The energy transtion has created opportunities towards decarbonization. While renewable energies are abundant, they are non programmable resources. Hydrogen can be the bridge between the rewewable energy and the chemical and power industries. However, its difficult transportation calls for its transformation into more handy chemicals such as ammonia or methane as energy carriers. This book presents all the steps from the hydrogen production to its storage in the form of chemicals and their use within a decarbonized and defossilized indsutry