The US’s demand for energy increased to fuel World War II because the Axis nations had three times more available power than the US. Shipyards, steel mills, aircraft and automobile manufacturers, and chemical companies all required vast amounts of energy. Additional dams made it possible for the US to expand its energy production quickly for war and civilian needs. After the Second World War, hydropower was pumped into peacetime industries, especially farming, with the additional benefit of providing land irrigation.
For centuries, small hydro power (SHP) has been an important source of energy in all European countries possessing water potentials and with the invention of more sophisticated turbines in the twentieth century, mini and small hydro plants were used for electricity generation in both Europe and the USA. In Europe they became the main source of electric energy. Townships in the mountains harnessed water resources to generate electricity. Water powered mills or factories were fitted with turbines and generators and the electric power was used for productive end use.
This development continued till 1950, when the national grids were extended and reached the SHP plants which up until then had been isolated. In many cases grid supply turned out to be cheaper than the operation, repair and maintenance of the SHP plants. In addition, stringent water management regulations and safety provisions for civil and electrical installations contributed to the early closure of many mini hydro plants which, from a technical point, were still perfectly operational but could not meet the new standards. In many areas the utility companies managed to enforce closure even when the supply from the grid was more costly from a mini hydro plant. If production and feed-in existed at all, prices paid by the utilities were so low that only the existing plants remained economical and this only, as long as no major repairs became necessary.
