Elliptic Paraboloid-based Solar Spectrum Splitters for Self-powered Photobioreactors

Abstract Microalgae has potential for large-scale biofuel production and CO2 remediation, however its growth is energy intensive and easily hindered by contamination, unsuitable conditions, and photosaturation. To mitigate these problems the solar irradiance can be partitioned into photosynthetically active radiation (PAR) and photosynthetically inactive radiation (non-PAR). The PAR can be used for algae growth in a photobioreactor under controlled conditions. The non-PAR can be used to generate electricity in photovoltaic (PV) cells to power the photobioreactor. We present numerical analysis of a luminescent solar spectrum splitter (SSS) that partitions the solar irradiance into PAR and non-PAR to simultaneously power algae cultivation systems and PV cells, respectively. The SSS directs non-PAR to PV cells with emission losses of 6%, and an optical efficiency of 73%. Furthermore, the Shockley-Queisser efficiency limit for non-PAR is calculated to be 24% and the SSS enables a non-PAR conversion efficiency of 15.8% for direct solar irradiance. This is enough power to provide for the cultivation and harvesting processes in the photobioreactor. Results show the generated power can also be used to increase algae growth by 9.3 %. The luminescent SSS enables self-powered photobioreactors with increased utilization of space and solar radiation, and higher net energy gain ratios.