Microalgae Biorefineries for Energy and Coproduct Production

The 2015 Conference of the Parties (COP21) marked a turning point for global actions to mitigate atmospheric greenhouse gases, reduce the carbon dioxide emissions from fossil fuel combustion, and stabilize the global climate. On the other hand, the increase in energy demand asks for renewable sources and robust systems to supply energy and obtain product diversity like that obtained from a petroleum refinery. A biorefinery is the sustainable processing of biomass into a spectrum of profitable products and energy. Microalgal biomass is considered one of the most promising biorefinery feedstock providing alternatives for different areas, such as food, feed, cosmetics and health industries, fertilizers, plastics, and biofuels including biodiesel, methane, hydrogen, ethanol. Furthermore, microalgae can also be used for the treatment of wastewater and CO2 capture. However, microalgal biofuels are not currently cost competitive at large scale and to develop a sus- tainable and economically feasible process, most of the biomass components should be valorized. High-value coproducts from microalgae include pigments, proteins, lipids, carbohydrates, vitamins, and antioxidants, and they can improve the process economics in the biorefinery concept. Therefore, mild and energy-efficient down- stream processing techniques need to be chosen to maintain product properties and value. In this chapter, the existing products and microalgae biorefinery strategies will be presented, followed by new developments, sustainability assessments, and techno-economic evaluations. Finally, perspectives and challenges of microalgal biorefineries will be explored.