How Does Hydroelectric Energy Work

Although hydroelectric power is rapidly disappearing, renewable energy sources like solar and wind are quickly catching up, and it still accounts for the biggest portion of the world’s electricity.

Hydroelectric power was so prevalent in the 20th century that it earned the nickname “white coal” for its strength and abundance.

The original and most basic method of producing energy was hydroelectric power.

Simply put, hydroelectric power is the creation of energy from falling or moving water. On rivers, dams are built to generate electricity.

The turbines are then turned by the water’s continuous flow.

The most popular renewable energy source in the early 21st century was hydroelectricity, which in 2019 accounted for more than 18% of the world’s total power-producing capacity.

In “how does hydroelectric energy work”, we take a look at the working principle of hydroelectric energy.

What is Hydroelectric Energy?

Hydroelectric energy is an environmentally friendly and renewable source of energy that generates power by using a dam or diversion structure to alter the natural flow of a river or other body of water.

Hydroelectric power, also called hydropower produces electricity from generators that are driven by turbines converting the potential energy of falling or fast-flowing water into mechanical energy.

Advantages of Hydroelectric Energy

No kind of energy generation, according to the U.S. Geological Service (USGS), offers a perfect solution, yet hydroelectric power can still offer several benefits.

Source: What Are Some Advantages and Disadvantages of Hydroelectric Energy? (Solar Website)

1. Source of Renewable Energy

Because it makes use of the water on the planet to generate electricity, hydroelectric power is seen as a renewable resource.

When the sun shines, water on the earth’s surface evaporates, creates clouds, and eventually returns to the planet as rain and snow.

Since we cannot exhaust it, we are not concerned about its price rising as a result of scarcity.

Hydroelectric plants are therefore made to last. In other situations, machinery that was intended to last 25 years is still in use after having been in use for twice as long.

2. Clean Energy Source

One of the many “green” and “clean” alternative energy sources is hydroelectric electricity. Hydroelectric power generation does not contaminate the environment.

Hydroelectric power facilities don’t release any harmful or greenhouse gases into the atmosphere while they generate energy.

The period when pollution is most severe is when power plants are being built.

Compared to coal, oil, or natural gas, the operating hydroelectric plant produces fewer greenhouse gases, which reduces climate change, acid rain, and smog.

Because it doesn’t release air pollutants, hydroelectric power helps to improve the quality of the air we breathe.

Additionally, the plants don’t create any hazardous byproducts.

Today, the use of hydropower prevents the release of greenhouse emissions equivalent to over 4.5 million barrels of oil, which would hasten the rate of global warming.

3. Affordable Energy Source

Despite the expensive initial construction expenses, hydroelectric power is a cost-effective source of energy.

River water is a limitless resource that is unaffected by fluctuations in the market.

The price of fossil fuel-based energy sources including coal, oil, and natural gas is greatly impacted by market volatility, which can cause it to rise or fall sharply.

With an average lifespan of 50 to 100 years, hydroelectric power facilities are long-term investments that can benefit many generations to come.

They also offer far lower operating and maintenance expenses and can be simply modified to meet the technical requirements of today.

4. Assists Remote Communities in Development

These renewable energy facilities not only produce jobs but also clean energy for usage by locals and businesses.

Remote areas in need of electricity are served by hydroelectric power plants, which also draw industry, commerce, transportation, and other vital community development.

All of these initiatives help to improve local economies, access to healthcare and education, and inhabitants’ overall quality of life.

The EIA claims that this dependable and adaptable power source increases a community’s appeal to other developers.

5. Recreational Opportunities

Fishing, boating, and swimming are all possible recreational activities in the lake that creates behind the dam.

Water from the lake may potentially be used for irrigation. Large dams also become popular destinations for tourists.

Hydroelectric generating facilities can store enormous amounts of water for use as needed and for irrigation when rainfall is scarce.

