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124-422: The lines is the smallest and least trafficked railway line from Oslo, and the only single track line in the capital. Like most other Norwegian railway lines, the entire 124 km long line is electrified at 15 kV  16.7 Hz AC . It serves some of the northern neighborhoods of Oslo, and has a few stations in the woods of Nordmarka . Further north the line serves the municipality of Nittedal . At Roa ,

248-402: A (nearly) continuous conductor running along the track that usually takes one of two forms: an overhead line , suspended from poles or towers along the track or from structure or tunnel ceilings, or a third rail mounted at track level and contacted by a sliding " pickup shoe ". Both overhead wire and third-rail systems usually use the running rails as the return conductor, but some systems use

372-490: A Southern Europe hydropower race. In Italy's Po Valley , the main 20th-century transition was not the creation of hydropower but the transition from mechanical to electrical hydropower. 12,000 watermills churned in the Po watershed in the 1890s, but the first commercial hydroelectric plant, completed in 1898, signaled the end of the mechanical reign. These new large plants moved power away from rural mountainous areas to urban centers in

496-443: A billion tonnes of CO2 greenhouse gas a year. This occurs when organic matters accumulate at the bottom of the reservoir because of the deoxygenation of water which triggers anaerobic digestion . People who live near a hydro plant site are displaced during construction or when reservoir banks become unstable. Another potential disadvantage is cultural or religious sites may block construction. A watermill or water mill

620-433: 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 crane-like irrigation tool), and a reciprocating device with hinged valves. In the 19th century, French engineer Benoît Fourneyron developed the first hydropower turbine. This device

744-435: A distance. A hydropower resource can be evaluated by its available power . Power is a function of the hydraulic head and volumetric flow rate . 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

868-573: A higher total efficiency. Electricity for electric rail systems can also come from renewable energy , nuclear power , or other low-carbon sources, which do not emit pollution or emissions. Electric locomotives may easily be constructed with greater power output than most diesel locomotives. For passenger operation it is possible to provide enough power with diesel engines (see e.g. ' ICE TD ') but, at higher speeds, this proves costly and impractical. Therefore, almost all high speed trains are electric. The high power of electric locomotives also gives them

992-467: A historical concern for double-stack rail transport regarding clearances with overhead lines but it is no longer universally true as of 2022 , with both Indian Railways and China Railway regularly operating electric double-stack cargo trains under overhead lines. Railway electrification has constantly increased in the past decades, and as of 2022, electrified tracks account for nearly one-third of total tracks globally. Railway electrification

1116-427: A low-carbon means for economic development . Since ancient times, hydropower from watermills has been used as a renewable energy source for irrigation and the operation of mechanical devices, such as gristmills , sawmills , textile mills, trip hammers , dock cranes , domestic lifts , and ore mills . A trompe , which produces compressed air from falling water, is sometimes used to power other machinery at

1240-460: 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. Evidence suggests that the fundamentals of hydropower date to ancient Greek civilization . Other evidence indicates that the waterwheel independently emerged in China around

1364-462: A more dependable source of power by smoothing seasonal changes in water flow. However, reservoirs have a significant environmental impact , 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 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

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1488-490: A mutual need for hydropower could lead to cooperation between otherwise adversarial nations. Hydropower technology and attitude began to shift in the second half of the 20th century. While countries had largely abandoned their small hydropower systems by the 1930s, the smaller hydropower plants began to make a comeback in the 1970s, boosted by government subsidies and a push for more independent energy producers. Some politicians who once advocated for large hydropower projects in

1612-524: A number of European countries, India, Saudi Arabia, eastern Japan, countries that used to be part of the Soviet Union, on high-speed lines in much of Western Europe (including countries that still run conventional railways under DC but not in countries using 16.7   Hz, see above). Most systems like this operate at 25   kV, although 12.5   kV sections exist in the United States, and 20   kV

1736-454: A power grid that is delivered to a locomotive, and within the locomotive, transformed and rectified to a lower DC voltage in preparation for use by traction motors. These motors may either be DC motors which directly use the DC or they may be three-phase AC motors which require further conversion of the DC to variable frequency three-phase AC (using power electronics). Thus both systems are faced with

1860-498: A relative lack of flexibility (since electric trains need third rails or overhead wires), and a vulnerability to power interruptions. Electro-diesel locomotives and electro-diesel multiple units mitigate these problems somewhat as they are capable of running on diesel power during an outage or on non-electrified routes. Different regions may use different supply voltages and frequencies, complicating through service and requiring greater complexity of locomotive power. There used to be

1984-525: 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 m 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

2108-481: A separate fourth rail for this purpose. In comparison to the principal alternative, the diesel engine , electric railways offer substantially better energy efficiency , lower emissions , and lower operating costs. Electric locomotives are also usually quieter, more powerful, and more responsive and reliable than diesel. They have no local emissions, an important advantage in tunnels and urban areas. Some electric traction systems provide regenerative braking that turns

