Understanding The Facts and Information About Hydropower

Currently, hydropower is a slumbering giant in the energy industry offering approximately 16% of the world’s electricity. However, since the 1960s, its use has drastically gone down compared to other sources of energy.

What is hydropower?

Hydropower is the massive production of energy that makes it possible to generate electricity without the need for fossil fuels. It involves converting the kinetic energy in water into electricity. Usually, hydropower doesn’t produce emissions as is the case with electricity from coal, oil, or gas power plants. This therefore means that hydropower is environmentally friendly and hence perfectly falls under the green energy category.

How hydropower is generated

Hydropower Explained
Hydropower Explained

Usually, the awesomeness of hydropower lies in its simplicity. Kinetic energy (Moving water) spins mechanical energy (a wheel or turbine), which drives electrical energy.

According to research that dates back 5,000 years to 3,000 years BC, there has been evidence of water storage dams in Egypt, Jordan, and other places in the Middle East.

Vitruvius, one of the greatest Roman designers, architect, and engineer, documented his plans that could generate power in 70 BC–. 25 BC. The Romans built several waterwheels in the 4th century, with Barbegal, France being one of the most desired. Connected to a gigantic aqueduct system that provides water to the Arles city was a great flour mill with approximately 16 waterwheels in two parallel rows. The water moved the first wheels, moved downwards to the second pair of wheels, then downhill once more until it moved through all the 8 sets. Afterward, it ran into a pool at the bottom of the hill.

Nowadays, instead of utilizing waterwheels through a duct or moving river, the most hydroelectric plants depend on the energy coming from a vertical distance from where the water drops. The water is directed through a gate, sluice, or enclosed pipes that channel water to the turbines. The channels are regarded as penstocks. Basically, hydroelectric plants require four things to generate power.


Dam – Photo by John Gibbons on Unsplash

A dam holds the water from a river, increase the water level, and control the flow of water to the penstocks. Dams offer reservoirs that can be utilized for recreation purposes; however, it is the height deviation between the turbines below and the stored water that represent the energy.


Hydro Turbines
Hydro Turbines

The water in the dam is directed towards the penstock, past spinning blades of turbines. This converts the moving water (kinetic energy) to mechanical energy. The force created by the falling water pushes the turbine’s blades causing them to spin. Normally, the turbines are just like a windmill, except that the energy is offered by falling water and not the wind. The turbines are responsible for converting moving water energy into mechanical energy.


Hydroelectric Generator
Hydroelectric Generator – Source

The turbine’s shaft turns a generator, therefore, converting the energy (mechanical) to electrical energy.

Transmission lines

Hydroelectric Transmission Lines
Hydroelectric Transmission Lines

The electricity produced is channeled to the substations and transported to consumers through transmission power lines.

How much electricity does a hydroelectric plant make?

The amount produced by hydropower plant depends on two aspects:

  • The amount of water

Normally, the more the water falls on the turbines, the more power it will produce. The available water depends on the amount flowing down the river. Bigger rivers have a significant amount of water, which means they can produce more energy. Overall, the power produced is directly proportional to the amount of water flowing in the river. A river with thrice the amount of flowing water as another can arguably produce thrice as much energy.

  • The distance of the falling water/ height

Basically, the higher the waterfalls, the more the power produced. Normally, the distance depends on the dam size. The higher the dam, the greater the distance the water will fall, hence more power. Overall, the falling distance is directly proportional to the power produced.

Factors to consider before settling for hydropower

Usually, setting hydropower is a major undertaking; therefore, you need to be sure not to miss a thing. For a successful hydropower project, you need to comprehend some technical challenges and how to solve them. In addition, having some engineering knowledge can be a gateway to a successful project. There are physical and economic factors affecting the development and generation of hydropower. Let’s have a look at some aspects to consider before settling for hydropower.

Physical factors

Before settling for hydropower, the physical conditions below are important for the construction and success of hydropower:

  • The degree of slope: Ensure the selected physical location is characterized by a rugged topography
  • Quantity of water: Ensure there is enough water supply which can effectively turn the turbines
  • Availability of waterfalls: If waterfall is available, it will significantly reduce your budget of enhancing the kinetic energy of water.
  • Sturdy rock structure: presence of a rock structure provides a perfect run-way for water and therefore there is minimal seepage of water
  • Presence of lakes: Lakes rarely run dry and therefore they can be good sources of water even in a dry period.
  • An ideal climate, for instance, the temperature that is above the freezing point
  • Silt-free water: This ensures there is no blockage in turbines and also minimizes the budget of filtering the water.

Of these factors, the main ones are the degree of slope and the quantity of the water. The more the quantity of water, the longer or steeper the slope, and the power generated. The two aspects, slope, and water are compensatory; this means that if a small amount of water falls from a high height, it can generate a large amount of power. Similarly, a high amount of water can generate a large amount of power on a slight slope. The streams producing power can, therefore, be categorized into two. I.e. the streams of high fall and the streams of low fall. in relation to cost, high fall streams are advantageous over the low fall counterpart because their maintenance is somehow cheap. The advantage, therefore, lies with the slope over the volume. As evidenced from the point above, water-power can be created only;

  • When the fall is available, such falls particularly occur in glaciated areas or rugged mountainous areas.
  • When the stream volume is more or less uniform since flood can destroy plants while the low flow of water can cause stoppage due to insufficiency.


