In Medieval England, ambient energy was the labour saving power source of choice. Wind and water power, including tidal, was harnessed to run mills and forges all across England; there were thousands of them, perhaps around 10,000 in the early 14th century.
We can get a sense of their ubiquity from the following maps, first showing just the windmills recorded on manors in escheats (inquisitions post mortem). Source: Mills in the medieval economy: England, 1300-1540 By John Langdon.
Water was also widely harnessed on manor lands, both inland and at the coast as tidal mills.
To get a sense of how common water and wind power was – when it used to be in everyone’s backyard – I also recommend reading The Medieval Machine: The Industrial Revolution of the Middle Ages by Jean Gimpel.