The highly proactive policy of developing renewable energies that Germany implemented from the beginning of the 2000s has been taken as a model to follow to achieve the energy transition by substituting renewable energies for fossil fuels. The increase in the production of renewable energies has offset the sharp drop in production from nuclear and coal-fired power stations. This apparent success of the Energiewende partly inspired the Green Deal aimed at decarbonizing the European economy by 2050, by replacing fossil fuels with renewable energies. Germany has also set itself very ambitious targets for the development of renewable energies and makes it possible to achieve carbon neutrality by 2045. However, achieving such goals in the foreseen time frame is likely to prove particularly difficult, as several major obstacles have been greatly underestimated. In the absence of sufficient energy storage capacity, it is then necessary to build even larger capacity of intermittent renewable energy. But even in the hypothesis of the production of an energy vector allowing storage such as hydrogen, it would be necessary to build large renewable capacity. The challenge to be met is all the greater since electricity represents only 20% of the country’s final energy consumption. The rest, corresponding mainly to the production of fuels and residential heating and industrial and tertiary activities, is provided mainly by gas and oil which, together, constitute approximately 60% of final energy consumption.