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Hydropower (from
Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...
-, "water"), also known as water power or water energy, is the use of falling or fast-running
water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...
to produce electricity or to power machines. This is achieved by
converting Conversion or convert may refer to: Arts, entertainment, and media * ''The Convert'', a 2023 film produced by Jump Film & Television and Brouhaha Entertainment * "Conversion" (''Doctor Who'' audio), an episode of the audio drama ''Cyberman'' * ...
the
gravitational potential In classical mechanics, the gravitational potential is a scalar potential associating with each point in space the work (energy transferred) per unit mass that would be needed to move an object to that point from a fixed reference point in the ...
or
kinetic energy In physics, the kinetic energy of an object is the form of energy that it possesses due to its motion. In classical mechanics, the kinetic energy of a non-rotating object of mass ''m'' traveling at a speed ''v'' is \fracmv^2.Resnick, Rober ...
of a water source to produce power. Hydropower is a method of
sustainable energy Energy system, Energy is sustainability, sustainable if it "meets the needs of the present without compromising the ability of future generations to meet their own needs." Definitions of sustainable energy usually look at its effects on the e ...
production. Hydropower is now used principally for
hydroelectric power generation Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other renewable sources combined and also ...
, and is also applied as one half of an energy storage system known as
pumped-storage hydroelectricity Pumped-storage hydroelectricity (PSH), or pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage used by electric power systems for load balancing (electrical power), load balancing. A PSH system stores energy i ...
. Hydropower is an attractive alternative to
fossil fuel A fossil fuel is a flammable carbon compound- or hydrocarbon-containing material formed naturally in the Earth's crust from the buried remains of prehistoric organisms (animals, plants or microplanktons), a process that occurs within geolog ...
s as it does not directly produce
carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
or other atmospheric pollutants and it provides a relatively consistent source of power. Nonetheless, it has economic, sociological, and environmental downsides and requires a sufficiently energetic source of water, such as a
river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...
or elevated
lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...
. International institutions such as the
World Bank The World Bank is an international financial institution that provides loans and Grant (money), grants to the governments of Least developed countries, low- and Developing country, middle-income countries for the purposes of economic development ...
view hydropower as a low-carbon means for
economic development In economics, economic development (or economic and social development) is the process by which the economic well-being and quality of life of a nation, region, local community, or an individual are improved according to targeted goals and object ...
. Since ancient times, hydropower from
watermill A watermill or water mill is a mill that uses hydropower. It is a structure that uses a water wheel or water turbine to drive a mechanical process such as mill (grinding), milling (grinding), rolling, or hammering. Such processes are needed in ...
s has been used as a
renewable energy Renewable energy (also called green energy) is energy made from renewable resource, renewable natural resources that are replenished on a human lifetime, human timescale. The most widely used renewable energy types are solar energy, wind pow ...
source for
irrigation Irrigation (also referred to as watering of plants) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has bee ...
and the operation of mechanical devices, such as
gristmill A gristmill (also: grist mill, corn mill, flour mill, feed mill or feedmill) grinds cereal grain into flour and Wheat middlings, middlings. The term can refer to either the grinding mechanism or the building that holds it. Grist is grain that h ...
s,
sawmill A sawmill (saw mill, saw-mill) or lumber mill is a facility where logging, logs are cut into lumber. Modern sawmills use a motorized saw to cut logs lengthwise to make long pieces, and crosswise to length depending on standard or custom sizes ...
s,
textile Textile is an Hyponymy and hypernymy, umbrella term that includes various Fiber, fiber-based materials, including fibers, yarns, Staple (textiles)#Filament fiber, filaments, Thread (yarn), threads, and different types of #Fabric, fabric. ...
mills,
trip hammer Trip may refer to: Arts and entertainment Books Fictional characters * Trip (Pokémon), Trip (''Pokémon''), a ''Pokémon'' character * Trip (Power Rangers), in the American television series ''Time Force Power Rangers'' * Trip, in the 2013 film ...
s, dock cranes, domestic lifts, and
ore mill Mineral processing is the process of separating commercially valuable minerals from their ores in the field of extractive metallurgy. Depending on the processes used in each instance, it is often referred to as ore dressing or ore milling. Be ...
s. A
trompe A trompe is a water-powered air compressor, commonly used before the advent of the electric-powered compressor. A trompe is somewhat like an airlift pump working in reverse. Trompes were used to provide compressed air for bloomery furnaces ...
, which produces compressed air from falling water, is sometimes used to power other machinery at a distance.


