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Hydropower (from el, ὕδωρ, "water"), also known as water power, is the use of falling or fast-running
water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...
to produce electricity or to power machines. This is achieved by converting the
gravitational potential In classical mechanics, the gravitational potential at a location is equal to the work (energy transferred) per unit mass that would be needed to move an object to that location from a fixed reference location. It is analogous to the electric ...
or
kinetic energy In physics, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acce ...
of a water source to produce power. Hydropower is a method of
sustainable energy Energy is sustainable if it "meets the needs of the present without compromising the ability of future generations to meet their own needs". Most definitions of sustainable energy include considerations of environmental aspects such as green ...
production. Hydropower is now used principally for hydroelectric power generation, 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. The method stores energy in the form of gravitational potent ...
. Hydropower is an attractive alternative to
fossil fuel A fossil fuel is a hydrocarbon-containing material formed naturally in the Earth's crust from the remains of dead plants and animals that is extracted and burned as a fuel. The main fossil fuels are coal, oil, and natural gas. Fossil fuels ma ...
s as it does not directly produce
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...
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 flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of ...
or elevated
lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...
. International institutions such as the
World Bank The World Bank is an international financial institution that provides loans and grants to the governments of low- and middle-income countries for the purpose of pursuing capital projects. The World Bank is the collective name for the Inte ...
view hydropower as a low-carbon means for
economic development In the economics study of the public sector, 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 ...
. 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 milling (grinding), rolling, or hammering. Such processes are needed in the production ...
s has been used as a
renewable energy Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy ...
source for
irrigation Irrigation (also referred to as watering) 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 been devel ...
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 middlings. The term can refer to either the grinding mechanism or the building that holds it. Grist is grain that has been separat ...
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, different #Fabric, fabric types, etc. At f ...
mills,
trip hammer A trip hammer, also known as a tilt hammer or helve hammer, is a massive powered hammer. Traditional uses of trip hammers include pounding, wikt:decorticate, decorticating and polishing of grain in agriculture. In mining, trip hammers were used f ...
s, dock
cranes Crane or cranes may refer to: Common meanings * Crane (bird), a large, long-necked bird * Crane (machine), industrial machinery for lifting ** Crane (rail), a crane suited for use on railroads People and fictional characters * Crane (surname ...
, domestic lifts, and
ore mill In the field of extractive metallurgy, mineral processing, also known as ore dressing, is the process of separating commercially valuable minerals from their ores. History Before the advent of heavy machinery the raw ore was broken up usin ...
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 most often refers to: * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power * Power (social and political), the ability to influence people or events ** Abusive power Power may a ...
. Power is a function of the
hydraulic head Hydraulic head or piezometric head is a specific measurement of liquid pressure above a vertical datum., 410 pages. See pp. 43–44., 650 pages. See p. 22. It is usually measured as a liquid surface elevation, expressed in units of length, ...
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 ). I ...
. 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 animal t ...
flow rate out) is the useful power output (SI unit:
watt The watt (symbol: W) is the unit of 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 quantify the rate of energy transfer. The watt is named after James ...
s) ::* \eta ("
eta Eta (uppercase , lowercase ; grc, ἦτα ''ē̂ta'' or ell, ήτα ''ita'' ) is the seventh letter of the Greek alphabet, representing the close front unrounded vowel . Originally denoting the voiceless glottal fricative in most dialects, ...
") is the efficiency of the turbine (
dimensionless A dimensionless quantity (also known as a bare quantity, pure quantity, or scalar quantity as well as quantity of dimension one) is a quantity to which no physical dimension is assigned, with a corresponding SI unit of measurement of one (or 1) ...
) ::* \dot is the
mass flow rate In physics and engineering, mass flow rate is the mass of a substance which passes per unit of time. Its unit is kilogram per second in SI units, and slug per second or pound per second in US customary units. The common symbol is \dot ('' ...
(SI unit:
kilogram The kilogram (also kilogramme) is the unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially. ...
s per second) ::* \rho ("
rho Rho (uppercase Ρ, lowercase ρ or ; el, ρο or el, ρω, label=none) is the 17th letter of the Greek alphabet. In the system of Greek numerals it has a value of 100. It is derived from Phoenician letter res . Its uppercase form uses the sa ...
") is the
density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematicall ...
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 ). I ...
(SI unit: cubic metres per second) ::* g is the acceleration due to gravity (SI unit:
metres The metre (British spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography, the two most notable va ...
per second per second) ::* \Delta h (" Delta 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 145 metres (480 feet), 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 ...
PTC 18 and
IEC The International Electrotechnical Commission (IEC; in French: ''Commission électrotechnique internationale'') is an international standards organization that prepares and publishes international standards for all electrical, electronic and r ...
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 known as the significant digits, ''precision'' or ''resolution'') of a number in positional notation are digits in the number that are reliable and necessary to indicate the quantity of something. If a number expres ...
s of constants must be considered. Some hydropower systems such as
water wheel A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel (usually constructed from wood or metal), with a number of blades or buckets ...
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 energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acce ...
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 effects of human activity on the biophysical environment, most often of which are harmful effects that cause environmental degradation. Environmental protection is the practice of protecting the natural environment on t ...
, 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 th ...
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.. Dams and
reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contr ...
s can have major negative impacts on river
ecosystems An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...
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 emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and ...
from underwater rotting vegetation. Furthermore, although at lower levels than other
renewable energy Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy ...
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 relative abundance of methane ...
gas which is a
greenhouse A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of transparent material, such as glass, in which plants requiring regulated climatic conditions are grown.These ...
gas. This occurs when organic matters accumulate at the bottom of the
reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contr ...
because of the deoxygenation 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 manage waste or to produce fuels. Much of the ferm ...
. People who live near a hydro plant site are displaced during construction or when
reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contr ...
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 is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches, an ...
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 1,118 at the 2016 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 ...
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.  Hydroelectricity generation starts with converting either the
potential energy In physics, potential energy is the energy held by an object because of its position relative to other objects, stresses within itself, its electric charge, or other factors. Common types of potential energy include the gravitational potenti ...
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 energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acce ...
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 (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contr ...
. 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 (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contr ...
. 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, to large plants supply that 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 held by an object because of its position relative to other objects, stresses within itself, its electric charge, or other factors. Common types of potential energy include the gravitational potenti ...
between two reservoirs at different heights with pumped-storage. 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. ...
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 USACE Chief Joseph Dam Project Office and the ...
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 2,409 at the 2010 census. Bridgeport is located near the Chief Joseph Dam. History Th ...
, is a major run-of-the-river station without a sizeable reservoir. File:Nw vietnam hydro.jpg, Micro hydro in Northwest Vietnam File:Stwlan.dam.jpg, The upper reservoir and dam of the Ffestiniog Pumped Storage Scheme in
Wales Wales ( cy, Cymru ) is a country that is part of the United Kingdom. It is bordered by England to the east, the Irish Sea to the north and west, the Celtic Sea to the south west and the Bristol Channel to the south. It had a population in ...
. The lower power station can generate 360 MW of electricity.


