[en] New and renewable energies (hydro-power, wind-power, solar, biomass, biogas, geothermal and fuel cells) are progressively entering the industrialization phase (except for hydro-power which is already largely developed). Thus they are no more considered as solutions for utopian ecologists but have reached the status of alternative technologies. This study takes stock of the following questions: what are the applications of renewable energies, what is their stage of development and their potential with respect to fossil fuels, what are their perspectives of development, and what are the strategies developed by the actors of the sector? The main stakes of the renewable energy sector are: fulfilling the increasing power needs (in particular with the wind and solar power in isolated areas), improving the competitiveness (reduction of the investment costs), developing financial incentives (tax relief, financial helps, eco-taxes..), participating to the reduction of pollutant emissions. The renewable energy sector is progressively structuring and profits by the increasing implication of major energy actors, such as the oil companies. The behaviour and strategy of 14 major actors of the renewable energy sector is also analyzed. (J.S.)