摘要：Scanning the last 250 years, we can observe five great technological transformations that happened in the socio-eco-nomic development. On the other hand, there is a relationship between the socio-economic development and the substi-tution process of primary energy sources. Since the industrial revolution, there has been a smooth but growing substitu-tion among primary energy sources. First the switch from wood to coal, then this last one by oil and natural gas. These are non-solid fossils, which leads to a decrease of the carbonic intensity. These substitutions implied some important technological transformations. Bearing in mind a sustainable development of energy systems and using technological forecasting tolls, this study points out to the leadership of the alternative energies among the primary energy sources until 2050 - 2070. In this sense, even with the predictable overall increase of energy consumption, this study also shows that through the substitution dynamic it is possible not only to reduce the carbonic intensity, but also to reduce the car-bonic emission in absolute terms from 2040 - 2060 on.