Rain power

Rain has been referred to as "one of the last unexploited energy sources in nature. When it rains, billions of litres of water can fall, which have enormous electric potential 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 method in which this has been attempted 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 devices, which generate power when they move, to extract 12 milliwatts from a raindrop. Over a year, this would amount to less than 0.001kWh 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

Evidence suggests that the fundamentals of hydropower date to ancient Greek civilization. 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 energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel (usually constructed from wood or metal), with a number of blades or buckets ...
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 milling (grinding), rolling, or hammering. Such processes are needed in the production ...
s date to the
ancient Near East The ancient Near East was the home of early civilizations within a region roughly corresponding to the modern Middle East: Mesopotamia (modern Iraq, southeast Turkey, southwest Iran and northeastern Syria), ancient Egypt, ancient Iran ( Elam, ...
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 in the historical region of southern Mesopotamia (south-central Iraq), emerging during the Chalcolithic and early Bronze Ages between the sixth and fifth millennium BC. It is one of the cradles of ...
and
Babylonia Babylonia (; Akkadian: , ''māt Akkadī'') was an ancient Akkadian-speaking state and cultural area based in the city of Babylon in central-southern Mesopotamia (present-day Iraq and parts of Syria). It emerged as an Amorite-ruled state c ...
. Studies suggest that the water wheel was the initial form of water power and it was driven by either humans or animals. In the
Roman Empire The Roman Empire ( la, Imperium Romanum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post-Roman Republic, Republican period of ancient Rome. As a polity, it included large territorial holdings aro ...
, water-powered mills were described by
Vitruvius Vitruvius (; c. 80–70 BC – after c. 15 BC) was a Roman architect and engineer during the 1st century BC, known for his multi-volume work entitled '' De architectura''. He originated the idea that all buildings should have three attribut ...
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 Roman water-powered stone sawmill at Hierapolis, Asia Minor (modern-day Turkey). Dating to the second half of the 3rd century AD, the sawmill is considered the earliest known machine to combine a crank with a connect ...
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 referred to as the Eastern Roman Empire or Byzantium, was the continuation of the Roman Empire primarily in its eastern provinces during Late Antiquity and the Middle Ages, when its capital city was Constantinopl ...
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 (; grc-gre, Ἔφεσος, Éphesos; tr, Efes; may ultimately derive from hit, 𒀀𒉺𒊭, Apaša) was a city in ancient Greece on the coast of Ionia, southwest of present-day Selçuk in İzmir Province, Turkey. It was built i ...
and
Gerasa Jerash ( ar, جرش ''Ǧaraš''; grc, Γέρασα ''Gérasa'') 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 north of the capital cit ...
respectively. The crank 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 in Chinese history, imperial dynasty of China (202 BC – 9 AD, 25–220 AD), established by Emperor Gaozu of Han, Liu Bang (Emperor Gao) and ruled by the House of Liu. The dynasty was preceded by th ...
(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 "forced" or supplied above atmospheri ...
bellows. Many texts describe the Hun waterwheel; some of the earliest ones are the '' Jijiupian'' dictionary of 40 BC, Yang Xiong's text known as the '' Fangyan'' of 15 BC, as well as ''Xin Lun,'' written by Huan Tan about 20 AD. It was also during this time that the engineer Du Shi (c. AD 31) applied the power of
waterwheel A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel (usually constructed from wood or metal), with a number of blades or bucke ...
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 and is made gas-t ...
-
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. 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 below ...
. Hushing is the use of the power of a wave of water released from a tank in the extraction of metal ores. The method was first used at the Dolaucothi Gold Mines in
Wales Wales ( cy, Cymru ) is a country that is part of the United Kingdom. It is bordered by England to the east, the Irish Sea to the north and west, the Celtic Sea to the south west and the Bristol Channel to the south. It had a population in ...
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 (province of León, Castile and León, Spain). It was the most important gold mine, as well as the largest open-pit gold mine in the entire ...
. Hushing was also widely used in
Britain Britain most often refers to: * The United Kingdom, a sovereign state in Europe comprising the island of Great Britain, the north-eastern part of the island of Ireland and many smaller islands * Great Britain, the largest island in the United King ...
in the
Medieval In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire a ...
and later periods to extract
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, ...
and tin 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) was a gold rush that 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 f ...
in the 19th century. The Islamic Empire 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 cultural, economic, and scientific flourishing in the history of Islam, traditionally dated from the 8th century to the 14th century. This period is traditionally understood to have begun during the reign ...
