Hydroelectricity or hydropower is the energy harnessed from the great kinetic energy (energy of motion) possessed by water. It is a renewable and sustainable energy. The word hydro means water, which refers to power from water. Due to gravitational force, water flows and falls with so much energy that can turn the turbines whose mechanical energy can activate the generator to produce electricity. To harness water to generate power, there are three components to consider, viz. the dam, reservoir and electrical plant.

Hydroelectric energy

Hydropower has been utilized for hundreds of years by humankind in various applications such as grinding wheat into flour. It was later realized that water has the potential to produce electricity. As thus, the first hydroelectric plant was constructed in 1879 in Niagara Falls which lighted street in 1881. Today hydropower contributes to about 10% of the energy consumed in the United States. Many countries are making use of this energy with China being the top producer.

There’s more to hydroelectric energy which we highlighted in this article. We are going to explore hydropower basics, uses, pros and cons of hydroelectric energy, yearly consumption in various top countries, and the social and economic impacts of hydropower. There are different ways of harnessing hydropower which we will also discuss hereunder.

Hydroelectric Energy Basics

Here we start by discussing the basics of hydropower.

How does hydroelectric energy work?

Hydroelectric energy basically works by channeling massive amounts of water to power turbines to make electricity. There are various types of hydroelectric plants which we will discuss subsequently. Nonetheless, they all use the kinetic energy possessed by large quantities of water which will activate machinery that produces power. The amount of power you can generate depends on the amount of water and the force it applies when it falls from the reservoirs.

The several hydropower facilities include run-of-river reservoir, pumped storage power stations, tidal power stations, and dammed water. We will review these types of hydroelectric power plants under technologies.


Let’s explore the various technologies used in harvesting hydroelectric energy from reservoirs. These technologies commonly use the kinetic energy from water to generate electricity or to be applied in various applications other than electricity production. We shall explore that later in the article.

1). Pumped Storage Power Stations

These stations essentially work on demand and supply basis. Two reservoirs are elevated on different levels and when the demand is less, water is pumped into the highly elevated reservoir. When the demand increases, the water is pumped back to the lowered reservoir with a higher gravitational force to generate electricity.

pumped storage hydroelectric power station

Pumped Storage Hydroelectric Diagram – researchgate.net

2). Dammed Water

This facility uses the dam to store massive amounts of water in a reservoir. It is also referred to as the storage hydropower. The system provides a base load of electricity to consumers. It can also be shut down or activated anytime depending on power demands. To generate electricity, the water is extracted from the reservoir directly to the turbine which is connected to the electric generator. The generator will then give us electricity. This technology can store power which is independent to the inconveniences of water-flow for a couple of months.

Dammed water -storage hydropower

3). Run-of-the-river hydroelectric stations

This technology harnesses the natural flow of the river in producing the power. The water flows naturally from upstream and gets directed to the turbines which will activate the generator to produce power. Because of this natural flow of water in the river, the system does not necessarily need the storage. The system is continuous so it will provide the base load continuously to the end-user.

Run of river HydroElectric Station

4). Tidal Power Stations

Tidal power stations take advantage of tidal waves in the oceans. These waves fluctuate on account of the attraction of the moon to the earth and they often happen twice a day. The waves are effective in generating electricity by turning the turbines.

tidal powerstation

Hydroelectric Energy Applications

Hydroelectric energy has many uses some of which date back to thousands of years in history. It was largely used in agriculture to grind grain. Today, hydroelectric energy examples include irrigation, flood avoidance, electricity production, and industrial applications in addition to agriculture. Let’s explore these applications below:

1). Electricity Production

This is a global talk nowadays. Hydropower is touted as one of the largest sources of renewable energies around the world with China at the helm of leading hydroelectric energy producers. Not only is it the largest but also the cleanest with no air pollutions. According to reports, hydroelectric energy contributes to about 74% [1] of the total renewable electricity production. The International Energy Agency (IEA) pushes the agenda to see the figure doubling by the year 2050.

