Perspectives of Energy Production from Microalgae: The Biodiesel and Cogeneration Cases

During the last two decades, the use of biofuels has shown rapid growth, driven mostly by policies focused on increasing energy efficiency, and replacing fossil energy by renewable energy. There are different biomass raw materials that have been evaluated for the production of several added-value products. These raw materials have been classified into the first generation (agricultural and edible crops), second generation (inedible agroindustrial residues) and third generation (algae). The interest in the cultivation of microalgae has been increasing due to the high value products that can be obtained. Additionally, the oils present in microalgae are used for the production of biodiesel and the cake resulting after processing can be used for the production of bioethanol, biobutanol or energy. Based on this, this chapter first introduces the current uses and applications of multiple species of microalgae in terms of energy production and describes the technologies being used for the production of bioenergy using microalgae. Then, two specific cases are analyzed: cogeneration and biodiesel production. The performed analysis serves to conclude that in order to establish microalgae as an energy-producing feedstock, it is necessary to integrate their use to obtain multiple products simultaneously: metabolites due to their high value, oils to produce biodiesel and the dry cake for thermochemical production of energy. The extraction of multiple products can only be made possible if a biorefinery concept is applied.

Keywords: Microalgae, Biorefineries, Bioenergy, Biofuels, Biodiesel, Cogeneration.