2232-418: A third rail. The key advantage of the four-rail system is that neither running rail carries any current. This scheme was introduced because of the problems of return currents, intended to be carried by the earthed (grounded) running rail, flowing through the iron tunnel linings instead. This can cause electrolytic damage and even arcing if the tunnel segments are not electrically bonded together. The problem

2356-712: A tool to interfere in the economic development of African countries, such as the World Bank with the Kariba and Akosombo Dams , and the Soviet Union with the Aswan Dam . The Nile River especially has borne the consequences of countries both along the Nile and distant foreign actors using the river to expand their economic power or national force. After the British occupation of Egypt in 1882,

2480-479: 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 developed

2604-535: 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 of many material goods, including flour , lumber , paper , textiles , and many metal products. These watermills may comprise gristmills , sawmills , paper mills , textile mills , hammermills , trip hammering mills, rolling mills , and wire drawing mills. One major way to classify watermills

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2728-423: Is an attractive alternative to fossil fuels as it does not directly produce carbon dioxide 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 or elevated lake . International institutions such as the World Bank view hydropower as

2852-501: 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 . 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

2976-400: Is by an essential trait about their location: tide mills use the movement of the tide; ship mills are water mills onboard (and constituting) a ship. A plentiful head of water can be made to generate compressed air 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

3100-445: 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

3224-420: Is by wheel orientation (vertical or horizontal), one powered by a vertical waterwheel through a gear mechanism, and the other equipped with a horizontal waterwheel without such a mechanism. The former type can be further subdivided, depending on where the water hits the wheel paddles, into undershot, overshot, breastshot and pitchback (backshot or reverse shot) waterwheel mills. Another way to classify water mills

3348-411: Is derived by using resistors which ensures that stray earth currents are kept to manageable levels. Power-only rails can be mounted on strongly insulating ceramic chairs to minimise current leak, but this is not possible for running rails, which have to be seated on stronger metal chairs to carry the weight of trains. However, elastomeric rubber pads placed between the rails and chairs can now solve part of

3472-451: Is effected by one contact shoe each that slide on top of each one of the running rails . This and all other rubber-tyred metros that have a 1,435 mm ( 4 ft  8 + 1 ⁄ 2  in ) standard gauge track between the roll ways operate in the same manner. Railways and electrical utilities use AC as opposed to DC for the same reason: to use transformers , which require AC, to produce higher voltages. The higher

3596-526: Is electrified, companies often find that they need to continue use of diesel trains even if sections are electrified. The increasing demand for container traffic, which is more efficient when utilizing the double-stack car , also has network effect issues with existing electrifications due to insufficient clearance of overhead electrical lines for these trains, but electrification can be built or modified to have sufficient clearance, at additional cost. A problem specifically related to electrified lines are gaps in

3720-486: Is limited and losses are significantly higher. However, the higher voltages used in many AC electrification systems reduce transmission losses over longer distances, allowing for fewer substations or more powerful locomotives to be used. Also, the energy used to blow air to cool transformers, power electronics (including rectifiers), and other conversion hardware must be accounted for. Standard AC electrification systems use much higher voltages than standard DC systems. One of

3844-439: 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 from underwater rotting vegetation. Furthermore, although at lower levels than other renewable energy sources, it was found that hydropower produces methane equivalent to almost

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3968-755: Is no longer exactly one-third of the grid frequency. This solved overheating problems with the rotary converters used to generate some of this power from the grid supply. In the US , the New York, New Haven, and Hartford Railroad , the Pennsylvania Railroad and the Philadelphia and Reading Railway adopted 11   kV 25   Hz single-phase AC. Parts of the original electrified network still operate at 25   Hz, with voltage boosted to 12   kV, while others were converted to 12.5 or 25   kV 60   Hz. In

4092-447: Is sufficient traffic, the reduced track and especially the lower engine maintenance and running costs exceed the costs of this maintenance significantly. Newly electrified lines often show a "sparks effect", whereby electrification in passenger rail systems leads to significant jumps in patronage / revenue. The reasons may include electric trains being seen as more modern and attractive to ride, faster, quieter and smoother service, and

4216-410: Is that the power-wasting resistors used in DC locomotives for speed control were not needed in an AC locomotive: multiple taps on the transformer can supply a range of voltages. Separate low-voltage transformer windings supply lighting and the motors driving auxiliary machinery. More recently, the development of very high power semiconductors has caused the classic DC motor to be largely replaced with

4340-796: Is the countrywide system. 3   kV DC is used in Belgium, Italy, Spain, Poland, Slovakia, Slovenia, South Africa, Chile, the northern portion of the Czech Republic, the former republics of the Soviet Union , and in the Netherlands on a few kilometers between Maastricht and Belgium. It was formerly used by the Milwaukee Road from Harlowton, Montana , to Seattle, across the Continental Divide and including extensive branch and loop lines in Montana, and by