Calculating the amount of available power

A hydropower resource can be evaluated by its available
power Power may refer to: Common meanings * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power, a type of energy * Power (social and political), the ability to influence people or events Math ...
. Power is a function of the
hydraulic head Hydraulic head or piezometric head is a measurement related to liquid pressure (normalized by specific weight) and the liquid elevation above a vertical datum., 410 pages. See pp. 43–44., 650 pages. See p. 22, eq.3.2a. It is usually meas ...
and
volumetric flow rate In physics and engineering, in particular fluid dynamics, the volumetric flow rate (also known as volume flow rate, or volume velocity) is the volume of fluid which passes per unit time; usually it is represented by the symbol (sometimes \do ...
. The head is the energy per unit weight (or unit mass) of water. The static head is proportional to the difference in height through which the water falls. Dynamic head is related to the velocity of moving water. Each unit of water can do an amount of work equal to its weight times the head. The power available from falling water can be calculated from the flow rate and density of water, the height of fall, and the local acceleration due to gravity: ::\dot_\text =-\eta \ \dot g \ \Delta h =-\eta \ \rho \dot \ g \ \Delta h :where ::* \dot_\text (
work Work may refer to: * Work (human activity), intentional activity people perform to support themselves, others, or the community ** Manual labour, physical work done by humans ** House work, housework, or homemaking ** Working animal, an ani ...
flow rate out) is the useful power output (SI unit:
watt The watt (symbol: W) is the unit of Power (physics), power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantification (science), quantify the rate of Work ...
s) ::* \eta ("
eta Eta ( ; uppercase , lowercase ; ''ē̂ta'' or ''ita'' ) is the seventh letter of the Greek alphabet, representing the close front unrounded vowel, . Originally denoting the voiceless glottal fricative, , in most dialects of Ancient Greek, it ...
") is the efficiency of the turbine (
dimensionless Dimensionless quantities, or quantities of dimension one, are quantities implicitly defined in a manner that prevents their aggregation into units of measurement. ISBN 978-92-822-2272-0. Typically expressed as ratios that align with another sy ...
) ::* \dot is the
mass flow rate In physics and engineering, mass flow rate is the Temporal rate, rate at which mass of a substance changes over time. Its unit of measurement, unit is kilogram per second (kg/s) in SI units, and Slug (unit), slug per second or pound (mass), pou ...
(SI unit:
kilogram The kilogram (also spelled kilogramme) is the base unit of mass in the International System of Units (SI), equal to one thousand grams. It has the unit symbol kg. The word "kilogram" is formed from the combination of the metric prefix kilo- (m ...
s per second) ::* \rho ("
rho Rho (; uppercase Ρ, lowercase ρ or ; or ) is the seventeenth letter of the Greek alphabet. In the system of Greek numerals it has a value of 100. It is derived from Phoenician alphabet, Phoenician letter resh . Its uppercase form uses the same ...
") is the
density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...
of water (SI unit: kilograms per
cubic metre The cubic metre (in Commonwealth English and international spelling as used by the International Bureau of Weights and Measures) or cubic meter (in American English) is the unit of volume in the International System of Units (SI). Its symbol is m ...
) ::* \dot is the
volumetric flow rate In physics and engineering, in particular fluid dynamics, the volumetric flow rate (also known as volume flow rate, or volume velocity) is the volume of fluid which passes per unit time; usually it is represented by the symbol (sometimes \do ...
(SI unit: cubic metres per second) ::* g is the acceleration due to gravity (SI unit:
metres The metre (or meter in US spelling; symbol: m) is the base unit of length in the International System of Units (SI). Since 2019, the metre has been defined as the length of the path travelled by light in vacuum during a time interval of of ...
per second per second) ::* \Delta h ("
Delta Delta commonly refers to: * Delta (letter) (Δ or δ), the fourth letter of the Greek alphabet * D (NATO phonetic alphabet: "Delta"), the fourth letter in the Latin alphabet * River delta, at a river mouth * Delta Air Lines, a major US carrier ...
h") is the difference in height between the outlet and inlet (SI unit: metres) To illustrate, the power output of a turbine that is 85% efficient, with a flow rate of 80 cubic metres per second (2800 cubic feet per second) and a head of , is 97 megawatts: :\dot_\text = 0.85\times 1000 \ (\text/\text^3) \times 80 \ (\text^3/\text) \times 9.81 \ (\text/\text^2) \times 145 \ \text = 97 \times 10^6 \ (\text\ \text^2/\text^3) = 97 \ \text Operators of hydroelectric stations compare the total electrical energy produced with the theoretical potential energy of the water passing through the turbine to calculate efficiency. Procedures and definitions for calculation of efficiency are given in test codes such as
ASME The American Society of Mechanical Engineers (ASME) is an American professional association that, in its own words, "promotes the art, science, and practice of multidisciplinary engineering and allied sciences around the globe" via "continuing edu ...
PTC 18 and
IEC The International Electrotechnical Commission (IEC; ) is an international standards organization that prepares and publishes international standards for all electrical, electronic and related technologies. IEC standards cover a vast range of ...
60041. Field testing of turbines is used to validate the manufacturer's efficiency guarantee. Detailed calculation of the efficiency of a hydropower turbine accounts for the head lost due to flow friction in the power canal or penstock, rise in tailwater level due to flow, the location of the station and effect of varying gravity, the air temperature and barometric pressure, the density of the water at ambient temperature, and the relative altitudes of the forebay and tailbay. For precise calculations, errors due to rounding and the number of
significant digit Significant figures, also referred to as significant digits, are specific Numerical digit, digits within a number that is written in positional notation that carry both reliability and necessity in conveying a particular quantity. When presen ...
s of constants must be considered. Some hydropower systems such as
water wheel A water wheel is a machine for converting the kinetic energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a large wheel (usually constructed from wood or metal), with numerous b ...
s can draw power from the flow of a body of water without necessarily changing its height. In this case, the available power is the
kinetic energy In physics, the kinetic energy of an object is the form of energy that it possesses due to its motion. In classical mechanics, the kinetic energy of a non-rotating object of mass ''m'' traveling at a speed ''v'' is \fracmv^2.Resnick, Rober ...
of the flowing water. Over-shot water wheels can efficiently capture both types of energy. The flow in a stream can vary widely from season to season. The development of a hydropower site requires analysis of flow records, sometimes spanning decades, to assess the reliable annual energy supply. Dams and reservoirs provide a more dependable source of power by smoothing seasonal changes in water flow. However, reservoirs have a significant
environmental impact Environmental issues are disruptions in the usual function of ecosystems. Further, these issues can be caused by humans ( human impact on the environment) or they can be natural. These issues are considered serious when the ecosystem cannot reco ...
, as does alteration of naturally occurring streamflow. Dam design must account for the worst-case, "probable maximum flood" that can be expected at the site; a
spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...
is often included to route flood flows around the dam. A computer model of the hydraulic basin and rainfall and snowfall records are used to predict the maximum flood.


Disadvantages and limitations

Some disadvantages of hydropower have been identified.
Dam failure A dam failure or dam burst is a catastrophic type of structural failure characterized by the sudden, rapid, and uncontrolled release of impounded water or the likelihood of such an uncontrolled release. Between the years 2000 and 2009 more than ...
s can have catastrophic effects, including loss of life, property and pollution of land.
Dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aqua ...
s and
reservoir A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of wa ...
s can have major negative impacts on river
ecosystems An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...
such as preventing some animals traveling upstream, cooling and de-oxygenating of water released downstream, and loss of nutrients due to settling of particulates. River sediment builds river deltas and dams prevent them from restoring what is lost from erosion. Furthermore, studies found that the construction of dams and reservoirs can result in habitat loss for some aquatic species.Large and deep dam and reservoir plants cover large areas of land which causes
greenhouse gas emissions Greenhouse gas (GHG) emissions from human activities intensify the greenhouse effect. This contributes to climate change. Carbon dioxide (), from burning fossil fuels such as coal, petroleum, oil, and natural gas, is the main cause of climate chan ...
from underwater rotting vegetation. Furthermore, although at lower levels than other
renewable energy Renewable energy (also called green energy) is energy made from renewable resource, renewable natural resources that are replenished on a human lifetime, human timescale. The most widely used renewable energy types are solar energy, wind pow ...
sources, it was found that hydropower produces
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...
(CH4) equivalent to almost a billion tonnes of CO2 greenhouse gas a year. This occurs when organic matters accumulate at the bottom of the reservoir because of the
deoxygenation Deoxygenation is a chemical reaction involving the removal of oxygen atoms from a molecule. The term also refers to the removal of molecular oxygen (O2) from gases and solvents, a step in air-free technique and gas purifiers. As applied to orga ...
of water which triggers
anaerobic digestion Anaerobic digestion is a sequence of processes by which microorganisms break down biodegradable material in the absence of oxygen. The process is used for industrial or domestic purposes to Waste management, manage waste or to produce fuels. Mu ...
. People who live near a hydro plant site are displaced during construction or when
reservoir A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of wa ...
banks become unstable. Another potential disadvantage is cultural or religious sites may block construction.


Applications


Mechanical power


Watermills


Compressed air

A plentiful head of water can be made to generate
compressed air Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air in vehicle tires and shock absorbers are commonly used for improved traction and reduced vibration. Compressed air is an important medium for t ...
directly without moving parts. In these designs, a falling column of water is deliberately mixed with air bubbles generated through turbulence or a venturi pressure reducer at the high-level intake. This allows it to fall down a shaft into a subterranean, high-roofed chamber where the now-compressed air separates from the water and becomes trapped. The height of the falling water column maintains compression of the air in the top of the chamber, while an outlet, submerged below the water level in the chamber allows water to flow back to the surface at a lower level than the intake. A separate outlet in the roof of the chamber supplies the compressed air. A facility on this principle was built on the Montreal River at Ragged Shutes near
Cobalt, Ontario Cobalt is a town in Timiskaming District, Ontario, Canada. It had a population of 989 at the 2021 Census. In the early 1900s, the area was heavily mined for silver; the silver ore also contained cobalt. By 1910, the community was the fourth hi ...
, in 1910 and supplied 5,000 horsepower to nearby mines.


