Is Hydro Energy Potential?
Hydroelectric power is a form of renewable energy that generates electricity from the natural flow of water. It relies on the water cycle and gravity to produce power, without emitting any greenhouse gases. Hydroelectric dams use the energy from flowing water to spin large turbines that are connected to generators in order to produce electricity. The biggest advantage of hydroelectric power is that it is a clean and sustainable energy source. Once facilities are constructed, the fuel source (flowing water) is free and abundant. However, there are also some notable disadvantages and environmental concerns related to hydro dams, such as impacts on fish migration and habitat. This article will provide an overview of the pros and cons of hydroelectric power and examine its potential as a renewable energy source.
History of Hydroelectric Power
Hydroelectric power has been utilized for thousands of years, with early uses of water wheels for mechanical processes like grinding grain. According to the Department of Energy, the first hydroelectric power plant was built at Niagara Falls in 1879. By the early 20th century, many hydroelectric plants were built to generate electricity. The History of Hydropower article by the Department of Energy describes massive growth in hydroelectric power in the early 20th century, with over 45% of the United States’ electricity coming from hydro by 1920. The Hoover Dam, completed in 1936, was one of the largest hydroelectric projects of its time and helped spur development and population growth in the western United States by providing electricity and irrigation.
According to the International Hydropower Association’s A Brief History of Hydropower, global hydro capacity grew rapidly in the mid-20th century. Large dam projects were constructed around the world to provide electricity and promote development. The International Hydropower Association states that hydroelectricity remains the largest renewable energy source globally, supplying 71% of renewable electricity.
How Hydroelectric Power Works
Hydroelectric power plants generate electricity using the power of water flowing through dams and turbines. Here is an overview of the process:
Dams are built to control water flow and create reservoirs. The water in the reservoir has potential energy due to its elevation. When water is released from the reservoir, it flows through a turbine, causing it to spin. The turbine is connected to a generator that converts the mechanical energy from the spinning turbine into electrical energy (U.S. Geological Survey, 2022).
The moving water spins the turbine blades, which causes a shaft to rotate. This shaft is connected to a generator made up of magnets surrounded by coils of copper wire. As the shaft spins, it causes the magnets in the generator to spin near the coils, generating electricity through electromagnetic induction. The electricity is then sent through transformers to increase its voltage and transmitted through power lines.
Hydroelectric plants can generate power on demand by controlling water flow through the turbines. They operate efficiently for short bursts or sustained periods. The reservoirs also enable hydro plants to store energy by pumping water back into the reservoir during periods of low electricity demand (U.S. Geological Survey, 2022).
Pros of Hydroelectric Power
Hydroelectric power has several major advantages that make it an attractive energy source:
Renewable – Hydroelectric power is considered a renewable energy source because it relies on the water cycle. Rain and snow replenish the water in rivers and reservoirs used to generate electricity. As long as there is sufficient water supply, hydroelectric power can be generated indefinitely.
According to the U.S. Department of Energy, hydropower provides over 90,000 megawatts of renewable electricity in the United States, avoiding over 200 million metric tons of carbon emissions each year (Source: https://www.energy.gov/eere/water/benefits-hydropower).
Low Operating Costs – Once a hydroelectric plant is constructed, the cost of generating electricity is relatively low compared to other sources. Fuel costs are minimal since the energy source is renewable flowing water. Operational and maintenance costs are also low.
This makes the cost per kilowatt-hour of hydroelectricity very competitive with other energy sources. According to the U.S. Energy Information Administration, hydroelectricity has the lowest operating costs of any renewable energy source (Source: https://www.eia.gov/outlooks/aeo/pdf/electricity_generation.pdf).
Storage Capabilities – Hydroelectric facilities can store water in reservoirs to be released on demand for electricity generation. This storage capability allows hydroelectric systems to efficiently manage electricity supplies to meet peak load demands.
Storing energy allows more flexibility in operating hydroelectric plants compared to other renewables like wind and solar power that rely on variable natural resources. According to the U.S. Geological Survey, hydroelectricity can supply peak power for short periods and store energy for reliable electricity supply (Source: https://www.usgs.gov/special-topics/water-science-school/science/hydroelectric-power-advantages-production-and-usage).
Cons of Hydroelectric Power
While hydroelectric power has many advantages, it also has some drawbacks. Three major cons of hydroelectric power are the high upfront costs, habitat destruction, and drought concerns.
Constructing hydroelectric dams and power plants requires huge initial investments (https://earth.org/pros-and-cons-of-hydroelectric-energy/). Building large dams can cost billions of dollars. The machinery, construction, and flooding of land add up.
Dams can also lead to habitat destruction as rivers are flooded or rerouted (https://kiwienergy.us/pros-and-cons-of-hydroelectric-energy/). This flooding obliterates habitats and displaces plants, wildlife, and even humans. Fish migration routes are often blocked too.
Droughts and climate change can reduce water levels behind dams. This makes power generation inconsistent. During droughts and dry seasons, hydroelectric output falls. So it’s limited by water availability and rain cycles (https://www.energysage.com/about-clean-energy/hydropower/pros-cons-hydropower/).
