Water is not only an indispensable resource for life but also a renewable source of energy. In particular, hydroelectric energy allows us to obtain energy from water in a sustainable way, i.e. without the production of CO2 emissions into the atmosphere, which cause global warming and climate change.
Man has exploited water energy for hundreds of years. However, while in the past hydraulic energy was transformed into mechanical energy, today it is converted into electrical energy. In this way, water, a green and clean energy source, allows us to improve the energy mix and reduce dependence on fossil fuels.
As a renewable energy, water guarantees countless advantages. Still, preserving freshwater resources is essential to satisfy the need for drinking water for human consumption and the demand for water from farms and industries. Let’s see everything you need to know about hydroelectric energy to understand its role and prospects better.
What is Hydroelectric Energy
The combination of energy and water represents one of the oldest energy sources, still today the most important renewable energy source in many countries worldwide, including the Philippines. What is hydroelectric energy used for? It is mainly used for electricity generation, while in the past, it was used for food production.
It is possible to obtain hydroelectric current through unique power plants, transforming the movement of enormous masses of water into electricity. It is a highly efficient energy with a low environmental impact, in fact, no climate-altering gases are emitted, and it is possible to convert approximately 90% of the water’s energy into electricity.
The first water wheels appeared as early as 100 BC when in Alexandria, Egypt, these systems were used to drive grain mills. In the 9th century, the power of water was exploited for numerous uses, from grinding sugar to tanning leather, while in the Middle Ages, mills began to spread on a large scale.
The industrial application of water power began in the 18th century in England, with the creation of the first spinning wheel driven by water power, until the invention of the first hydraulic turbine in 1881 by James B. Francis.
After the introduction of the dynamo in 1860, with the contribution of Thomas Edison in 1882 the first hydroelectric power plant in the world was created in Appleton, in the State of Wisconsin in the United States, beginning hydroelectric energy in modern society.
How Hydroelectric Energy Works
We must start from an artificial or natural water basin to understand how hydroelectric energy is produced. To power the power plants, you first need a reserve of fresh water, which is generally created with the construction of a dam, to block the flow of a river and have all the water necessary to power the turbines available.
At this point, it is possible to understand how hydroelectric energy is produced, in fact hydraulic force is exploited to produce energy through the force of gravity and special power generators.
In detail, the water is made to enter special conduits in a controlled manner, after which it falls downwards due to the force of gravity thanks to a specific difference in height between the reservoir and the point where the hydroelectric turbines are positioned.
The acceleration of the water allows its potential energy to be increased, so the water drives the turbines, which in turn turn on an alternator, which produces electricity. The electricity then passes through a transformer to regulate the intensity and voltage of the electric current and feed it into the grid in an optimal form for long-distance transport and distribution.
The Types of Hydroelectric Power Station
Hydroelectric power plants are not all the same. Although the general functioning is the same, there are various types of plants. All power plants exploit the driving force of water to obtain mechanical energy, to be transformed into electrical energy using a rotating generator.
The hydroelectric energy in the reservoir power plant is produced from a reservoir, which can be artificial by constructing a dam or natural by exploiting an existing lake. The water is then forced into hydraulic turbines to generate electricity and then feeds a stilling basin to reduce the force of the water before returning it to the watercourse.
On the other hand, run-of-river power plants use a difference in height between the watercourse and the turbines to obtain a head to operate the generators by conveying the water without forced conduits. Unlike basin power plants, these plants do not allow optimal control of water flows and have electricity production that is more subject to variations and oscillations.
The third type is the storage power station, consisting of a water tank upstream and one downstream, and the latter is used as a potential energy reserve for the hydroelectric power station. When the water level in the upstream basin is too low, for example, due to a prolonged drought or an increase in electricity demand, water from the downstream basin is pumped into the upper basin to increase the flow rate—water and electricity production capacity.
Hydroelectric energy has been the great protagonist among renewables for over a century, with production reaching almost 50 terawatt hours in 2018 and over 4,400 power plants. The distribution is not homogeneous in the country, with a prevalence of plants in Northern Luzon, where the primary national water basins are located.
Hydroelectric Energy: Advantages and Disadvantages
Evaluating the pros and cons of hydroelectric energy is essential to understand its prospects in terms of the energy transition, i.e. the transition from fossil fuels to renewable energy.
Without a doubt, hydroelectricity plays an indisputable role in the Philippine energy autonomy and in the reduction of greenhouse gas emissions. However, it is necessary to comprehensively analyze the advantages and disadvantages of hydroelectric energy to consider the actual ecological footprint accurately.
Disadvantages of Hydroelectric Energy
High environmental impact: due to the modification of waterways, which leads to alterations in the hydrosphere, the loss of natural habitats, and extensive damage to the animal and plant species that inhabit the area;
1. Inconvenience to local populations
Inhabited centers or local activities often have to be moved, in addition to the noise of hydroelectric power plants and the space required for the water used in the turbines to escape;
2. Aesthetic damage to the landscape
Linked to the aesthetic disfigurement caused by the construction of the power plant and, if necessary, of the dam within natural environments;
3. Water consumption
Hydroelectric power plants cause the overexploitation of an increasingly scarce resource such as freshwater, which is also used for human consumption and agricultural and industrial activities.
Advantages of Hydroelectric Energy
1. Economic energy source
Given a considerable initial investment, in the long term, the cost of producing hydroelectric energy is among the lowest ever;
2. High versatility
Usable both for the generation of electricity on a large scale through large power plants and for the production of electricity locally through small and medium-sized plants;
3. Low greenhouse gas emissions
Mainly linked to methane emitted from the water accumulated in the reservoir due to the decomposition of organic residues;
4. Demand-driven production management
By controlling water flow through dams and efficiently managing downstream and upstream reserves;
5. Proven reliability
As it is a technology used successfully for over a century and capable of stabilizing the national electricity system;
6. Clean energy source
since the energy potential is contained within the water itself and only accelerated by pumping systems or differences in level, without the need to purchase raw materials abroad or obtain them from underground;
7. Stabilization of renewables
The consistency of hydroelectric energy makes it possible to cover temporary and seasonal reductions in other, more volatile green energies such as photovoltaic and wind power.
Hydroelectric energy represents a strategic renewable source for sustainable development. However, managing water responsibly and protecting this reserve for human life and natural ecosystems is essential.