As one of the world’s most important renewable energy sources, with a development history of more than a century, hydropower is a core energy option for many countries, including the United States, Canada, Brazil, and China.
The biggest hydroelectric power plant is based in Three Gorges Dam on the Yangtze River in China. Its key advantage is that it requires no combustion of fossil fuel, yet it has long been plagued by controversy: supporters affirm its clean, renewable nature, while critics highlight three major flaws: severe environmental risks, exorbitantly
high construction costs, and damage to local ecosystems. To make rational decisions for the future of global energy.
It is necessary to strike a balance between these two opposing views. In the following sections of this guide, we will use plain, accessible language to break down hydropower’s working mechanisms, core values, existing shortcomings, and the rationale for its sustainability positioning.
What is hydropower?
Hydropower refers to the generation of electricity from the energy that is present in moving water. Hydropower stations require the construction of a dam to manage the flow of a river. Once the water is flowing, the moving water is made to spin turbines, and the generators then convert the kinetic energy of the flowing water to electrical energy. Hydropower stations are divided into large-scale, medium-scale, and small-scale facilities. Large-scale stations have the capacity to generate power to supply entire cities. Medium-scale stations power larger regional areas, and small-scale micro-hydropower systems are able to supply electricity to rural communities. Hydropower is much cleaner than coal-fired and natural gas power plants, which burn fossil fuels. It is estimated that hydropower projects serve about 16% of the world’s total electricity generation and are one of the world’s leading renewable sources of electricity.
Pros of Hydroelectric Energy
1. As a clean energy source widely used across the globe, hydropower has multi-dimensional core competitiveness: it relies on Earth’s water cycle to achieve perpetual use. Unlike gradually depletable fossil fuels such as coal and oil, it is a core option in the long-term energy layouts of many countries.
2. During its operational period, it produces almost no direct air pollution, with emission levels far lower than those of fossil fuel power plants. For this reason, it is included in countries’ climate emission reduction plans and can deliver multiple environmental benefits, such as cutting carbon emissions, improving air quality, reducing reliance on fossil fuels, and supporting the achievement of renewable energy targets.
3. Producing electricity from solar and wind sources is heavily reliant on the prevailing weather conditions. Compared to other sources, output from electricity generation from hydropower is predictable and reliable. Additionally, hydropower plants can manage the flow of water and generate electricity at the time of peak demand, thus balancing the electricity grid.
4. Hydropower plants are very capital-intensive to build, but once they are completed, the water that is used to generate the electricity is free, and the plants do not incur any costs to buy fuel.5. Hydropower stations are very long-lived, and their dams, built many years ago, are still operating to this day, resulting in very low operational costs over many years.6. Reservoir areas can develop five types of recreational projects, such as fishing and boating, driving growth in the local cultural and tourism economy.
Cons of Hydroelectric Energy
1. First, construction costs are extremely high, covering five categories of costs, including dam construction and land acquisition, environmental studies, infrastructure development, and relocation of communities. Large-scale projects cost billions of US dollars and have very long construction cycles.
2. It damages original ecosystems, alters natural river systems, and blocks the breeding routes of migratory fish such as salmon. Reservoir water storage also submerges forests and wildlife habitats.
3. In terms of environmental challenges, hydropower, as a source of renewable energy, does face issues as it is extremely vulnerable to drought. Since water availability is essential to hydropower, droughts lead to the left of water at the reservoirs and the power produced drastically decreases, and energy supply can be insufficient, resulting in energy shortages. Climate change can worsen this problem.
4. Concerns arise from relocating communities and forcing indigenous populations and riverside towns to move. This has long-lasting social and economic effects.
5. Dams cause injuries to fish when they are struck by moving turbine blades, alter the temperature of waters, reduce the levels of dissolved oxygen and modify the transport of sediments, all of which have serious impacts on the threat of extinction.
6. Although hydropower is a cleaner source of energy than traditional fossil fuels, the submerged vegetation in tropical reservoirs that decays causes the release of methane, which questions the argument that all forms of hydropower are carbon-free.
7. Although the failure of a dam is rare, it can have disastrous consequences as it causes massive floods, destruction of property, and death to many people. In addition to these, the failure of a dam can have long-term environmental consequences. When the failure of a dam is a fundamental concern, high standards in engineering design can improve, but cannot eliminate this challenge.
Summary:
In global dialogues on energy issues, hydropower has always occupied a unique dialectical position: it is cleaner than fossil fuels, can stably output massive volumes of electricity over decades, and outperforms most other renewable energy sources in terms of scale and stability. Yet it also reshapes natural landforms, disrupts wildlife survival, and undermines the development of local communities. Moving beyond black-and-white binary judgments, the core priority is how to utilize hydropower responsibly. Drawing on technological iteration and growing environmental awareness to balance power generation and ecological protection, hydropower remains a core renewable energy tool for the world, carrying both notable potential and inherent challenges.
Hydroelectric Energy vs Other Renewable Energy Sources
Here’s how hydropower compares to other renewable energy technologies.
| Energy Source | Reliability | Environmental Impact | Operating Cost | Weather Dependence |
|---|
| Hydroelectric | High | Moderate to High | Low | Moderate |
| Solar | Medium | Low | Very Low | High |
| Wind | Medium | Low | Low | High |
| Geothermal | High | Low | Moderate | Low |
| Biomass | Medium | Moderate | Moderate | Low |