Hydroelectric Power Capacity
Globally, hydroelectric power continues to be a major source of renewable energy. As of 2020, worldwide installed hydroelectric capacity was estimated at 1,308 gigawatts (GW), accounting for approximately 16% of total electricity generation capacity (Hydroelectricity – Wikipedia). China leads the world with over 352 GW of hydroelectric capacity, representing over one-quarter of total global capacity. The United States has the fourth largest hydroelectric capacity at 102 GW, behind Canada and Brazil (Hydropower – IEA).
While growth in hydroelectric capacity has slowed in recent years, there are still notable capacity increases, especially in developing countries. The International Hydropower Association expects 132 GW of new hydroelectric capacity to come online between 2019-2023. Major projects underway include the Belo Monte Dam in Brazil, expected to add over 11 GW when fully operational (Hydroelectricity – Wikipedia).
Environmental Impacts
Hydroelectric power can have significant environmental impacts, particularly on wildlife, vegetation, and water quality. According to the U.S. Geological Survey, hydroelectric facilities change the environment and affect land use, homes, and natural habitats (https://www.usgs.gov/special-topics/water-science-school/science/hydroelectric-power-water-use).
The reservoirs created by hydroelectric dams flood large areas of land to store water. This destroys forests, wildlife habitats, and agricultural lands in the flooded area. For example, the Three Gorges Dam in China created a reservoir that flooded 13 cities, 140 towns, and over 1,350 villages (U.S. Geological Survey). The flooded land kills or displaces wildlife and vegetation.
Damming rivers for hydroelectricity also changes the quality of the water and the natural water temperature variations downstream. This damages the ecosystem and fish habitats. According to the U.S. Energy Information Administration, dams and hydroelectric generator operations alter oxygen levels and nutrient flows, affecting downstream water quality and impacting fish that require certain conditions to thrive (https://www.eia.gov/energyexplained/hydropower/hydropower-and-the-environment.php).
Case Studies
The Three Gorges Dam in China is one of the world’s largest hydroelectric power plants. According to the Gilkes case study, this project supplies energy to cities as far as 1,500 km away. It has an installed capacity of 22,500 MW and contributes to flood control and improved navigation on the Yangtze River. However, the project has also been controversial due to the large-scale flooding of land and displacement of over 1 million people.
The Itaipu Dam on the Brazil-Paraguay border has been a major success story for hydroelectric power. With an installed capacity of 14,000 MW, Itaipu is one of the world’s largest hydroelectric facilities. As per the Gilkes case study, Itaipu supplies 17% of Brazil’s electricity and accounts for 90% of Paraguay’s annual electricity consumption. Construction of the dam led to loss of forest area but also allowed improved navigation and opportunities for tourism.
The Grand Coulee Dam in the United States is a major hydroelectric facility with over 6,800 MW of installed capacity. According to Gilkes, its construction in the 1930s and 40s supported development of industries and agriculture in the region. However, the dam also disrupted Native American tribal lands and traditional fishing areas.
Future Outlook
The future outlook for hydroelectric power is generally positive, with projections for continued growth globally. According to a report by the International Energy Agency (IEA), global hydroelectricity generation is projected to grow by over 25% between 2019 and 2040 under stated policies, reaching over 5,000 TWh. Much of this growth is expected to come from emerging economies like India, Brazil, and countries in Southeast Asia as they expand access to electricity.[1]
In the United States, one report by the Department of Energy projects that U.S. hydropower capacity could grow from 101 GW in 2016 to nearly 150 GW in 2050 through a combination of powering existing non-powered dams and new stream-reach development. This growth in capacity is projected to lead to over 50% more generation from hydropower compared to 2016 levels.[2]
New technologies and design improvements are also poised to aid future growth of hydroelectric power. Advancements like fish-friendly turbines, pumped storage, and modular hydrokinetic technologies that extract energy from waves and tides offer ways to further expand hydro with lower environmental impacts. Continued innovation and research will be key in developing hydro’s full potential moving forward.[3]
Overall, while growth rates may slow in some developed countries, global hydroelectric generation is still expected to expand at an important rate in the decades ahead thanks to untapped potential in emerging markets and new technologies coming online.
[1] https://www.iea.org/energy-system/renewables/hydroelectricity
[2] https://www.energy.gov/articles/hydropower-vision-new-report-highlights-future-pathways-us-hydropower
[3] https://www.energy.gov/eere/water/articles/hydropower-key-clean-energy-future-heres-why
Conclusion
In summary, hydroelectric power has immense potential as a renewable energy source, but also some downsides that must be considered. Hydroelectric dams provide clean, emissions-free electricity that can help combat climate change. The potential capacity for new hydroelectric projects, especially pumped storage, is significant in locations like the United States (cite: https://www.nrel.gov/news/program/2023/unlocking-hydropower-potential.html). However, hydroelectric power can also negatively impact local ecosystems and communities. Projects must be pursued thoughtfully and sustainably. Overall, hydroelectricity will likely play a major role in the global renewable energy transition, but its full potential depends on continued technological innovation and responsible implementation.
