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123-629: The Ennore Thermal Power Station is a coal based power plant located in Chennai Ennore , Tamil Nadu . Ennore Thermal Power Station was constructed to serve the purpose of energy generation in the year 1970. It is one of the four major thermal power plants of Tamil Nadu established by the Tamil Nadu Generation and Distribution Corporation Limited ( TANGEDCO ). Presently it has an installed capacity of 450  MW (600,000  hp ). The necessary coal arrives through ship to

246-444: A blunderbuss , each guard carried a secure timepiece by which departure times at each stage of the journey were strictly regulated. In 1830 mail was carried by train for the first time, on the newly-opened Liverpool and Manchester Railway ; over the next decade the railways replaced mail coaches as the principal means of conveyance (the last mail coach departed from London on 6 January 1846). The first Travelling Post Office (TPO)

369-571: A lottery bond called the Premium Bond was introduced. In the mid-1960s the GPO was asked by the government to expand into banking services which resulted in the creation of the National Giro in 1968. When new forms of communication came into existence in the 19th and early 20th centuries the GPO claimed monopoly rights on the basis that like the postal service they involved delivery from

492-447: A magnetic field and a conductor creates an electric current . The energy source harnessed to turn the generator varies widely. Most power stations in the world burn fossil fuels such as coal , oil , and natural gas to generate electricity. Low-carbon power sources include nuclear power , and use of renewables such as solar , wind , geothermal , and hydroelectric . In early 1871 Belgian inventor Zénobe Gramme invented

615-557: A proclamation 'for the settling of the Letter-office of England and Scotland', an event which 'may properly be regarded as the origin of the British post-office'. By this decree, Thomas Witherings (who had been appointed 'Postmaster of England for foreign parts' three years earlier) was empowered to provide for the carriage of private letters at fixed rates 'betwixt London and all parts of His Majesty's dominions'. To this end,

738-494: A sender and to a receiver . The theory was used to expand state control of the mail service into every form of electronic communication possible on the basis that every sender used some form of distribution service. These distribution services were considered in law as forms of electronic post offices. This applied to telegraph and telephone switching stations. In 1846, the Electric Telegraph Company ,

861-579: A transformer to step up voltage for long-distance transmission and then stepped it back down for indoor lighting, a more efficient and less expensive system which is similar to modern systems. The war of the currents eventually resolved in favor of AC distribution and utilization, although some DC systems persisted to the end of the 20th century. DC systems with a service radius of a mile (kilometer) or so were necessarily smaller, less efficient of fuel consumption, and more labor-intensive to operate than much larger central AC generating stations. AC systems used

984-675: A bell to attract custom was adopted by the Post Office and went on to be employed in major cities until the mid-19th century. In 1761 permission was given for the establishment of penny-post arrangements elsewhere in the realm, to function along the same lines as the London office, if they could be made financially viable; by the end of the century there were penny-post systems operating in Birmingham, Bristol, Dublin, Edinburgh and Manchester (to be joined by Glasgow and Newcastle-upon-Tyne in

1107-420: A byproduct of the useful electrical energy produced. The amount of waste heat energy equals or exceeds the amount of energy converted into useful electricity . Gas-fired power plants can achieve as much as 65% conversion efficiency, while coal and oil plants achieve around 30–49%. The waste heat produces a temperature rise in the atmosphere, which is small compared to that produced by greenhouse-gas emissions from

1230-642: A court ruling obliged the London Penny Post to come under the authority of the Postmaster General. Although now part of the GPO, the London Penny Post continued to operate entirely independently of the General (or 'Inland') Post until 1854 (when the two systems were combined). An attempt by Charles Povey to set up a rival halfpenny post in 1709 was halted after several months' operation; however Povey's practice of having letter-carriers ring

1353-545: A fee. The trade in these 'ship letters' was acknowledged (and legitimised) in the Post Office Acts of 1657 and 1660. Attempts were made to levy Post Office fees on these letters and 'ship letter money' was offered to captains for each letter given to a postmaster on arrival in England in order for these charges to be applied; however they were under no legal obligation to comply and the majority of ship letters evaded

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1476-427: A generator powerful enough to produce power on a commercial scale for industry. In 1878, a hydroelectric power station was designed and built by William, Lord Armstrong at Cragside , England . It used water from lakes on his estate to power Siemens dynamos . The electricity supplied power to lights, heating, produced hot water, ran an elevator as well as labor-saving devices and farm buildings. In January 1882

