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Aerial view of a dam

As the world slowly shifts to a more renewable-heavy energy supply, hydropower energy is becoming an increasingly important part of the global market. Here in the United States, water-powered electricity plants are creating sustainable solutions to ever-growing power demands. 

What Is Hydropower Energy? 

Hydropower is a type of energy generation that uses the movement of water to produce electricity; it’s also called hydroelectric power. Plants harness the kinetic energy stored in flowing water and convert it into electric power. These facilities are typically located on or near a river or another large water source. 

As energy companies continue to find new solutions in the face of depleting natural resources and climate change, hydropower is a promising solution. This clean, sustainable energy source offers a number of advantages over traditional types of power, making it an important part of our future. 

The History of Hydropower 

Hydropower isn’t new; people have been using the energy of water for centuries. In ancient Rome, Vitruvius used a water wheel to irrigate fields, and the Greeks used water wheels for grinding operations. The water wheel has a long history of powering a range of mechanical devices, including mine hoists and wood grinders. Hydroelectric plants were invented in the late 1800s, and the essential design has stayed the same over the years. 

How Does Hydropower Work? 

There are several types of hydropower plants, but each one uses the same basic principle: they move flowing water into hydropower turbines. The water spins the turbine blades, which rotates the attached rotor shaft. The shaft is connected to a generator, which converts the movement into electricity. 

To maximize the energy in the water, hydroelectric facilities usually place the turbines at a lower elevation. As the water flows downward, it gains force and generates more electricity. 

Infogrpahic of the sources if hydroelectric power
  • Impoundment (storage). These facilities use a large dam to create a reservoir in a river. The water flows down the dam through a sloped penstock, into the turbines, and back into the river at the bottom of the dam. This is a popular type of hydropower because it allows controlled production — operators can release water from the reservoir to accommodate shifts in electricity demand. 
  • Run-of-river (diversion). This type of plant uses the continuous force of a flowing river to generate a steady stream of electricity. It features a diversion structure that redirects part of the river into a channel. The water flows through the canal, down a penstock, and into downstream hydro turbines. From there, it empties back out into the river. 
  • Pumped storage. A pumped storage hydropower facility features two reservoirs: an upper and a lower. When demand for electricity is low, the plant pumps water from a low-lying reservoir into a reservoir located at a higher elevation. As demand rises, the plant reverses the process, using the force of gravity to increase flow rates and send the water into hydro turbines at high speeds. This type of plant may or may not be connected to a river. 

Of these three hydropower plants, impoundment facilities are most common. Because they store a large volume of water, they offer more flexibility in power generation. Diversion hydropower plants have smaller physical footprints, but the power supply will vary naturally with changes in the water level and flow rate.  Pumped storage facilities are gaining popularity due to their ability to store intermittent renewable energy sources, like solar and wind power.

Is Hydropower Renewable? 

Hydropower is a renewable source of energy with a lower environmental impact than many other sources. It creates electricity without consuming natural resources — the water flows right back into the river. The system relies on the earth’s natural water cycle, which repeats continuously and creates a constant “fuel” supply. 

What Effects Does Hydropower Have on the Environment? 

It’s important to note that even though it’s renewable, hydropower does affect the environment. Altering the natural flow of a river impacts its ecosystems. For example, dams tend to cause a buildup of sediment that damages fish habitats and spawning grounds. They also change water temperature, alter flow rates, and prevent logs and rocks from moving past the dam, which can impact downstream habitats. Any structure that blocks a river can inhibit fish migration; to get around this issue, many facilities install fish ladders. 

Large hydropower reservoirs also change the surrounding environment. Expanding a river automatically reduces usable land; in some cases, it submerges houses or farmland. Engineers must also consider how the reservoir and the lower water levels downstream might change plant life, agricultural activities, and water supplies. 

Why Is Hydropower Important? 

Hydropower energy is critical to the future of the United States because, unlike other power sources, it can be generated quickly and on demand. In an impoundment facility, engineers can simply adjust the water-release gates; as the water flows, it powers the generator and feeds energy into the grid right away. This convenient setup enables companies to create electricity when it’s needed most — during power outages or major storms, for example. 

The renewable nature of hydropower also underscores its importance. Compared to non-renewable fuel sources, including oil and coal, water is endlessly available. Paired with wind and solar power sources, it has the potential to create a strong foundation for a sustainable energy landscape. 

