You're mixing up historic costs with current costs. As an illustration: the moon landing cost just $25 billion dollars, the Manhattan project even just $2 billion, what do you think a project of these scales would cost today?
You're also mixing the status quo with your (unclear) desire of how the world should be. Germany spent the last 80 years to build up an energy grid built on coal – nuclear peaked at 30%!. Of course they emit more CO2 today compared to the French!
But if anything, that's an argument for why Germany should start agressively building out renewables (aggression there was abandoned 20 years ago by the Merkel admin).
> 3 trillion or more till 2045
Looking at decades is a surefire way to get big numbers. But depending on your starting points (I guess 1999 during SPD/Greens coalition), that's just €60 billion per year. A lot of money but not exactly shocking.
> The idea to produce wind in the south of Germany is part of such madness.
Even the state of Bavaria - not exactly known to be mad for wind power - classifies more than half of its area as containing locations suitable for wind power. Of course that's nothing compared to Lower Saxony, but that's why they aim for total installed capacity of just 6 GW by 2050 (source for all that is the Bayrischer Windatlas issued by the, again, very sceptical of wind power, CSU government of Bavaria).
You're really just decade old fud against renewables. Do you really think that in the whole of 70 thousand square kilometres of Bavaria there are no points where the wind is strong enough 150 m above ground to produce power profitably? Because that's just not true. And 6 GW, by the way, are just one to four thousand modern turbines. Across the largest state of Germany. There's nothing mad about that at all.