Water is the most important fluid that exists on Earth and offers us many resources and services. Water has allowed the development of life, has contributed to the regulation of the climate and also provides us with energy. Energy is another of the most necessary resources for human beings since without it, we would not have electricity or heat, for example. Perhaps the most well-known form of energy in water is hydraulic or hydroelectric energy, however, this is obtained from other energies, which are kinetic and potential energies.
What is energy: simple definition
First of all, we have to know what energy is. Energy is understood as the ability of an object to do work and to transfer heat . In turn, work corresponds to the effort that must be made to move an object or substance over a certain distance. But, as we talked at the beginning, energy is also heat and, therefore, energy can also be defined as the flow of heat that moves from an object or a substance that is hot to another that is colder.
Energy can be in many forms, such as light, heat, electricity, chemical energy, and / or mechanical energy. The latter is based on the movement of matter and is normally defined as the sum of the kinetic and potential energies . The flow of water is a clear example of this mechanical energy and next we are going to see what the kinetic energy and the potential energy of water consist of.
The kinetic energy is the energy associated with any body that is moving. To calculate kinetic energy, it must be taken into account that its calculation depends on both the mass and the speed of the body. Therefore, knowing this general definition of kinetic energy, we could define the kinetic energy of water as that energy that comes from its movement or flow. The greater the volume (and mass) of water and the greater its velocity, the greater its kinetic energy.
However, there is another form of energy that is closely related to kinetic energy, and that is potential energy . This potential energy is simply energy that can potentially be transformed into another form of energy, normally kinetic. In other words, potential energy is that which is stored in a body and can be used.
While water has kinetic energy, there is also the potential energy of water . The potential energy of water is that which is stored in a body of water and which is transformed into kinetic energy when it begins to flow. Potential energy depends to a large extent on height, therefore, those bodies of water that are higher up have higher potential energy. In this way, those bodies of water that are found in gorges or have cataracts have a higher potential energy and if the water flows also higher kinetic energy.
As we have well explained, the kinetic energy of water can be used when it flows or moves. Consequently, this energy can be used in the execution of processes such as moving a turbine. On the other hand, to take advantage of the highest possible kinetic energy, the maximum potential energy is also needed. Hydraulic energy is based on this principle and for this the construction of dams is necessary. Dams and reservoirs also make it possible to store water and thus make it available for consumption and other activities such as agriculture.
To take full advantage of hydraulic energy, two important factors must be taken into account:
- The flow.
- The height of the waterfall.
The dams are used to regulate the flow depending on the time of year and also to increase the waterfall and thus the potential energy.
To produce electrical energy , the dam is opened and some of the stored water is dropped, thus converting potential energy into kinetic energy. The falling water drives a turbine that is linked to an electrical power generator. Thus, it is achieved that the water that passes through the turbines at high speed causes the rotational movement of the turbines, generating electricity. In this way electricity is produced from the kinetic (and potential) energy of water.
There are other ways to increase the height of the waterfall. One of them consists of diverting the river water through a channel with a small slope (less than that of the river bed). Thus, with this technique a greater unevenness is achieved between the channel and the river bed. On the other hand, in many countries (especially in developing countries) small plants have been installed, with low powers, but which allow the production of enough electrical energy to power small regions. This is the case in China or Costa Rica where these small dams are the main source of electricity. This miniaturized form of hydraulic power is known as mini-hydro power and is considered more environmentally friendly.
The hydraulic energy obtained from the kinetic energy of water and the potential has advantages and disadvantages, like all.
Advantages of hydropower
- It is considered a renewable and clean energy.
- Very stable energy production.
- Flexible production thanks to the flow of water.
- Safe energy, unlike other non-renewable ones, such as nuclear energy.
Disadvantages of hydropower
- It depends on the rains and thaws, as well as whether there are no major droughts.
- The places for its installation are limited.
- High initial investment.
- It has an environmental impact, more specifically on the landscape.