Microalgae cultivation in semi-transparent photovoltaic bioreactor for sustainable power generation, wastewater treatment and biodiesel production

• Semi-transparent photovoltaic bioreactor improved microalgae growth rate. • Nutrients removal efficiency by microalgae promoted in the designed bioreactor. • Lipid content of the microalgae increased (3%) by in the designed bioreactor. • 37 kWh/m 2 electrical energy was generated by the semi-transparent photovoltaic. Sustainable energy harvesting from renewable resources such as sunlight and microalgal biomass has received great attention due to the depletion of conventional energy sources and the increasing demand for clean energy. In this research, a novel approach for simultaneous electric power generation and biofuel production was developed by microalgae cultivation in semi-transparent photovoltaic bioreactor which has the potential to be applied as a building facade. According to the results, the maximum biomass concentration of Chlorella sorokiniana and Chlorella vulgaris increased from 2.5 to 2.9 g/L (15 %) and from 2.7 to 3.2 g/L (18 %) by using semi-transparent photovoltaic instead of glass in a photobioreactor, respectively. The wastewater treatment ability and high-value production (i.e., lipid, lutein and chlorophyll a and b) of the green microalgae were also improved by microalgae cultivation in the semi-transparent photovoltaic-photobioreactor. This was attributed to the better light quality and temperature of the medium in the semi-transparent photovoltaic- photobioreactor. More than 37 kWh/m 2 of electrical energy was generated from the semi-transparent photovoltaic-photobioreactor during microalgae cultivation which was enough to provide the electric power required for light operation. The scale-up analysis suggested the proposed approach as a promising technique for biological wastewater treatment and renewable energy generation from solar irradiation and microalgae biomass.