We describe a methodology to investigate the potential of given microalgae species for biodiesel production by characterizing their productivity in terms of both biomass and lipids. A multi-step approach was used: determination of biological needs for macronutrients (nitrate, phosphate and sulphate), determination of maximum biomass productivity (the "light-limited" regime), scaling-up of biomass production in photobioreactors, including a theoretical framework to predict corresponding productivities, and investigation of how nitrate starvation protocol affects cell biochemical composition and triggers triacylglycerol (TAG) accumulation. The methodology was applied to two freshwater strains, Chlorella vulgaris and Neochloris oleoabundans, and one seawater diatom strain, Cylindrotheca closterium. The highest total lipid content was achieved with N. oleoabundans (25-37% of DW), while the highest TAG content was found in C. vulgaris (11-14% of DW). These two species showed similar TAG productivities.

International audienceVertical flat-panel photobioreactors for microalgae culture can be integrated into building facades. On topof providing the large solar illuminated surfaces needed for microalgae production, this original combinationopens various optimization opportunities, such as the possibility to create mutual benefits forboth systems with appropriate and efficient integration. For example, microalgal photosynthesis canbe used to fix the CO2 contained in flue gas emitted from the building (in a factory set-up) or to significantlyreduce energy consumption for thermal regulation of both photobioreactors and building.Here we report the results of a theoretical modelling-based investigation designed to define how thespecific building integration conditions affect photobioreactor operation. Expected biomass productionand light attenuation conditions encountered in the culture volume were determined for the greenmicroalgae Chlorella vulgaris for a location based in Nantes (France). Results were compared to figuresfrom the more conventional systems such as horizontal or ideally-inclined microalgal culture systems.We conclude with an energetic analysis that underlines the relevance of optimizing thermal exchangesbetween microalgal culture and building