1599-430: A hand bell. While postmasters were not obliged to deliver items to places outside the boundary, they could agree to do so on payment of an extra fee. In the 1780s, Britain's General Post network was revolutionised by theatrical impresario John Palmer 's idea of using mail coaches in place of the longstanding use of post horses. After initial resistance from the postal authorities, a trial took place in 1784, by which it

1722-409: A horse and cart or waggon, while the universities, along with certain municipal and other corporations, maintained their own correspondence networks. Many letters went by foot-post rather than on horseback. Footposts or runners were employed by many towns, cities and other communities, and had been for many years. A 16th-century footpost would cover around 30 miles per day, on average. At the time of

1845-596: A hundred miles a day. Under King Henry VIII a concerted effort was made to maintain a regular postal system for the conveyance of royal and government despatches (in times of peace as well as in time of war). To oversee the system, the king appointed Brian Tuke to serve as 'Master of the Postes'. By the 1550s five post roads were in place, connecting London with Dover , Edinburgh , Holyhead (via Chester ), Milford Haven (via Bristol ) and Plymouth . (A sixth post road, to Norwich via Colchester , would be added in

1968-425: A hydroelectric power station water flows through turbines using hydropower to generate hydroelectricity . Power is captured from the gravitational force of water falling through penstocks to water turbines connected to generators . The amount of power available is a combination of height and water flow. A wide range of Dams may be built to raise the water level, and create a lake for storing water . Hydropower

2091-403: A lower reservoir to an upper reservoir. Because the pumping takes place "off peak", electricity is less valuable than at peak times. This less valuable "spare" electricity comes from uncontrolled wind power and base load power plants such as coal, nuclear and geothermal, which still produce power at night even though demand is very low. During daytime peak demand, when electricity prices are high,

2214-539: A major provider of electricity in the state and its production capacity has been improved over the years. The Ennore Power Station has also garnered various awards from the TANGEDCO . However power deficit seems to be playing an important role for the recent decision. It also has a special treatment plant to dispose the ash slurry in a proper way. Coal for ETPS is received from MCL (Talchar and Ib Valley), Orissa and ECL, Raniganj, West Bengal. The plant load factor (PLF) for

2337-406: A material that enhances the mixing of the upflowing air and the down-flowing water. In areas with restricted water use, a dry cooling tower or directly air-cooled radiators may be necessary, since the cost or environmental consequences of obtaining make-up water for evaporative cooling would be prohibitive. These coolers have lower efficiency and higher energy consumption to drive fans, compared to

2460-569: A pipe containing a heat transfer fluid, such as oil. The heated oil is then used to boil water into steam, which turns a turbine that drives an electrical generator. The central tower type of solar thermal power plant uses hundreds or thousands of mirrors, depending on size, to direct sunlight onto a receiver on top of a tower. The heat is used to produce steam to turn turbines that drive electrical generators. Wind turbines can be used to generate electricity in areas with strong, steady winds, sometimes offshore . Many different designs have been used in

2583-592: A power station is nearly the maximum electrical power that the power station can produce. Some power plants are run at almost exactly their rated capacity all the time, as a non-load-following base load power plant , except at times of scheduled or unscheduled maintenance. However, many power plants usually produce much less power than their rated capacity. In some cases a power plant produces much less power than its rated capacity because it uses an intermittent energy source . Operators try to pull maximum available power from such power plants, because their marginal cost

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2706-549: A regular mail-carrying service in exchange for a fee or subsidy. In the following century, packet services out of Falmouth began to sail to the West Indies, North America and other transatlantic destinations. Packet boats, however, were not the only means of conveying letters overseas: there had always been the option of sending them by merchant ship, and coffee houses had long been accustomed to receiving letters and packages on behalf of ships' captains, who would carry them for

2829-511: A regular public postal service came the need for waterborne mail services (carrying letters to and from Ireland, continental Europe and other destinations) to be placed on a more regular footing. ' Packet boats ', offering a regular scheduled mail service, were already in use for the passage between Holyhead and Dublin; but for letters to and from the Continent the post was entrusted to messengers, who would make their own travel arrangements. This

2952-421: A steam turbine. Bioenergy can also be processed through a range of temperatures and pressures in gasification , pyrolysis or torrefaction reactions. Depending on the desired end product, these reactions create more energy-dense products ( syngas , wood pellets , biocoal ) that can then be fed into an accompanying engine to produce electricity at a much lower emission rate when compared with open burning. It