The kinetic energy possessed by water is of high magnitude to produce so much power to power millions of homes around the world. All that is needed is sufficient supply of water in oceans, artificial lakes to store the water and the electric plants installed in close proximity to generate power. The electricity will then be taken to the electricity grid to the consumers. While the capital costs may be exorbitant, the running costs of hydropower are cheaper since there is little maintenance involved.

2). Irrigation

Many misconceptions state that hydropower compromises irrigation which is not true in large water sources that are predominantly used for hydroelectric production. The large reservoirs that are built for the purposes of hydropower generation can also feed more water to irrigation facilities. These reservoirs collect large volumes of water which can be directed to the irrigation systems.

3). Flood Avoidance

In areas frequented by floods, hydropower applications can hinder the occurrence of floods. The hydropower plants are often constructed in such areas to control floods because large reservoirs are built to collect large volumes of water, especially in dammed water systems. Instead of giving way to flood pathways, they are redirected to a large retention. Small retentions of water are also effective in managing floods.

4). Industrial Applications

In the extraction of metals and in controlling small furnaces, hydropower is also used as a reliable alternative to the depleting fossil fuels. There are many industrial applications which will differ from one industry to the other.

5). Storing Energy

Hydroelectricity plants can also be used in energy storage. Currently, about 90 GW of Pumped Hydro Storage exists in the world. Pumped Hydro Storage is a system mainly used to store grid energy, and utilities are at the forefront of this technology. Essentially, it benefits them in load balancing, intermittent solutions, and capital investment reduction. Wind and solar energy, for example, are intermittent energy sources, so hydropower storage becomes useful at such times.

Pros and Cons of Hydroelectric Energy

Hydropower is touted as the best energy to power homes and potentially replace large portions of fossil-fuel-generated power in the coming years. However, it has some drawbacks which should be weighed too. But, in overall, the pros of hydroelectric energy outweigh the cons, which then make it an attractive and lucrative energy option. Let’s highlight the pros and the cons of this energy.


  • It is renewable – there is no way we can use up the water required to make hydroelectric energy. It keeps on being replenished by rainfalls. But there is a limit of places where we can erect reservoirs.
  • It is reliable – hydropower can be used as a base load energy source, especially in countries that have more hydropower resources. The energy is reliable and a consistent output can be generated as long as there are maximum volumes of water in the reservoirs.
  • It emits no pollution – there are no greenhouse gas emissions with hydropower plants when compared with the conventional carbon-emitting power plants. The only accountable emission happens when these plants are constructed. It is not continuous.
  • There is no fuel required – with the global depletion of fossil fuels to make electricity, hydroelectric energy is immune to such depletion because it only requires abundant supply of water. It is also immune to the ever-increasing costs of fossil fuels
  • Save electricity bills – the only costs involved are the startup ones as well as maintenance costs. Nonetheless, you will be saving more money with hydropower.
  • Little maintenance – hydroelectric energy plants require only little maintenance. The systems can last for 50 to 100 years.
  • Can store other energy sources – the Pumped Hydro Storage, as explained above, helps in storing the intermittent wind and solar energy for later use.
  • It has positive economic impacts so that consumers will save lots of money including their country


  • Negative environmental impacts – the installation of hydropower plants interferes with the environment. It compromises wildlife, displaces people, and destroys nearby houses. The inhabitants of the dam and ocean may be affected by the hydropower plants.
  • Expensive capital costs – the high costs of installing hydropower plants are prohibitive. The largest hydropower plants in China – The Three Gorges Dam, has cost the country $28 billion. Many countries in need of this renewable resource of energy may be reluctant of investing so much. Some may not even afford it.
  • Limited reservoirs – although the energy is renewable and we cannot deplete water around the world, the reservoirs are limited with the place to install them. Every place has to be accessed thoroughly first before the project can be deemed suitable.
  • Negatives of drought – where water resources are not abundant, the output of hydropower production may be affected by drought.

