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Hydroelectricity is gaining renewed interest as a source of clean, renewable energy. Hydroelectric dams are the best known type, but other methods are being developed, including tidal power, wave energy, and ocean thermal energy conversion. The idea of using water as an energy source dates back to ancient Greece, and hydroelectric power was rapidly advanced in the late 1800s. Today, most of the best locations for large hydroelectric plants have been exploited in the developed world, so new projects are happening mostly in developing nations like China.
Humans have harnessed the power of moving water for thousands of years, but today hydroelectricity is gaining renewed interest as a source of clean, renewable energy. Hydroelectric dams are the best known type of hydroelectric power, but several other methods are under development to harness the power of moving water. The Earth’s oceans are being searched for for new types of hydroelectric energy.
The idea of using water as an energy source dates back at least to ancient Greece, where the power of flowing rivers was captured by water wheels and used to grind grain into flour. Similar devices were developed in other parts of the world, and early European and American factories and factories were powered by water wheels. Up until the end of the 19th century, water provided only mechanical energy; the movement of water wheels was used to turn saws and other machinery.
In the late 1800s, rapid advances were made in hydroelectric power, a form of hydroelectric power in which the movement of water is converted into electricity. The United States alone had over two hundred hydroelectric facilities at the turn of the century, most of them located on medium to large dams. Today, most of the best locations for large hydroelectric plants have been exploited in the developed world, so new projects are happening mostly in developing nations like China. Small-scale hydroelectric plants are being examined in both the developed and developing world.
The world’s oceans also contain many potential sources of energy that hydroelectricity could tap into. Tidal power aims to harness changing ocean levels in coastal areas. Although a large tidal power plant began operating in France in the late 1960s, high construction costs and a limited number of suitable locations prevented tidal power from gaining widespread use.
Another potential option is wave energy, which can be harnessed in a number of ways. A demonstration project in Norway uses the motion of waves to push and pull air through a tube, which in turn spins a turbine to generate electricity. Portugal, Australia and the UK have all experimented with wave parks, clusters of devices that generate electricity from wave energy. Some other devices attempt to capture marine currents far below the surface of the water.
Ocean thermal energy conversion (OTEC) differs from other types of hydroelectricity in that it does not capture energy directly from water movement. Instead, OTEC takes advantage of the temperature differences found at different depths of the ocean. Hot water at the ocean’s surface is pressurized and turned into steam, or used to heat another fluid that is turned into steam. The steam can then be used to power turbines and generate energy, and cold water is then pumped from greater depths, turning the steam into liquid and restarting the cycle. Experimental OTEC systems have been built in places like Hawaii, but pumping cold water from great depths reduces system efficiency, making it difficult for OTEC systems to work efficiently.
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