3075-643: A steam turbine. The combination of a "top" cycle and a "bottom" cycle produces higher overall efficiency than either cycle can attain alone. In 2018, Inter RAO UES and State Grid Archived 21 December 2021 at the Wayback Machine planned to build an 8-GW thermal power plant, which's the largest coal-fired power plant construction project in Russia . A prime mover is a machine that converts energy of various forms into energy of motion. Power plants that can be dispatched (scheduled) to provide energy to

3198-556: A system for the conveyance of foreign dispatches had been set up, organised by Flemish merchants in the City of London ; but in 1558, after a dispute arose between Italian, Flemish and English merchants on the matter, the Master of the King's Posts was granted oversight of it instead. In 1619, James I appointed a separate Postmaster General 'for foreign parts', granting him (and his appointees)

3321-495: A system include: Non-dispatchable plants include such sources as wind and solar energy; while their long-term contribution to system energy supply is predictable, on a short-term (daily or hourly) base their energy must be used as available since generation cannot be deferred. Contractual arrangements ("take or pay") with independent power producers or system interconnections to other networks may be effectively non-dispatchable. All thermal power plants produce waste heat energy as

3444-441: A team of four horses, rather than six as was usual for a stage coach at that time). The long-established practice of 'riding post' was acknowledged through the provision of four seats inside the coach for passengers. The mail bags were carried in a locked box at the back, above which sat a scarlet-coated guard. While the coaches and coachmen were provided by contractors, the guards worked for the Post Office. As well as two pistols and

3567-682: A turbine is spun creating energy. This method is being specifically studied by the Norwegian utility Statkraft, which has calculated that up to 25 TWh/yr would be available from this process in Norway. Statkraft has built the world's first prototype osmotic power plant on the Oslo fjord which was opened on 24 November 2009. In January 2014, however, Statkraft announced not to continue this pilot. Biomass energy can be produced from combustion of waste green material to heat water into steam and drive

3690-445: A typical wet, evaporative cooling tower. Power plants can use an air-cooled condenser, traditionally in areas with a limited or expensive water supply. Air-cooled condensers serve the same purpose as a cooling tower (heat dissipation) without using water. They consume additional auxiliary power and thus may have a higher carbon footprint compared to a traditional cooling tower. Electric companies often prefer to use cooling water from

3813-487: A wide range of frequencies depending on the type of load; lighting load using higher frequencies, and traction systems and heavy motor load systems preferring lower frequencies. The economics of central station generation improved greatly when unified light and power systems, operating at a common frequency, were developed. The same generating plant that fed large industrial loads during the day, could feed commuter railway systems during rush hour and then serve lighting load in

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3936-424: Is a matter of general concernment, and of great advantage, as well for the preservation of trade and commerce as otherwise". To begin with the Post Office was again farmed, nominally to Henry Bishop , but the deal was bankrolled by John Wildman (a gentleman of dubious repute, who kept a tight rein on his investment). Two years later Wildman was imprisoned, implicated in a plot against the King, whereupon Bishop sold

4059-583: Is possible to store energy and produce electrical power at a later time as in pumped-storage hydroelectricity , thermal energy storage , flywheel energy storage , battery storage power station and so on. The world's largest form of storage for excess electricity, pumped-storage is a reversible hydroelectric plant. They are a net consumer of energy but provide storage for any source of electricity, effectively smoothing peaks and troughs in electricity supply and demand. Pumped storage plants typically use "spare" electricity during off peak periods to pump water from

4182-518: Is practically zero, but the available power varies widely—in particular, it may be zero during heavy storms at night. In some cases operators deliberately produce less power for economic reasons. The cost of fuel to run a load following power plant may be relatively high, and the cost of fuel to run a peaking power plant is even higher—they have relatively high marginal costs. Operators keep power plants turned off ("operational reserve") or running at minimum fuel consumption ("spinning reserve") most of

4305-465: Is produced in 150 countries, with the Asia-Pacific region generating 32 percent of global hydropower in 2010. China is the largest hydroelectricity producer, with 721 terawatt-hours of production in 2010, representing around 17 percent of domestic electricity use. Solar energy can be turned into electricity either directly in solar cells , or in a concentrating solar power plant by focusing

4428-410: Is used intermittently (peak load). Steam turbines generally operate at higher efficiency when operated at full capacity. Besides use of reject heat for process or district heating, one way to improve overall efficiency of a power plant is to combine two different thermodynamic cycles in a combined cycle plant. Most commonly, exhaust gases from a gas turbine are used to generate steam for a boiler and

