120-546: Little Goose Lock and Dam is a hydroelectric , concrete, run-of-the-river dam in the northwest United States, on the lower Snake River in southeast Washington . At the dam, the river is the border between Columbia and Whitman counties ; it is nine miles (14 km) northeast of Starbuck and 25 miles (40 km) north of Dayton . Little Goose Dam is part of the Columbia River Basin system of dams. Lake Bryan , named for Enoch Albert Bryan ,
240-455: A conductor 's surface, since otherwise there would be a force along the surface of the conductor that would move the charge carriers to even the potential across the surface. The electric field was formally defined as the force exerted per unit charge, but the concept of potential allows for a more useful and equivalent definition: the electric field is the local gradient of the electric potential. Usually expressed in volts per metre,
360-461: A force on each other, an effect that was known, though not understood, in antiquity. A lightweight ball suspended by a fine thread can be charged by touching it with a glass rod that has itself been charged by rubbing with a cloth. If a similar ball is charged by the same glass rod, it is found to repel the first: the charge acts to force the two balls apart. Two balls that are charged with a rubbed amber rod also repel each other. However, if one ball
480-745: A greenhouse gas . According to the World Commission on Dams report, where the reservoir is large compared to the generating capacity (less than 100 watts per square metre of surface area) and no clearing of the forests in the area was undertaken prior to impoundment of the reservoir, greenhouse gas emissions from the reservoir may be higher than those of a conventional oil-fired thermal generation plant. In boreal reservoirs of Canada and Northern Europe, however, greenhouse gas emissions are typically only 2% to 8% of any kind of conventional fossil-fuel thermal generation. A new class of underwater logging operation that targets drowned forests can mitigate
600-463: A low-head hydro power plant with hydrostatic head of few meters to few tens of meters can be classified either as an SHP or an LHP. The other distinction between SHP and LHP is the degree of the water flow regulation: a typical SHP primarily uses the natural water discharge with very little regulation in comparison to an LHP. Therefore, the term SHP is frequently used as a synonym for the run-of-the-river power plant . The largest power producers in
720-409: A steady state current, but instead blocks it. The inductor is a conductor, usually a coil of wire, that stores energy in a magnetic field in response to the current through it. When the current changes, the magnetic field does too, inducing a voltage between the ends of the conductor. The induced voltage is proportional to the time rate of change of the current. The constant of proportionality
840-456: A central role in many modern technologies, serving in electric power where electric current is used to energise equipment, and in electronics dealing with electrical circuits involving active components such as vacuum tubes , transistors , diodes and integrated circuits , and associated passive interconnection technologies. The study of electrical phenomena dates back to antiquity, with theoretical understanding progressing slowly until
960-432: A charge of Q coulombs every t seconds passing through an electric potential ( voltage ) difference of V is where Electric power is generally supplied to businesses and homes by the electric power industry . Electricity is usually sold by the kilowatt hour (3.6 MJ) which is the product of power in kilowatts multiplied by running time in hours. Electric utilities measure power using electricity meters , which keep
1080-516: A common reference point to which potentials may be expressed and compared is useful. While this could be at infinity, a much more useful reference is the Earth itself, which is assumed to be at the same potential everywhere. This reference point naturally takes the name earth or ground . Earth is assumed to be an infinite source of equal amounts of positive and negative charge and is therefore electrically uncharged—and unchargeable. Electric potential
1200-472: A current of one amp. The capacitor is a development of the Leyden jar and is a device that can store charge, and thereby storing electrical energy in the resulting field. It consists of two conducting plates separated by a thin insulating dielectric layer; in practice, thin metal foils are coiled together, increasing the surface area per unit volume and therefore the capacitance . The unit of capacitance
1320-494: A dampened kite string and flown the kite in a storm-threatened sky . A succession of sparks jumping from the key to the back of his hand showed that lightning was indeed electrical in nature. He also explained the apparently paradoxical behavior of the Leyden jar as a device for storing large amounts of electrical charge in terms of electricity consisting of both positive and negative charges. In 1775, Hugh Williamson reported
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#17327717479451440-421: A flood and fail. Changes in the amount of river flow will correlate with the amount of energy produced by a dam. Lower river flows will reduce the amount of live storage in a reservoir therefore reducing the amount of water that can be used for hydroelectricity. The result of diminished river flow can be power shortages in areas that depend heavily on hydroelectric power. The risk of flow shortage may increase as
1560-538: A key element for creating secure and clean electricity supply systems. A hydroelectric power station that has a dam and reservoir is a flexible source, since the amount of electricity produced can be increased or decreased in seconds or minutes in response to varying electricity demand. Once a hydroelectric complex is constructed, it produces no direct waste, and almost always emits considerably less greenhouse gas than fossil fuel -powered energy plants. However, when constructed in lowland rainforest areas, where part of
1680-425: A large lightning cloud may be as high as 100 MV and have discharge energies as great as 250 kWh. The field strength is greatly affected by nearby conducting objects, and it is particularly intense when it is forced to curve around sharply pointed objects. This principle is exploited in the lightning conductor , the sharp spike of which acts to encourage the lightning strike to develop there, rather than to
1800-809: A large natural height difference between two waterways, such as a waterfall or mountain lake. A tunnel is constructed to take water from the high reservoir to the generating hall built in a cavern near the lowest point of the water tunnel and a horizontal tailrace taking water away to the lower outlet waterway. A simple formula for approximating electric power production at a hydroelectric station is: P = − η ( m ˙ g Δ h ) = − η ( ( ρ V ˙ ) g Δ h ) {\displaystyle P=-\eta \ ({\dot {m}}g\ \Delta h)=-\eta \ ((\rho {\dot {V}})\ g\ \Delta h)} where Efficiency