Electricity

Hydroelectricity is the biggest hydropower application. Hydroelectricity generates about 15% of global electricity and provides at least 50% of the total electricity supply for more than 35 countries. In 2021, global installed hydropower electrical capacity reached almost 1400 GW, the highest among all renewable energy technologies.
Hydroelectricity Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...
generation starts with converting either the
potential energy In physics, potential energy is the energy of an object or system due to the body's position relative to other objects, or the configuration of its particles. The energy is equal to the work done against any restoring forces, such as gravity ...
of water that is present due to the site's elevation or the
kinetic energy In physics, the kinetic energy of an object is the form of energy that it possesses due to its motion. In classical mechanics, the kinetic energy of a non-rotating object of mass ''m'' traveling at a speed ''v'' is \fracmv^2.Resnick, Rober ...
of moving water into electrical energy. Hydroelectric power plants vary in terms of the way they harvest energy. One type involves a dam and a
reservoir A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of wa ...
. The water in the reservoir is available on demand to be used to generate electricity by passing through channels that connect the dam to the reservoir. The water spins a turbine, which is connected to the generator that produces electricity. The other type is called a run-of-river plant. In this case, a barrage is built to control the flow of water, absent a
reservoir A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of wa ...
. The run-of river power plant needs continuous water flow and therefore has less ability to provide power on demand. The kinetic energy of flowing water is the main source of energy. Both designs have limitations. For example, dam construction can result in discomfort to nearby residents. The dam and reservoirs occupy a relatively large amount of space that may be opposed by nearby communities. Moreover, reservoirs can potentially have major environmental consequences such as harming downstream habitats. On the other hand, the limitation of the run-of-river project is the decreased efficiency of electricity generation because the process depends on the speed of the seasonal river flow. This means that the rainy season increases electricity generation compared to the dry season. The size of hydroelectric plants can vary from small plants called
micro hydro Micro hydro is a type of hydroelectric power that typically produces from 5 kW to 100 kW of electricity using the natural flow of water. Installations below 5 kW are called pico hydro. These installations can provide power to an ...
, to large plants that supply power to a whole country. As of 2019, the five largest power stations in the world are conventional hydroelectric power stations with dams. Hydroelectricity can also be used to store energy in the form of
potential energy In physics, potential energy is the energy of an object or system due to the body's position relative to other objects, or the configuration of its particles. The energy is equal to the work done against any restoring forces, such as gravity ...
between two reservoirs at different heights with
pumped-storage Pumped-storage hydroelectricity (PSH), or pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage used by electric power systems for load balancing. A PSH system stores energy in the form of gravitational potent ...
. Water is pumped uphill into reservoirs during periods of low demand to be released for generation when demand is high or system generation is low. Other forms of electricity generation with hydropower include
tidal stream generator A tidal stream generator, often referred to as a tidal energy converter (TEC), is a machine that extracts energy from moving masses of water, in particular tides, although the term is often used in reference to machines designed to extract energy ...
s using energy from
tidal power Tidal power or tidal energy is harnessed by converting energy from tides into useful forms of power, mainly electricity using various methods. Although not yet widely used, tidal energy has the potential for future electricity generation. T ...
generated from oceans, rivers, and human-made canal systems to generating electricity. File:Hydroelectric dam.svg, A conventional dammed-hydro facility (hydroelectric dam) is the most common type of hydroelectric power generation. File:Chief Joseph Dam.jpg,
Chief Joseph Dam The Chief Joseph Dam is a concrete gravity dam on the Columbia River, upriver from Bridgeport, Washington. The dam is upriver from the mouth of the Columbia at Astoria, Oregon. It is operated by the U.S. Army Corps of Engineers, USACE Chief Jose ...
near
Bridgeport, Washington Bridgeport is a city in Douglas County, Washington. It is part of the Wenatchee−East Wenatchee Metropolitan Statistical Area. Bridgeport's population was 2,141 at the 2020 census. Bridgeport is located near the Chief Joseph Dam. History T ...
, is a major run-of-the-river station without a sizeable reservoir. File:Nw vietnam hydro.jpg,
Micro hydro Micro hydro is a type of hydroelectric power that typically produces from 5 kW to 100 kW of electricity using the natural flow of water. Installations below 5 kW are called pico hydro. These installations can provide power to an ...
in Northwest Vietnam File:Stwlan.dam.jpg, The upper reservoir and dam of the Ffestiniog Pumped Storage Scheme in
Wales Wales ( ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by the Irish Sea to the north and west, England to the England–Wales border, east, the Bristol Channel to the south, and the Celtic ...
. The lower power station can generate 360 MW of electricity.


Rain power

Billions of litres of rainwater can fall, which can generate huge amounts of electrical energy if used in the right way. Research is being done into the different methods of generating power from rain, such as by using the energy in the impact of raindrops. This is in its very early stages, with new and emerging technologies being tested, prototyped and created. Such power has been called rain power. One way in which this has been tried is by using hybrid solar panels called "all-weather solar panels" that can generate electricity from both the sun and the rain. According to zoologist and science and technology educator, Luis Villazon, a 2008 French study estimated that you could use
piezoelectric Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied stress (mechanics), mechanical s ...
devices, which generate power when they move, to extract 12 milliwatts from a raindrop. Over a year, this would amount to less than 1 Wh per square metre – enough to power a remote sensor. Villazon suggested a better application would be to collect the water from fallen rain and use it to drive a turbine, with an estimated energy generation of 3 kWh of energy per year for a 185 m2 roof. A microturbine-based system created by three students from the Technological University of Mexico has been used to generate electricity. The Pluvia system "uses the stream of rainwater runoff from houses' rooftop rain gutters to spin a microturbine in a cylindrical housing. Electricity generated by that turbine is used to charge 12-volt batteries." The term rain power has also been applied to hydropower systems which include the process of capturing the rain.