4464-403: 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 that supply power to a whole country. As of 2019, the five largest power stations in

4588-565: Is the development of powering trains and locomotives using electricity instead of diesel or steam power . The history of railway electrification dates back to the late 19th century when the first electric tramways were introduced in cities like Berlin , London , and New York City . In 1881, the first permanent railway electrification in the world was the Gross-Lichterfelde Tramway in Berlin , Germany. Overhead line electrification

4712-423: 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

4836-461: Is the use of falling or fast-running water to produce electricity or to power machines. This is achieved by converting the gravitational potential or kinetic energy of a water source to produce power. Hydropower is a method of sustainable energy 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 . Hydropower

4960-420: Is typically generated in large and relatively efficient generating stations , transmitted to the railway network and distributed to the trains. Some electric railways have their own dedicated generating stations and transmission lines , but most purchase power from an electric utility . The railway usually provides its own distribution lines, switches, and transformers . Power is supplied to moving trains with

5084-834: Is used on some narrow-gauge lines in Japan. On "French system" HSLs, the overhead line and a "sleeper" feeder line each carry 25   kV in relation to the rails, but in opposite phase so they are at 50   kV from each other; autotransformers equalize the tension at regular intervals. Various railway electrification systems in the late nineteenth and twentieth centuries utilised three-phase , rather than single-phase electric power delivery due to ease of design of both power supply and locomotives. These systems could either use standard network frequency and three power cables, or reduced frequency, which allowed for return-phase line to be third rail, rather than an additional overhead wire. The majority of modern electrification systems take AC energy from

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5208-891: The Columbia River and its tributaries. The Bureau of Reclamation built the Hoover Dam in 1931, symbolically linking the job creation and economic growth priorities of the New Deal . The federal government quickly followed Hoover with the Shasta Dam and Grand Coulee Dam . Power demand in Oregon did not justify damming the Columbia until WWI revealed the weaknesses of a coal-based energy economy. The federal government then began prioritizing interconnected power—and lots of it. Electricity from all three dams poured into war production during WWII . After

5332-638: The Delaware, Lackawanna and Western Railroad (now New Jersey Transit , converted to 25   kV   AC) in the United States, and the Kolkata suburban railway (Bardhaman Main Line) in India, before it was converted to 25   kV 50   Hz. DC voltages between 600   V and 750   V are used by most tramways and trolleybus networks, as well as some metro systems as the traction motors accept this voltage without

5456-639: The Democratic Republic of the Congo and Ghana , frequently sell excess power to neighboring countries. Foreign actors such as Chinese hydropower companies have proposed a significant amount of new hydropower projects in Africa, and already funded and consulted on many others in countries like Mozambique and Ghana. Small hydropower also played an important role in early 20th century electrification across Africa. In South Africa, small turbines powered gold mines and

5580-683: The HSL-Zuid and Betuwelijn , and 3,000   V south of Maastricht . In Portugal, it is used in the Cascais Line and in Denmark on the suburban S-train system (1650   V DC). In the United Kingdom, 1,500   V   DC was used in 1954 for the Woodhead trans-Pennine route (now closed); the system used regenerative braking , allowing for transfer of energy between climbing and descending trains on

5704-579: The Industrial Revolution 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 's water frame . 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

5828-674: The Innovia ART system. While part of the SkyTrain network, the Canada Line does not use this system and instead uses more traditional motors attached to the wheels and third-rail electrification. A few lines of the Paris Métro in France operate on a four-rail power system. The trains move on rubber tyres which roll on a pair of narrow roll ways made of steel and, in some places, of concrete . Since

5952-670: The Mauryan , Gupta and Chola empires. Another example of the early use of hydropower is seen in hushing , a historic method of mining that uses flood or torrent of water to reveal mineral veins. The method was first used at the Dolaucothi Gold Mines in Wales from 75 AD onwards. This method was further developed in Spain in mines such as Las Médulas . Hushing was also widely used in Britain in

6076-853: The Medieval and later periods to extract lead and tin ores. It later evolved into hydraulic mining when used during the California Gold Rush 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 and the Arab Agricultural Revolution (8th–13th centuries), hydropower was widely used and developed. Early uses of tidal power emerged along with large hydraulic factory complexes. A wide range of water-powered industrial mills were used in

6200-527: The Roa–Hønefoss Line branches off to Hønefoss , where it continues as the Bergen Line . Formerly, most trains between Oslo and Bergen used this route, but nowadays most passenger trains run on the route through Drammen , which is slightly longer but which runs through more densely populated areas. Freight trains use the line over Roa, and sometimes passenger trains also use this line as a reserve line if

6324-616: The Southern Railway serving Coulsdon North and Sutton railway station . The lines were electrified at 6.7   kV 25   Hz. It was announced in 1926 that all lines were to be converted to DC third rail and the last overhead-powered electric service ran in September 1929. AC power is used at 60   Hz in North America (excluding the aforementioned 25   Hz network), western Japan, South Korea and Taiwan; and at 50   Hz in

