Please do not use german within the english threads, you can make a topic in the german sub forums for that, I'm hence continuing to answer in english:
The point of Eco is not to represent maximum realism, but to provide an abstraction with balanced gameplay, that sometimes just makes it necessary to do things differently - this is the case here, we wanted the machinist tables to require power in a way that windmills and water wheels cannot easily provide, so the use of a steam generator is required for that.
Your second comment is based on electricity, e.g. electrical power. The wind _turbine_ and solar panels are suitable for that and still have sufficient energy output, but with the Industrial Generator there is a high power dirty alternative. It is intended to be like that - players need to choose if they want to pay more and push tech further to avoid that or use the cheap energy that has negative effects. That's the point of Eco.
Please note that you can set resource cost modifiers for singleplayer. All our recipes are balanced around multiplayer public servers.