1920-451: A larger amount of methane than those in temperate areas. Like other non-fossil fuel sources, hydropower also has no emissions of sulfur dioxide, nitrogen oxides, or other particulates. Reservoirs created by hydroelectric schemes often provide facilities for water sports , and become tourist attractions themselves. In some countries, aquaculture in reservoirs is common. Multi-use dams installed for irrigation support agriculture with
2040-402: A millimetre per second, the electric field that drives them itself propagates at close to the speed of light , enabling electrical signals to pass rapidly along wires. Current causes several observable effects, which historically were the means of recognising its presence. That water could be decomposed by the current from a voltaic pile was discovered by Nicholson and Carlisle in 1800,
2160-553: A more reliable source of electrical energy than the electrostatic machines previously used. The recognition of electromagnetism , the unity of electric and magnetic phenomena, is due to Hans Christian Ørsted and André-Marie Ampère in 1819–1820. Michael Faraday invented the electric motor in 1821, and Georg Ohm mathematically analysed the electrical circuit in 1827. Electricity and magnetism (and light) were definitively linked by James Clerk Maxwell , in particular in his " On Physical Lines of Force " in 1861 and 1862. While
2280-425: A positive current is defined as having the same direction of flow as any positive charge it contains, or to flow from the most positive part of a circuit to the most negative part. Current defined in this manner is called conventional current . The motion of negatively charged electrons around an electric circuit , one of the most familiar forms of current, is thus deemed positive in the opposite direction to that of
2400-420: A positive or negative electric charge produces an electric field . The motion of electric charges is an electric current and produces a magnetic field . In most applications, Coulomb's law determines the force acting on an electric charge. Electric potential is the work done to move an electric charge from one point to another within an electric field, typically measured in volts . Electricity plays
2520-592: A positive risk adjusted return, unless appropriate risk management measures are put in place. While many hydroelectric projects supply public electricity networks, some are created to serve specific industrial enterprises. Dedicated hydroelectric projects are often built to provide the substantial amounts of electricity needed for aluminium electrolytic plants, for example. The Grand Coulee Dam switched to support Alcoa aluminium in Bellingham, Washington , United States for American World War II airplanes before it
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#17327717479452640-891: A practical generator, but it showed the possibility of generating electric power using magnetism, a possibility that would be taken up by those that followed on from his work. An electric circuit is an interconnection of electric components such that electric charge is made to flow along a closed path (a circuit), usually to perform some useful task. The components in an electric circuit can take many forms, which can include elements such as resistors , capacitors , switches , transformers and electronics . Electronic circuits contain active components , usually semiconductors , and typically exhibit non-linear behaviour, requiring complex analysis. The simplest electric components are those that are termed passive and linear : while they may temporarily store energy, they contain no sources of it, and exhibit linear responses to stimuli. The resistor
2760-406: A process now known as electrolysis . Their work was greatly expanded upon by Michael Faraday in 1833. Current through a resistance causes localised heating, an effect James Prescott Joule studied mathematically in 1840. One of the most important discoveries relating to current was made accidentally by Hans Christian Ørsted in 1820, when, while preparing a lecture, he witnessed the current in
2880-471: A rapidly changing one. Electric power is the rate at which electric energy is transferred by an electric circuit . The SI unit of power is the watt , one joule per second . Electric power, like mechanical power , is the rate of doing work , measured in watts , and represented by the letter P . The term wattage is used colloquially to mean "electric power in watts." The electric power in watts produced by an electric current I consisting of
3000-548: A relatively constant water supply. Large hydro dams can control floods, which would otherwise affect people living downstream of the project. Managing dams which are also used for other purposes, such as irrigation , is complicated. In 2021 the IEA called for "robust sustainability standards for all hydropower development with streamlined rules and regulations". Large reservoirs associated with traditional hydroelectric power stations result in submersion of extensive areas upstream of
3120-489: A resistance is directly proportional to the potential difference across it. The resistance of most materials is relatively constant over a range of temperatures and currents; materials under these conditions are known as 'ohmic'. The ohm , the unit of resistance, was named in honour of Georg Ohm , and is symbolised by the Greek letter Ω. 1 Ω is the resistance that will produce a potential difference of one volt in response to
3240-540: A result of climate change . One study from the Colorado River in the United States suggest that modest climate changes, such as an increase in temperature in 2 degree Celsius resulting in a 10% decline in precipitation, might reduce river run-off by up to 40%. Brazil in particular is vulnerable due to its heavy reliance on hydroelectricity, as increasing temperatures, lower water flow and alterations in
3360-595: A running total of the electric energy delivered to a customer. Unlike fossil fuels , electricity is a low entropy form of energy and can be converted into motion or many other forms of energy with high efficiency. Electronics deals with electrical circuits that involve active electrical components such as vacuum tubes , transistors , diodes , sensors and integrated circuits , and associated passive interconnection technologies. The nonlinear behaviour of active components and their ability to control electron flows makes digital switching possible, and electronics
3480-431: A scientific curiosity into an essential tool for modern life. In 1887, Heinrich Hertz discovered that electrodes illuminated with ultraviolet light create electric sparks more easily. In 1905, Albert Einstein published a paper that explained experimental data from the photoelectric effect as being the result of light energy being carried in discrete quantized packets, energising electrons. This discovery led to
