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A dam producing clean and affordable hydroelectric power.

Hydroelectric Power Pros & Cons

In this article, you will learn about the different hydroelectric power pros and cons. We use hydroelectric power more than any other form of renewable energy. This is mainly because of the number of advantages it has. However, hydropower has some significant disadvantages associated with it. The following sections explain both the pros and cons of this energy source.

The Pros

Here are the many advantages of hydroelectric power.

Renewable & Sustainable

Water is a renewable and sustainable energy source that will never run. The use of this resource allows us to conserve non-renewable alternatives for other uses. As a result of this, countries can become less reliant on external supplies of fossil fuels. Conflict, economic issues, and general supply and demand can all affect the supply of these resources.

Environmentally Friendly

Hydroelectric power is a very clean and environmentally friendly form of energy. No fossil fuels need to be burnt in order to produce it. As a result of this, hydroelectricity doesn’t produce any harmful emissions. This is great for the environment and helps to reduce carbon emissions.

Efficient & Reliable

Hydroelectricity is highly efficient. Turbines used at hydroelectric power plants are often capable of 90% efficiency. This means they are able to convert 90% of the energy of flowing water into electricity.

Hydropower isn’t just efficient, it is also very reliable. With a good supply of moving water, hydroelectric turbines can generate electricity almost non stop. In this case, the only downtime a hydroelectric facility will experience is for general maintenance, upgrades, and repairs. Because of this reliability, hydropower is often advantageous over other renewable energy sources. For example, solar panels can only produce electricity during the day. Similarly, wind turbines can only produce electricity when there is enough wind.


Hydroelectric dams have a degree of flexibility when it comes to meeting energy demands. Operators of a hydroelectric dam can alter its water intake to increase or decrease the flow of water. As a result of this, the dam can generate a suitable level of electricity for the current demand. Engineers can perform this process in a very short space of time in comparison to traditional power stations.


After the initial cost of building a hydroelectric dam, it can generate power very cheaply. Hydroelectric dams have very low running costs when compared to traditional power stations. As a result of this, they are very economical. In addition, hydroelectric power isn’t vulnerable to the fluctuating cost of fossil fuels. This helps to provide a more stable economy with predictable energy prices.

Some countries have been successful in producing most of their energy supply from hydropower. For example, Paraguay is able to produce almost 100% of its electricity supply from the energy source.

Additional Uses

Hydroelectric dams often feature a large reservoir to one side of the dam wall. This is where a hydroelectric turbine will source its water from. We can also use such reservoirs as a water supply for surrounding towns and cities. This reduces the cost of building a separate reservoir and/or water towers.

Civilians can often make use of reservoirs situated next to hydroelectric dams for recreational purposes. Many of these reservoirs feature kayaking and windsurfing facilities for visitors to enjoy. In addition, large hydroelectric dams can sometimes become well-known landmarks of a country or region. This can help to attract large volumes of tourists each year, providing a boost to the local economy.

The Cons

Below you will find the various disadvantages of hydroelectric power.

Environmental Impact

Although hydroelectric power is environmentally friendly, the construction of a hydroelectric dam can have an impact on the environment. When a hydroelectric dam is built, it forms a reservoir behind one face of the dam wall. Depending on the size of the dam, this can have an impact over a large area. Environmental effects can be seen both upstream and downstream of the location of the dam.

As engineers begin to flood land to form the reservoir, wildlife can have their habitats destroyed. Changes in river levels, flow patterns, and water temperatures can also have a significant impact on fish. In addition, vast quantities of vegetation will die and begin to rot. This process emits methane – a greenhouse gas known to contribute to climate change.

Hydroelectric dams can even cause drought due to the amount of water they hold back. This impact can negatively affect the relationship one country has with its neighbor. This happens when ‘Country A’ builds a dam that causes drought further downstream in ‘Country B’.

Interested in reading more on this subject? If so, we have created a page dedicated to the environmental impacts of hydroelectric dams.

Displacement of People

The construction of a hydroelectric dam will often result in people becoming displaced. This happens when large areas of land are flooded in order to form a reservoir. Villages,  towns, and even cities may have to relocate to make way for a reservoir. As a result of this, communities can be broken up. It can also force some people to relocate from the place they have called home since they were born. Because of this disruption, financial incentives are often available to persuade people to relocate.

Expensive To Build

Hydroelectric dams are notoriously expensive to build. Lots of planning, engineering, and construction needs to happen before a dam can start producing power. It is only at this point that the dam can start to provide a return on investment. This is a process that can take many years.

Limited Places To Build

Hydroelectric dams have to be built in areas with the perfect conditions. An area’s landscape and precipitation levels need to be taken into account before considering such facilities. The majority of suitable locations have already been developed for hydroelectricity. Nowadays, there are limited places where we can build efficient hydroelectric dams.

Safety Concerns

Although the safety of modern hydroelectric facilities is often good, there are fears over the safety of older dams. There have been numerous disasters relating to dam failure throughout history. The most notable of which took place in China in 1975 and killed 171,000 people.


We can see from the pros and cons of hydroelectric power that there is a case for and against the technology. On the one hand, hydroelectricity is capable of providing a source of clean, reliable and renewable electricity. On the other hand, hydroelectricity can destroy habitats and displace people.