Properly investing in hydroelectric power in areas where water resource is not an issue will lead to a successful project. However, you should also note that areas with plenty of water can lead to failure in the future due to climate change. To maximize the success of your project for both long-term and short-term, it is vital to create climate resilience into the project. This needs expert hydrological modeling depending on the best historical data and professional future projections while considering the range of impacts on rainfall, water availability, climate, and inflows.

The effect of climate may result in reduced water availability. In other cases, the hydropower scheme requires to hold and use the increased inflow or rainfall.  So you need to be ready for the uncertain future resource through thorough research and investigation of how the climate used to be in the last few years, how it is currently, and future predictions.

Economic factors

Economic factors play an integral role in the development of hydropower. Some of these factors include;

Power demand

The hydropower project is expensive and for you to compensate the amount, it is critical to know the demand for power. High demand means that generated electricity will be utilized in the local area. If you need to set up hydropower, ensure that the area around is densely-populated, and the need for power is high.

Other energy sources

An area with other energy sources is not suitable to set up hydropower due to competition. In areas where petroleum and coal are available in large amounts, electricity is as well generated with them. Oil and coal deficiency countries like Norway, Japan, and Sweden, etc., rely on hydro-electricity.

Capital investment

Before settling for hydropower, you need to have enough capital. Basically, the project is generally costly involving dam erection, construction of power plant, transmission cost, all year round maintenance cost, incidental compensation cost, etc. Normally, from the point of generating power to the point of distributing it to consumers involves a lot of servicing and construction work, high-tension cables, and transmission lines.

You also need to get permission from the authorities and the owners when the transmission line passes across private land. Besides, a team of professional wiremen, engineers, and administrative staff has to be paid to run the whole operation.

Therefore, you should be ready for initial cost and maintenance cost. It is a common myth that setting hydroelectric power is cheap since water is free. However, you should also consider other costs involved in the whole project.

Other factors

Hydroelectric plant schemes

Hydroelectric Plant Schemes
Hydroelectric Plant Schemes – See more on Wikipedia

There are 3 primary kinds of hydroelectric plant arrangements, grouped according to the technique of controlling the flow of hydraulic at the site. They are;

  • Storage plants – these can store water and control the flow on the plant on a seasonal or daily basis.
Hydro News 30
Hydro News 30
  • Run-of-the-river plants – these have small water storage capacity and therefore little flow through the plant.
Hydroelectric Run Of The River Plant
Hydroelectric Run Of The River Plant
  • Pumped storage plants–These alter the rotational direction of turbines in the off-peak hours, directing water from the lower reservoir to the high reservoir, therefore, storing energy used for electricity production.
Hydroelectric Pumped Storage Plants
Hydroelectric Pumped Storage Plants / Rio Grande Hydropower (Argentina)

Plant capacity selection, energy, and other features

The capacity of the hydroelectric plant to generate electricity is determined by the head and the rate of water flow discharged from the hydraulic turbines. Here is the equation of what happens.

P = 9.8 η Q H


P = power,

η = plant efficiency

Q = flow rate discharge

H = Head

The head and the flow rate are affected by the reservoir inflow, equipment, and plant design features, storage characteristics, minimum downstream releases, flow restriction by irrigation, and flood control prerequisite. Usually, the energy, plant capacity, and physical features like spillway structures and dams are optimized through technical-economic studies that evaluate the hydrological data, plant equipment performance characteristics, the value of energy and capacity, planned reservoir operation, and discount rates. Another planning thing worth considering is the selection of size and the number of generating units installed to attain the required plant capacity and energy, considering the unit availability, installed unit costs, efficiencies in different power unit output.

Benefits of hydropower

Hydropower provides several advantages to the areas that they serve. Below are a few benefits that hydroelectric power has over other energy sources.

  • It is a renewable source of energy

The hydropower energy source is renewable. It is renewable because it utilizes water on the river to produce electricity. Normally, when the sun shines, water evaporates. Evaporated water forms the clouds which later fall onto the earth’s surface as rain and snow. Lakes and rivers that usually generate electric power will never come to vanish. This means that anyone can use water without worrying about it becoming scarce or expensive. That said, there are a few appropriate repositories where a power plant can be built and fewer areas where such undertakings are helpful.

  • Cost-effective

Even if the upfront cost of building hydropower is high, the overall power is cost-competitive. River or lake water is an endless source that can’t be altered whatsoever by the volatility of the market. On the other hand, fossil fuel energy like oil, coal, and natural gas are highly affected by the volatility of the market, driving up or greatly lowering their prices.

On average, hydropower plants possess approximately 50-100 years of a lifetime. This implies that it is a great investment that guarantees support for several future generations. They can also be improved to modern-day technological requirements and posses significantly lower maintenance and operating costs.

