The actual predominance of fossil energy, among the different sources that supply the global need, gives rise to serious geopolitical and environmental problems, which represent one of the most urgent challenges that mankind is facing today. A sustainable mix of alternative and renewable sources is required to face this challenge. However, the present solar and wind technologies, which actually represent the most relevant renewable sources, have strong limitations, due to their high costs and their low generated power density per km2, so that incentives are required for their application. In this paper, we describe a radical innovation in wind energy generation, based on the idea of employing controlled tethered airfoils to extract energy from wind at higher elevation (up to 1000 m above the ground) with respect to the actual wind towers. This way, the stronger and more constant high-altitude wind, blowing everywhere in the world, is exploited for energy generation. Through numerical simulations, prototype experiments and wind data analyses we demonstrate that such technology may represent a quantum leap in wind power generation, providing large quantities of renewable energy, available everywhere, with production cost even lower than oil. It is expected that the industrialization of the proposed wind technology may require from 3 to 5 years, since no more basic research or technological innovations are needed, but only the fusion of advanced competencies already available in different engineering fields, such as modelling and control, aerodynamics and flight mechanics, materials and mechatronics. Thus, the described high-altitude wind technology may contribute, in a relatively short time, to a major reduction of the global dependence on fossil sources, far beyond the EU goal of 20% of renewables for the 2020, considered indeed by many experts and governements very ambitious and hard to reach with the present renewable technologies.