Hydropower

4th century BC

The ancient Near East produced the earliest evidence of water wheels and watermills

Archaeological evidence dates water wheels and watermills in the ancient Near East to the 4th century BC, with related irrigation machinery attributed to Sumer and Babylonia. Studies suggest the water wheel was the initial form of water power, the ancestor of all later hydropower machinery.

1st century BC

Vitruvius described water-powered mills in the Roman Empire

The Roman writer Vitruvius set out descriptions of water-powered mills by the first century BC. Roman practice scaled up substantially: the Barbegal mill in modern France ran 16 water wheels and processed up to 28 tons of grain a day.

40 BC

Chinese texts on the Hun waterwheel recorded early water-powered trip hammers and bellows

The Jijiupian dictionary of 40 BC, followed by Yang Xiong's Fangyan and Huan Tan's Xin Lun, describe the Hun waterwheel used in Han China. Historians argue waterwheels rather than water scoops drove blast furnace bellows, since scoops would have lacked the motive force.

1st century

Du Shi applied waterwheel power to piston-bellows for forging cast iron

The Han engineer Du Shi, active around AD 31, connected waterwheels to piston-bellows in iron forging. This marked one of the earliest industrial applications of hydropower to metallurgy.

1st century

Roman miners at the Dolaucothi Gold Mines first used hushing to expose mineral veins in Wales

From AD 75 onwards, torrents of water were released at Dolaucothi in Wales to strip ground and reveal ore. The technique spread to Spanish mines such as Las Medulas, was used in medieval Britain for lead and tin, and evolved into hydraulic mining during the 19th-century California Gold Rush.

late 3rd century

Roman sawmill builders at Hierapolis used waterwheels with crank-and-connecting-rod saws

The Hierapolis sawmill used a waterwheel driving two crank-and-connecting rods to power two marble saws, converting rotary into linear motion. Comparable Eastern Roman sawmills were excavated at Ephesus and Gerasa from the 6th century.

early 4th century

India received Roman water mills and baths

Greek sources record the transfer of Roman water mills and bath technology to India in the early 4th century AD. Dams, spillways, reservoirs, channels and water balance works subsequently developed under the Mauryan, Gupta and Chola empires.

1136–1206

Al-Jazari described 50 devices, many water-powered, in his Book of Knowledge of Ingenious Mechanical Devices

The Muslim mechanical engineer Al-Jazari documented water-powered clocks, wine-serving automata and five water-lifting machines. His designs included an endless belt with jugs attached and a reciprocating device with hinged valves, codifying hydraulic engineering knowledge.

8th–13th century

The Islamic Empire spread water-powered industrial mills across Asia, Africa and Al-Andalus

During the Islamic Golden Age and the Arab Agricultural Revolution hydropower was widely developed, with fulling, paper, sugar, steel, stamp and tide mills, plus early tidal power and large hydraulic factory complexes. Muslim engineers used water turbines, gearing, and pioneered dams as a source of water power. By the 11th century every province of the empire had such industrial mills in operation.

1753

Bernard Forest de Belidor published Architecture Hydraulique describing vertical- and horizontal-axis hydraulic machines

The French engineer's treatise systematised the design of hydraulic machinery on both axis orientations. It provided an engineering reference as water power entered the industrial era.

1848

James B. Francis created a reaction turbine with 90% efficiency

As head engineer of Lowell's Locks and Canals company, Francis applied scientific principles and systematic testing to turbine design, moving hydropower from the open water wheel to the enclosed turbine. His mathematical and graphical methods allowed turbines to be matched confidently to a site's flow conditions, and the Francis turbine remains in use.

18th–19th century

Richard Arkwright's water frame made water the main power source of the early Industrial Revolution in Britain

At the start of the Industrial Revolution water drove new textile machinery such as the water frame. Even after steam displaced water in larger mills, water power persisted through the 18th and 19th centuries in small blast furnaces and gristmills, including those exploiting the 50-foot drop at Saint Anthony Falls on the Mississippi.

19th century

Benoit Fourneyron developed the first hydropower turbine

The French engineer's turbine design established the basic machine of hydroelectric generation. A Fourneyron unit was installed in the commercial plant at Niagara Falls in 1895 and is reported still to be operating.

1870s

Lester Allan Pelton developed the high-efficiency Pelton wheel impulse turbine

Deriving from Californian mining practice, Pelton's impulse wheel exploited the high-head streams of the Sierra Nevada. It complemented reaction turbines by making steep, low-flow sites economically usable.

1882–1934

Britain and Egypt built and twice heightened the first Aswan Dam

After the British occupation of Egypt in 1882 the two states constructed the first Aswan Dam, raising it in 1912 and again in 1934 to hold back Nile floods. This established the Nile as a contested site of hydropower and water control by both riparian and foreign actors.

1890s

Small hydro operators in South Africa used small turbines to power gold mines and the first electric railway

Small hydropower was central to early electrification in parts of Africa, powering South African gold mines and the region's first electric railway. Zimbabwean farmers installed their own small hydropower stations in the 1930s before national grids displaced them.

