The contemporary debate on global warming has made the distinction between renewable and non-renewable energies a fundamental intellectual tool for future-oriented studies. From an historical perspective, the study of transitions associated with industrialization and reliance on fossil fuel use has clarified the place of energy in the innovation processes of the last two centuries. Nevertheless, the notion of renewable energies, now central to any prefiguration of future technological and economic systems, remains to be defined in terms of economic history. E. A. Wrigley drew attention, in a series of pioneering publications, to what he called the "organic economy", showing that economies based on the exploitation of the biological resources of ecosystems could undergo phases of growth and innovation, and that it was on one of them that the English industrial revolution was built. On the other hand, R. C. Allen showed in the case of England that it was necessary to distinguish between the diffusion of coal as a fuel, attested from even before the beginning of the modern era, and industrialization itself, which responds to a different logic. Finally, various authors, in particular L. C. Hunter, have shown that, outside the British Isles, the industrial transition may have included a massive share of renewable energy, particularly hydro, wind and biomass. While the category of fossil fuel does not raise definitional problems, the category of renewable systems has so far remained outside historians' discussions. The finalism that most often marks the debates on industrialisation makes it possible for many scholars to be satisfied with a minimalist definition: renewable energies are those that preceded the fossil energies which were used during and after the industrial revolution. Any researcher familiar with the history of technology knows, however, that transition phenomena do not result in the complete replacement of old technologies but in their integration into a new mix. The session will focus on the economic characterization of renewable technological systems over the long term. The notion of renewable energy, as opposed to fossil fuels, involves the distinction between energy flow and stock. Some renewable energy systems (hydropower and wind power in particular) take advantage of (usually minimal) fractions of energy flows from the sun, or derived from the solar flux; the others manage to immobilize or slow down these flows to build up stocks of potential energy. The study of these mechanisms over the long term suggests that their technical characteristics are intrinsically linked to their institutional aspects and that the political and social choices that make them possible are also those which determine the conditions of access to energy resources. The case studies presented by the session participants will focus on the institutional construction of the category of resource and the economic specificities of renewable systems of yesterday and today. Papers : A “Carpocene” in 16th century Bohemia: the invention of a new resource carp in seigneurial fish farming (Sarah Claire - CNRS-CRH-EHESS, UMR 8558) The Oil in the Renewable: How Incumbent Oil Constellations Have Shaped Renewable Energy Systems in the Twentieth Century (Odinn Melsted - Maastricht University) Paris 1200: Metropolitan process and Energy issues (Arnoux Mathieu - Université Paris Cité) Energy metabolism in a trading metropolis: 1552-1913 (Sofia Henriques - CITCEM - University of Porto, António Henriques - University of Porto) Biological Invasion, Mesoamerican Resilience and Agrarian Expansion after the Spanish Conquest (1500-1700) (Jerónimo Bermúdez - Ecole des hautes études en sciences sociales, Zacarias Moutoukias - Laboratoire Interdisciplinaire des Energies de Demain)