3600-575: A series of experiments to the Royal Society on the shocks delivered by the electric eel ; that same year the surgeon and anatomist John Hunter described the structure of the fish's electric organs . In 1791, Luigi Galvani published his discovery of bioelectromagnetics , demonstrating that electricity was the medium by which neurons passed signals to the muscles. Alessandro Volta 's battery, or voltaic pile , of 1800, made from alternating layers of zinc and copper, provided scientists with
3720-515: A series of observations on static electricity around 600 BCE, from which he believed that friction rendered amber magnetic , in contrast to minerals such as magnetite , which needed no rubbing. Thales was incorrect in believing the attraction was due to a magnetic effect, but later science would prove a link between magnetism and electricity. According to a controversial theory, the Parthians may have had knowledge of electroplating , based on
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3840-448: A small TV/radio). Even smaller turbines of 200–300 W may power a few homes in a developing country with a drop of only 1 m (3 ft). A Pico-hydro setup is typically run-of-the-river , meaning that dams are not used, but rather pipes divert some of the flow, drop this down a gradient, and through the turbine before returning it to the stream. An underground power station is generally used at large facilities and makes use of
3960-477: A solid crystal (such as a germanium crystal) to detect a radio signal by the contact junction effect. In a solid-state component, the current is confined to solid elements and compounds engineered specifically to switch and amplify it. Current flow can be understood in two forms: as negatively charged electrons , and as positively charged electron deficiencies called holes . These charges and holes are understood in terms of quantum physics. The building material
4080-455: A source of low-cost renewable energy. Alternatively, small hydro projects may be built in isolated areas that would be uneconomic to serve from a grid, or in areas where there is no national electrical distribution network. Since small hydro projects usually have minimal reservoirs and civil construction work, they are seen as having a relatively low environmental impact compared to large hydro. This decreased environmental impact depends strongly on
4200-414: A start-up time of the order of a few minutes. Although battery power is quicker its capacity is tiny compared to hydro. It takes less than 10 minutes to bring most hydro units from cold start-up to full load; this is quicker than nuclear and almost all fossil fuel power. Power generation can also be decreased quickly when there is a surplus power generation. Hence the limited capacity of hydropower units
4320-581: A total of 1,500 terawatt-hours (TWh) of electrical energy in one full cycle" which was "about 170 times more energy than the global fleet of pumped storage hydropower plants". Battery storage capacity is not expected to overtake pumped storage during the 2020s. When used as peak power to meet demand, hydroelectricity has a higher value than baseload power and a much higher value compared to intermittent energy sources such as wind and solar. Hydroelectric stations have long economic lives, with some plants still in service after 50–100 years. Operating labor cost
4440-511: A wire disturbing the needle of a magnetic compass. He had discovered electromagnetism , a fundamental interaction between electricity and magnetics. The level of electromagnetic emissions generated by electric arcing is high enough to produce electromagnetic interference , which can be detrimental to the workings of adjacent equipment. In engineering or household applications, current is often described as being either direct current (DC) or alternating current (AC). These terms refer to how
4560-448: A wire suspended from a pivot above the magnet and dipped into the mercury. The magnet exerted a tangential force on the wire, making it circle around the magnet for as long as the current was maintained. Experimentation by Faraday in 1831 revealed that a wire moving perpendicular to a magnetic field developed a potential difference between its ends. Further analysis of this process, known as electromagnetic induction , enabled him to state
4680-402: A wire. The informal term static electricity refers to the net presence (or 'imbalance') of charge on a body, usually caused when dissimilar materials are rubbed together, transferring charge from one to the other. Charge can be measured by a number of means, an early instrument being the gold-leaf electroscope , which although still in use for classroom demonstrations, has been superseded by
4800-457: A year's worth of rain fell within 24 hours (see 1975 Banqiao Dam failure ). The resulting flood resulted in the deaths of 26,000 people, and another 145,000 from epidemics. Millions were left homeless. The creation of a dam in a geologically inappropriate location may cause disasters such as 1963 disaster at Vajont Dam in Italy, where almost 2,000 people died. Electricity Electricity
4920-452: Is hydroelectric power on a scale serving a small community or industrial plant. The definition of a small hydro project varies but a generating capacity of up to 10 megawatts (MW) is generally accepted as the upper limit. This may be stretched to 25 MW and 30 MW in Canada and the United States. Small hydro stations may be connected to conventional electrical distribution networks as
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5040-584: Is a scalar quantity . That is, it has only magnitude and not direction. It may be viewed as analogous to height : just as a released object will fall through a difference in heights caused by a gravitational field, so a charge will 'fall' across the voltage caused by an electric field. As relief maps show contour lines marking points of equal height, a set of lines marking points of equal potential (known as equipotentials ) may be drawn around an electrostatically charged object. The equipotentials cross all lines of force at right angles. They must also lie parallel to
5160-411: Is a vector field . The study of electric fields created by stationary charges is called electrostatics . The field may be visualised by a set of imaginary lines whose direction at any point is the same as that of the field. This concept was introduced by Faraday, whose term ' lines of force ' still sometimes sees use. The field lines are the paths that a point positive charge would seek to make as it
5280-635: Is also usually low, as plants are automated and have few personnel on site during normal operation. Where a dam serves multiple purposes, a hydroelectric station may be added with relatively low construction cost, providing a useful revenue stream to offset the costs of dam operation. It has been calculated that the sale of electricity from the Three Gorges Dam will cover the construction costs after 5 to 8 years of full generation. However, some data shows that in most countries large hydropower dams will be too costly and take too long to build to deliver
