Light Emitting Diode Systems for Artificial Photobioreactors Used in Algal Biofuel Production: A Systematic and Trend Analysis

Photobioreactors (PBR) support the production of algal biomass which is a known resource in producing biofuel. Different LED system configurations, however, affect the growth of algae. This study aims to do a literature review on the different light utilization trends of photobioreactors used for cultivating algae. This study also seeks to fill in the gaps common to the trends by using engineering principles. Photobioreactors and their working principle are introduced. Importance of light in photobioreactors is emphasized and different journals on LED trends such as LED placement, light intensity, flashing light, and light spectral quality are peer-reviewed. Results show that bottom surface directional lighting helps the cultivation more in comparison to upper surface directional lighting. Higher levels of light intensity on the other hand support the growth of algae although excessive levels cause the protective mechanism to weaken. Flashing light is also found to be slightly more conducive than continuous light mostly based on flashing light being more energy efficient. For light spectral quality, it was reported that blue and red lights are important to promote the growth of the culture. However, with regards to spectral composition of light, the best fit for one algae strain may differ from that of another strain. As such, investigation of the best-fit spectral composition for the strain to be used must be done when designing a PBR. Some recent LED system advancements were discussed and were found to be efficient devices that can be used for photobioreactors although costing remains to be a problem. Application of electronics engineering principles on the possible synchronous use of solar and artificial light is recommended to lessen the cost. Such advancement can pave the way for efficiently using LEDs in photobioreactors for large-scale deployment.