Biomass conversion technologies for a circular carbon economy

Using biomass for energy and chemical sources is one of the effective strategies to develop a sustainable society and attain a net zero and biobased economic future. Biomass-derived bioenergy releases carbon dioxide (CO₂), which can be reabsorbed quantitatively into the plants’ biomass through photosynthesis during the growth stage, resulting in a net zero CO₂ emission. Biomass can be derived from a broad spectrum of raw resources, including forests, wood processing residues, agricultural crop wastes, energy crops, algae (e.g., microalgae), and fractions of organic waste products. A range of energy requirements may be achieved by biomass, including power production, home heating, transportation fuels, as well as value-added chemicals. It is possible to achieve these through biomass conversion technologies and biorefineries, leading to a biobased economy. This chapter aims to provide an overview of several biomass conversion technologies (thermochemical and biochemical) and the concept of biorefinery, highlighting the use of microalgal biomass as a feedstock. Matching biomass feedstock with conversion technologies based on biomass characteristics, technological features, and the kind of bioenergy required is presented as crucial for maximizing energy production and efficiency. Moreover, the circular carbon economy strategies for biobased economy implementation in biorefineries are also critically reviewed. In summary, the chapter provides fresh insights and directions for future research on biomass conversion processes and biorefinery, while highlighting the existing areas of applications that require scaling up.