History


Ancient history

Evidence suggests that the fundamentals of hydropower date to
ancient Greek civilization Ancient Greece () was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity (), that comprised a loose collection of culturally and linguistically rel ...
. Other evidence indicates that the waterwheel independently emerged in China around the same period. Evidence of
water wheel A water wheel is a machine for converting the kinetic energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a large wheel (usually constructed from wood or metal), with numerous b ...
s and
watermill A watermill or water mill is a mill that uses hydropower. It is a structure that uses a water wheel or water turbine to drive a mechanical process such as mill (grinding), milling (grinding), rolling, or hammering. Such processes are needed in ...
s date to the
ancient Near East The ancient Near East was home to many cradles of civilization, spanning Mesopotamia, Egypt, Iran (or Persia), Anatolia and the Armenian highlands, the Levant, and the Arabian Peninsula. As such, the fields of ancient Near East studies and Nea ...
in the 4th century BC. Moreover, evidence indicates the use of hydropower using irrigation machines to ancient civilizations such as
Sumer Sumer () is the earliest known civilization, located in the historical region of southern Mesopotamia (now south-central Iraq), emerging during the Chalcolithic and Early Bronze Age, early Bronze Ages between the sixth and fifth millennium BC. ...
and
Babylonia Babylonia (; , ) was an Ancient history, ancient Akkadian language, Akkadian-speaking state and cultural area based in the city of Babylon in central-southern Mesopotamia (present-day Iraq and parts of Kuwait, Syria and Iran). It emerged as a ...
. Studies suggest that the water wheel was the initial form of water power. In the
Roman Empire The Roman Empire ruled the Mediterranean and much of Europe, Western Asia and North Africa. The Roman people, Romans conquered most of this during the Roman Republic, Republic, and it was ruled by emperors following Octavian's assumption of ...
, water-powered mills were described by
Vitruvius Vitruvius ( ; ; –70 BC – after ) was a Roman architect and engineer during the 1st century BC, known for his multi-volume work titled . As the only treatise on architecture to survive from antiquity, it has been regarded since the Renaissan ...
by the first century BC. The Barbegal mill, located in modern-day France, had 16 water wheels processing up to 28 tons of grain per day. Roman waterwheels were also used for sawing marble such as the
Hierapolis sawmill The Hierapolis sawmill was a water-powered stone sawmill in the Ancient Greek city of Hierapolis in Roman Asia (modern-day Turkey). Dating to the second half of the 3rd century AD, the sawmill is considered the earliest known machine to combine ...
of the late 3rd century AD. Such sawmills had a waterwheel that drove two crank-and-connecting rods to power two saws. It also appears in two 6th century
Eastern Roman The Byzantine Empire, also known as the Eastern Roman Empire, was the continuation of the Roman Empire centred on Constantinople during late antiquity and the Middle Ages. Having survived the events that caused the fall of the Western Roman E ...
sawmill A sawmill (saw mill, saw-mill) or lumber mill is a facility where logging, logs are cut into lumber. Modern sawmills use a motorized saw to cut logs lengthwise to make long pieces, and crosswise to length depending on standard or custom sizes ...
s excavated at
Ephesus Ephesus (; ; ; may ultimately derive from ) was an Ancient Greece, ancient Greek city on the coast of Ionia, in present-day Selçuk in İzmir Province, Turkey. It was built in the 10th century BC on the site of Apasa, the former Arzawan capital ...
and
Gerasa Jerash (; , , ) is a city in northern Jordan. The city is the administrative center of the Jerash Governorate, and has a population of 50,745 as of 2015. It is located 30.0 miles north of the capital city Amman. The earliest evidence of settl ...
respectively. The
crank Crank may refer to: Mechanisms * Crank (mechanism), in mechanical engineering, a bent portion of an axle or shaft, or an arm keyed at right angles to the end of a shaft, by which motion is imparted to or received from it * Crankset, the componen ...
and connecting rod mechanism of these Roman watermills converted the rotary motion of the waterwheel into the linear movement of the saw blades. Water-powered trip hammers and bellows in China, during the
Han dynasty The Han dynasty was an Dynasties of China, imperial dynasty of China (202 BC9 AD, 25–220 AD) established by Liu Bang and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–206 BC ...
(202 BC – 220 AD), were initially thought to be powered by water scoops. However, some historians suggested that they were powered by waterwheels. This is since it was theorized that water scoops would not have had the motive force to operate their
blast furnace A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. ''Blast'' refers to the combustion air being supplied above atmospheric pressure. In a ...
bellows. Many texts describe the Hun waterwheel; some of the earliest ones are the ''
Jijiupian The ''Jijiupian'' is a Chinese character Primer (textbook), primer that was compiled by the Han dynasty scholar Shi You around 40 BCE. Similar to an abecedarium, it contains a series of orthography, orthographic word lists, categorized according ...
'' dictionary of 40 BC, Yang Xiong's text known as the '' Fangyan'' of 15 BC, as well as ''Xin Lun,'' written by
Huan Tan Huan Tan (BC– AD28) was a Chinese philosopher, poet, and politician of the Western Han and its short-lived interregnum between AD9 and 23, known as the Xin dynasty. Life Huan worked as an official under the administrations of Emperor Ai of ...
about 20 AD. It was also during this time that the engineer
Du Shi Du Shi (, d. 38'' Book of Later Han'', vol. 31Crespigny, 183.) was a Chinese hydrologist, inventor, mechanical engineer, metallurgist, and politician of the Eastern Han dynasty. Du Shi is credited with being the first to apply hydraulic power ...
(c. AD 31) applied the power of
waterwheel A water wheel is a machine for converting the kinetic energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a large wheel (usually constructed from wood or metal), with numerous blade ...
s to
piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder (engine), cylinder a ...
-
bellows A bellows or pair of bellows is a device constructed to furnish a strong blast of air. The simplest type consists of a flexible bag comprising a pair of rigid boards with handles joined by flexible leather sides enclosing an approximately airtig ...
in forging cast iron. Ancient Indian texts dating back to the 4th century BC refer to the term ''cakkavattaka'' (turning wheel), which commentaries explain as ''arahatta-ghati-yanta'' (machine with wheel-pots attached), however whether this is water or hand powered is disputed by scholars On this basis,
Joseph Needham Noel Joseph Terence Montgomery Needham (; 9 December 1900 – 24 March 1995) was a British biochemist, historian of science and sinologist known for his scientific research and writing on the history of Chinese science and technology, initia ...
suggested that the machine was a
noria A noria (, ''nā‘ūra'', plural ''nawāʿīr'', from , ''nā‘orā'', lit. "growler") is a hydropowered '' scoop wheel'' used to lift water into a small aqueduct, either for the purpose of irrigation or to supply water to cities and village ...
. Terry S. Reynolds, however, argues that the "term used in Indian texts is ambiguous and does not clearly indicate a water-powered device." Thorkild Schiøler argued that it is "more likely that these passages refer to some type of tread- or hand-operated water-lifting device, instead of a water-powered water-lifting wheel." India received Roman water mills and baths in the early 4th century AD when a certain according to Greek sources. Dams, spillways, reservoirs, channels, and water balance would develop in India during the
Mauryan The Maurya Empire was a geographically extensive Iron Age historical power in South Asia with its power base in Magadha. Founded by Chandragupta Maurya around c. 320 BCE, it existed in loose-knit fashion until 185 BCE. The primary sourc ...
,
Gupta Gupta () is a common surname of Indian origin, meaning "guardian" or "protector". Origins and distribution The name is based on the Sanskrit word गोप्तृ ''goptṛ'', which means "guardian" or "protector". According to historian ...
and
Chola The Chola Empire, which is often referred to as the Imperial Cholas, was a medieval thalassocratic empire based in southern India that was ruled by the Chola dynasty, and comprised overseas dominions, protectorates and spheres of influence ...
empires. Another example of the early use of hydropower is seen in
hushing Hushing is an ancient and historic mining method using a flood or torrent of water to reveal mineral veins. The method was applied in several ways, both in prospecting for ores, and for their exploitation. Mineral veins are often hidden bel ...
, a historic method of mining that uses flood or torrent of water to reveal mineral veins. The method was first used at the
Dolaucothi Gold Mines The Dolaucothi Gold Mines (; ) (), also known as the Ogofau Gold Mine, are ancient Roman surface and underground mines located in the valley of the River Cothi, near Pumsaint, Carmarthenshire, Wales. The gold mines are located within the ...
