Large Scale Hydroelectricity Dams

Written-by

Janet Richardson

Reviewed-by

Richard Burdett-Gardiner

Updated on

Apr 21, 2023

Large Scale Hydroelectricity Dams

The US currently has the largest collection of hydroelectric plants in the world, the most famous probably being the Hoover Dam in Black Canyon that was built in the 30s. These plants present hydroelectricity production on a grand scale and are some of the most impressive constructions in the world of renewable energy. Whilst the emphasis may be more on micro hydro nowadays, there is no doubt that large scale hydroelectric dams have played a major role in energy production over the last 100 years.

The Hoover Dam in the US

Built during the Great Depression, the Hoover Dam was one of the biggest construction projects undertaken in 1930s America and took the lives of over a hundred people working on it. The cost at the time was about $49 million dollars which would equate to around $900 million in today’s money. The reservoir it contains is called Lake Mead and is still the biggest in the US, 112 miles long and 180 metres deep. The hydroelectric power plant attached to the dam produces 2,080 MW that is fed to the states of Nevada, Arizona and California.

• The wall of the dam is 660 feet thick at its base.
• It rises to 726 feet and is 1200 feet wide at the top.
• It has 12 turbines that produce over 4 billion kW per year providing power for a million people.

The Three Gorges Dam in China

The Three Gorges Hydroelectric Dam spans the River Yangtze in China and dwarfs the Hoover in capacity, producing a staggering 22,500 MW producing over 80 TWh annually. It contains 32 separate 700 MW turbines and, although construction was started in the 1950s it did not begin producing electricity until 2003 because of political interference.

• The generators for the electricity production each weigh 7,000 tonnes.
• In 2003 the hydroelectric dam produced 8.6 TWh with 6 turbines. By 2013 this had risen to 83 TWh with 32 turbines.
• The project was supposed to provide 10% of China’s electricity supply but, with increasing consumption, it is only currently supply just under 2%.
• The dam has a problem with erosion, depositing 40 million tonnes of silt into the Yangtze every year. It also sits on an earthquake fault line.

Ffestiniog Power Station in Wales

On a much smaller scale is the Ffestiniog Hydroelectric Power Station in North Wales that was commissioned in 1963 and has four generators capable of producing an output of 360 MW of electricity. Water comes from Llyn Stwlan above the power station and is collected in the secondary reservoir, Tan-y-Grisiau, before being pumped back up.

• The upper reservoir can discharge 27 cubic metres per second of water to the turbines below.
• It was the first big pump storage system in the UK when it was built in the 60s.
• The maximum height of the dam is just 34 metres and the reservoir can hold over 2 million cubic metres of water.
• Two shafts nearly 200 metres long connect the reservoir to the turbines below and the gradient is 1 in 40.

Karcham Wangtoo Hydroelectric Plant in India

On the Sutlej River in India, the Karcham Wantoo Hydroelectric Dam is 98 metres high and 177 metres wide at its top. Construction was begun in 1993 but it did not become fully operational until 2005 at a cost of $687 million. With 4 turbines it produces 1,000 MW of electricity and an annual output of around 4,500 GWh.

Atatürk Dam in Turkey

The third largest dam in the country, Ataturk is found on the Euphrates and rises to a height of 169 metres with a length of 1,800 metres. The cost of construction was just under 1.2 billion dollars and uses 8 Francis turbines that produce a combined power of 2,800 MW and 8,900 GW annually.

Snowy Mountains Scheme in Australia

Found in the South East of Australia, the Snowy Mountains Scheme is both an irrigation and hydroelectric project. There are actually 16 dams in the construction with 7 smaller power stations, stretching over the length of the river, producing a combined power of 3.7 GW. The project was a long term undertaking by the Australians, beginning shortly after the Second World War and continuing to this day. The cost would be, in today’s terms, around $6 billion and over 100,000 people were employed in building it over the years.

The Sayano–Shushenskaya Dam in Russia

The largest dam in Russia and the 6^th largest in the world, the Sayano–Shushenskaya Dam is on the Yenisei River in Khakasia. Construction on the plant started in 1968 and it went operational ten years later. The dam wall is 242 metres high and over 1,000 metres wide, with the current capacity provided by 8 turbines that help produce 630 MW each. The average annual production for the hydroelectric dam is about 23.5 TWh. In 2009, there was a big accident when the engine and turbine rooms were flooded killing 75 people.