It is advantageous to be able to store water since it reduces our susceptibility to droughts and floods and protects water levels from depletion.

6. Bolster Peak Demand

Hydroelectric power is praised by the USGS for its quick and dependable capacity to run from zero demand up to peak output.

More quickly than any other energy source, producers can transform this type of renewable energy into electricity and add it to power grids.

Hydropower is the best option for adjusting to changing consumer needs because of this feature.

7. Offers a Versatile Energy Solution

For instance, hydroelectric generation increases the viability of other renewable energy sources like water and solar energy.

Hydroelectric power facilities are the ideal complement to solar and wind energy since they can fluctuate depending on the climate.

As a result, hydropower has a big potential in the future with only renewable energy sources.

Disadvantages of Hydroelectric Energy

Hydroelectric power plants have many advantages, but like any energy source, they must be developed and used wisely to minimize risks and drawbacks.

While some of these disadvantages might apply to virtually any energy plant, problems with water diversion are unique to hydropower.

Source: 5 Disadvantages Of Hydroelectric Energy (PMCAOnline)

1. Environmental Damage

Natural water flow disruptions can significantly affect the environment and the river ecosystem.

When there is a food shortage or the start of the breeding season, certain fish species and other wildlife typically migrate.

The construction of dams may block their routes, halting water flow, which causes habitats along rivers to start to disappear.

This may even prevent animals from reaching water, which could prevent fish from reproducing or cause fish fatalities.

Because of water damming, altered river flow, the construction of streets, and the installation of power lines, the natural effects of hydropower are associated with interruptions in nature.

Although it is difficult to study this process and make judgments based on just one component, hydroelectric power plants may have an impact on fish and the way that they migrate.

More client investments have been linked to the mistreatment of fish species, indicating that many people feel strongly about this topic.

2. Environmental Impact of Dam Construction

Although hydropower is a renewable resource, the production of the steel and concrete needed in dam construction may produce greenhouse emissions.

There aren’t many locations around the globe that are appropriate for building plants.

Additionally, some of these locations are far from big cities where the energy may be used to its maximum potential.

3. High Initial Capital Expenses

The construction of any power plant is difficult and expensive, but hydroelectric plants do need a dam to stop the flow of water.

As a result, they are more expensive than fossil fuel facilities of comparable scale.

Due to logistical difficulties like geography, putting foundations underwater, and the materials necessary to build them, hydroelectric power facilities are exceedingly expensive to build.

The sole benefit is that it won’t need as much upkeep after it’s finished.

To recuperate the money invested in the construction, the hydroelectric plant will still need to be in operation for a considerable amount of time.

4. Potential for Conflict

To harness the water, nations with abundant hydroelectric power sources frequently construct dams across rivers.

Although this deed is commendable, it may prevent natural water flow from one direction to another.

To accommodate people wishing to construct dams in various regions, water that is not needed in one place is diverted to another.

But if there is a water shortage there, it can lead to war, hence it is necessary to stop the flow of water to the dams.

5. Might cause Droughts

Although hydropower is the most dependable renewable energy source, it is reliant on the availability of water in a particular area.

Thus, a drought may have a big impact on how well a hydro plant operates.

The total cost of energy and power is calculated based on the availability of water.

Dry spells can have a big influence on people’s ability to get water since they prevent them from getting the power they require.

And as our globe continues to heat up due to climate change, this might happen more commonly.

6. Risk of Floods in Lower Elevations

Communities living downstream are at risk of flooding when dams are erected at higher elevations, which increases the likelihood of powerful water currents being released from the dam causing flooding.

Despite the strength of the dams’ construction, there are still dangers. The Banqiao Dam failure is the biggest dam disaster in recorded history.

The dam broke because of excessive rainfall brought on by a typhoon. As a result, 171,000 people passed away.

7. Carbon dioxide and Methane Emission

Large amounts of carbon dioxide and methane are released from the hydroelectric power reservoir.

