This article by Pierre Radanne summarizes in a few pages the key challenges raised by the third energy crisis that has been affecting the world for the past year or so. He first offers a brief description of the cyclical nature of energy and then goes on to describe how this recent crisis developed, stressing the way that concerns about climate change have put the present oil shock on a very different plane to previous ones. The challenge now is at a much broader level, relating to how people live: Western lifestyles cannot be adopted by the whole planet; consequently it is imperative that the industrialized countries seek new patterns of behaviour that reduce energy consumption. Pierre Radanne argues that public authorities, especially in Europe, must rank their priorities and establish long-term strategies, involving a certain "re-regulation" of the energy sector. He concludes that it is essential to be equipped to make a success of the 21st century by using the energy sector as a vector for tackling the problems of climate change and an approach to creating a new form of civilization for the whole planet.