in
Wales Wales ( ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by the Irish Sea to the north and west, England to the England–Wales border, east, the Bristol Channel to the south, and the Celtic ...
from 75 AD onwards. This method was further developed in Spain in mines such as
Las Médulas Las Médulas () is a historic gold-mining site near the town of Ponferrada in the comarca of El Bierzo (León (province), province of León, Castile and León, Spain). It was the most important gold gold mining, mine, as well as the largest open ...
. Hushing was also widely used in
Britain Britain most often refers to: * Great Britain, a large island comprising the countries of England, Scotland and Wales * The United Kingdom of Great Britain and Northern Ireland, a sovereign state in Europe comprising Great Britain and the north-eas ...
in the
Medieval In the history of Europe, the Middle Ages or medieval period lasted approximately from the 5th to the late 15th centuries, similarly to the post-classical period of World history (field), global history. It began with the fall of the West ...
and later periods to extract
lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...
and
tin Tin is a chemical element; it has symbol Sn () and atomic number 50. A silvery-colored metal, tin is soft enough to be cut with little force, and a bar of tin can be bent by hand with little effort. When bent, a bar of tin makes a sound, the ...
ores. It later evolved into
hydraulic mining Hydraulic mining is a form of mining that uses high-pressure jets of water to dislodge rock material or move sediment.Paul W. Thrush, ''A Dictionary of Mining, Mineral, and Related Terms'', US Bureau of Mines, 1968, p.560. In the placer mining of ...
when used during the
California Gold Rush The California gold rush (1848–1855) began on January 24, 1848, when gold was found by James W. Marshall at Sutter's Mill in Coloma, California. The news of gold brought approximately 300,000 people to California from the rest of the U ...
in the 19th century. The
Islamic Empire This article includes a list of successive Islamic states and Muslim dynasties beginning with the time of the Islamic prophet Muhammad (570–632 CE) and the early Muslim conquests that spread Islam outside of the Arabian Peninsula, and continuin ...
spanned a large region, mainly in Asia and Africa, along with other surrounding areas. During the
Islamic Golden Age The Islamic Golden Age was a period of scientific, economic, and cultural flourishing in the history of Islam, traditionally dated from the 8th century to the 13th century. This period is traditionally understood to have begun during the reign o ...
and the
Arab Agricultural Revolution The Arab Agricultural Revolution was the transformation in agriculture in the Old World during the Islamic Golden Age (8th to 13th centuries). The agronomic literature of the time, with major books by Ibn Bassal and Ibn al-'Awwam, demonstrates t ...
(8th–13th centuries), hydropower was widely used and developed. Early uses of
tidal power Tidal power or tidal energy is harnessed by converting energy from tides into useful forms of power, mainly electricity using various methods. Although not yet widely used, tidal energy has the potential for future electricity generation. T ...
emerged along with large hydraulic
factory A factory, manufacturing plant or production plant is an industrial facility, often a complex consisting of several buildings filled with machinery, where workers manufacture items or operate machines which process each item into another. Th ...
complexes. A wide range of water-powered industrial mills were used in the region including
fulling Fulling, also known as tucking or walking ( Scots: ''waukin'', hence often spelt waulking in Scottish English), is a step in woollen clothmaking which involves the cleansing of woven cloth (particularly wool) to eliminate ( lanolin) oils, ...
mills,
gristmill A gristmill (also: grist mill, corn mill, flour mill, feed mill or feedmill) grinds cereal grain into flour and Wheat middlings, middlings. The term can refer to either the grinding mechanism or the building that holds it. Grist is grain that h ...
s,
paper mill A paper mill is a factory devoted to making paper from vegetable fibres such as wood pulp, old rags, and other ingredients. Prior to the invention and adoption of the Fourdrinier machine and other types of paper machine that use an endless belt ...
s, hullers,
sawmill A sawmill (saw mill, saw-mill) or lumber mill is a facility where logging, logs are cut into lumber. Modern sawmills use a motorized saw to cut logs lengthwise to make long pieces, and crosswise to length depending on standard or custom sizes ...
s,
ship mill A ship mill, more commonly known as a boat mill, is a type of watermill. The milling and grinding technology and the drive ( waterwheel) are built on a floating platform on this type of mill. "Deutsches Museum: Ship Mill", The Deutsches Museu ...
s,
stamp mill A stamp mill (or stamp battery or stamping mill) is a type of Mill (grinding), mill machine that crushes material by pounding rather than Mill (grinding), grinding, either for further processing or for extraction of metallic ores. Breaking materia ...
s,
steel mill A steel mill or steelworks is an industrial plant for the manufacture of steel. It may be an integrated steel works carrying out all steps of steelmaking from smelting iron ore to rolled product, but may also be a plant where steel semi-fini ...
s,
sugar mills A sugar cane mill is a factory that processes sugar cane to produce raw sugar or plantation white sugar. Some sugar mills are situated next to a back-end refinery, that turns raw sugar into (refined) white sugar. The term is also used to refer ...
, and
tide mill A tide mill is a water mill driven by tidal rise and fall. A dam with a sluice is created across a suitable tidal inlet, or a section of river estuary is made into a reservoir. As the tide comes in, it enters the mill pond through a one-way ga ...
s. By the 11th century, every province throughout the Islamic Empire had these industrial mills in operation, from
Al-Andalus Al-Andalus () was the Muslim-ruled area of the Iberian Peninsula. The name refers to the different Muslim states that controlled these territories at various times between 711 and 1492. At its greatest geographical extent, it occupied most o ...
and
North Africa North Africa (sometimes Northern Africa) is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region. However, it is sometimes defined as stretching from the Atlantic shores of t ...
to the
Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...
and
Central Asia Central Asia is a region of Asia consisting of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. The countries as a group are also colloquially referred to as the "-stans" as all have names ending with the Persian language, Pers ...
. Muslim engineers also used
water turbine A water turbine is a rotary machine that converts kinetic energy and potential energy of water into mechanical work. Water turbines were developed in the 19th century and were widely used for industrial power prior to electrical grids. Now, t ...
s while employing
gear A gear or gearwheel is a rotating machine part typically used to transmit rotational motion and/or torque by means of a series of teeth that engage with compatible teeth of another gear or other part. The teeth can be integral saliences or ...
s in watermills and water-raising machines. They also pioneered the use of
dams A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, ...
as a source of water power, used to provide additional power to watermills and water-raising machines. Islamic irriguation techniques including Persian Wheels would be introduced to India, and would be combined with local methods, during the
Delhi Sultanate The Delhi Sultanate or the Sultanate of Delhi was a Medieval India, late medieval empire primarily based in Delhi that stretched over large parts of the Indian subcontinent for more than three centuries.
and the
Mughal Empire The Mughal Empire was an Early modern period, early modern empire in South Asia. At its peak, the empire stretched from the outer fringes of the Indus River Basin in the west, northern Afghanistan in the northwest, and Kashmir in the north, to ...
. Furthermore, in his book, ''The Book of Knowledge of Ingenious Mechanical Devices'', the Muslim mechanical engineer,
Al-Jazari Badīʿ az-Zaman Abu l-ʿIzz ibn Ismāʿīl ibn ar-Razāz al-Jazarī (1136–1206, , ) was a Muslim polymath: a scholar, inventor, mechanical engineer, artisan and artist from the Artuqid Dynasty of Jazira in Mesopotamia. He is best known for ...
(1136–1206) described designs for 50 devices. Many of these devices were water-powered, including clocks, a device to serve wine, and five devices to lift water from rivers or pools, where three of them are animal-powered and one can be powered by animal or water. Moreover, they included an endless belt with jugs attached, a cow-powered
shadoof A shadoof or shaduf, well pole, well sweep, sweep,Knight, Edward Henry. ''Knight's American mechanical dictionary''. Vol. 3. New York, Hurd and Houghton: Riverside Press, 1877. 2,468. Print. swape, or simply a lift is a tool that is used to lift w ...
(a crane-like irrigation tool), and a reciprocating device with hinged valves.