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6448-454: The United States , the New York, New Haven and Hartford Railroad was one of the first major railways to be electrified. Railway electrification continued to expand throughout the 20th century, with technological improvements and the development of high-speed trains and commuters . Today, many countries have extensive electrified railway networks with 375 000  km of standard lines in

6572-433: The 4th century BC refer to the term cakkavattaka (turning wheel), which commentaries explain as arahatta-ghati-yanta (machine with wheel-pots attached), however whether this is water or hand powered is disputed by scholars India received Roman water mills and baths in the early 4th century AD when a certain according to Greek sources. Dams, spillways, reservoirs, channels, and water balance would develop in India during

6696-807: The American West, organized opposition to hydroelectric dams sparked up in the 1950s and 60s based on environmental concerns. Environmental movements successfully shut down proposed hydropower dams in Dinosaur National Monument and the Grand Canyon , and gained more hydropower-fighting tools with 1970s environmental legislation. As nuclear and fossil fuels grew in the 70s and 80s and environmental activists push for river restoration, hydropower gradually faded in American importance. Foreign powers and IGOs have frequently used hydropower projects in Africa as

6820-656: The British worked with Egypt to construct the first Aswan Dam, which they heightened in 1912 and 1934 to try to hold back the Nile floods. Egyptian engineer Adriano Daninos developed a plan for the Aswan High Dam, inspired by the Tennessee Valley Authority's multipurpose dam. When Gamal Abdel Nasser took power in the 1950s, his government decided to undertake the High Dam project, publicizing it as an economic development project. After American refusal to help fund

6944-672: The Grand Coulee to build a nuclear site placed on the banks of the Columbia. The nuclear site leaked radioactive matter into the river, contaminating the entire area. Post-WWII Americans, especially engineers from the Tennessee Valley Authority , refocused from simply building domestic dams to promoting hydropower abroad. While domestic dam building continued well into the 1970s, with the Reclamation Bureau and Army Corps of Engineers building more than 150 new dams across

7068-596: 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 waterwheels to piston - bellows in forging cast iron. Ancient Indian texts dating back to

7192-684: The Netherlands, New Zealand ( Wellington ), Singapore (on the North East MRT line ), the United States ( Chicago area on the Metra Electric district and the South Shore Line interurban line and Link light rail in Seattle , Washington). In Slovakia, there are two narrow-gauge lines in the High Tatras (one a cog railway ). In the Netherlands it is used on the main system, alongside 25   kV on

7316-622: The Nile, hydroelectric projects cover the rivers and lakes of Africa. The Inga powerplant on the Congo River had been discussed since Belgian colonization in the late 19th century, and was successfully built after independence. Mobutu's government failed to regularly maintain the plants and their capacity declined until the 1995 formation of the Southern African Power Pool created a multi-national power grid and plant maintenance program. States with an abundance of hydropower, such as

7440-720: The UK, the London, Brighton and South Coast Railway pioneered overhead electrification of its suburban lines in London, London Bridge to Victoria being opened to traffic on 1   December 1909. Victoria to Crystal Palace via Balham and West Norwood opened in May 1911. Peckham Rye to West Norwood opened in June 1912. Further extensions were not made owing to the First World War. Two lines opened in 1925 under

7564-1179: The United States' hydroelectric plants in Niagara Falls and the Sierra Nevada inspired bigger and bolder creations across the globe. American and USSR financers and hydropower experts also spread the gospel of dams and hydroelectricity across the globe during the Cold War , contributing to projects such as the Three Gorges Dam and the Aswan High Dam . Feeding desire for large scale electrification with water inherently required large dams across powerful rivers, which impacted public and private interests downstream and in flood zones. Inevitably smaller communities and marginalized groups suffered. They were unable to successfully resist companies flooding them out of their homes or blocking traditional salmon passages. The stagnant water created by hydroelectric dams provides breeding ground for pests and pathogens , leading to local epidemics . However, in some cases,

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7688-494: The ability to pull freight at higher speed over gradients; in mixed traffic conditions this increases capacity when the time between trains can be decreased. The higher power of electric locomotives and an electrification can also be a cheaper alternative to a new and less steep railway if train weights are to be increased on a system. On the other hand, electrification may not be suitable for lines with low frequency of traffic, because lower running cost of trains may be outweighed by

7812-516: The advantages of raising the voltage is that, to transmit certain level of power, lower current is necessary ( P = V × I ). Lowering the current reduces the ohmic losses and allows for less bulky, lighter overhead line equipment and more spacing between traction substations, while maintaining power capacity of the system. On the other hand, the higher voltage requires larger isolation gaps, requiring some elements of infrastructure to be larger. The standard-frequency AC system may introduce imbalance to

