5. Hydropower: Assessment of Energy Potential and Environmental Issues in the Local and Global Scales

Hydropower has been used for energy supply for many centuries. Now it accounts for about a few percent of world energy production. Hydropower is described as a renewable source, but it is slightly different, because it occupies large areas of land and can disrupt the local ecosystems. The dam prevents the upstream migration of aquatic animals, which can be overcome by building fish ladders. The areas below the dam are deprived of silt that causes lower yield in organic farming. Hydroelectric power is widely utilized by mountainous countries like Austria, Norway, and Switzerland. Nowadays, the expansion is limited in many developed countries, because most of the suitable sites have already been used. The hydroelectric potential can be increased by the concept of distributed generation from small hydro plants that are connected to conventional electrical distribution networks as a source of low-cost renewable energy. Also small hydro projects may be built in isolated areas, where there is no national electrical distribution network. Since small hydro projects generating capacity of 1–20 megawatts have minimal civil construction work, they are seen as having a relatively low environmental impact compared to large hydro plants.