19th century

In the 19th century, French engineer
Benoît Fourneyron Benoît Fourneyron (31 October 1802 – 31 July 1867) was a French engineer, born in Saint-Étienne, Loire. Fourneyron made significant contributions to the development of water turbines. Benoît Fourneyron was educated at the École Nation ...
developed the first hydropower turbine. This device was implemented in the commercial plant of
Niagara Falls Niagara Falls is a group of three waterfalls at the southern end of Niagara Gorge, spanning the Canada–United States border, border between the Provinces and territories of Canada, province of Ontario in Canada and the state of New York (s ...
in 1895 and it is still operating. In the early 20th century, English engineer William Armstrong built and operated the first private electrical power station which was located in his house in
Cragside Cragside is a Victorian era, Victorian Tudor Revival architecture, Tudor Revival country house near the town of Rothbury in Northumberland, England. It was the home of William Armstrong, 1st Baron Armstrong, founder of the Armstrong Whitworth a ...
in
Northumberland Northumberland ( ) is a ceremonial counties of England, ceremonial county in North East England, on the Anglo-Scottish border, border with Scotland. It is bordered by the North Sea to the east, Tyne and Wear and County Durham to the south, Cumb ...
, England. In 1753, the French engineer
Bernard Forest de Bélidor Bernard Forest de Bélidor (1698, Catalonia, Spain – 8 September 1761, Paris, France) was a French engineer, significant to the development of the science of hydraulics and ballistics. He was the son of Jean Baptiste Foret de Belidor, an offic ...
published his book, ''Architecture Hydraulique'', which described vertical-axis and horizontal-axis hydraulic machines. The growing demand for the
Industrial Revolution The Industrial Revolution, sometimes divided into the First Industrial Revolution and Second Industrial Revolution, was a transitional period of the global economy toward more widespread, efficient and stable manufacturing processes, succee ...
would drive development as well. At the beginning of the Industrial Revolution in Britain, water was the main power source for new inventions such as
Richard Arkwright Sir Richard Arkwright (23 December 1732 – 3 August 1792) was an English inventor and a leading entrepreneur during the early Industrial Revolution. He is credited as the driving force behind the development of the spinning frame, known as ...
's
water frame The water frame is a spinning frame that is powered by a water-wheel. History Richard Arkwright, who patented the technology in 1769, designed a model for the production of cotton thread, which was first used in 1765. The Arkwright water f ...
. Although water power gave way to steam power in many of the larger mills and factories, it was still used during the 18th and 19th centuries for many smaller operations, such as driving the bellows in small
blast furnace A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. ''Blast'' refers to the combustion air being supplied above atmospheric pressure. In a ...
s (e.g. the Dyfi Furnace) and
gristmill A gristmill (also: grist mill, corn mill, flour mill, feed mill or feedmill) grinds cereal grain into flour and Wheat middlings, middlings. The term can refer to either the grinding mechanism or the building that holds it. Grist is grain that h ...
s, such as those built at
Saint Anthony Falls Saint Anthony Falls, or the Falls of Saint Anthony (), located at the northeastern edge of downtown Minneapolis, Minnesota, was the only natural major waterfall on the Mississippi River. Throughout the mid-to-late 1800s, various dams were built ...
, which uses the drop in the
Mississippi River The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...
. Technological advances moved the open water wheel into an enclosed
turbine A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced can be used for generating electrical ...
or water motor. In 1848, the British-American engineer
James B. Francis James Bicheno Francis (May 18, 1815 – September 18, 1892) was a British-American civil engineer, who invented the Francis turbine. Early years James Francis was born in South Leigh, near Witney, Oxfordshire, in England, United Kingdom. ...
, head engineer of Lowell's Locks and Canals company, improved on these designs to create a turbine with 90% efficiency. He applied scientific principles and testing methods to the problem of turbine design. His mathematical and graphical calculation methods allowed the confident design of high-efficiency turbines to exactly match a site's specific flow conditions. The Francis reaction turbine is still in use. In the 1870s, deriving from uses in the California mining industry,
Lester Allan Pelton Lester Allan Pelton (September 5, 1829 – March 14, 1908) was an American inventor who contributed significantly to the development of hydroelectricity and hydropower in the American Old West as well as world-wide. In the late 1870s, he invented ...
developed the high-efficiency Pelton wheel impulse turbine, which used hydropower from the high head streams characteristic of the
Sierra Nevada The Sierra Nevada ( ) is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primari ...
.


20th century

The modern history of hydropower begins in the 1900s, with large dams built not simply to power neighboring mills or factories but provide extensive electricity for increasingly distant groups of people. Competition drove much of the global hydroelectric craze: Europe competed amongst itself to electrify first, and the United States' hydroelectric plants in
Niagara Falls Niagara Falls is a group of three waterfalls at the southern end of Niagara Gorge, spanning the Canada–United States border, border between the Provinces and territories of Canada, province of Ontario in Canada and the state of New York (s ...
and the
Sierra Nevada The Sierra Nevada ( ) is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primari ...
inspired bigger and bolder creations across the globe. American and USSR financers and hydropower experts also spread the gospel of dams and hydroelectricity across the globe during the
Cold War The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...
, contributing to projects such as the
Three Gorges Dam The Three Gorges Dam (), officially known as Yangtze River Three Gorges Water Conservancy Project () is a hydroelectric gravity dam that spans the Yangtze River near Sandouping in Yiling District, Yichang, Hubei province, central China, downs ...
and the
Aswan High Dam The Aswan Dam, or Aswan High Dam, is one of the world's largest embankment dams, which was built across the Nile in Aswan, Egypt, between 1960 and 1970. When it was completed, it was the tallest earthen dam in the world, surpassing the Chatug ...
. Feeding desire for large scale electrification with water inherently required large dams across powerful rivers, which impacted public and private interests downstream and in flood zones. Inevitably smaller communities and marginalized groups suffered. They were unable to successfully resist companies flooding them out of their homes or blocking traditional
salmon Salmon (; : salmon) are any of several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the genera ''Salmo'' and ''Oncorhynchus'' of the family (biology), family Salmonidae, native ...
passages. The stagnant water created by hydroelectric dams provides breeding ground for pests and
pathogens In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ. The term ...
, leading to local
epidemics An epidemic (from Ancient Greek, Greek ἐπί ''epi'' "upon or above" and δῆμος ''demos'' "people") is the rapid spread of disease to a large number of Host (biology), hosts in a given population within a short period of time. For example ...
. However, in some cases, a mutual need for hydropower could lead to cooperation between otherwise adversarial nations. Hydropower technology and attitude began to shift in the second half of the 20th century. While countries had largely abandoned their small hydropower systems by the 1930s, the smaller hydropower plants began to make a comeback in the 1970s, boosted by government subsidies and a push for more independent energy producers. Some politicians who once advocated for large hydropower projects in the first half of the 20th century began to speak out against them, and citizen groups organizing against dam projects increased. In the 1980s and 90s the international anti-dam movement had made finding government or private investors for new large hydropower projects incredibly difficult, and given rise to NGOs devoted to fighting dams. Additionally, while the cost of other energy sources fell, the cost of building new hydroelectric dams increased 4% annually between 1965 and 1990, due both to the increasing costs of construction and to the decrease in high quality building sites. In the 1990s, only 18% of the world's electricity came from hydropower.
Tidal power Tidal power or tidal energy is harnessed by converting energy from tides into useful forms of power, mainly electricity using various methods. Although not yet widely used, tidal energy has the potential for future electricity generation. T ...
production also emerged in the 1960s as a burgeoning alternative hydropower system, though still has not taken hold as a strong energy contender.


