Development of an Integrated Process for Bio-oil Production from Microalgae

In this paper an integrated process for bio-oil, fine chemicals and energy production from microalgae in photobioreactors is proposed. The proposed process is aimed to: fix carbon dioxide coming from thermovalorization plants; use the industrial effluents containing organic carbon and nitrogen for the heterotrophic growth of microalgae; obtain bio-oil as raw material for biodiesel production; produce high value-added fine chemicals; increase the thermal value of the solid residue for energy production. The selected strains (Chlorella vulgaris and Nannochloropsis oculata) were used in labscale reactors in order to optimise the operating conditions for maximising oil production. The development of new technologies producing alternative and renewable energy is a priority target of institutional governments and private enterprises due to the depletion of fossil oil reservoirs and the dramatic increase of energy requirements from emerging countries. The Mediterranean Basin is characterized by wide regions with significant solar irradiation which could be exploited for the production of renewable combustibles and, among then, oil for biodiesel and hydrogen (Scott et al., 2010). Biodiesel can be produced by alkali treatment with methanol of different kinds of oils as raw material. Oils are mainly obtained by agro-industrial productions (first generation biocombustibles). Actually in Europe, and in particular in Italy, biodiesel is produced using palm oil imported from Asia making rise the global impact associated to the production of this biocombustible due to energy consumption for the transport. The low yield of oil from agricultural cultures along with the growing need of fields to be used for food production, make microalgae a good alternative candidate for oil production. Some microalgae can give up to 70% of oil as dry weight; they grow easily and rapidly if exposed to the proper solar irradiation, and oil extraction can be simply obtained by pressing them (Wijffels and Barbosa, 2010). The availability in the Mediterranean Basin of oil as raw material for biodiesel production will contribute to the diffusion of this biocombustible by diminishing its price (today up to 90% of production costs for biodiesel can be due to raw material). In addition building such full-plants in geographical regions that are without alternative use, will be a way to valorize them promoting the technological, economical and social development of the area.