In a new wave of construction from 1970 to 1979, their number increased from 26,000 to 90,000, with mean size doubling to only 70 kW. Much larger hydro plants in the MW and GW ranges have been built since the 1980s. Many technical and maintenance problems (silting, drought, leaks) with hastily built microplants meant low load factors and relatively high costs (Smil, 2010a). In 2006, China completed the world’s largest hydropower plant, with a capacity of 18.2 GW.