Is Hydroelectric Power Plant Good Or Bad?

Hydroelectric power is a form of renewable energy that uses the natural flow of water to generate electricity. It is considered a clean and green source of energy since it does not produce greenhouse gas emissions or toxic waste. However, there is an ongoing debate around whether hydroelectric power is ultimately good or bad for the environment.

On one hand, hydroelectric dams provide carbon-free renewable energy and help meet electricity demands without relying on fossil fuels. On the other hand, constructing dams can negatively impact wildlife habitats, ecosystems, and natural water flows. There are also concerns around methane emissions from reservoirs and high upfront costs of building hydroelectric plants.

In this article, we will examine the pros and cons around hydroelectric power being a sustainable and eco-friendly energy source. By evaluating the environmental impacts, costs, and reliability, we can gain a balanced perspective on the overall benefits and drawbacks of hydroelectricity.

Pros of Hydroelectric Power

Hydroelectric power offers several key benefits that make it an attractive energy source:

  • It is a renewable source of energy. The water cycle continuously renews the water supply used to generate electricity at hydroelectric plants.
  • Operating costs are relatively low compared to fossil fuel plants. The fuel (flowing water) is free and does not need to be mined, transported, or processed.
  • Output can be adjusted quickly to meet variable demands for electricity. Hydroelectric generators offer more flexibility than steam turbines in responding to rapid fluctuations in grid power needs.
  • Hydroelectric dams often create reservoirs that are used for recreation, like boating, swimming, and fishing. Many hydro facilities are multipurpose and also provide flood control, irrigation, navigation, and water supplies.

According to the U.S. Energy Information Administration, hydropower accounts for over 6% of net electricity generation in the United States, making it an important domestic energy source.

Cons of Hydroelectric Power

While hydroelectric power has some advantages, it also has some significant drawbacks and negative environmental impacts that need to be considered. Some of the main cons of hydroelectric power include:

High Upfront Costs

Constructing a hydroelectric power plant and dam requires huge upfront investments. The costs involved in site preparation, construction materials, turbines and generators are very high compared to other energy sources like wind or solar (Environmental Impacts of Hydroelectric Power). This makes the payback period for hydroelectric projects very long.

Disrupts River Systems and Wildlife Habitats

The reservoirs created by damming rivers cover large areas that were once forests, fields, wildlife habitats and human settlements. This destroys existing ecosystems both upstream and downstream, and fragments riparian habitats (Hydroelectric Power Water Use).

Methane Emissions from Reservoirs

Organic matter like vegetation and soil gets flooded in hydroelectric reservoirs. As this material decomposes underwater, it releases methane, a potent greenhouse gas. Some studies suggest reservoirs may have higher emissions than fossil fuel plants (Hydropower and the environment).

Impact on Wildlife

Hydroelectric power plants can have significant impacts on wildlife habitats and populations. The dams built to create reservoirs flood large areas of land, displacing or destroying habitats critical for wildlife. According to, these changes can negatively affect native plants and animals in and around the river.

The dams act as barriers that disrupt fish migration and prevent access to spawning habitat. As noted in, the reservoirs created by dams flood forests, wetlands, and other wildlife habitats. This fragments or eliminates habitats that are important for the survival of many species. The changes to water flow and levels also impact food sources and ecosystems downstream.

Overall, the flooding of land to construct hydroelectric reservoirs can destroy significant wildlife habitat and disrupt critical ecosystem functions. The dams impede fish migration and prevent access to spawning areas upstream. These impacts can harm local plant and animal populations if not properly mitigated.

Greenhouse Gas Emissions

Hydroelectric power plants produce greenhouse gas emissions, primarily in the form of methane from reservoirs. As vegetation decays underwater in reservoirs, it releases methane into the atmosphere. According to the IPCC, hydropower’s median greenhouse gas emission intensity is 24 gCO2-eq/kWh (Hydropower’s carbon footprint). This is lower than fossil fuel power plants, but still a concern for renewable energy goals.

Methane is a potent greenhouse gas, with more than 25 times the global warming potential of carbon dioxide over a 100-year period (Tracking the Carbon Footprint of Hydropower). Proper site selection and management strategies can help reduce methane emissions from reservoirs. For example, boreal and tropical regions tend to produce more methane than temperate climates. Overall, hydroelectric’s lifecycle emissions are typically far less than fossil fuel alternatives.


