Luminescent solar concentrator panels for increasing the efficiency of mass microalgal production

Highlights: • Photolimitation and photoinhibition reduce algal productivity. • Spatial light dilution systems can enhance algal productivity. • Luminescent solar concentrators downgrade light to a region suitable for microalgae. • Luminescent solar concentrators can cogenerate electricity. -- Abstract: Raceway open ponds are preferred cultivation system for mass algal commodity production. For operational reasons, large-scale raceway ponds must be operated at a depth greater than 20 cm meaning that algal cultures are normally light limited as light cannot penetrate into the depth below 5 cm. For the efficient distribution of light into the culture, different light delivery systems such as temporal and spatial have been proposed. If the proper mixing created, the flashing light effect can be created and that would result in a significant increase in biomass productivity. However, to date, this method has not been achieved in outdoor raceway open ponds. On the other hand, spatial light dilution systems are found to be more effective and economical that temporal light dilution systems. Among spatial dilution systems, luminescent solar concentrator (LSC) panels have a potential to be commercialized for mass microalgae production. Luminescent solar concentrators combine spectrum shifting properties with spatial dilution to channel the light into the culture where it is needed. There is also the possibility of electricity production as well as higher algal biomass production when using LSC panels in open ponds or PBRs. Additionally, compared to other proposed methods, the lower capital cost can be expected when using LSCs in algal cultivation systems as there is no need to use a solar tracking system to track the sun. In this review article, the effects of photolimitation, photosaturation and, photoinhibition in concentrated microalgal cultures, as well as the impact of applying different light distribution systems on the biomass productivity and photosynthetic efficiency as a result of having more uniform distribution of light into the culture, have been outlined.