5400-452: Is an important difference. Gravity always acts in attraction, drawing two masses together, while the electric field can result in either attraction or repulsion. Since large bodies such as planets generally carry no net charge, the electric field at a distance is usually zero. Thus gravity is the dominant force at distance in the universe, despite being much weaker. An electric field generally varies in space, and its strength at any one point
5520-401: Is charged by the glass rod, and the other by an amber rod, the two balls are found to attract each other. These phenomena were investigated in the late eighteenth century by Charles-Augustin de Coulomb , who deduced that charge manifests itself in two opposing forms. This discovery led to the well-known axiom: like-charged objects repel and opposite-charged objects attract . The force acts on
5640-473: Is defined as negative, and that by protons is positive. Before these particles were discovered, Benjamin Franklin had defined a positive charge as being the charge acquired by a glass rod when it is rubbed with a silk cloth. A proton by definition carries a charge of exactly 1.602 176 634 × 10 coulombs . This value is also defined as the elementary charge . No object can have a charge smaller than
5760-483: Is defined as the force (per unit charge) that would be felt by a stationary, negligible charge if placed at that point. The conceptual charge, termed a ' test charge ', must be vanishingly small to prevent its own electric field disturbing the main field and must also be stationary to prevent the effect of magnetic fields . As the electric field is defined in terms of force , and force is a vector , having both magnitude and direction , it follows that an electric field
5880-521: Is formed behind the dam. The lake stretches to the base of Lower Granite Dam , 37 miles (60 km) upstream. Lake Herbert G. West , formed from Lower Monumental Dam runs 28 miles (45 km) downstream from the base of the dam. Generating capacity is 810 megawatts (1,090,000 hp), with an overload capacity of 932 megawatts (1,250,000 hp); the spillway has eight gates and is 512 feet (156 m) in length. Construction began in June 1963 on what
6000-470: Is highest in the winter when solar energy is at a minimum. Pico hydro is hydroelectric power generation of under 5 kW . It is useful in small, remote communities that require only a small amount of electricity. For example, the 1.1 kW Intermediate Technology Development Group Pico Hydro Project in Kenya supplies 57 homes with very small electric loads (e.g., a couple of lights and a phone charger, or
6120-445: Is initially produced during construction of the project, and some methane is given off annually by reservoirs, hydro has one of the lowest lifecycle greenhouse gas emissions for electricity generation. The low greenhouse gas impact of hydroelectricity is found especially in temperate climates . Greater greenhouse gas emission impacts are found in the tropical regions because the reservoirs of power stations in tropical regions produce
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#17327717479456240-531: Is integral to applications spanning transport , heating , lighting , communications , and computation , making it the foundation of modern industrial society. Long before any knowledge of electricity existed, people were aware of shocks from electric fish . Ancient Egyptian texts dating from 2750 BCE described them as the "protectors" of all other fish. Electric fish were again reported millennia later by ancient Greek , Roman and Arabic naturalists and physicians . Several ancient writers, such as Pliny
6360-406: Is mediated by the magnetic field each current produces and forms the basis for the international definition of the ampere . This relationship between magnetic fields and currents is extremely important, for it led to Michael Faraday's invention of the electric motor in 1821. Faraday's homopolar motor consisted of a permanent magnet sitting in a pool of mercury . A current was allowed through
6480-415: Is most often a crystalline semiconductor . Solid-state electronics came into its own with the emergence of transistor technology. The first working transistor, a germanium -based point-contact transistor , was invented by John Bardeen and Walter Houser Brattain at Bell Labs in 1947, followed by the bipolar junction transistor in 1948. By modern convention, the charge carried by electrons
6600-462: Is not an energy source, and appears as a negative number in listings. Run-of-the-river hydroelectric stations are those with small or no reservoir capacity, so that only the water coming from upstream is available for generation at that moment, and any oversupply must pass unused. A constant supply of water from a lake or existing reservoir upstream is a significant advantage in choosing sites for run-of-the-river. A tidal power station makes use of
6720-452: Is not generally used to produce base power except for vacating the flood pool or meeting downstream needs. Instead, it can serve as backup for non-hydro generators. The major advantage of conventional hydroelectric dams with reservoirs is their ability to store water at low cost for dispatch later as high value clean electricity. In 2021, the IEA estimated that the "reservoirs of all existing conventional hydropower plants combined can store
6840-410: Is often higher (that is, closer to 1) with larger and more modern turbines. Annual electric energy production depends on the available water supply. In some installations, the water flow rate can vary by a factor of 10:1 over the course of a year. Hydropower is a flexible source of electricity since stations can be ramped up and down very quickly to adapt to changing energy demands. Hydro turbines have
6960-403: Is perhaps the simplest of passive circuit elements: as its name suggests, it resists the current through it, dissipating its energy as heat. The resistance is a consequence of the motion of charge through a conductor: in metals, for example, resistance is primarily due to collisions between electrons and ions. Ohm's law is a basic law of circuit theory , stating that the current passing through
7080-531: Is subjected to transients , such as when first energised. The concept of the electric field was introduced by Michael Faraday . An electric field is created by a charged body in the space that surrounds it, and results in a force exerted on any other charges placed within the field. The electric field acts between two charges in a similar manner to the way that the gravitational field acts between two masses , and like it, extends towards infinity and shows an inverse square relationship with distance. However, there
7200-406: Is termed the inductance . The unit of inductance is the henry , named after Joseph Henry , a contemporary of Faraday. One henry is the inductance that will induce a potential difference of one volt if the current through it changes at a rate of one ampere per second. The inductor's behaviour is in some regards converse to that of the capacitor: it will freely allow an unchanging current, but opposes