United States

Especially at the start of the American hydropower experiment, engineers and politicians began major hydroelectricity projects to solve a problem of 'wasted potential' rather than to power a population that needed the electricity. When the
Niagara Falls Power Company Niagara Falls Hydraulic Power & Manufacturing Company was an American company, based in Niagara Falls, New York, Niagara Falls, New York (state), New York that was the first company to generate hydroelectric power from Niagara Falls in 1882. The ...
began looking into damming Niagara, the first major hydroelectric project in the United States, in the 1890s they struggled to transport electricity from the falls far enough away to actually reach enough people and justify installation. The project succeeded in large part due to Nikola Tesla's invention of the alternating current motor. On the other side of the country,
San Francisco San Francisco, officially the City and County of San Francisco, is a commercial, Financial District, San Francisco, financial, and Culture of San Francisco, cultural center of Northern California. With a population of 827,526 residents as of ...
engineers, the
Sierra Club The Sierra Club is an American environmental organization with chapters in all 50 U.S. states, Washington, D.C., Washington D.C., and Puerto Rico. The club was founded in 1892, in San Francisco, by preservationist John Muir. A product of the Pro ...
, and the federal government fought over acceptable use of the
Hetch Hetchy Valley Hetch Hetchy is a valley, reservoir, and water system in California in the United States. The glacial Hetch Hetchy Valley lies in the northwestern part of Yosemite National Park and is drained by the Tuolumne River. For thousands of years before ...
. Despite ostensible protection within a national park, city engineers successfully won the rights to both water and power in the Hetch Hetchy Valley in 1913. After their victory they delivered Hetch Hetchy hydropower and water to San Francisco a decade later and at twice the promised cost, selling power to
PG&E The Pacific Gas and Electric Company (PG&E) is an American investor-owned utility (IOU). The company is headquartered at Kaiser Center, in Oakland, California. PG&E provides natural gas and electricity to 5.2 million households in the norther ...
which resold to San Francisco residents at a profit. The American West, with its mountain rivers and lack of coal, turned to hydropower early and often, especially along the
Columbia River The Columbia River (Upper Chinook language, Upper Chinook: ' or '; Sahaptin language, Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river headwater ...
and its tributaries. The
Bureau of Reclamation The Bureau of Reclamation, formerly the United States Reclamation Service, is a List of United States federal agencies, federal agency under the U.S. Department of the Interior, which oversees water resource management, specifically as it ...
built the
Hoover Dam The Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado, Black Canyon of the Colorado River (U.S.), Colorado River, on the border between the U.S. states of Nevada and Arizona. Constructed between 1931 and 1936, d ...
in 1931, symbolically linking the job creation and economic growth priorities of the
New Deal The New Deal was a series of wide-reaching economic, social, and political reforms enacted by President Franklin D. Roosevelt in the United States between 1933 and 1938, in response to the Great Depression in the United States, Great Depressi ...
. The federal government quickly followed Hoover with the
Shasta Dam Shasta Dam (called Kennett Dam before its construction) is a concrete arch-gravity dam across the Sacramento River in Northern California in the United States. At high, it is the eighth-tallest dam in the United States. Located at the north e ...
and
Grand Coulee Dam Grand Coulee Dam is a concrete gravity dam on the Columbia River in the U.S. state of Washington, built to produce hydroelectric power and provide irrigation water. Constructed between 1933 and 1942, Grand Coulee originally had two powerhous ...
. Power demand in
Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...
did not justify damming the Columbia until
WWI World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a global conflict between two coalitions: the Allies (or Entente) and the Central Powers. Fighting took place mainly in Europe and th ...
revealed the weaknesses of a coal-based energy economy. The federal government then began prioritizing interconnected power—and lots of it. Electricity from all three dams poured into war production during
WWII World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
. After the war, the
Grand Coulee Dam Grand Coulee Dam is a concrete gravity dam on the Columbia River in the U.S. state of Washington, built to produce hydroelectric power and provide irrigation water. Constructed between 1933 and 1942, Grand Coulee originally had two powerhous ...
and accompanying hydroelectric projects electrified almost all of the rural Columbia Basin, but failed to improve the lives of those living and farming there the way its boosters had promised and also damaged the river ecosystem and migrating salmon populations. In the 1940s as well, the federal government took advantage of the sheer amount of unused power and flowing water from the Grand Coulee to build a
nuclear Nuclear may refer to: Physics Relating to the nucleus of the atom: *Nuclear engineering *Nuclear physics *Nuclear power *Nuclear reactor *Nuclear weapon *Nuclear medicine *Radiation therapy *Nuclear warfare Mathematics * Nuclear space *Nuclear ...
site placed on the banks of the Columbia. The nuclear site leaked radioactive matter into the river, contaminating the entire area. Post-WWII Americans, especially engineers from the
Tennessee Valley Authority The Tennessee Valley Authority (TVA) is a federally owned electric utility corporation in the United States. TVA's service area covers all of Tennessee, portions of Alabama, Mississippi, and Kentucky, and small areas of Georgia, North Carolin ...
, refocused from simply building domestic dams to promoting hydropower abroad. While domestic dam building continued well into the 1970s, with the Reclamation Bureau and Army Corps of Engineers building more than 150 new dams across the American West, organized opposition to hydroelectric dams sparked up in the 1950s and 60s based on environmental concerns. Environmental movements successfully shut down proposed hydropower dams in
Dinosaur National Monument Dinosaur National Monument is an American national monument located on the southeast flank of the Uinta Mountains on the border between Colorado and Utah at the confluence of the Green River (Colorado River tributary), Green and Yampa River, Y ...
and the
Grand Canyon The Grand Canyon is a steep-sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is long, up to wide and attains a depth of over a mile (). The canyon and adjacent rim are contained within Grand Canyon Nati ...
, and gained more hydropower-fighting tools with 1970s environmental legislation. As nuclear and fossil fuels grew in the 70s and 80s and environmental activists push for river restoration, hydropower gradually faded in American importance.


