This book highlights the processes of biomass thermochemical conversion, covering topics from combustion and gasification, to pyrolysis and liquefaction. Heat, power, biofuels and green chemicals can all be produced by these thermochemical processes. The different scales of investigation are presented: from the bioenergy chains, to the reactors and molecular mechanisms. The author uses current research and data to present bioenergy chains from forest to final use, including the biomass supply chains, as well as the life cycle assessment of different process chains. Biomass conversion reactors are also presented, detailing their technologies for combustion, gasification and syngas up-grading systems, pyrolysis and bio-oil upgrading. The physical-chemical mechanisms occurring in all these reactors are presented highlighting the main pathways for gas, char and bio-oil formation from biomass. This book offers an overview of biomass valorization for students, engineers or developers in chemistry, chemical, environmental or mechanical engineering.