CHAPTER 9Hydropower Plants – Wet Electricity

Today there are far fewer hydroelectric plants than there were in their heyday at the end of the eighteenth century. At that time between 500 000 and 600 000 water mills were running in Europe alone [Köni99]. In those days France was the country with the highest number, although thousands were also being used in other parts of Europe. Water wheels not only drive mills but also power a number of other tools and machines. Flowing waterfalls were harnessed by watermills with wheels up to 18 m in diameter. At five to seven horsepower the average power of water mills at that time was still comparatively modest (Figure 9.1).

The illustration shows an image of a watermill in the Alps.

Figure 9.1 Historic watermill in the Alps. Source: Verbund,

As more and more mills were built on rivers and streams, the activity was strictly regulated, and mill operators were instructed on how long mills could be used and how large they could be. This may have been an annoyance for them, but it was a good thing because it promoted technical development and ensured that optimal use was made of existing mills. This constant drive to improve gave rise to the modern, highly efficient turbines used in hydropower plants today.

The introduction of the steam engine slowly displaced water-powered systems. But, in contrast to wind power, the use of hydropower did not vanish with the increased exploitation ...

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