algal cultivation and offset its benefits to some extent. Herein, we designed scalable membrane shade materials that suppress water evaporation in microalgal cultures and assessed their effects on algal growth. The anti-transpirant shades are hydrophobic (131.5 ± 0.9 °), recyclable electrospun nanofibrous membranes composed of polylactic acid (biodegradable) or poly(methyl methacrylate) (recyclable). Industrial composting confirmed the biodegradability of polylactic acid shades, whereas poly(methyl methacrylate) samples showed no detectable biodegradation, indicating their suitability for systems requiring long-term material stability. These shades combine excellent thermal and mechanical strength with high visible-light transmission and ultraviolet filtering while maintaining CO 2 and O 2 gas exchange. They reduced water loss by up to 87% and dampened outdoor irradiance spikes down to ~500−530 μmol m −2 s −1 , improving the uniformity of the light profile. Although the shades slightly lowered the final cell densities and biomass (8.7 ± 0.4 g L –1 ) of Chlorella sorokiniana cultures compared with uncovered controls (12.4 ± 0.2 g L –1 ), they enhanced the consistency, reproducibility, and predictability of growth, facilitating harvesting and reducing the exposure of cultures to airborne particles. By combining effective evaporation control with light stabilization and adequate gas transfer capability, these recyclable, scalable nanofiber shades can pave the way for predictable, water-efficient microalgal cultivation and potentially enable large-scale outdoor operations in arid environments.
Oldal et al. (2026) studied this question.