  • An environmental friendly energy source

You can attest that hydropower is one of the clean and green alternative sources of energy out there. Producing energy from water is not contaminating. The hydroelectric plants utilized in the whole process do not produce or rather emit any greenhouse or toxic gases that would otherwise pollute the environment. The only time pollution happens is when building power plants.

Compared to other alternative energy sources, hydropower plants emit fewer greenhouse gases, which assist mitigate the acid rains, climate change, and smog. Hydropower also enhances the quality of air that we breathe since they don’t emit any pollutants. In addition to that, the plants don’t produce any toxic byproducts.

  • Remote community development

Hydroelectric power contributes to the development in remote areas; attract industries, construction of highways, and commerce. These activities serve to improve the remote area’s economy, increase accessibility to healthcare and schools, and improve the life standard of the residents. Hydroelectric power technology has been measured for several years, and many people have witnessed how helpful technology is. Hydropower is forever available where development is required.

  • Recreation opportunities

The lakes and rivers that form after the dam are made can be utilized as a good recreational opportunity, providing outdoor activities like boating, fishing, and swimming. The river water can still be utilized for irrigation needs. Besides this, big dams are a great spot for tourist attractions.

Usually, a hydroelectric power plant can store a lot of water for irrigation when there is no rainfall and for consumption when there is a shortage of water. The ability of water storage is beneficial because it protects the water table and reduces the susceptibility of floods and droughts.

  • The primary vehicle for resourceful development

The energy technologies organized and operated in economically viable, environmentally sensible and socially responsible models indicate a massive notion of sustainable development. This implies the development models currently that point out an individual’s needs without hindering the ability of future generations for engaging their needs. Hydropower is actually on the list of these energy technologies.

Disadvantages of hydropower

  • Environmental damage

Interruptions of the flow of water can result in a significant impact to the environment and ecosystem. Some aquatic species like fish and other creatures usually move from one place to another in search of food or during the breeding season. If you construct a dam, you will be cutting off their path, making them not reproduce or even die.

Normally, the natural impact of hydropower is seen with the intervention of nature due to the altered flow of water, damming of water, and the development of power lines and streets. Hydropower plants can influence aquatic species and the way they migrate, however, it is a hard process to research and challenging to make a determination depending on one factor.

  • Upfront capital cost

The cost of developing hydroelectric power is very high, no matter the kind of project you’re undertaking. Hydropower plants are expensive to construct because of the logistical issues like topography, underwater foundation, and materials required to build it. The sole benefit as far as cost is concerned is that after completing the project, the maintenance cost is relatively low. Overall, the project has to run for a long time before you recover the money injected into the whole project.

  • Conflict

Countries that have successfully created hydroelectric power normally build dams across the lakes or rivers to get the water. Although hydropower project is a good idea, it can lead to interruption of the flow of water from one particular area to another. When a certain area doesn’t need much water, it can be channeled to another area to cater for people who want to create dams in their area. However, if the scarcity of water occurs in those areas, it can cause conflict because it would mean altering or terminating the whole project.

  • Can cause draught

One of the primary setbacks to setting up hydropower is the issue of draught. The overall power and energy costs are realized depending on the accessibility of water. This accessibility can be greatly altered by dry spells resulting in people not accessing the power they need.

  • Risk of floods

People living in the lower elevation are vulnerable to flooding should water increase from the dam. Basically, the livelihood of individuals living in such areas can be destroyed.

  • Methane and carbon dioxide emission

The hydropower reservoir emits a significant amount of methane and carbon dioxide. Normally, there is a lot of water in the areas around the dam. Therefore, plants below the water will start to rot and decompose. This type of decomposition occurs without oxygen, resulting in methane and carbon dioxide production, increasing pollution.


When did electricity become common?

The electrification of the house in North America and Europe started in the early 20th century in the main cities and in regions served by electric railways. The use of electricity significantly increased until 1930, when approximately 70% of all the houses in the U.S. had electricity.

Is water renewable?

Water is regarded as a renewable material when carefully used, treated, and released. If not properly used, it can be non-renewable resource. The reason why it is considered a renewable resource is that it evaporates out of the river/lakes/oceans to form clouds, which later fall as rain. The water then gets back to the river where it is utilized again for industrial, agriculture, and domestic purpose.


Building dams in particular areas with the potential to generate massive amounts of energy can introduce several issues. Although the hydropower project comes with myriads of benefits to the final consumer, there are variables that can hinder its development. With this in mind, it is wise to figure out and weigh the benefits and setbacks associated with the whole project before investing in it. If you need to start this project, you should consider a nice course of action, which is to conduct a comprehensive analysis of local statistics before getting started. Many major considerations are to ensure that your hydropower project doesn’t affect the environment and people living around. It needs also to comply with local safety requirements.

Written by M Eduard

M. Eduard was born and raised in San Francisco, CA. Eduard spent his MBA summer internship at Sungevity, a residential solar energy retail company in Oakland, CA. He started this website to share his knowledge about renewable energy.