7320-415: Is the farad , named after Michael Faraday , and given the symbol F : one farad is the capacitance that develops a potential difference of one volt when it stores a charge of one coulomb. A capacitor connected to a voltage supply initially causes a current as it accumulates charge; this current will however decay in time as the capacitor fills, eventually falling to zero. A capacitor will therefore not permit
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#17327717479457440-430: Is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge . Electricity is related to magnetism , both being part of the phenomenon of electromagnetism , as described by Maxwell's equations . Common phenomena are related to electricity, including lightning , static electricity , electric heating , electric discharges and many others. The presence of either
7560-529: Is therefore 0 at all places inside the body. This is the operating principal of the Faraday cage , a conducting metal shell which isolates its interior from outside electrical effects. The principles of electrostatics are important when designing items of high-voltage equipment. There is a finite limit to the electric field strength that may be withstood by any medium. Beyond this point, electrical breakdown occurs and an electric arc causes flashover between
7680-409: Is usually measured in volts , and one volt is the potential for which one joule of work must be expended to bring a charge of one coulomb from infinity. This definition of potential, while formal, has little practical application, and a more useful concept is that of electric potential difference , and is the energy required to move a unit charge between two specified points. An electric field has
7800-536: Is widely used in information processing , telecommunications , and signal processing . Interconnection technologies such as circuit boards , electronics packaging technology, and other varied forms of communication infrastructure complete circuit functionality and transform the mixed components into a regular working system . Today, most electronic devices use semiconductor components to perform electron control. The underlying principles that explain how semiconductors work are studied in solid state physics , whereas
7920-679: The Bonneville Dam in 1937 and being recognized by the Flood Control Act of 1936 as the premier federal flood control agency. Hydroelectric power stations continued to become larger throughout the 20th century. Hydropower was referred to as "white coal". Hoover Dam 's initial 1,345 MW power station was the world's largest hydroelectric power station in 1936; it was eclipsed by the 6,809 MW Grand Coulee Dam in 1942. The Itaipu Dam opened in 1984 in South America as
8040-549: The Industrial Revolution would drive development as well. In 1878, the world's first hydroelectric power scheme was developed at Cragside in Northumberland , England, by William Armstrong . It was used to power a single arc lamp in his art gallery. The old Schoelkopf Power Station No. 1 , US, near Niagara Falls , began to produce electricity in 1881. The first Edison hydroelectric power station,
8160-806: The International Exhibition of Hydropower and Tourism , with over one million visitors 1925. By 1920, when 40% of the power produced in the United States was hydroelectric, the Federal Power Act was enacted into law. The Act created the Federal Power Commission to regulate hydroelectric power stations on federal land and water. As the power stations became larger, their associated dams developed additional purposes, including flood control , irrigation and navigation . Federal funding became necessary for large-scale development, and federally owned corporations, such as
8280-721: The Neo-Latin word electricus ("of amber" or "like amber", from ἤλεκτρον, elektron , the Greek word for "amber") to refer to the property of attracting small objects after being rubbed. This association gave rise to the English words "electric" and "electricity", which made their first appearance in print in Thomas Browne 's Pseudodoxia Epidemica of 1646. Isaac Newton made early investigations into electricity, with an idea of his written down in his book Opticks arguably
8400-633: The Tennessee Valley Authority (1933) and the Bonneville Power Administration (1937) were created. Additionally, the Bureau of Reclamation which had begun a series of western US irrigation projects in the early 20th century, was now constructing large hydroelectric projects such as the 1928 Hoover Dam . The United States Army Corps of Engineers was also involved in hydroelectric development, completing
8520-583: The Vulcan Street Plant , began operating September 30, 1882, in Appleton, Wisconsin , with an output of about 12.5 kilowatts. By 1886 there were 45 hydroelectric power stations in the United States and Canada; and by 1889 there were 200 in the United States alone. At the beginning of the 20th century, many small hydroelectric power stations were being constructed by commercial companies in mountains near metropolitan areas. Grenoble , France held
8640-423: The electromagnetic force , one of the four fundamental forces of nature. Experiment has shown charge to be a conserved quantity , that is, the net charge within an electrically isolated system will always remain constant regardless of any changes taking place within that system. Within the system, charge may be transferred between bodies, either by direct contact, or by passing along a conducting material, such as
8760-506: The potential energy of dammed water driving a water turbine and generator . The power extracted from the water depends on the volume and on the difference in height between the source and the water's outflow. This height difference is called the head . A large pipe (the " penstock ") delivers water from the reservoir to the turbine. This method produces electricity to supply high peak demands by moving water between reservoirs at different elevations. At times of low electrical demand,
8880-522: The quantum revolution. Einstein was awarded the Nobel Prize in Physics in 1921 for "his discovery of the law of the photoelectric effect". The photoelectric effect is also employed in photocells such as can be found in solar panels . The first solid-state device was the " cat's-whisker detector " first used in the 1900s in radio receivers. A whisker-like wire is placed lightly in contact with
9000-452: The strong interaction , but unlike that force it operates over all distances. In comparison with the much weaker gravitational force , the electromagnetic force pushing two electrons apart is 10 times that of the gravitational attraction pulling them together. Charge originates from certain types of subatomic particles , the most familiar carriers of which are the electron and proton . Electric charge gives rise to and interacts with