7936-441: The bellows in small blast furnaces (e.g. the Dyfi Furnace ) and gristmills , such as those built at Saint Anthony Falls , which uses the 50-foot (15 m) drop in the Mississippi River . Technological advances moved the open water wheel into an enclosed turbine or water motor . In 1848, the British-American engineer James B. Francis , head engineer of Lowell's Locks and Canals company, improved on these designs to create

8060-440: The cost of building new hydroelectric dams increased 4% annually between 1965 and 1990, due both to the increasing costs of construction and to the decrease in high quality building sites. In the 1990s, only 18% of the world's electricity came from hydropower. Tidal power production also emerged in the 1960s as a burgeoning alternative hydropower system, though still has not taken hold as a strong energy contender. Especially at

8184-439: The dam, and anti-British sentiment in Egypt and British interests in neighboring Sudan combined to make the United Kingdom pull out as well, the Soviet Union funded the Aswan High Dam. Between 1977 and 1990 the dam's turbines generated one third of Egypt's electricity. The building of the Aswan Dam triggered a dispute between Sudan and Egypt over the sharing of the Nile, especially since the dam flooded part of Sudan and decreased

8308-410: The distance they could transmit power. However, in the early 20th century, alternating current (AC) power systems were developed, which allowed for more efficient power transmission over longer distances. In the 1920s and 1930s, many countries worldwide began to electrify their railways. In Europe, Switzerland , Sweden , France , and Italy were among the early adopters of railway electrification. In

8432-456: The early 20th century, two major factors motivated the expansion of hydropower in Europe: in the northern countries of Norway and Sweden , high rainfall and mountains proved exceptional resources for abundant hydropower, and in the south, coal shortages pushed governments and utility companies to seek alternative power sources. Early on, Switzerland dammed the Alpine rivers and the Swiss Rhine , creating, along with Italy and Scandinavia ,

8556-448: The electrification. Electric vehicles, especially locomotives, lose power when traversing gaps in the supply, such as phase change gaps in overhead systems, and gaps over points in third rail systems. These become a nuisance if the locomotive stops with its collector on a dead gap, in which case there is no power to restart. This is less of a problem in trains consisting of two or more multiple units coupled together, since in that case if

8680-404: The end of funding. Most electrification systems use overhead wires, but third rail is an option up to 1,500   V. Third rail systems almost exclusively use DC distribution. The use of AC is usually not feasible due to the dimensions of a third rail being physically very large compared with the skin depth that AC penetrates to 0.3 millimetres or 0.012 inches in a steel rail. This effect makes

8804-440: The experiment was curtailed. In 1970 the Ural Electromechanical Institute of Railway Engineers carried out calculations for railway electrification at 12 kV DC , showing that the equivalent loss levels for a 25 kV AC system could be achieved with DC voltage between 11 and 16   kV. In the 1980s and 1990s 12 kV DC was being tested on the October Railway near Leningrad (now Petersburg ). The experiments ended in 1995 due to

8928-500: The fact that electrification often goes hand in hand with a general infrastructure and rolling stock overhaul / replacement, which leads to better service quality (in a way that theoretically could also be achieved by doing similar upgrades yet without electrification). Whatever the causes of the sparks effect, it is well established for numerous routes that have electrified over decades. This also applies when bus routes with diesel buses are replaced by trolleybuses. The overhead wires make

9052-555: The falls far enough away to actually reach enough people and justify installation. The project succeeded in large part due to Nikola Tesla's invention of the alternating current motor . On the other side of the country, San Francisco engineers, the Sierra Club , and the federal government fought over acceptable use of the Hetch Hetchy Valley . Despite ostensible protection within a national park, city engineers successfully won

9176-584: 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 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 sawmills excavated at Ephesus and Gerasa respectively. The crank and connecting rod mechanism of these Roman watermills converted

9300-446: The first electric railway in the 1890s, and Zimbabwean farmers installed small hydropower stations in the 1930s. While interest faded as national grids improved in the second half of the century, 21st century national governments in countries including South Africa and Mozambique, as well as NGOs serving countries like Zimbabwe, have begun re-exploring small-scale hydropower to diversify power sources and improve rural electrification. In

9424-403: The first half of the 20th century began to speak out against them, and citizen groups organizing against dam projects increased. In the 1980s and 90s the international anti-dam movement had made finding government or private investors for new large hydropower projects incredibly difficult, and given rise to NGOs devoted to fighting dams. Additionally, while the cost of other energy sources fell,

9548-453: The flow of a body of water without necessarily changing its height. In this case, the available power is the kinetic energy 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

9672-1012: The general power grid. This is especially useful in mountainous areas where heavily loaded trains must descend long grades. Central station electricity can often be generated with higher efficiency than a mobile engine/generator. While the efficiency of power plant generation and diesel locomotive generation are roughly the same in the nominal regime, diesel motors decrease in efficiency in non-nominal regimes at low power while if an electric power plant needs to generate less power it will shut down its least efficient generators, thereby increasing efficiency. The electric train can save energy (as compared to diesel) by regenerative braking and by not needing to consume energy by idling as diesel locomotives do when stopped or coasting. However, electric rolling stock may run cooling blowers when stopped or coasting, thus consuming energy. Large fossil fuel power stations operate at high efficiency, and can be used for district heating or to produce district cooling , leading to

