The German economic boom was over in the 1970’s. Since then its been developed economy slow growth. Back when they had a boom, 1950’s-70’s their principal energy source was - coal. And energy is a small % of economic output for Germany. They will get over this pretty quick. They are a rich and capable people.
A basic grounding in the economic history of Europe, energy industries, and probably basic economics wouldn’t hurt. Its a damned big subject, but essential. I always recommend Yergin’s “The Prize” as a starter on energy, strategy and how they relate to economics. Its also a great story.
They did just great over the last 20 years. Germany was a toilet compared to the UK in the 1990s, now it is the other way around.