By 2020, a fifth of all energy consumption in European Union (EU) member countries must come from renewable sources – hydro, wave, solar, wind, and biomass. This mandate, which EU leaders signed in March 2007, is part of a proposal designed to cut greenhouse gas emissions by 20 percent (compared with 1990 levels).

The emphasis in Western Europe is retrofitting hydro plants with modern equipment, usually upgrading the capacity of the plant. In Eastern Europe, the focus is rehabilitating aging plants that often were allowed to deteriorate during the era of the Soviet Union.