Green Technology

Hydroelectricity 101: Should We Support this Form of Energy?

January 22, 2018

At first glance, hydroelectricity may seem like the ultimate renewable energy resource. It’s readily available, relatively inexpensive and uses natural resources to produce electricity. On the other hand, it can negatively impact marine life and their habitats, change the landscape and alter natural water flow patterns.

This Hydroelectricity 101 guide explains the basic process of how hydroelectricity works. Basically, hydroelectricity is the result of damming rivers. Water builds in a reservoir, creating a pressure differential. The pressure differential forces water through a penstock, which turns a turbine connected to an electric generator. Higher dams have more energy potential, since steeper penstocks create more energy.

The ocean also represents another potential form of hydroelectric power in the form of tide cycles and waves. In fact, coastal water resources have the potential to generate up to 1,000 terawatts of energy in the United States alone. Some offshore hydroelectric sources are in use, though at a much smaller scale compared to hydroelectric power.

Do the benefits of hydroelectric power outweigh the risks? Industry experts, state and federal governments haven’t yet reached a conclusion. While the EPA considers hydroelectric power a renewable resource, many states use differing criteria as to whether hydroelectric power counts toward their renewable energy goals. Here are the main factors in the Hydroelectricity 101 debate.

Resource Availability

Nearly 70 percent of Earth’s surface is covered by water. With the availability of both inland and offshore water resources, the possibilities for hydroelectric power are endless. Water is also technically a renewable resource. In the water cycle, water is constantly changing forms and is redeposited to the planet’s surface in the form of precipitation. For this reason, the EPA considers hydroelectric power, like wind and solar power, to be a renewable energy resource.

Wind and solar energy, however, have grown in popularity in recent years, with more companies committing to use these renewable energy resources to power their facilities. Hydroelectric power, however, has remained relatively stagnant, despite its enormous potential. Part of this lack of interest may be due to the fact that many states don’t consider all hydroelectric power resources to be renewable energy resources.

States such as California worry that by including hydroelectric power as a renewable energy resource, states will reduce their efforts to expand their use of renewable energy. Since many states already have hydroelectric facilities, changing this distinction would increase the amount of renewable energy the states were using, and perhaps decrease their incentive to invest in new technologies.

Reduced Cost and Carbon Footprint

Hydroelectric facilities have low operation and maintenance costs, since they don’t require fuel. Additionally, the infrastructure is built to last up to 100 years, if not longer. As a whole, hydroelectric power is more cost-effective when compared to other energy resources.

No fuel also means hydroelectric plants don’t release harmful greenhouse gas emissions. Energy production is responsible for nearly 25 percent of global carbon emissions. By using power generated from clean sources, it will be possible to reduce the global carbon footprint and potentially slow the rate of global climate change.

Another benefit of hydroelectric power is that it can vary to meet shifting changes in energy needs. Solar energy can only be collected when the sun is shining, and wind energy can only be collected when the wind is blowing. The ability to meet the varying energy demand means energy prices will be kept more stable.

Hydroelectric power is also abundantly available domestically, which can help maintain price stability. Instead of relying on foreign oil imports, it can be generated throughout the nation. Additionally, dams create reservoirs that can be used for recreational activities and boost local tourism and quality of life.

Environmental Impact

Dams change the environment downstream of a river considerably. Flowing rivers carry sediments that naturally settle along the river’s bottom and banks. Dams prevent these sediments from flowing downstream, which leads to incising, or the deepening of the river. While this may not seem like a problem initially, it can lead to changes in the groundwater table over time.

As the river cuts deeper into the ground, it will lower the surrounding water table, making it more difficult for vegetation to access surface water resources. Additionally, humans relying on private wells may need to drill deeper to access groundwater supplies. In some instances, extreme reservoirs actually cause downstream rivers to run seasonally dry, which lowers the groundwater table even more.

A seasonally dry water table means certain marine life downstream may die off. Many of the hydroelectric dams throughout the northwest interrupted salmon spawning patterns, which led to significant population decreases. Reduced water flows may also change the volume of dissolved oxygen in the water, which plants and fish need to breathe. Once the oxygen level drops too low, nothing in the water will be able to survive.

From a larger perspective, plants and trees that relied on the river will also be compromised. Farmers will need to invest in expensive irrigation systems or find alternative water sources to continue to water their crops. Animals will need to migrate to find new sources of water, since their current supply was diminished.

Hope for the Future

While conventional hydropower infrastructure may seem to be too risky or costly for the environment to implement, new research may yield strategies that preserve environmental conditions, while also maximizing electricity output. Additionally, smaller hydroelectric facilities may help reduce the environmental impact.


Hydroelectricity sits in a precarious position. While it produces no greenhouse gas emissions and offers a cost-effective, stable solution to electricity generation, it also comes with other environmental impacts that are difficult to ignore. However, continued research and new technological innovations may find solutions to preserving environmental conditions, while also allowing us to take advantage of this abundant resource.

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