and the Arab Agricultural Revolution (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. ...
emerged along with large hydraulic
factory A factory, manufacturing plant or a 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. ...
complexes. A wide range of water-powered industrial mills were used in the region including
fulling Fulling, also known as felting, tucking or walking ( Scots: ''waukin'', hence often spelled waulking in Scottish English), is a step in woollen clothmaking which involves the cleansing of woven or knitted cloth (particularly wool) to eli ...
mills,
gristmill A gristmill (also: grist mill, corn mill, flour mill, feed mill or feedmill) grinds cereal grain into flour and middlings. The term can refer to either the grinding mechanism or the building that holds it. Grist is grain that has been separat ...
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 Museum ...
s,
stamp mill A stamp mill (or stamp battery or stamping mill) is a type of mill machine that crushes material by pounding rather than grinding, either for further processing or for extraction of metallic ores. Breaking material down is a type of unit operati ...
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 or white sugar. The term is also used to refer to the equipment that crushes the sticks of sugar cane to extract the juice. Processing There are a number of steps in pro ...
, 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 translit. ; an, al-Andalus; ast, al-Ándalus; eu, al-Andalus; ber, ⴰⵏⴷⴰⵍⵓⵙ, label= Berber, translit=Andalus; ca, al-Àndalus; gl, al-Andalus; oc, Al Andalús; pt, al-Ândalus; es, al-Ándalus () was the M ...
and
North Africa North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in ...
to the
Middle East The Middle East ( ar, الشرق الأوسط, ISO 233: ) is a geopolitical region commonly encompassing Arabian Peninsula, Arabia (including the Arabian Peninsula and Bahrain), Anatolia, Asia Minor (Asian part of Turkey except Hatay Pro ...
and
Central Asia Central Asia, also known as Middle Asia, is a region of Asia that stretches from the Caspian Sea in the west to western China and Mongolia in the east, and from Afghanistan and Iran in the south to Russia in the north. It includes the fo ...
. 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, ...
s while employing
gear A gear is a rotating circular machine part having cut teeth or, in the case of a cogwheel or gearwheel, inserted teeth (called ''cogs''), which mesh with another (compatible) toothed part to transmit (convert) torque and speed. The basic ...
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. 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, ar, بديع الزمان أَبُ اَلْعِزِ إبْنُ إسْماعِيلِ إبْنُ الرِّزاز الجزري, ) was a polymath: a scholar, ...
(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 (from the Arabic word , ''šādūf'') is an irrigation tool. It is highly efficient, and has been known since 3000 BCE. Names It is also called a lift, well pole, well sweep, or simply a sweep in the US.Knight, Edward Henry ...
(a crane-like irrigation tool), and a reciprocating device with hinged valves. 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 U.S. state, state ...
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 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 armaments firm. An industrial magnate, scientist, phila ...
in
Northumberland Northumberland () is a county in Northern England, one of two counties in England which border with Scotland. Notable landmarks in the county include Alnwick Castle, Bamburgh Castle, Hadrian's Wall and Hexham Abbey. It is bordered by land ...
,
England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...
. 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 offi ...
published his book, ''Architecture Hydraulique'', which described vertical-axis and horizontal-axis hydraulic machines. The growing demand for the
Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
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. Water frames in general have existed since Ancient Egypt times. Richard Arkwright, who patented the technology in 1769, designed a model for the production of cotton thread; ...
. 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 "forced" or supplied above atmospheri ...
s (e.g. the
Dyfi Furnace Dyfi Furnace is a restored mid 18th century charcoal fired blast furnace used for smelting iron ore. It has given its name to the adjoining hamlet of Furnace ( cy, Ffwrnais). Location The Dyfi Furnace is in the village of Furnace, Ceredigion, W ...
) and
gristmill A gristmill (also: grist mill, corn mill, flour mill, feed mill or feedmill) grinds cereal grain into flour and middlings. The term can refer to either the grinding mechanism or the building that holds it. Grist is grain that has been separat ...
s, such as those built at
Saint Anthony Falls Saint Anthony Falls, or the Falls of Saint Anthony ( dak, italics=no, Owámniyomni, ) located at the northeastern edge of downtown Minneapolis, Minnesota, is the only natural major waterfall on the Mississippi River. Throughout the mid-to-late 1 ...
, which uses the 50-foot (15 m) drop in the
Mississippi River The Mississippi River is the List of longest rivers of the United States (by main stem), second-longest river and chief river of the second-largest Drainage system (geomorphology), drainage system in North America, second only to the Hudson B ...
. 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 by a turbine can be used for generating ...
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 primar ...
.