Where Is Hydropower Used? 

Hydropower is in use today across the United States and the world. States with the highest capacity include Washington, Oregon, and California; these three states account for 50% of all the hydroelectricity generation capacity in the country. Montana, New York, and Alabama also have highly productive sources. 

The biggest hydroelectric dams in the world are all located outside the United States. The largest is located at the Three Gorges Dam on the Yangtze River in China; it can produce up to 22.5 gigawatts. Compare that to the biggest hydroelectric plant in the United States — the Grand Coulee Dam in Washington — which has a 6.5-gigawatt capacity. 

What Is the Cost of Hydropower? 

The cost of hydropower energy varies based on plant size. Between 2009 and 2020, small plants saw costs per unit of approximately $0.05. Other plants range from $0.01 to $0.015 per unit, with higher-capacity facilities boasting the lowest costs. Compared to many other energy sources, hydropower can be a cost-effective option. 

Hydropower Energy Rates 

On average, hydropower rates in the United States are about $0.85 per kWh. Rates vary based on the area and facility but, in general, are usually lower than traditional energy sources. 

Pros and Cons of Hydropower 

What Are the Benefits of Hydropower Energy? 

  • Renewable: Hydropower plants use water, which is a renewable resource thanks to the water cycle. Water returns to its source after it powers turbines, which helps reduce the impact on the environment.
  • Efficient: In general, hydropower plants tend to be more efficient than other power-generation systems. Hydro turbines lose a small amount of energy in the conversion process, making it easier to maximize potential capacity.
  • Competitive energy rates: When plants are designed effectively, hydropower energy offers competitive rates.
  • Flexible generation: Many hydropower plants can generate electricity on demand in response to changing needs.
  • Environmental benefits: Diverting the flow of a river has benefits in addition to drawbacks. Because engineers can control the water, it’s easier to prevent disastrous flooding to downstream areas. In dry weather, it’s possible to release a higher flow to protect plants and ecosystems. 
  • Not dependent on international sources: Because this type of electricity is generated by water, it can be produced within the United States. Even townships and municipalities can use smaller plants to supplement their electricity needs.
  • Job creation: Building and running a hydropower plant is a significant undertaking; the process creates a variety of temporary and permanent jobs. Hydropower plants are often located in remote areas away from large cities, so they also benefit small surrounding communities.
  • Recreation creation: The reservoirs at a hydropower facility can create new opportunities for recreation, including boating, fishing, and swimming. Some areas also build campgrounds around the perimeter to expand usage opportunities.

What Are the Disadvantages of Hydropower Energy?

  • Environmental impact: Even though they produce relatively clean energy, hydroelectric plants can have a negative impact on the surrounding and downstream environment.
  • Vulnerable to environmental conditions: In times of drought, hydropower plants produce less energy. They also require a water source, making this type of power inaccessible in areas without a body of water.
  • High construction costs: Damming or diverting a water source is a significant and expensive project. Some companies reduce costs by utilizing existing structures.
  • Potential emissions: Building a hydropower plant requires steel and heavy construction, which produces emissions. When a facility creates a reservoir, the biomass in and around the water can release greenhouse gas as it decomposes.
  • Physical disruption: Hydroelectric plants take up space and impact the usage of land and waterways. They tend to affect recreation opportunities, particularly on waterways that are popular for long-distance boating and hiking.

How Much Energy Does Hydropower Produce?

As it stands, hydropower facilities in the United States produce 28.7% of all renewable energy in the country. This type of power is a relatively small part of the electricity market, accounting for about 6.2% of utility-scale generation in the country.

Building a Sustainable Energy Supply With Hydropower

As businesses around the world move toward an increasingly sustainable power supply, hydropower energy is likely to play an important role. Cost-effective, green, and readily available, this power source is a viable supplement to traditional fossil fuels.

If your company is looking to transition to a green energy supply, Integrity Energy can help you secure competitive commercial energy rates. Leverage our energy experts to request a quote and build an energy plan that keeps costs in check and meets your unique needs.

AUTHOR Jasmine Capen picture

Jasmine Capen

Unlock the world of Energy Technology & Deregulation with Jasmine, an energy expert with over 10 years industry experience. Dive into her latest blogs today.

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