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Tidal Energy, Wind energy & Geothermal Energy

Tidal energy

Tidal energy is a form of hydropower that converts the energy obtained from tides into useful power, such as electricity. Tides are created by the gravitational effect of the moon and the sun on the earth causing cyclical movement of the seas. One of the strengths of harnessing power from tidal ranges and tidal streams over other forms of renewable energy is that the process is entirely predictable.

Tidal range technology makes use of the vertical differences in height between high tide and low tide. The project takes the form of the tidal barrages or lagoons that use turbines in the barrier to the lagoon to generate electricity as the tide floods into a reservoir. When the tide outside the barrier recedes the water retained can then be released through turbines, which generates electricity. In Nepal, there is no sea and ocean, so the source of tidal energy cannot be imagined.

Wind Energy

Anything that moves has kinetic energy, and scientists and engineers are using the wind's kinetic energy to create electricity. Wind energy is created using a turbine, a device that channels the power to generate electricity. Traditionally, it was used to separate the husk from grains and to drive windmills, which in turn operates water lifting pumps and flour mills. It is also used to propel sailboats. 

Geothermal energy

The form of energy conversion where the heat energy from Earth is captured and harnessed for cooking, bathing, space heating, electrical power generation, and other uses. 

Image: Nesjavellir Geothermal power plant, Iceland.

The heat from Earth's interior generates surface phenomena such as lava flows, geysers, hot springs, and mud pots. The heat is mainly produced by the radioactive decay of potassium, thorium and uranium in Earth's crust and mantle and also by friction generated along the margin of continental plates. The subsequent annual low-grade heat flow to the surface averages between 50 and 70 milliwatts per square meter worldwide. In contrast, incoming solar radiation striking Earth's surface provides 342 watts per square meter annually. Geothermal heat energy can be recovered and exploited for human use, and it is available anywhere on Earth's surface. The estimated energy that can be recovered and utilized on the Earth's surface is 4.5*106 exajoules, or around 1.4*106 terrawatt-years, which equates to roughly three times the world's annual consumption of all types of energy.