The development of innovative technologies in the energy field constitutes one of the major difficulties facing the future. The repercussions for the environment will be crucial. What are the various types of innovations in the field of energy: are they incremental or radical? What are the main driving forces behind these innovations? We describe the various mechanisms behind these types of innovation in both a French and European context using three different examples: compact heat exchangers, refrigeration equipment, hydrogen and fuel cells. (c) 2004 Elsevier Ltd. All rights reserved.