Rivers were used to turn watermills and the Romans even used geothermal water for heating. Until the middle of the 18th century renewable sources of energy were the only forms of energy available, but then, with the advent of the Industrial Revolution, fossil fuels began to be exploited.
The Sidereal Zodiac is the position of the sun referenced against the star background, as a measure of the flow of time. The framework for the star background is the constellations the sun passes in front of. This is the one astronomers use.
It is too easy to say that the sidereal zodiac or the tropical zodiac is the right one to use. What often appears to be polar points of view can both be right or, at the very least, aspects of both be correct. Sometimes we just have to couch the other s perspective in our own terms.