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 30 by 30 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 synthetic E-Fuel or E-Gas) 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.
There are 5 aspects to consider in the scenarios.
Aspect 1. On the Tables and Explanations and Compact Data page, it was explained that we would need to greatly increase current investments in solar and wind. By a factor of 15, in fact, to achieve CO2-free energy production in one generation. This is theoretically possible, but the resources are not available 41). It is a challenge to find the resources for the accelerated build-up of green energy capacity. This must be achieved through increased efficiency and improved technology. If the problem cannot be solved, the missing share of green energy can in principle only be generated with nuclear power plants. However, this should be avoided if possible.
Aspect 2: Even if it is possible to achieve CO2 neutrality in one generation, the CO2 content in the atmosphere that has increased by then will remain. This, of course, also means that the temperature will continue to increase. This would have to be reduced by about one third to reach the level of 1900. That is one third of approx. 800 gigatonnes of CO2 42). That is 264 gigatonnes of CO2. This corresponds to 72 gigatonnes of carbon. It is assumed 1 cubic metre of wood for an average tree (D x L=0,3m x 10m). One tonne of weight is assumed for one cubic metre. Then a tree stores half a tonne of carbon 43). About 200 billion (10^9) trees would have to be planted to store this amount of carbon. Then the CO2 content of the year 1900 would be reached again 45), namely approx. 300 ppm instead of 425 ppm. For comparison, there are currently about 3 trillion (10^12) trees in the world with diameters larger than 10 cm. That is 3000 billion trees 44).
Aspect 3. In fact, the energy consumption world will increase even further. Hopefully, nuclear fusion will become a reality in the near future 45) 46). But even that will not allow infinite growth on a finite planet. Resettlement on suitable planets in the universe will remain science fiction forever. If not enough green energy capacity is invested, a 6th mass extinction on this world cannot be ruled out 47). In addition, the world population must not continue to increase, but better decrease. Consumer behaviour, including meat consumption, must be changed. The last two demands, however, are sufficiently well known.
Aspect 4: Hydrogen (storage medium) will play a major role in the success of CO2-neutral primary energy supply. Here, it is necessary to organize the production, transport, storage and distribution to the end users. Generation is still in its infancy. A big problem is that for the production of 1 kg hydrogen at least 9 kg water are needed (hydrogen has an atomic weight of 1, oxygen of 16, water H2O therefore 18. So for 2 parts hydrogen 18 parts H2O are needed and shortened that is 1 to 9. The water must currently still have drinking water quality. The problem is that drinking water is scarce in countries that have a lot of solar radiation. Bridging the gap with desalination plants makes no sense because the efficiency would drop even further. So it must be possible to produce hydrogen safely from seawater using green electricity. First approaches exist, see the page "News". But the most efficient and economical way is always the direct consumption of green generated electricity. The production of green hydrogen only makes sense where this is not possible.
Aspect 5: The calculations shown above and the data in the image are the worst case. Here, 100% of the primary energy is replaced by renewable energy. This is not necessary, since renewable energy can be used more efficiently than fossil energy. For Germany, the optimised values have already been calculated on the page "Explanations Tables" in scenario 4 and table "FINTAXD2". The upper left corner of the Excel chart is cell B2. The energy in cells E7 and F7 Biomass and Green Power is already neutral. With an additional 2.39% land area (cell Q30), 404 TWh are produced (cell K4). For the rest, hydrogen is imported and used with an efficiency of about 50%, e.g. for gas turbines, fuel cells, industrial gas, combustion), which is the sum of the marked cells in column J plus elimination of nuclear 230TWh equals 849 TWh multiplied by 2. This means that in addition to 174 TWh of green electricity produced in 2018 (cell F7), 404 TWh of green electricity would have to be produced on an additional 2.39% land area. In addition, about 51 million tonnes of hydrogen would have to be imported. That is the challenge.
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