Hydro-power is the kind of energy that transforms the gravitational potential energy, typical of water bodies in height to kinetic energy when it exceeds a certain unevenness, this kinetic energy is converted into electricity through a power generator thanks to the phenomenon of electromagnetic induction. For its implementation is essential the existence of a waterbody, such as the stream bed of a river or lake and through the construction of a dam, the potential energy channeling through conduits in unevenness.

Hydro-power is a clean energy source, since there are no harmful emissions to the environment also must emphasize that it is a renewable energy.

Water comes from an artificial reservoir through pipes to one or more turbines that moves because of hydrodynamic pressure produced by the water. The rate at which water will move the blades of the turbine is determined by the difference height between the turbine and the waterbody. Each turbine is coupled to an alternator that converts the kinetic motion of the rotation into electrical energy.

Hydroelectric plants have a particular feature, gates and valves may be activated and deactivated in minutes, giving the possibility to easily meet unexpected rises in water levels.

Often hydro-power are also equipped with a collection reservoir downstream. Water which has generated electricity during the day going through the turbines, can be drawn back upstream during the hours of requiring less energy (for example at night) by a pumping station, using this operation, the electrical energy in excess or low-cost produced by the type of plants "always functioning".

Hydroelectric plants by its flow is mainly categorized into: Central Reservoir and Run-of-the-river.

The distinction between hydro and mini-hydro is given by the power, referring to the ability to generate MW, a plant is considered mini-hydro if have an installed capacity below 10 MW. These smaller plants do not require large flows of water, however a power plant can achieve an output of thousands of megawatts, for example the 22,500 MW plant of the Three Gorges Dam in China or the 570 MW of Ralco Central in Alto Bio-Bio.

In recent years the creation of numerous small hydroelectric power generating increased to an estimated power of 85 Giga-Watts. Many of these small hydro are located in China, which has continued unabated growth to around 6 GW of power only during the period 2004-2008. In 2008 the large hydroelectric plants increased their power in more than 30 GW, a figure significantly higher than the 15 GW of China or the 5 GW of India, yet these countries remain industry leaders. Because of its particular geography and abundance of water in the southern territory, Chile has a high potential for hydroelectric power generation, but their use still does not guarantee the entire electricity supply for the whole country.


Run-of-the-river Plant

The Run-of-the-river plant is a method for generating electricity by exploiting the natural channel and the slope of a river without having a negative impact on the environment.

The project of a Run-of-the-river central are completely different way in design, appearance and environmental impact of conventional hydroelectric projects, those operating through the construction of large dams that serve to address seasonal fluctuations in the course of rivers or lakes, with consequent flooding of a large area of usable land and the destruction of flora and fauna. On the other hand, on a Run-of-the-river is not necessary to build a dam, instead only part of the water is diverted through a penstock or pipes, and because of the potential energy of the river, kinetic energy while changing height reach the necessary load to spin turbines and produce electricity.

Another type of Run-of-the-river central is build on the same channel of the river, made of concrete foundations, but leaving free passage for fish and aquatic life through mobile gates, which also regulate the river's level. In case of necessity, eg flood, all gates and closures open, thus avoiding the risk of flooding of the surrounding land securing also turbines and generators.

There is no alteration of any kind downstream in the river, nor any drop of water is lost in this process and all the water diverted through the penstock upstream is returned to the original stream.

The Run-of-the-river are those with the lowest emissions in relation to the amount of energy produced, contrary to what occurs with traditional hydroelectric. The amount of power passing through in recent years has been increasing, for example in Switzerland for 27% of base electricity is produced with this system, existing sometimes in the same river several run-of-the-river plants, without affecting the river flow. Also, Italy is legislating in this sense "no drop of water reach the sea without first produced electricity..." is part of a bill for the Region of Sardinia that seeks to enhance the production of electricity through run-of-the-river centrals.

Chile thanks to its privileged geography, has succeeded in recent decades to use water power to produce electricity, but today it is the time we must think which cost will pay our territory with the production of electricity through traditional hydroelectric dams and plants. That is why, alternative, renewable and environmentally friendly as are the Run-of-the-river, represent the true future of Chilean energy.