The vegetation below the water starts to decay and degrade in these wet places close to the dam.

Additionally, plants emit a lot of carbon and methane as they die.

8. Geological Damage

Grave geological harm can result from the construction of large-scale dams.

The building of the Hoover Dam in the United States, which sparked earthquakes and depressed the earth’s surface nearby, is a prime example of geological harm.

9. Reliance on Local Hydrology

Since hydropower depends solely on water flow, alterations in the environment may affect how successfully these dams generate electricity.

For instance, a hydroelectric dam may be less productive than anticipated if climate change lowers water flow in particular locations.

For instance, 66 percent of Kenya’s energy requirements are met by hydroelectric power.

Kenya has long been affected by energy constraints brought on by drought, claims International Rivers, a group devoted to the preservation of the world’s rivers.

On the other hand, some locations now face a greater danger of flooding as a result of climate change.

In these situations, dams can provide both flood control and the production of renewable energy.

How does Hydroelectric Energy Work?

How does hydroelectric energy work

Source: How Does a Hydropower Plant Work? A Brief History and Basic Mechanics (WIKA Blog – WIKA USA)

A dam or other construction that alters the natural flow of a river or other body of water is used to generate hydropower, often known as hydroelectric power.

To generate energy, hydropower uses the perpetual, never-ending water cycle, which uses water as a fuel and leaves no waste products behind.

Although there are many different kinds of hydropower plants, they are always propelled by the kinetic energy of water moving downstream.

To turn this kinetic energy into electricity, which may subsequently be used to power buildings, businesses, and other establishments, hydropower uses turbines and generators.

Hydropower facilities are typically situated on or close to a water source since they use water to produce energy.

The amount of energy that may be extracted from flowing water relies on both its volume and the elevation change, or “head,” between two points.

The amount of power that can be produced increases with flow and head.

At the plant level, water circulates via a pipe, also called a penstock, which rotates a turbine’s blades, which spins a generator, which generates energy.

This is how the majority of conventional hydroelectric facilities—including pumped storage and run-of-the-river systems—work.

Hydroelectric Power Plant Diagram

Diagram of a Hydroelectric power plant

Components of a Hydroelectric Power Plant

The major components of a hydroelectric plant are as follows.

  • Forebay and Intake Structure
  • Head Race or Intake Conduits
  • Penstock
  • Surge chamber
  • Hydraulic turbines
  • Power house
  • Draft tube and Tailrace

1. Forebay and Intake Structures

The forebay, as its name suggests, is a larger body of water in front of the intake. When a penstock draws water straight from a reservoir, the reservoir serves as a forebay.

Source: Hydro Power – Civil Engineering (energypedia)

The segment of the canal in front of the turbines is expanded to create a forebay when the canal transports water to the turbines.

For feeding water to the turbines, the forebay temporarily stores water. The water cannot be allowed to flow as it enters the canal or the reservoir.

To manage the inflow of water, hoists are installed at intake gates. To stop waste, trees, etc. from getting into the penstock, trash racks are placed in front of the gates.

Additionally, rakes are available to periodically clear the trash racks.

2. Head Race or Intake Conduits

They transport water from the reservoir to the turbines. Depending on the circumstances at the site, an open channel or a pressure conduit (Penstock) may be chosen.

The pressure conduit could be a flared intake passage in the dam’s body, a long steel or concrete conduit, or occasionally a tunnel that runs for a few kilometers between the reservoir and the power plant.

The gradient of the pressure conduit is determined by the site conditions and does not follow the contours of the earth. Water moves at a faster rate in the power conduit than it does in an open channel.

The velocity may vary between 2.5 and 3 m/sec up to a head height of roughly 60 meters.

The velocity may be even higher for higher heads. Sometimes it is practical or cost-effective to use an open channel as the primary conduit entirely or in part.

The head race canal is typically used in low-head systems where head losses are significant. It may direct water to the penstocks or turbines.