9796-502: 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 digits of constants must be considered. Some hydropower systems such as water wheels can draw power from

9920-419: 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: 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 (476 feet), is 97 megawatts: Operators of hydroelectric stations compare

10044-411: The high cost of the electrification infrastructure. Therefore, most long-distance lines in developing or sparsely populated countries are not electrified due to relatively low frequency of trains. Network effects are a large factor with electrification. When converting lines to electric, the connections with other lines must be considered. Some electrifications have subsequently been removed because of

10168-460: The high-efficiency Pelton wheel impulse turbine , which used hydropower from the high head streams characteristic of the Sierra Nevada . The modern history of hydropower begins in the 1900s, with large dams built not simply to power neighboring mills or factories but provide extensive electricity for increasingly distant groups of people. Competition drove much of the global hydroelectric craze: Europe competed amongst itself to electrify first, and

10292-400: 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

10416-401: The highest among all renewable energy technologies. Hydroelectricity generation starts with converting either the potential energy of water that is present due to the site's elevation or the kinetic energy 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 . The water in the reservoir

10540-591: 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 , in 1910 and supplied 5,000 horsepower to nearby mines. Hydroelectricity is the biggest hydropower application. Hydroelectricity generates about 15% of global electricity and provides at least 50% of the total electricity supply for more than 35 countries.  In 2021, global installed hydropower electrical capacity reached almost 1400 GW,

10664-497: The last unexploited energy sources in nature. When it rains, billions of litres of water can fall, which have an 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

10788-492: The losses (saving 2   GWh per year per 100   route-km; equalling about €150,000 p.a.). The line chosen is one of the lines, totalling 6000   km, that are in need of renewal. In the 1960s the Soviets experimented with boosting the overhead voltage from 3 to 6   kV. DC rolling stock was equipped with ignitron -based converters to lower the supply voltage to 3   kV. The converters turned out to be unreliable and

10912-500: The maximum flood. Some disadvantages of hydropower have been identified. Dam failures can have catastrophic effects, including loss of life, property and pollution of land. Dams and reservoirs can have major negative impacts on river ecosystems 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

11036-422: The maximum power that can be transmitted, also can be responsible for electrochemical corrosion due to stray DC currents. Electric trains need not carry the weight of prime movers , transmission and fuel. This is partly offset by the weight of electrical equipment. Regenerative braking returns power to the electrification system so that it may be used elsewhere, by other trains on the same system or returned to

11160-402: The need for overhead wires between those stations. Maintenance costs of the lines may be increased by electrification, but many systems claim lower costs due to reduced wear-and-tear on the track from lighter rolling stock. There are some additional maintenance costs associated with the electrical equipment around the track, such as power sub-stations and the catenary wire itself, but, if there

11284-453: The newly (2006) redesigned Type 69D multiple units named Type 69G , rebuilt in Denmark by Danske Statsbaner (DSB). Railway electrification system Railway electrification is the use of electric power for the propulsion of rail transport . Electric railways use either electric locomotives (hauling passengers or freight in separate cars), electric multiple units ( passenger cars with their own motors) or both. Electricity

11408-497: The phase separation between the electrified sections powered from different phases, whereas high voltage would make the transmission more efficient. UIC conducted a case study for the conversion of the Bordeaux-Hendaye railway line (France), currently electrified at 1.5   kV DC, to 9   kV DC and found that the conversion would allow to use less bulky overhead wires (saving €20 million per 100   route-km) and lower

11532-500: The problem by insulating the running rails from the current return should there be a leakage through the running rails. The Expo and Millennium Line of the Vancouver SkyTrain use side-contact fourth-rail systems for their 650 V DC supply. Both are located to the side of the train, as the space between the running rails is occupied by an aluminum plate, as part of stator of the linear induction propulsion system used on

11656-593: The region including fulling mills, gristmills , paper mills , hullers , sawmills , ship mills , stamp mills , steel mills , sugar mills , and tide mills . By the 11th century, every province throughout the Islamic Empire had these industrial mills in operation, from Al-Andalus and North Africa to the Middle East and Central Asia . Muslim engineers also used water turbines while employing gears in watermills and water-raising machines. They also pioneered

11780-460: The resistance per unit length unacceptably high compared with the use of DC. Third rail is more compact than overhead wires and can be used in smaller-diameter tunnels, an important factor for subway systems. The London Underground in England is one of few networks that uses a four-rail system. The additional rail carries the electrical return that, on third-rail and overhead networks, is provided by

