The realisation of energy systems that do not consume resources and do not produce waste is the new challenge of energy research. This kind of energy systems are to be based on what we call Closed cycles of energy resources. The realisation of Closed cycles of resources can be achieved in the energy sector by exploiting renewable resources and structurally integrating energy vectors in the energy system. So the inclusion of energy vectors (to be produced from several primary resources) in the energy system chain becomes a key concept of the entire human development model. In this new scenario, the opportunity of using hydrogen shows all its interest. Hydrogen, electricity and other energy vectors, in a large scale application, allow to fully satisfy all the final uses of energy that the human society needs for its social and economical development. Energy vectors like electricity, heat exchanging fluids, and "producible" fuels-as hydrogen-are the key for entering a new energy era. What many call "hydrogen era" is in effect "the era of energy vectors". (C) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.