Hydroelectric developments

The potential energy renewed each year at altitude in inland waters (rivers, snow and glaciers) is estimated worldwide at around 40,000 TWh per year, of which a large third (around 14,000 TWh) is exploitable with currently available techniques. Under the economic conditions prevailing at the beginning of the 21st century, 8,700 TWh are considered to be economically exploitable, compared with other energy sources. A total of 3,000 TWh of hydroelectric power is actually generated every year, representing some 16% of total electricity production worldwide. In Europe, hydroelectric schemes supply 99% of Norway's electricity needs and 12% of France's. In France, the third quarter of the 20th century saw the development of almost all economically exploitable hydroelectric resources. However, on a global scale, there is still an annual hydroelectric resource of around 5,700 TWh that could be profitably developed, especially in Africa, Asia and Latin America. This potential may even be much greater in the future, when primary energy resources will be under greater pressure, fossil fuel prices will be higher, and CO ₂ emissions will have to be further limited. What's more, hydropower is a renewable energy source that is not only regular and predictable, but can also be used to adapt production to requirements on an hour-by-hour basis, or to compensate for the intermittency of other renewable energies, provided that sufficient reservoirs are available at altitude. The development of hydroelectric power requires careful consideration of environmental aspects and the safety of people and property. Hydroelectric schemes are sometimes highly complex, incorporating a wide range of techniques.