Hydroelectric power plants have some of the highest upfront construction costs of any power generation technology. According to Statista, the global average installed cost for hydroelectricity was $2,881 per kW in 2022. This is significantly higher than the costs for fossil fuel or solar power plants.

However, hydroelectric plants have relatively low operating and maintenance costs over their lifetimes. Once constructed, the fuel (flowing water) is free. Routine maintenance and repairs are cheaper compared to fossil fuel plants. According to Hydro Review, hydro had the lowest total construction cost in the US in 2016 compared to solar and wind. So while initial costs are high, operating costs are low over the long term.

Reliability of Hydroelectric Power

Hydroelectric power is considered one of the most reliable forms of renewable energy, as it can generate electricity 24/7 and adapt quickly to demand fluctuations.1 The constant flow of water through hydroelectric dams allows them to provide stable baseload power to the grid. However, hydroelectric generation can be vulnerable to droughts and seasonal variability in precipitation.2

During periods of drought, the water flow into hydroelectric dams is reduced, which lowers electricity production. Many large hydroelectric facilities store water in reservoirs to hedge against droughts, but multi-year droughts can still impact output. Additionally, hydroelectric output varies seasonally with precipitation and snowmelt patterns, producing more electricity in spring and less during drier months.

Overall, hydroelectric power remains one of the most reliable renewable resources. But reliance on hydropower varies regionally based on water resources and vulnerability to drought. Diversifying the renewable energy mix with solar, wind, and geothermal can complement hydropower during periods of reduced water flow.

Case Studies

Some of the largest hydroelectric power plants in the world include:

The Three Gorges Dam in China has a capacity of 22,500 MW, making it the largest hydroelectric power station in the world by installed capacity. Completed in 2012, this massive project spans the Yangtze River and provides electricity to central and eastern China.

The Itaipu Dam on the border between Brazil and Paraguay has an installed capacity of 14,000 MW, generated from 20 hydraulic turbines. As of 2016, the Itaipu Dam accounted for 17% of the electricity consumed in Brazil and 75% of the energy consumed in Paraguay.

The Grand Ethiopian Renaissance Dam (GERD), currently under construction on the Blue Nile River in Ethiopia, will be the largest hydropower project in Africa upon completion. It is expected to have a capacity of over 6,000 MW.

The Grand Coulee Dam in the United States, completed in 1942, has a capacity of 6,809 MW generated from 33 hydroelectric power generating units. This gravity dam on the Columbia River is one of the largest concrete structures in the world.


There are renewable energy alternatives to hydroelectric power that can provide clean electricity with less environmental impact (Oxfam, 2022). Solar, wind, and geothermal energy are clean sources that allow rivers to flow freely without the ecological disruption caused by dams.

Solar power harnesses energy from the sun and converts it into electricity through photovoltaic panels. Solar farms can generate large amounts of renewable power without diverting waterways. Wind power utilizes wind turbines to generate electricity with minimal environmental footprint. Geothermal energy taps into underground reservoirs of steam and hot water to spin turbines without any emissions (LinkedIn, 2022).

Transitioning to more solar, wind, and geothermal energy can provide clean electricity while preserving river ecosystems and habitats. With advances in renewable technology and energy storage, these alternatives can potentially replace hydro dams in the future.


To recap, hydroelectric power has both advantages and disadvantages that must be weighed when considering it as an energy source. The main pros of hydroelectricity are its low operating costs once facilities are constructed, its ability to quickly adjust output to meet demand, and its lack of air pollution. The primary cons are the high upfront costs of building facilities, potential impacts on wildlife habitats and fish migration patterns, and the large land areas needed for reservoirs.

Overall, hydroelectricity can provide reliable, renewable energy at a reasonable cost, but steps must be taken to mitigate its environmental impact. Siting hydroelectric dams on existing reservoirs or rivers with low ecological value can help. Fish ladders and hatcheries may protect fish populations. In some cases, hydroelectricity’s benefits outweigh the costs, but each project should be evaluated individually based on its unique circumstances.

The verdict on whether hydroelectricity is “good” or “bad” depends on weighing these various factors. With proper planning and mitigation strategies, hydroelectric power can be a valuable component of a diversified energy portfolio. But hydropower is not appropriate everywhere, and other renewable sources like wind and solar may be preferable in some instances. Careful analysis is required to determine if hydroelectricity is the right solution for providing clean energy in a specific location.

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