In the near future, energy demand will have a great increase, due to the enhancing needs in life quality all over the world and especially from large emerging economies of Asian countries like India and China. Therefore, it is of most importance to find alternative fuels and to increase the contribution of renewable energy to world-wide energy production. These goals could be achieved by using biomass wastes for energy production, which would also allow decreasing large amounts of wastes with negative impact on environment and at he same time, decreasing CO2 emissions and global warming. This book analyses several gasification gas treatments, either thermal or catalytic to accomplish a considerable decrease of undesirable compounds to guarantee the production of a clean gasification gas with a wide range of applications.