Hydroelectricity, a renewable source of energy, accounted for 16% of global electricity last year and hydroelectricity grew at just 3% last year. There are five types of dams: arch dams, gravity dams, arch-gravity dams, barrages, and embankment dams and many uses of dams from producing electricity to altering the flow of rivers. Flowing water produces both kinetic (flow) and potential (falling) energy that has been used as an energy source for millennia.
Two of the World’s Largest Dams (see 4 more below)
While there are hundreds of dam projects worldwide, two of the world’s largest are the 1,099 ft (335m) Rogun Dam in Tajikistan, an embankment, earth and rock fill dam on the Vakhsh River.
In Iran, 1,033 ft (315m) Bakhtiari Dam, a concrete arch dam, is being built on the Bakhtiari River.
Ranking of Countries by Dam Terawatt Output
China has 15 large dam projects under construction and leads the world in hydroelectric output followed by Canada, United States, Brazil, Russia and India.
Major Dam Failures
In 2012 there were three major dam failures in Brazil, Bulgaria and Turkey. Dam failures occur for a variety of reasons including earthquakes, heavy rain, dam failure, poor maintenance,heavy icing and more. In China in 1975 the Banqiao and Shimantan Dams and dozens of smaller dams collapsed due to extremely heavy rainfall that was beyond the planned design capability of these and led to the deaths of over 100,000 people.
Engineering Considerations When Building a Dam
When building dams engineers have to take into account technical and geological factors including the permeability of the surrounding rock and soil, earthquake faults, landslides and slope stability, the area’s water table, peak and maximum flood flows, reservoir silting, environmental impacts on fisheries, forests and wildlife, impacts on human habitations, and more.
Four More of the Largest Dams in the World
Following are four of the largest dams in the world:
1) The Three Gorges Dam the world’s largest hydroelectric dam with a capacity of around 23 GW. We recently wrote about this project in IndustryTap here.
2) TheItaipu Hydroelectricity Power Plant on the Brazil is the second largest power plant in the world.. With 20 generator units and 14,250 MW of capacity.
3) The Guri Dam in Venezuela is the 3rd biggest hydroelectricity plant in the world with 10.5 GW capacity. Guri Dam was constructed in the Necuima Canyon and supplies 75% of Venezuela’s power needs.
4) Tucuruí Dam in Para,Brazil has a capacity of 8.5 GW, is a 255 feet (78 m) high and 6.9 km long concrete-gravity dam.This dam was started in 1975 and has suffered from massive cost overruns.
A comparison of levelized costs shows hydroelectric power to be among the cheapest alternatives available.With vast supplies of water from rivers and other flowing waterways we can expect the continued growth in hydroelectric power in coming decades.