The solutions for CO2 neutral generation of primary energy shown in the "summary" for the world and Germany are difficult to implement for 2 reasons. First, global coordination among each other does not work. This is a prerequisite. Because there are countries which do not have enough area to produce enough green energy via solar and wind. And others which can produce more than they need. So a distribution has to be organized. This will only be partially successful in the short term. Secondly, the current investment in solar and wind energy would have to be multiplied enormously.
In the picture below, firstly, the solution world is shown. Theoretically and also practically, CO2-free generation of primary energy is possible. However, with the restrictions mentioned above.
Secondly, a solution for Germany is shown. A self-sufficient energy production is impossible due to lack of area, shown on the left (20.84% of Germany's area including factor 1.2 for offshore). A possible variant is shown, representation on the right. Here, about one third of the required primary energy is generated via solar and wind. The area needed for this is about 150 km by 150 km. The other two-thirds are generated via gas turbines fueled by green hydrogen or fuel. Alternatively, small nuclear power plants can be used. Both power plants are expected to generate 400MW per plant. A land area requirement of 1 square kilometer per plant is assumed. There are about 670 power plants of various designs in Germany. In turn, about 600 new plants would be needed. Some of the existing gas turbines can be converted. The total area required for these plants is only 25 by 25 km. The land required for this type of energy generation is only about 1% of that required for solar or wind. In addition, about 65 million tons of hydrogen (or similar) would have to be imported. The hydrogen (or similar suitable green artificial fuels) are used on the one hand for the operation of the gas turbines. On the other hand for industry (e.g. steel mills) and heavy duty transport (trucks and possibly buses). The challenge is, to organize the import of these volumes of artificila fuels, to make contracts with suited countries and to transfer the Know-how.
Importing 65 million tonnes of hydrogen (or similar) is a challenge. Not only the import has to be realised. Storage, distribution and use must also function. However, today Germany imports much more than 65 million tonnes as sum of oil, coal and natural gas. These quantities are then no longer needed.
The area requirement in the image is larger than calculated in the other sheets. On the one hand, this is because the energy mix can still be optimized. On the other hand, not 100% of the primary energy is needed. This is because electric cars etc. are much more efficient than internal combustion engines. This is taken into account on the other pages.
The data for the image is included in the table next to it.