An open channel has the benefit that it can be used for navigation or irrigation.

3. Penstock

Source: Penstock (Energy Education)

Penstocks act as large, sloping pipes that transport water from reservoirs or intake structures to the turbines.

They operate under a certain amount of pressure, therefore abrupt closure or opening of penstock gates may result in water hammer on the penstocks.

So, aside from the fact that the penstock is like a regular pipe, these are made to withstand the water hammer impact.

To relieve this pressure, surge tanks are available for long penstocks and strong walls are available for short penstocks.

Penstocks are produced using steel or reinforced concrete. For each turbine, a separate penstock is used if the length is little.

Similarly, if the length is great, a single large penstock is used, and it is divided into branches at the end.

4. Surge Chamber

A surge chamber, sometimes known as a surge tank, is a cylinder with a top opening for controlling penstock pressure.

It is situated as close to the power house as is practical and is connected to the penstock.


The water level in the surge tank increases and controls the pressure in the penstock whenever the power house rejects the water load coming from the penstock.

Similar to this, the surge tank speeds up water flow into the power house when there is a high demand, which causes the water level to drop.

The surge tank’s water level stabilizes when the power house’s discharge is consistent.

Surge tanks come in a variety of varieties, and they are chosen depending on the needs of the plant, the length of the penstock, etc.

5. Hydraulic Turbines

A hydraulic turbine is an apparatus that transforms hydraulic energy into mechanical energy, which is then transformed into electrical energy by connecting the turbine’s shaft to the generator.

Source: Factors Affecting Selection of Hydraulic Turbine (The Constructor)

The mechanism in this instance is that the generator generates electricity whenever the water from the penstock comes into contact with the circular blades or runner under high pressure.

In general, the two types of hydraulic turbines are reaction turbines and impulse turbines.

Velocity turbine is another name for an impulse turbine. An example of an impulse turbine is a Pelton wheel turbine.

A pressure turbine is another name for a reaction turbine. This group includes Kaplan turbines and Francis turbines.

6. Power House

A facility known as a “power house” is set up to safeguard electrical and hydraulic machinery.

Typically, the foundation or substructure built for the power house supports the entire piece of equipment.

When creating the foundation for reaction turbines, some equipment, such as draft tubes and scroll casing, is fixed inside. As a result, the foundation is built on a large scale.

In terms of the superstructure, vertical turbines are positioned beneath generators on the ground floor.

Additionally, horizontal turbines are offered. On the first floor or mezzanine floor is a control room.

7. Draft Tube and Tail Race

The tail race refers to the passageway into which the turbine discharges in the case of an impulse wheel and through the draft tube in the case of a reaction turbine.

Source: Components of a Hydropower Plant and their Functions (The Constructor)

The suction pipe, also known as the draft tube, is simply an airtight tube installed on the outlet side of every reaction turbine.

It starts at the discharge end of the turbine runner and goes down to the tailwater level, which is 0.5 meters below the surface.

A flare of 4 to 6 degrees is typically applied to straight draft tubes to progressively slow down the flow of water.


With the working principle of a hydroelectric power plant being made known, it is good to know that something as sophisticated as this is renewable and can be able to last for 50-100 years. How awesome.


What is Hydropower used for?

Hydropower is used for generating electricity through the conversion of kinetic energy into electricity, which may subsequently be used to power buildings, businesses, and other establishments, hydropower uses turbines and generators for these processes.

Is hydroelectric energy renewable?

Hydroelectricity is a form of renewable energy, yes. Why? owing to the water. You may observe how water evaporates into clouds and returns as precipitation to the earth's surface. The water cycle is constantly renewed and can be used repeatedly to produce power.


Editor at EnvironmentGo! | | + posts

A passion-driven environmentalist by heart. Lead content writer at EnvironmentGo.
I strive to educate the public about the environment and its problems.
It has always been about nature, we ought to protect not destroy.

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