1890s

The Niagara Falls Power Company undertook the first major US hydroelectric project at Niagara

The company struggled to transmit electricity far enough from the falls to reach enough customers to justify installation. The project succeeded largely because of Nikola Tesla's alternating current motor, which made long-distance delivery of hydroelectricity viable and inspired bolder schemes worldwide.

2021

Global installed hydropower capacity reached almost 1400 GW, the largest of any renewable technology

Hydropower remained the leading renewable electricity source by installed capacity. As of 2019 the five largest power stations in the world were all conventional hydroelectric plants with dams.

2011

Ethiopia began construction of the Grand Ethiopian Renaissance Dam

Ethiopia had sought US assistance for Nile irrigation and hydropower in the 1960s, but progress stalled with the 1974 coup and the 17-year civil war. Construction from 2011 revived its claim on Nile hydropower.

2008

A French study estimated 12 milliwatts could be extracted from a raindrop by piezoelectric devices

The study examined rain power as a potential hydropower niche. Commentators judged collecting roof runoff to drive a turbine more practical, with an estimated 3 kWh a year from a 185 square metre roof.

1995

The Southern African Power Pool created a multi-national power grid and plant maintenance programme

Capacity at the Inga plant on the Congo River had declined under Mobutu's failure to maintain it; the power pool introduced coordinated maintenance and cross-border transmission. States with abundant hydropower such as the DRC and Ghana sell excess power to neighbours through such arrangements.

1980s–90s

The international anti-dam movement made financing new large hydropower projects extremely difficult

Opposition deterred government and private investors and gave rise to NGOs dedicated to fighting dams. Together with rising costs, this checked the mid-century era of large-dam expansion.

1977–1990

The Aswan High Dam's turbines generated one third of Egypt's electricity

Over this period the dam supplied a third of national power. It demonstrated the scale of national dependence a single hydropower scheme could create.

1970s

Small hydropower plants made a comeback after decades of abandonment

Countries had largely abandoned small hydropower systems by the 1930s in favour of large dams and national grids. Government subsidies and a push for more independent energy producers revived small plants in the 1970s.

1965–1990

Hydroelectric dam construction costs rose 4% annually as good sites ran out

Costs climbed because of rising construction expense and the dwindling supply of high-quality sites, while other energy sources became cheaper. By the 1990s only 18% of the world's electricity came from hydropower.

1960s

Tidal power production emerged as a burgeoning alternative hydropower system

Tidal schemes appeared as a new branch of hydropower in the 1960s. It has not since taken hold as a strong energy contender.

1950s–60s

American environmental movements mounted organised opposition to hydroelectric dams

Campaigns based on environmental concerns defeated proposed dams in Dinosaur National Monument and the Grand Canyon, even as the Reclamation Bureau and Army Corps built over 150 new dams across the American West into the 1970s. Environmental legislation of the 1970s gave opponents further tools, and hydropower gradually faded in American importance as nuclear and fossil fuels grew.

1950s

The Soviet Union funded the Aswan High Dam after Western withdrawal

Nasser's government adopted engineer Adriano Daninos's plan, modelled on the Tennessee Valley Authority's multipurpose dams, and publicised it as economic development. American refusal to fund and British withdrawal left Soviet finance decisive, making hydropower a Cold War instrument. The dam flooded part of Sudan and triggered a Nile-sharing dispute between Sudan and Egypt.

early 20th century

William Armstrong built and operated the first private electrical power station at Cragside

The English engineer's hydro-powered station at his Northumberland house was the first private electrical power station. It demonstrated domestic-scale hydroelectric generation.

1931

The US Bureau of Reclamation built the Hoover Dam

The dam symbolically linked hydropower to the job creation and economic growth priorities of the New Deal. The federal government followed quickly with the Shasta and Grand Coulee dams, and electricity from all three fed war production during the Second World War.

1924

Bavaria achieved a statewide power grid by damming the Walchensee

The scheme was prompted in part by the loss of coal reserves after the First World War. German dams originally built for flood control and irrigation, such as the Urft, Mohne and Eder, found hydropower an added benefit, especially in the coal-poor south.

1913

San Francisco city engineers won water and power rights in the Hetch Hetchy Valley

Despite the valley's protection within a national park, the city defeated the Sierra Club and secured rights after a prolonged fight with the federal government. Hetch Hetchy hydropower and water reached San Francisco a decade later at twice the promised cost, with power sold to PG&E and resold at a profit.

1910

A compressed-air hydropower facility at Ragged Shutes supplied 5,000 horsepower to nearby mines on the Montreal River

Built near Cobalt, Ontario, the plant used falling water to produce compressed air that was transmitted to mines. It showed hydropower could be delivered as pneumatic rather than electrical energy.

1898

Italy's Po Valley opened its first commercial hydroelectric plant, ending the mechanical era

Some 12,000 watermills operated in the Po watershed in the 1890s, but the 1898 plant marked the transition from mechanical to electrical hydropower. Large plants shifted power from rural mountain areas to urban centres on the plain, and Italy pursued near-nationwide electrification almost entirely from hydropower.