Flashing LEDs for Microalgal Production

Flashing lights are next-generation tools to mitigate light attenuation and increase the photosynthetic efficiency of microalgal cultivation systems illuminated by light-emitting diodes (LEDs). Optimal flashing light conditions depend on the reaction kinetics and properties of the linear electron transfer chain, energy dissipation, and storage mechanisms of a phototroph. In particular, extremely short and intense light flashes potentially mitigate light attenuation in photobioreactors without impairing photosynthesis. Intelligently controlling flashing light units and selecting electronic components can maximize light emission and energy efficiency. We discuss the biological, physical, and technical properties of flashing lights for algal production. We combine recent findings about photosynthetic pathways, self-shading in photobioreactors, and developments in solid-state technology towards the biotechnological application of LEDs to microalgal production. Light sources require technical fine-tuning for efficient emission of intense light flashes that match the kinetics of the photosynthetic apparatus and are able to penetrate deeper into microalgal cultures. Flashing light may decrease the energy required to achieve a given productivity compared to continuously supplied light. Flashing light systems require higher light output during the light period than standard light sources, and this can be achieved by increasing the current supplied to the LED. Efficient flashing light emitters are single-color LEDs and laser diodes rather than organic LEDs (OLEDs) or phosphor-converted white (pc-)LEDs. Laser diodes will be promising for future flashing-light sources and may induce beneficial quantum effects on microalgae.