Africa

Foreign powers and IGOs have frequently used hydropower projects in Africa as a tool to interfere in the economic development of African countries, such as the
World Bank The World Bank is an international financial institution that provides loans and Grant (money), grants to the governments of Least developed countries, low- and Developing country, middle-income countries for the purposes of economic development ...
with the Kariba and
Akosombo Dam The Akosombo Dam, also known as the Volta Dam, is a Hydroelectricity, hydroelectric dam on the Volta River in southeastern Ghana in the Akosombo gorge and part of the Volta River Authority. The construction of the dam flooded part of the Volta Riv ...
s, and the
Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
with the
Aswan Dam The Aswan Dam, or Aswan High Dam, is one of the world's largest embankment dams, which was built across the Nile in Aswan, Egypt, between 1960 and 1970. When it was completed, it was the tallest earthen dam in the world, surpassing the Chatuge D ...
. The
Nile River The Nile (also known as the Nile River or River Nile) is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa. It has historically been considered the longest river i ...
especially has borne the consequences of countries both along the Nile and distant foreign actors using the river to expand their economic power or national force. After the British occupation of
Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...
in 1882, the British worked with Egypt to construct the first Aswan Dam, which they heightened in 1912 and 1934 to try to hold back the Nile floods. Egyptian engineer
Adriano Daninos Adriano is the form of the Latin given name ''Hadrianus'' commonly used in the Italian language; the form Adrião can be used in the Portuguese language while the form Adrian is used in the English language. Notable people with the name include: ...
developed a plan for the Aswan High Dam, inspired by the Tennessee Valley Authority's multipurpose dam. When
Gamal Abdel Nasser Gamal Abdel Nasser Hussein (15 January 1918 – 28 September 1970) was an Egyptian military officer and revolutionary who served as the second president of Egypt from 1954 until his death in 1970. Nasser led the Egyptian revolution of 1952 a ...
took power in the 1950s, his government decided to undertake the High Dam project, publicizing it as an economic development project. After American refusal to help fund the dam, and anti-British sentiment in Egypt and British interests in neighboring
Sudan Sudan, officially the Republic of the Sudan, is a country in Northeast Africa. It borders the Central African Republic to the southwest, Chad to the west, Libya to the northwest, Egypt to the north, the Red Sea to the east, Eritrea and Ethiopi ...
combined to make the United Kingdom pull out as well, the Soviet Union funded the Aswan High Dam. Between 1977 and 1990 the dam's turbines generated one third of Egypt's electricity. The building of the Aswan Dam triggered a dispute between Sudan and Egypt over the sharing of the Nile, especially since the dam flooded part of Sudan and decreased the volume of water available to them.
Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...
, also located on the Nile, took advantage of the Cold War tensions to request assistance from the United States for their own irrigation and hydropower investments in the 1960s. While progress stalled due to the coup d'état of 1974 and following 17-year-long
Ethiopian Civil War The Ethiopian Civil War was a civil war in Ethiopia and present-day Eritrea, fought between the Ethiopian military junta known as the Derg and Ethiopian-Eritrean anti-government rebels from 12 September 1974 to 28 May 1991. The Derg overthre ...
Ethiopia began construction on the
Grand Ethiopian Renaissance Dam The Grand Ethiopian Renaissance Dam (GERD or TaIHiGe; , , ), formerly known as the Millennium Dam and sometimes referred to as the Hidase Dam (, ), is a gravity dam on the Blue Nile River in Ethiopia. The dam is in the Benishangul-Gumuz Region ...
in 2011. Beyond the Nile, hydroelectric projects cover the rivers and lakes of Africa. The Inga powerplant on the
Congo River The Congo River, formerly also known as the Zaire River, is the second-longest river in Africa, shorter only than the Nile, as well as the third-largest river in the world list of rivers by discharge, by discharge volume, following the Amazon Ri ...
had been discussed since Belgian colonization in the late 19th century, and was successfully built after independence. Mobutu's government failed to regularly maintain the plants and their capacity declined until the 1995 formation of the
Southern African Power Pool The Southern African Power Pool (SAPP) is a cooperation of the national electricity companies in Southern Africa under the auspices of the Southern African Development Community (SADC). The members of SAPP have created a common power grid betwe ...
created a multi-national power grid and plant maintenance program. States with an abundance of hydropower, such as the
Democratic Republic of the Congo The Democratic Republic of the Congo (DRC), also known as the DR Congo, Congo-Kinshasa, or simply the Congo (the last ambiguously also referring to the neighbouring Republic of the Congo), is a country in Central Africa. By land area, it is t ...
and
Ghana Ghana, officially the Republic of Ghana, is a country in West Africa. It is situated along the Gulf of Guinea and the Atlantic Ocean to the south, and shares borders with Côte d’Ivoire to the west, Burkina Faso to the north, and Togo to t ...
, frequently sell excess power to neighboring countries. Foreign actors such as Chinese hydropower companies have proposed a significant amount of new hydropower projects in Africa, and already funded and consulted on many others in countries like
Mozambique Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...
and Ghana. Small hydropower also played an important role in early 20th century electrification across Africa. In South Africa, small turbines powered gold mines and the first electric railway in the 1890s, and Zimbabwean farmers installed small hydropower stations in the 1930s. While interest faded as national grids improved in the second half of the century, 21st century national governments in countries including South Africa and Mozambique, as well as NGOs serving countries like Zimbabwe, have begun re-exploring small-scale hydropower to diversify power sources and improve rural electrification.


Europe

In the early 20th century, two major factors motivated the expansion of hydropower in Europe: in the northern countries of
Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...
and
Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...
, high rainfall and mountains proved exceptional resources for abundant hydropower, and in the south, coal shortages pushed governments and utility companies to seek alternative power sources. Early on,
Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...
dammed the Alpine rivers and the Swiss Rhine, creating, along with
Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...
and Scandinavia, a Southern Europe hydropower race. In Italy's Po Valley, the main 20th-century transition was not the creation of hydropower but the transition from mechanical to electrical hydropower. 12,000 watermills churned in the Po watershed in the 1890s, but the first commercial hydroelectric plant, completed in 1898, signaled the end of the mechanical reign. These new large plants moved power away from rural mountainous areas to urban centers in the lower plain. Italy prioritized early near-nationwide electrification, almost entirely from hydropower, which powered its rise as a dominant European and imperial force. However, they failed to reach any conclusive standard for determining water rights before WWI. Modern German hydropower dam construction was built on a history of small dams powering mines and mills in the 15th century. Some parts of the German industry relied more on waterwheels than steam until the 1870s. The German government did not set out building large dams such as the prewar Urft Dam, Urft, Möhne Reservoir, Mohne, and Edersee Dam, Eder dams to expand hydropower: they mostly wanted to reduce flooding and improve navigation. However, hydropower quickly emerged as a bonus for all these dams, especially in the coal-poor south. Bavaria even achieved a statewide power grid by damming the Walchensee in 1924, inspired in part by loss of coal reserves after WWI. Hydropower became a symbol of regional pride and distaste for northern 'coal barons', although the north also held strong enthusiasm for hydropower. Dam building rapidly increased after WWII, aiming to increase hydropower. However, conflict accompanied the dam building and spread of hydropower: agrarian interests suffered from decreased irrigation, small mills lost water flow, and different interest groups fought over where dams should be located, controlling who benefited and whose homes they drowned.


See also

* Deep water source cooling * Energy conversion efficiency * Gravitation water vortex power plant * Hydraulic ram * Hydropower Sustainability Assessment Protocol * International Hydropower Association * Low-head hydro power * Marine current power * Marine energy * Ocean thermal energy conversion * Osmotic power * Pumped-storage hydroelectricity * Run-of-the-river hydroelectricity *
Tidal power Tidal power or tidal energy is harnessed by converting energy from tides into useful forms of power, mainly electricity using various methods. Although not yet widely used, tidal energy has the potential for future electricity generation. T ...
* Tidal stream generator * Wave power


Notes


References


Sources

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External links


International Hydropower Association

International Centre for Hydropower (ICH)
hydropower portal with links to numerous organizations related to hydropower worldwide
IEC TC 4: Hydraulic turbines
(International Electrotechnical Commission – Technical Committee 4) IEC TC 4 portal with access to scope, documents an


Micro-hydro power
Adam Harvey, 2004, Intermediate Technology Development Group. Retrieved 1 January 2005
Microhydropower Systems
US Department of Energy, Energy Efficiency and Renewable Energy, 2005 {{Authority control Hydropower, Power station technology Energy conversion Hydraulic engineering Sustainable technologies