Hydropower

Hydropower was probably humans’ first successful way to capture mechanical energy, which could then be harnessed to do useful work. Moreover, water power seemed unlimited, driven as it was by the sun, wind, and rain. Civilizations throughout the Middle East, Asia, and China seem to have independently developed the technology, probably around the 4th century B.C.E.

Today, hydropower is responsible for major portions of electric capacity in many regions. Overbuilding, however, has caused unforeseen problems, including the destruction of migratory paths for fish and over-allocation of water resources. Climate change has exacerbated these problems and forced the re-evaluation of policies, and some dams are now being removed. While large new hydropower projects are unlikely, small-scale hydropower is still viable in some locations.