Hydropower uses the energy of moving water. Hydropower has been used to power watermills for about two thousand years. Early water mills were used to pound grain for flour, break ore to get metals, and in early paper-making.
Hydroelectricity generates electricity by harnessing the gravitational force of falling water. Hydroelectricity supplies around 17% of the world’s electricity, and 71% of all renewable electricity. Most hydroelectric power stations use water held in dams to drive turbines and generators which turn mechanical energy into electrical energy. The largest hydroelectric power station in the world is the Three Gorges Dam in China.
A small number of countries, including Norway, Canada, Brazil, New Zealand, Paraguay, Venezuela and Switzerland, produce the majority of their electricity through hydropower. Hydroelectricity is a renewable energy, but the building of the large facilities needed to make it can have negative effects on the environment, and the people who live near dams. These can include:
Farmland, homes and historic sites flooded by the new lake behind the dam.
Less water downstream for irrigation
Sediment builds up behind the dam
Other forms of hydropower Wave Power Waves are formed by winds blowing over the surface of the sea. The best place to put wave energy generators is in areas where strong winds have travelled over long distances. For this reason, the best sites for wave power stations in Europe occur along the western coasts which lie at the edge of the Atlantic Ocean, for example off the Highlands and Islands of Scotland. Nearer the coastline, wave energy decreases due to friction with the seabed, therefore waves in deeper, well exposed waters offshore will have the greatest energy.
Tidal Power The tides are created by the constantly changing gravitational pull of the moon and sun on the world’s oceans. Tides never stop, with water moving first one way, then the other, the world over. Generating electricity from tidal power is generally best in areas where a good tidal range exists, and where the speed of the currents are increased by the funnelling effect of the local coastline and seabed, for example, in narrow straits and inlets, around headlands, and in channels between islands.