11904-570: The revenue obtained for freight and passenger traffic. Different systems are used for urban and intercity areas; some electric locomotives can switch to different supply voltages to allow flexibility in operation. Six of the most commonly used voltages have been selected for European and international standardisation. Some of these are independent of the contact system used, so that, for example, 750   V   DC may be used with either third rail or overhead lines. There are many other voltage systems used for railway electrification systems around

12028-468: The rights to both water and power in the Hetch Hetchy Valley in 1913. After their victory they delivered Hetch Hetchy hydropower and water to San Francisco a decade later and at twice the promised cost, selling power to PG&E which resold to San Francisco residents at a profit. The American West, with its mountain rivers and lack of coal, turned to hydropower early and often, especially along

12152-511: 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 (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 bellows. Many texts describe

12276-641: The route from Hønefoss to Oslo via Drammen is temporarily closed. Further north, the Gjøvik Line runs through the district of Toten before ending at Gjøvik. The Gjøvik Line formerly had three branch lines, the Røykenvik Line , the Valdres Line and the Skreia Line . All these lines are now closed. Most of the service on the Gjøvik Line is provided by electric multiple units . The passenger routes are served by

12400-490: The running rails. On the London Underground, a top-contact third rail is beside the track, energized at +420 V DC , and a top-contact fourth rail is located centrally between the running rails at −210 V DC , which combine to provide a traction voltage of 630 V DC . The same system was used for Milan 's earliest underground line, Milan Metro 's line 1 , whose more recent lines use an overhead catenary or

12524-507: The same period. Evidence of water wheels and watermills date to the ancient Near East in the 4th century BC. Moreover, evidence indicates the use of hydropower using irrigation machines to ancient civilizations such as Sumer and Babylonia . 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 , water-powered mills were described by Vitruvius by

12648-464: The same task: converting and transporting high-voltage AC from the power grid to low-voltage DC in the locomotive. The difference between AC and DC electrification systems lies in where the AC is converted to DC: at the substation or on the train. Energy efficiency and infrastructure costs determine which of these is used on a network, although this is often fixed due to pre-existing electrification systems. Both

12772-584: The service "visible" even in no bus is running and the existence of the infrastructure gives some long-term expectations of the line being in operation. Due to the height restriction imposed by the overhead wires, double-stacked container trains have been traditionally difficult and rare to operate under electrified lines. However, this limitation is being overcome by railways in India, China and African countries by laying new tracks with increased catenary height. Hydropower Hydropower (from Ancient Greek ὑδρο -, "water"), also known as water power ,

12896-478: The start of the American hydropower experiment, engineers and politicians began major hydroelectricity projects to solve a problem of 'wasted potential' rather than to power a population that needed the electricity. When the Niagara Falls Power Company began looking into damming Niagara, the first major hydroelectric project in the United States, in the 1890s they struggled to transport electricity from

13020-555: The steep approaches to the tunnel. The system was also used for suburban electrification in East London and Manchester , now converted to 25   kV   AC. It is now only used for the Tyne and Wear Metro . In India, 1,500   V DC was the first electrification system launched in 1925 in Mumbai area. Between 2012 and 2016, the electrification was converted to 25   kV 50   Hz, which

13144-443: The supply grid, requiring careful planning and design (as at each substation power is drawn from two out of three phases). The low-frequency AC system may be powered by separate generation and distribution network or a network of converter substations, adding the expense, also low-frequency transformers, used both at the substations and on the rolling stock, are particularly bulky and heavy. The DC system, apart from being limited as to

13268-694: The three-phase induction motor fed by a variable frequency drive , a special inverter that varies both frequency and voltage to control motor speed. These drives can run equally well on DC or AC of any frequency, and many modern electric locomotives are designed to handle different supply voltages and frequencies to simplify cross-border operation. Five European countries – Germany, Austria, Switzerland, Norway and Sweden – have standardized on 15   kV 16 + 2 ⁄ 3   Hz (the 50   Hz mains frequency divided by three) single-phase AC. On 16 October 1995, Germany, Austria and Switzerland changed from 16 + 2 ⁄ 3   Hz to 16.7   Hz which

13392-575: The through traffic to non-electrified lines. If through traffic is to have any benefit, time-consuming engine switches must occur to make such connections or expensive dual mode engines must be used. This is mostly an issue for long-distance trips, but many lines come to be dominated by through traffic from long-haul freight trains (usually running coal, ore, or containers to or from ports). In theory, these trains could enjoy dramatic savings through electrification, but it can be too costly to extend electrification to isolated areas, and unless an entire network

13516-423: 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 PTC 18 and IEC 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

13640-466: The train stops with one collector in a dead gap, another multiple unit can push or pull the disconnected unit until it can again draw power. The same applies to the kind of push-pull trains which have a locomotive at each end. Power gaps can be overcome in single-collector trains by on-board batteries or motor-flywheel-generator systems. In 2014, progress is being made in the use of large capacitors to power electric vehicles between stations, and so avoid

