Thanks to human ingenuity and persistence, hydropower energy represents one of the oldest power sources on this planet. Best, its is clean, renewable, and sustainable as long as there is available water. That may be a larger challenge, according to some viewpoints.
A very quick glimpse into hydropower history
Humans have been harnessing water to perform work for thousands of years. Start with the Greeks over 2,000 years ago, when they used water wheels for grinding wheat into flour. Then came hydropower evolution. The modern hydropower turbine began in the mid-1700s, and in 1880, a dynamo driven by a water turbine was used to provide arc lighting, where an electric spark in the air between two conductors produced a light. Then came 1881, when a dynamo connected to a turbine in a flour mill was able to provide street lighting at Niagara Falls, New York using direct current. The first US commercial installation of an alternating current hydropower plant occurred at the Redlands Power Plant in California in 1893, using Pelton waterwheels.
Today numerous hydroelectric advancements have helped it become an integral part of the renewable energy mix around the globe.
Try out some of these facts, compliments of the US Department of Energy, to know more about this energy resource:
- Niagara Falls was the site of the country’s first hydroelectric generating facility — built in 1881 when Charles Brush connected a generator to turbines powered by the falls and used the electricity to power nighttime lighting for visiting tourists.
- America’s first commercial hydropower facility was built in 1882 in Appleton, Wisconsin to power lighting for both a paper mill and homes.
- Over 70% of Washington’s electricity comes from hydropower.
- States getting the majority of their electricity from hydropower include Idaho, Washington, and Oregon; their electricity bills are lower than the rest of the country.
- Hydroelectricity provides some 7% of the electricity generated in the United States, or about half of all renewable electricity.
- Devices at dams can help fish and other wildlife move freely around dams and between sections of rivers. Fish ladders and fish elevators are just some of the techniques used to help fish migrate.
- Dams are built for a number of uses in addition to producing electricity, such as irrigation, shipping and navigation, flood control or to create reservoirs for recreational activities. In fact, only 3 percent of the nation’s 80,000 dams currently generate power.
- An Energy Department-funded study found that 12 gigawatts of hydroelectric generating capacity could be added to existing dams around the country.
This video from the DOE provides a sound understanding about hydropower energy.
Typical hydro plants have three parts: an electric plant where the electricity is produced; a dam which can be opened or closed to control water flow; and a reservoir where water can be stored. The water behind the dam flows through an intake and pushes against blades in a turbine, causing them to turn. The turbine spins a generator to produce electricity.
Hydroelectric power provides almost one-fifth of the world’s electricity. China, Canada, Brazil, the United States, and Russia were the five largest producers of hydropower in 2004.
The seven largest hydro plants
- Three Gorges
Yangtze River, China
With a massive generating capacity of 22.5 GW, the Three Gorges Dam is the biggest hydro dam in the world. China had begun dreaming up this engineering showcase in 1919, and in 2008, it came alive.
Paraná River, Brazil/Paraguay
With 14 GW of installed capacity it straddles the line between two countries.
Jinsha River, China
This mew dam has a generating capacity of 13,860 and also provides flood control for the region.
Caroní River, Venezuela
The Guri Dam is 7,426 meters long and 162 meters high. It currently has a generating capacity of 10,235 MW.
Tocantins River, Brazil
This dam was the first large-scale hydro power project in the Amazon rainforest. It was commissioned in 1984 and has a generating capacity of 8,370 MW.
Jinsha River, China
This dam operates on a tributary of the Yangtze River and has a generating capacity of 6,400 MW.
- Grand Coulee
Columbia River, United States
Washington State’s Grand Coulee dam is the largest operation in the US. Built in 1933, it has a generating capacity of 6,809 MW.
Types of hydroelectric plants
According to Stuart Baird, hydroelectric power plants can generally be divided into two basic categories.
““High head” power plants are the most common and generally utilize a dam to store water at an increased elevation. The use of a dam to impound water also provides the capability of storing water during rainy periods and releasing it during dry periods. This results in the consistent and reliable production of electricity, able to meet demand. Heads for this type of power plant may be greater than 1000 m. Most large hydro-electric facilities are of the high head variety. High head plants with storage are very valuable to electric utilities because they can be quickly adjusted to meet the electrical demand on a distribution system.
““Low head” hydro-electric plants are power plants which generally utilize heads of only a few meters or less. Power plants of this type may utilize a low dam or weir to channel water, or no dam and simply use the “run of the river”. Run of the river generating stations cannot store water, thus their electric output varies with seasonal flows of water in a river. A large volume of water must pass through a low head hydro plant’s turbines in order to produce a useful amount of power. Hydro-electric facilities with a capacity of less than about 25 MW (1 MW = 1,000,000 Watts) are generally referred to as “small hydro”, although hydro-electric technology is basically the same regardless of generating capacity.”
While we learn hydro power is currently the world’s largest renewable source of electricity, accounting for 6% of worldwide energy supply or about 15% of the world’s electricity, it is not a perfect solution. Traditionally thought of as a cheap and clean source of electricity, most large hydroelectric operations being planned today face opposition from environmental groups and native people.
Until recently there was an almost universal belief that hydro power was a clean, environmentally safe method of producing electricity. Hydroelectric power plant proponents state environmental impacts must be weighed against the negative environmental from other sources of electricity, such as coal. Hydroelectric power plants do not emit any of the standard atmospheric pollutants such as carbon dioxide or sulfur dioxide given off by fossil fuel fired power plants. In this respect, hydro power is better than burning coal, oil or natural gas to produce electricity, as it does not contribute to global warming or acid rain, nor do they face the dangers associated with nuclear power plants.
Only 3% of this country’s 80,000 dams are used to produce electricity. Most dams are used for purposes such as irrigation, flood control, and water treatment.
According to Environment And Ecology, a dam and a reservoir may obstruct fish migration and affect their populations. Additionally, operating a hydroelectric power plant may change the water temperature and the river’s flow. “These changes may harm native plants and animals in the river and on land.”
“Reservoirs may cover people’s homes, important natural areas, agricultural land, and archeological sites. So building dams can require relocating people. Methane, a strong greenhouse gas, may also form in some reservoirs and be emitted to the atmosphere.”
Future demand for hydroelectricity dams
With world population growing at an alarming rate, the demand for clean electricity should be extremely predictable. However, changes in weather patterns must also be taken into account.
As Slate’s Eric Holthaus succinctly penned last year, “Since making electricity by water requires a steady supply, the world’s increasing commitment to hydropower bakes in significant risk should weather patterns continue to become more erratic. In general, global warming will result in more intense rainfall events as well as more intense droughts and a loss of mountain glaciers that feed rivers in many parts of the world. For some places like the American West, Latin America, India, and Africa, that erratic energy future is already here. And nearly everywhere, less reliable hydropower could lead to dirtier energy use overall, at least in the short term.”
Image: Water mill via Shutterstock; hydroelectric machine hall via Shutterstock;
Missing here is mention of small-scale hydro. Why not divert some water in a stream to a pipe with head enough to drop into a pelton-wheel generator (or some such) and then return the water to the stream? Why create huge dams that ruin ecosystems when lots of small streams might be supplying local power?