9120-400: The water frame , and continuous production played a significant part in the development of the factory system, with modern employment practices. In the 1840s, hydraulic power networks were developed to generate and transmit hydro power to end users. By the late 19th century, the electrical generator was developed and could now be coupled with hydraulics. The growing demand arising from
9240-541: The 17th and 18th centuries. The development of the theory of electromagnetism in the 19th century marked significant progress, leading to electricity's industrial and residential application by electrical engineers by the century's end. This rapid expansion in electrical technology at the time was the driving force behind the Second Industrial Revolution , with electricity's versatility driving transformations in both industry and society. Electricity
9360-545: The 1936 discovery of the Baghdad Battery , which resembles a galvanic cell , though it is uncertain whether the artifact was electrical in nature. Electricity would remain little more than an intellectual curiosity for millennia until 1600, when the English scientist William Gilbert wrote De Magnete , in which he made a careful study of electricity and magnetism, distinguishing the lodestone effect from static electricity produced by rubbing amber. He coined
9480-656: The Elder and Scribonius Largus , attested to the numbing effect of electric shocks delivered by electric catfish and electric rays , and knew that such shocks could travel along conducting objects. Patients with ailments such as gout or headache were directed to touch electric fish in the hope that the powerful jolt might cure them. Ancient cultures around the Mediterranean knew that certain objects, such as rods of amber , could be rubbed with cat's fur to attract light objects like feathers. Thales of Miletus made
9600-463: The IEA released a main-case forecast of 141 GW generated by hydropower over 2022–2027, which is slightly lower than deployment achieved from 2017–2022. Because environmental permitting and construction times are long, they estimate hydropower potential will remain limited, with only an additional 40 GW deemed possible in the accelerated case. In 2021 the IEA said that major modernisation refurbishments are required. Most hydroelectric power comes from
9720-464: The ability to transport particles heavier than itself downstream. This has a negative effect on dams and subsequently their power stations, particularly those on rivers or within catchment areas with high siltation. Siltation can fill a reservoir and reduce its capacity to control floods along with causing additional horizontal pressure on the upstream portion of the dam. Eventually, some reservoirs can become full of sediment and useless or over-top during
9840-742: The area nearest to the Little Goose Lock and Dam, is one of the many Pacific Northwest (PNW) Tribes fighting for the LSR dams to be breached. Salmon and the acts of hunting and fishing are culturally significant to the tribes living in the Columbia River Basin. Salmon fishing is not only a major source of subsistence, but a spiritual tether to the land. The dams have altered the landscape where tribes have historically carried out their ways of life. It’s estimated that nearly 34,000 acres of land and 150 miles of riverside would be restored if
9960-595: The balance between stream flow and power production. Micro hydro means hydroelectric power installations that typically produce up to 100 kW of power. These installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks. There are many of these installations around the world, particularly in developing nations as they can provide an economical source of energy without purchase of fuel. Micro hydro systems complement photovoltaic solar energy systems because in many areas water flow, and thus available hydro power,
10080-408: The beginning of the field theory of the electric force. Further work was conducted in the 17th and early 18th centuries by Otto von Guericke , Robert Boyle , Stephen Gray and C. F. du Fay . Later in the 18th century, Benjamin Franklin conducted extensive research in electricity, selling his possessions to fund his work. In June 1752 he is reputed to have attached a metal key to the bottom of
10200-419: The building it serves to protect. The concept of electric potential is closely linked to that of the electric field. A small charge placed within an electric field experiences a force, and to have brought that charge to that point against the force requires work . The electric potential at any point is defined as the energy required to bring a unit test charge from an infinite distance slowly to that point. It
10320-426: The charged particles themselves, hence charge has a tendency to spread itself as evenly as possible over a conducting surface. The magnitude of the electromagnetic force, whether attractive or repulsive, is given by Coulomb's law , which relates the force to the product of the charges and has an inverse-square relation to the distance between them. The electromagnetic force is very strong, second only in strength to
10440-450: The charged parts. Air, for example, tends to arc across small gaps at electric field strengths which exceed 30 kV per centimetre. Over larger gaps, its breakdown strength is weaker, perhaps 1 kV per centimetre. The most visible natural occurrence of this is lightning , caused when charge becomes separated in the clouds by rising columns of air, and raises the electric field in the air to greater than it can withstand. The voltage of
10560-411: The current varies in time. Direct current, as produced by example from a battery and required by most electronic devices, is a unidirectional flow from the positive part of a circuit to the negative. If, as is most common, this flow is carried by electrons, they will be travelling in the opposite direction. Alternating current is any current that reverses direction repeatedly; almost always this takes
10680-404: The daily rise and fall of ocean water due to tides; such sources are highly predictable, and if conditions permit construction of reservoirs, can also be dispatchable to generate power during high demand periods. Less common types of hydro schemes use water's kinetic energy or undammed sources such as undershot water wheels . Tidal power is viable in a relatively small number of locations around
10800-632: The dam argue that removing it would cause more reliance on fossil fuel based energy. Some species of salmon native to the Columbia River Basin are protected under the Endangered Species Act, which requires the federal government to come up with a plan to restore their populations. Breaching the Little Goose Dam and the other LSR dams is considered by many environmentalists to be the best option in restoring salmon populations quickly before they completely die out. In 1855 and 1856,