13764-713: The train's kinetic energy back into electricity and returns it to the supply system to be used by other trains or the general utility grid. While diesel locomotives burn petroleum products, electricity can be generated from diverse sources, including renewable energy . Historically, concerns of resource independence have played a role in the decision to electrify railway lines. The landlocked Swiss confederation which almost completely lacks oil or coal deposits but has plentiful hydropower electrified its network in part in reaction to supply issues during both World Wars. Disadvantages of electric traction include: high capital costs that may be uneconomic on lightly trafficked routes,

13888-413: The transmission and conversion of electric energy involve losses: ohmic losses in wires and power electronics, magnetic field losses in transformers and smoothing reactors (inductors). Power conversion for a DC system takes place mainly in a railway substation where large, heavy, and more efficient hardware can be used as compared to an AC system where conversion takes place aboard the locomotive where space

14012-470: The tyres do not conduct the return current, the two guide bars provided outside the running ' roll ways ' become, in a sense, a third and fourth rail which each provide 750 V DC , so at least electrically it is a four-rail system. Each wheel set of a powered bogie carries one traction motor . A side sliding (side running) contact shoe picks up the current from the vertical face of each guide bar. The return of each traction motor, as well as each wagon ,

14136-703: The use of dams as a source of water power, used to provide additional power to watermills and water-raising machines. Islamic irriguation techniques including Persian Wheels would be introduced to India, and would be combined with local methods, during the Delhi Sultanate and the Mughal Empire . Furthermore, in his book, The Book of Knowledge of Ingenious Mechanical Devices , the Muslim mechanical engineer, Al-Jazari (1136–1206) described designs for 50 devices. Many of these devices were water-powered, including clocks,

14260-432: The voltage, the lower the current for the same power (because power is current multiplied by voltage), and power loss is proportional to the current squared. The lower current reduces line loss, thus allowing higher power to be delivered. As alternating current is used with high voltages. Inside the locomotive, a transformer steps the voltage down for use by the traction motors and auxiliary loads. An early advantage of AC

14384-545: The volume of water available to them. Ethiopia , also located on the Nile, took advantage of the Cold War tensions to request assistance from the United States for their own irrigation and hydropower investments in the 1960s. While progress stalled due to the coup d'état of 1974 and following 17-year-long Ethiopian Civil War Ethiopia began construction on the Grand Ethiopian Renaissance Dam in 2011. Beyond

14508-473: The war, the Grand Coulee Dam and accompanying hydroelectric projects electrified almost all of the rural Columbia Basin , but failed to improve the lives of those living and farming there the way its boosters had promised and also damaged the river ecosystem and migrating salmon populations. In the 1940s as well, the federal government took advantage of the sheer amount of unused power and flowing water from

14632-405: The weight of an on-board transformer. Increasing availability of high-voltage semiconductors may allow the use of higher and more efficient DC voltages that heretofore have only been practical with AC. The use of medium-voltage DC electrification (MVDC) would solve some of the issues associated with standard-frequency AC electrification systems, especially possible supply grid load imbalance and

14756-618: The world are conventional hydroelectric power stations with dams. Hydroelectricity can also be used to store energy in the form of potential energy 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 generators using energy from tidal power generated from oceans, rivers, and human-made canal systems to generating electricity. Rain has been referred to as "one of

14880-532: The world, and the list of railway electrification systems covers both standard voltage and non-standard voltage systems. The permissible range of voltages allowed for the standardised voltages is as stated in standards BS   EN   50163 and IEC   60850. These take into account the number of trains drawing current and their distance from the substation. 1,500   V DC is used in Japan, Indonesia, Hong Kong (parts), Ireland, Australia (parts), France (also using 25 kV 50 Hz AC ) ,

15004-527: The world, including China , India , Japan , France , Germany , and the United Kingdom . Electrification is seen as a more sustainable and environmentally friendly alternative to diesel or steam power and is an important part of many countries' transportation infrastructure. Electrification systems are classified by three main parameters: Selection of an electrification system is based on economics of energy supply, maintenance, and capital cost compared to

15128-437: Was exacerbated because the return current also had a tendency to flow through nearby iron pipes forming the water and gas mains. Some of these, particularly Victorian mains that predated London's underground railways, were not constructed to carry currents and had no adequate electrical bonding between pipe segments. The four-rail system solves the problem. Although the supply has an artificially created earth point, this connection

15252-543: Was first applied successfully by Frank Sprague in Richmond, Virginia in 1887-1888, and led to the electrification of hundreds of additional street railway systems by the early 1890s. The first electrification of a mainline railway was the Baltimore and Ohio Railroad's Baltimore Belt Line in the United States in 1895–96. The early electrification of railways used direct current (DC) power systems, which were limited in terms of

15376-652: Was implemented in the commercial plant of Niagara Falls 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 in Northumberland , England. In 1753, the French engineer Bernard Forest de Bélidor published his book, Architecture Hydraulique , which described vertical-axis and horizontal-axis hydraulic machines. The growing demand for

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