Red luminescent solar concentrators to enhance Scenedesmus sp. biomass productivity

Abstract

Increasing biomass productivity of an outdoor mass microalgal culture is the main aim of any large-scale algal producer. Under nutrient enriched conditions, light is the primary limits to growth of any microalgae. This normally results in a high level of photolimitation when paddle wheel driven raceway ponds are used as no light can penetrate beyond the top few centimetres of the culture. To achieve high biomass productivity, there is a need to develop an efficient system to deliver light into the depth of microalgal cultures in raceway ponds. We investigated red luminescent solar concentrators (LSCs) in outdoor raceway ponds to downgrade the sunlight, re-emit and, deliver it into the depth of Scenedesmus sp. cultures operated at 21 cm depth. Biomass productivity of Scenedesmus sp. significantly increased by 18.5% when red LSCs were used (9.4 g m−2 d−1). Scenedesmus sp. protein (52.9% of biomass) and lipid (16.5% of biomass) contents with red LSCs were also 15% and 10% higher than those in control with no LSCs. Protein, lipid and carbohydrate productivity of Scenedesmus sp. were also improved by 35%, 20% and 16% when red LSCs used. Therefore, if the aim is biomass production for animal feed, there would be 18.5% less cultivation area for generating the same biomass productivity using red LSCs. This can lead to a significant reduction in the cost of biomass production.