Integrated processes for the production of bioenergy and biofuels based on microalgae cultivation

Microalgae are an interesting substrate to produce biofuels from renewable sources and high-added value compounds, used for nutraceuticals, food additives, nutritional supplements, cosmetics and pharmaceutical products. The scientific project “PON01_02061” – carried out with public fundings from MIUR (Italy) – allowed the implementation of a biorefinery realized in modular and expandable plant, currently operative, based on an outdoor pilot plant with energy-integrated photobioreactors to produce microalgae in Gioiosa Jonica (Calabria, Italy), in order to realize a biorefinery. Microalgae cultivation, harvesting, extraction and residual-biomass valorization have been integrated to produce biodiesel and biogas. Different microalgae have been tested with the aim to select the strain showing the best performance depending on different light and temperature conditions, up to 40°C in summer. For the cultivation of the selected Chlorella strain, a large scale plant has been realized. Temperature, CO2 and oxygen as well as microalgae growth and nutrient consumption were continuously monitored. Innovative separation system was selected for the microalgae harvesting, in large pilot scale to process several tens of m3 of medium with more than 99% of water. Wet microalgae were dried and then supplied to the solvent extraction pilot plant designed for the recovery of almost the 100% of lipids, taking into account that total lipids in microalgae are about the 10% respect to dry biomass. Waste biomass after extraction was fed to an anaerobic digester, where biogas was continuously produced.