This book confers a comprehensive discussion on the production and biorefining of biocrude oil derived from second- and third-generation biomass feedstocks. It discusses about the concept of biorefinery—fundamentals, biorefining raw materials, and feedstocks and its associated challenges. The book emphasizes on the 3rd-generation biorefining feedstock (algae) as an emerging feedstock for the biorefineries. In addition, co-feedstocks employed in biorefinery are also deliberated. It also presents various thermochemical conversion approaches such as hydrothermal liquefaction, pyrolysis, Fischer-Tropsch process and hydroprocessing. It deals with the sustainable production of biocrude oil from algal biomass and its upgradation for enhanced fuel properties. The book also deliberates on current scenario and future developments in the field of biorefining of biocrude oil and catalysts. A comparative assessment of properties and downstream upgradation of biocrude oil through hydrothermal and pyrolysis processes is presented. Moreover, sustainable production of biofuels and value-added products from biorefinery, life cycle and techno-economic assessment of the conversion of biocrude oil from pyrolysis, and biocrude upgrading technology and challenges are also discussed. This book is a good reference for professionals, post-graduate students, researchers, and policymakers working in the areas of biorefineries for sustainable development.