Social and Environmental effects of hydropower

Let’s discuss the negative effects of hydroelectric power on the environment, how does hydropower affect the environment and the social impact of hydro power plant. These are the factors that have to be considered before the project is given a green light. The incumbent installers of hydropower plants have to do research and weigh the social and environmental effects of hydropower.

Negative effects of hydroelectric power on the environment

It is important to research about the ownership of land and the dam prior to installing the plant because these issues may hinder the progress of the plant. There have been many places where this has occurred. Some of the negative effects this energy product has, include the killings of fish and ecosystem health due to some traces of methane emitted from water.

Social impact of hydro power plant

The construction of reservoirs and installation of plants may force the eviction of households in the precinct of the water resource. Before the project starts, you have to find an alternative accommodation of the people and that may be costly. The project may also compromise agricultural land and historic landscapes in close proximity to the dam.

Facts and Figures

Many countries have come to the forefront of utilizing hydropower as potential alternative to fossil fuels-generated power. Let’s check the facts and figures of annual consumption in selected countries such as the US, China, Russia, Brazil, India and Canada.

Yearly hydropower consumption in China

The Three Gorges Dam in China is the world’s largest hydropower dam with a capacity of 22.5 GW. The dam has 26 turbines of 700 MW each which were built in 2008. In total, the country is currently producing 200 GW of hydropower and foresees doubling that to 400 GW in 2020 [2].

Yearly hydropower consumption in Brazil

Brazil is also the largest producer of hydroelectric energy in the country. The country is home to the second largest hydropower plant in the world with an installed capacity of 14 000 MW [2] and 20 generators. Today, the country generates about 70 GW of hydroelectricity.

Yearly hydropower consumption in US

The United States is also one of the largest producers of hydroelectricity energy in the world. Hydropower provides 10% of electricity [3] in the United States. That is equivalent to over 250 billion kilowatt hours annually.

Yearly Consumption of hydropower in Russia, India, and Canada

Russia consumes about 45 GW, while India consumes about 33 GW whereas Canada is leading with 89 GW.

Worldwide, hydropower contributes about 16% of electricity [4] on a yearly basis. Over 60 countries rely on hydropower for half of their energy consumption. Since 2013, the usage of hydroelectric energy has grown by 4% because the energy is seen as the potential renewable source.

Economic effects of hydro electric energy

Hydropower has economic impacts in our countries. What are the economic impacts of hydropower that these countries should put an eye onto?

The greatest impact is that, hydropower generation brings absolute low-costs of energy usage to consumers and government. Amid ever skyrocketing fossil fuels prices, hydropower can save many households lots of money. While capital costs may be exorbitant, operating costs are infinitesimal. Moreover, these hydropower plants have an incredibly long lifespan of 50 to 100 years. If the system was built many years ago, it would take time to replace it. The hydropower system repays itself in fewer years.

Hydroelectric Energy Potential

Hydropower has lots of potential in future. The future looks bright because the conventional fossil fuels are getting depleted. Experts see hydropower as the potential to replace carbon emissions and thus cut greenhouse gas pollution. EU (European Union) has already encouraged its member states to reduce carbon emissions by 20% in 2020, which then gives way to renewable energies such as hydropower. The United States has also proposed to generate 15% of hydropower by the year 2030. On top of that, the International Energy Agency proposes a doubling of hydropower worldwide by 2050 from 16% to 32%. Worldwide, the hydropower output is about 1000 GW, and this is foreseen to grow even more.

Wrap up!

This marks the end of our comprehensive review of hydroelectric energy. The energy is seen as the potential replacement of the carbon-emitting fossil fuels. The ease of generating this energy makes it possible for countries to harness even though the cash-strapped countries find it difficult to invest exorbitant capital costs.

Despite the environmental impacts, the hydropower has positive outlook and economic impacts. As a result, world leaders are proposing a huge output in the coming years.

We have discussed everything you need to know about hydroelectric energy. This includes the pros and cons, hydroelectric energy basics and the applications.

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