10920-454: The dams were breached, allowing tribal hunting and fishing to be revitalized in areas that have been flooded and/or engineered for decades. Breaching the dams would also provide PNW tribes along the Columbia River Basin the chance to care for and reconnect with places that are considered sacred or used for ceremonial purposes. Tribes argue the dams have significantly reduced tribal wealth and well-being; tearing them down would not only help restore
11040-505: The dams, sometimes destroying biologically rich and productive lowland and riverine valley forests, marshland and grasslands. Damming interrupts the flow of rivers and can harm local ecosystems, and building large dams and reservoirs often involves displacing people and wildlife. The loss of land is often exacerbated by habitat fragmentation of surrounding areas caused by the reservoir. Hydroelectric projects can be disruptive to surrounding aquatic ecosystems both upstream and downstream of
11160-516: The design and construction of electronic circuits to solve practical problems are part of electronics engineering . Faraday's and Ampère's work showed that a time-varying magnetic field created an electric field, and a time-varying electric field created a magnetic field. Thus, when either field is changing in time, a field of the other is always induced. These variations are an electromagnetic wave . Electromagnetic waves were analysed theoretically by James Clerk Maxwell in 1864. Maxwell developed
11280-478: The early 19th century had seen rapid progress in electrical science, the late 19th century would see the greatest progress in electrical engineering . Through such people as Alexander Graham Bell , Ottó Bláthy , Thomas Edison , Galileo Ferraris , Oliver Heaviside , Ányos Jedlik , William Thomson, 1st Baron Kelvin , Charles Algernon Parsons , Werner von Siemens , Joseph Swan , Reginald Fessenden , Nikola Tesla and George Westinghouse , electricity turned from
11400-705: The effect of forest decay. Another disadvantage of hydroelectric dams is the need to relocate the people living where the reservoirs are planned. In 2000, the World Commission on Dams estimated that dams had physically displaced 40–80 million people worldwide. Because large conventional dammed-hydro facilities hold back large volumes of water, a failure due to poor construction, natural disasters or sabotage can be catastrophic to downriver settlements and infrastructure. During Typhoon Nina in 1975 Banqiao Dam in Southern China failed when more than
11520-427: The effect was reciprocal: a current exerts a force on a magnet, and a magnetic field exerts a force on a current. The phenomenon was further investigated by Ampère , who discovered that two parallel current-carrying wires exerted a force upon each other: two wires conducting currents in the same direction are attracted to each other, while wires containing currents in opposite directions are forced apart. The interaction
11640-448: The electronic electrometer . The movement of electric charge is known as an electric current , the intensity of which is usually measured in amperes . Current can consist of any moving charged particles; most commonly these are electrons, but any charge in motion constitutes a current. Electric current can flow through some things, electrical conductors , but will not flow through an electrical insulator . By historical convention,
11760-416: The electrons. However, depending on the conditions, an electric current can consist of a flow of charged particles in either direction, or even in both directions at once. The positive-to-negative convention is widely used to simplify this situation. The process by which electric current passes through a material is termed electrical conduction , and its nature varies with that of the charged particles and
11880-428: The elementary charge, and any amount of charge an object may carry is a multiple of the elementary charge. An electron has an equal negative charge, i.e. −1.602 176 634 × 10 coulombs . Charge is possessed not just by matter , but also by antimatter , each antiparticle bearing an equal and opposite charge to its corresponding particle. The presence of charge gives rise to an electrostatic force: charges exert
12000-399: The excess generation capacity is used to pump water into the higher reservoir, thus providing demand side response . When the demand becomes greater, water is released back into the lower reservoir through a turbine. In 2021 pumped-storage schemes provided almost 85% of the world's 190 GW of grid energy storage and improve the daily capacity factor of the generation system. Pumped storage
12120-417: The federal government negotiated treaties with local Columbia River Basin tribes that guaranteed them the right to fish for salmon in areas where people had started to colonize in exchange for several million acres of land. Tribes are arguing now that they can’t fish for salmon on ancestral lands anymore because the populations have declined so dramatically as a result of the dams. The Nez Perce Tribe, located in
12240-534: The forest is inundated, substantial amounts of greenhouse gases may be emitted. Construction of a hydroelectric complex can have significant environmental impact, principally in loss of arable land and population displacement. They also disrupt the natural ecology of the river involved, affecting habitats and ecosystems, and siltation and erosion patterns. While dams can ameliorate the risks of flooding, dam failure can be catastrophic. In 2021, global installed hydropower electrical capacity reached almost 1,400 GW,
12360-495: The form of a sine wave . Alternating current thus pulses back and forth within a conductor without the charge moving any net distance over time. The time-averaged value of an alternating current is zero, but it delivers energy in first one direction, and then the reverse. Alternating current is affected by electrical properties that are not observed under steady state direct current, such as inductance and capacitance . These properties however can become important when circuitry
12480-506: The highest among all renewable energy technologies. Hydroelectricity plays a leading role in countries like Brazil, Norway and China. but there are geographical limits and environmental issues. Tidal power can be used in coastal regions. China added 24 GW in 2022, accounting for nearly three-quarters of global hydropower capacity additions. Europe added 2 GW, the largest amount for the region since 1990. Meanwhile, globally, hydropower generation increased by 70 TWh (up 2%) in 2022 and remains
12600-519: The largest renewable energy source, surpassing all other technologies combined. Hydropower has been used since ancient times to grind flour and perform other tasks. In the late 18th century hydraulic power provided the energy source needed for the start of the Industrial Revolution . In the mid-1700s, French engineer Bernard Forest de Bélidor published Architecture Hydraulique , which described vertical- and horizontal-axis hydraulic machines, and in 1771 Richard Arkwright 's combination of water power ,
