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What Is Hydro Power?

Hydro is a Greek word, which means water. Hydro electricity is the conversion of the mechanical energy in flowing water into electricity. Hydro electricity is generated when the force of falling water from dams, rivers or waterfalls is used to turn turbines, which then drives generators that produce electricity. The energy produced is directed to a substation, where transformers "step up" the voltage before its transmission to the electricity grid. The amount of power that can be generated by a hydro station depends on the height from which the waterfalls (called the head) and the amount of water available (the flow). The greater the head and the flow, the more electricity can be produced.

The Technology Of Generating Hydro Energy

Hydropower plants capture the kinetic energy of falling water to generate electricity. A turbine and a generator convert the energy from the water to mechanical and then electrical energy. The turbines and generators are installed either in or adjacent to dams, or use pipelines (penstocks) to carry the pressured water below the dam or diversion structure to the powerhouse. Hydropower projects are generally operated in a run-of-river, peaking, or storage mode. Run-of-river projects use the natural flow of the river and produce relatively little change in the stream channel and stream flow.

A peaking project impounds and releases water when the energy is needed. A storage project extensively   impounds and stores water during high-flow periods to augment the water available during low-flow periods, allowing the flow releases and power production to be more constant. Many projects combine the modes. The power capacity of a hydropower plant is primarily the function of two variables:

(1) flow rate expressed in cubic feet per second (ft3/s), and

(2) the hydraulic head, which is the elevation difference the water falls in passing through the plant. Project design may concentrate on either of these variables or both.

Application Of Hydro Energy

Hydro power accounts for some 24% of the world's electricity, around 675,000MW. In all, there are more than 300 large scale hydro power generators worldwide. Canada, Brazil and New Zealand have the highest proportions of hydro electricity generation. While hydro electricity provides great potential for electricity generation, there are environmental constraints on the development of new hydro stations. Creating new dams to facilitate the construction of these plants would involve the inundation of ecosystems, and the generation of greenhouse gases through anaerobic decay of vegetation trapped under water. Increased interest has therefore been generated by alternate hydro systems, such as "run of river" schemes, which use the flow of a river to turn turbines, or the use of existing dams to house new hydro plants.


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