Systematic insights into electricity cost of LED lighting in photobioreactors for biomass and pigment production in Limnospira maxima (Spirulina)—Light spectra and intensities examined
摘要
This study provides missing data for Limnospira (formerly Arthrospira) maxima cultivation and key insights for evaluating the optimal artificial light source for photoautotrophic production of biomass and pigments. Rigorous experimental datasets were analyzed to clarify the relationship between illumination (LEDs) characteristics (intensity and spectral composition) and biomass/pigments production, considering lighting energy costs in the technologically relevant light-limited region of the photosynthesis-irradiance curve (up to 550 µmol photons m−2 s−1). Using the same light spectrum (cool white), higher light intensities consistently increased biomass productivity, with a maximum of 0.97 g L−1 day−1 at 550 µmol photons m−2 s−1. However, the lowest lighting energy costs per unit of biomass and pigments were achieved under low light intensity of 100 µmol photons m−2 s−1 (0.57 kWh g−1 of biomass, 2.45 kWh g−1 of phycocyanin, 51.4 kWh g−1 of carotenoids, and 15.4 kWh g−1 of chlorophyll a). When spectral composition was varied at constant light intensity of 50 µmol photons m−2 s−1, the highest productivity and lowest energy costs were observed under daylight white (0.06 kWh g−1, 0.31 g L−1 day−1) and warm white light (0.08 kWh g−1, 0.29 g L−1 day−1), followed by red light (0.15 kWh g−1, 0.27 g L−1 day−1). Surprisingly, pigment content remained relatively stable across all spectra. These findings provide practical guidance for optimizing L. maxima cultivation by balancing productivity and energy efficiency. By coupling biological outputs with measured wall-plug power, we report product-specific lighting electricity costs (kWh g−1) and identify daylight white and warm white LEDs as practical, energy-efficient options for Limnospira maxima cultivation in the light-limited regime.