12720-750: The largest, producing 14 GW , but was surpassed in 2008 by the Three Gorges Dam in China at 22.5 GW . Hydroelectricity would eventually supply some countries, including Norway , Democratic Republic of the Congo , Paraguay and Brazil , with over 85% of their electricity. In 2021 the International Energy Agency (IEA) said that more efforts are needed to help limit climate change . Some countries have highly developed their hydropower potential and have very little room for growth: Switzerland produces 88% of its potential and Mexico 80%. In 2022,
12840-400: The material through which they are travelling. Examples of electric currents include metallic conduction, where electrons flow through a conductor such as metal, and electrolysis , where ions (charged atoms ) flow through liquids, or through plasmas such as electrical sparks. While the particles themselves can move quite slowly, sometimes with an average drift velocity only fractions of
12960-633: The plant site. Generation of hydroelectric power changes the downstream river environment. Water exiting a turbine usually contains very little suspended sediment, which can lead to scouring of river beds and loss of riverbanks. The turbines also will kill large portions of the fauna passing through, for instance 70% of the eel passing a turbine will perish immediately. Since turbine gates are often opened intermittently, rapid or even daily fluctuations in river flow are observed. Drought and seasonal changes in rainfall can severely limit hydropower. Water may also be lost by evaporation. When water flows it has
13080-428: The principle, now known as Faraday's law of induction , that the potential difference induced in a closed circuit is proportional to the rate of change of magnetic flux through the loop. Exploitation of this discovery enabled him to invent the first electrical generator in 1831, in which he converted the mechanical energy of a rotating copper disc to electrical energy. Faraday's disc was inefficient and of no use as
13200-450: The rainfall regime, could reduce total energy production by 7% annually by the end of the century. Lower positive impacts are found in the tropical regions. In lowland rainforest areas, where inundation of a part of the forest is necessary, it has been noted that the reservoirs of power plants produce substantial amounts of methane . This is due to plant material in flooded areas decaying in an anaerobic environment and forming methane,
13320-439: The replacement energy sources for the dam. Hydroelectric 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 more than nuclear power . Hydropower can provide large amounts of low-carbon electricity on demand, making it
13440-485: The salmon population but also provide justice to PNW tribes. The Little Goose Dam alone generates 810 megawatts (MW) of electricity. The combined generated electricity of the 4 LSR dams is about 3000 MWs, or enough electricity to light 50 million light bulbs. Some argue breaching the dams would lead to fossil fuel reliance in the region. The Washington State Government has a goal of reaching net-zero carbon emissions by 2050 and are highly considering solar and wind power to be
13560-454: The special property that it is conservative , which means that the path taken by the test charge is irrelevant: all paths between two specified points expend the same energy, and thus a unique value for potential difference may be stated. The volt is so strongly identified as the unit of choice for measurement and description of electric potential difference that the term voltage sees greater everyday usage. For practical purposes, defining
13680-418: The two forces of nature then known. The force on the compass needle did not direct it to or away from the current-carrying wire, but acted at right angles to it. Ørsted's words were that "the electric conflict acts in a revolving manner." The force also depended on the direction of the current, for if the flow was reversed, then the force did too. Ørsted did not fully understand his discovery, but he observed
13800-417: The vector direction of the field is the line of greatest slope of potential, and where the equipotentials lie closest together. Ørsted's discovery in 1821 that a magnetic field existed around all sides of a wire carrying an electric current indicated that there was a direct relationship between electricity and magnetism. Moreover, the interaction seemed different from gravitational and electrostatic forces,
13920-524: The world are hydroelectric power stations, with some hydroelectric facilities capable of generating more than double the installed capacities of the current largest nuclear power stations . Although no official definition exists for the capacity range of large hydroelectric power stations, facilities from over a few hundred megawatts are generally considered large hydroelectric facilities. Currently, only seven facilities over 10 GW ( 10,000 MW ) are in operation worldwide, see table below. Small hydro
14040-539: The world. The classification of hydropower plants starts with two top-level categories: The classification of a plant as an SHP or LHP is primarily based on its nameplate capacity , the threshold varies by the country, but in any case a plant with the capacity of 50 MW or more is considered an LHP. As an example, for China, SHP power is below 25 MW, for India - below 15 MW, most of Europe - below 10 MW. The SHP and LHP categories are further subdivided into many subcategories that are not mutually exclusive. For example,
14160-415: Was Little Goose Island. The main structure and three generators were completed 54 years ago in 1970, with an additional three generators finished in 1978. There have been calls to remove the Little Goose Lock and Dam along with the other Lower Snake River (LSR) dams due to their impact on the salmon population and the fishing rights of local Native American tribes in the region. Those in favor of keeping
14280-586: Was allowed to provide irrigation and power to citizens (in addition to aluminium power) after the war. In Suriname , the Brokopondo Reservoir was constructed to provide electricity for the Alcoa aluminium industry. New Zealand 's Manapouri Power Station was constructed to supply electricity to the aluminium smelter at Tiwai Point . Since hydroelectric dams do not use fuel, power generation does not produce carbon dioxide . While carbon dioxide
14400-543: Was forced to move within the field; they are however an imaginary concept with no physical existence, and the field permeates all the intervening space between the lines. Field lines emanating from stationary charges have several key properties: first, that they originate at positive charges and terminate at negative charges; second, that they must enter any good conductor at right angles, and third, that they may never cross nor close in on themselves. A hollow conducting body carries all its charge on its outer surface. The field
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