See also

* Deep water source cooling *
Gravitation water vortex power plant The gravitation water vortex power plant is a type of micro hydro vortex turbine system which is capable of converting energy in a moving fluid to rotational energy using a low hydraulic head of . The technology is based on a round basin with a ce ...
*
Hydraulic efficiency Energy conversion efficiency (''η'') is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The input, as well as the useful output may be chemical, electric power, mechanical work, light (radia ...
*
Hydraulic ram A hydraulic ram, or hydram, is a cyclic water pump powered by hydropower. It takes in water at one "hydraulic head" (pressure) and flow rate, and outputs water at a higher hydraulic head and lower flow rate. The device uses the water hammer ef ...
* International Hydropower Association * Low head hydro power * Marine current power *
Marine energy Marine energy or marine power (also sometimes referred to as ocean energy, ocean power, or marine and hydrokinetic energy) refers to the energy carried by ocean waves, tides, salinity, and ocean temperature differences. The movement of water in ...
*
Ocean thermal energy conversion Ocean Thermal Energy Conversion (OTEC) uses the ocean thermal gradient between cooler deep and warmer shallow or surface seawaters to run a heat engine and produce useful work, usually in the form of electricity. OTEC can operate with a very hi ...
* Osmotic power *
Wave power Wave power is the capture of energy of wind waves to do useful work – for example, electricity generation, water desalination, or pumping water. A machine that exploits wave power is a wave energy converter (WEC). Waves are generated by win ...


Notes


References


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 Power station technology Energy conversion Hydraulic engineering Sustainable technologies