4551-494: The Ennore Port . However, the construction of the 1,000 MW plants (1,300,000 hp) in the premise began in the year 2007. The Station presently consists of two 60-MW and three 110-MW units. A 500-MW coal-based unit was proposed, and its development started in the month of November 2007. The total cost of the venture was 270 crores . The plant was shut down on 31.03.2017 and will be replaced. The Power Station has been

4674-765: The Leeward Islands was enjoined. The Irish post at this time operated as part of the GPO under a Deputy Postmaster General based in Dublin; but in 1784 an Act was passed by the Parliament of Ireland providing for an independent Post Office in Ireland under its own Postmaster General (an arrangement that remained in place until 1831). The established post roads in Britain ran to and from London. The use of other roads required government permission (for example, it

4797-760: The Roscoe Wind Farm is the largest onshore wind farm in the world, producing 8000  MW of power, followed by the Zhang Jiakou (3000 MW). As of January 2022, the Hornsea Wind Farm in United Kingdom is the largest offshore wind farm in the world at 1218 MW, followed by Walney Wind Farm in United Kingdom at 1026 MW. In 2021, the worldwide installed capacity of power plants increased by 347 GW. Solar and wind power plant capacities rose by 80% in one year.  As of 2022 ,

4920-757: The Royal Mail Steam Packet Company ran ships out of Southampton to the West Indies and South America, the British and North American Royal Mail Steam-Packet Company (aka the Cunard Line ) covered the North Atlantic route, while the Peninsular and Oriental Steam Navigation Company provided services on eastward routes to the Mediterranean, India and Australia. From 1840 vessels carrying mail under Admiralty contract had

5043-484: The Spanish Armada every parish was by royal command required to provide a footpost, and every town a horse-post, to help convey news in the event of an imminent invasion. By the early 1600s there were two options for couriers using the post system: they could either ride 'through-post', carrying the correspondence the full distance; or they could use the 'post of the packet', whereby the letters were carried by

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5166-630: The Strowger system for small and medium cities and towns. The telephone systems of Jersey and the Isle of Man , obtained from the NTC were offered for sale to the respective governments of the islands. Both initially refused, but the States of Jersey did eventually take control of their island's telephones in 1923. On 27 July 1896, Guglielmo Marconi gave the first demonstration of wireless telegraphy from

5289-646: The War of the Spanish Succession ). The distribution network was centred on the General Letter Office in London (which was on Threadneedle Street prior to the Great Fire of London , after which it moved first to Bishopsgate and then to Lombard Street in 1678). The incoming post arrived each week on Mondays, Wednesdays and Fridays; it was sorted and stamped : London letters went to

5412-488: The largest photovoltaic (PV) power plants in the world are led by Bhadla Solar Park in India, rated at 2245 MW. Solar thermal power stations in the U.S. have the following output: Large coal-fired, nuclear, and hydroelectric power stations can generate hundreds of megawatts to multiple gigawatts. Some examples: Gas turbine power plants can generate tens to hundreds of megawatts. Some examples: The rated capacity of

5535-439: The second law of thermodynamics ; therefore, there is always heat lost to the environment. If this loss is employed as useful heat, for industrial processes or district heating , the power plant is referred to as a cogeneration power plant or CHP (combined heat-and-power) plant. In countries where district heating is common, there are dedicated heat plants called heat-only boiler stations . An important class of power stations in

5658-452: The sole privilege of carrying foreign correspondence to and from London. (The separate Postmaster General appointments were consolidated in 1637, but the 'foreign' and 'inland' postal services remained separate in terms of administration and accounting until the mid-19th century). It was not until 1635 that a general or public post was properly established, for inland letters as for foreign ones. On 31 July that year, King Charles I issued

5781-426: The 'windows' where members of the public were able to collect them from the office in person (once they had paid the requisite fee), while 'Country letters' were dispatched along the relevant post road. The outgoing post went on Tuesdays, Thursdays and Saturdays. Postage was payable by the recipient (rather than the sender) and depended on the length of the letter and the distance it had travelled; each individual charge

5904-645: The 1830s). In 1801 the cost of posting a letter within the central London area was doubled; thenceforward the London District Post was known as the 'Two-penny Post' until its amalgamation into the General Post 53 years later. During the reign of King William III , the General Post Office created a network of 'receiving-houses', in London and the larger provincial towns, where senders could submit items. A Scottish Post Office

6027-490: The 20th century central stations became larger, using higher steam pressures to provide greater efficiency, and relying on interconnections of multiple generating stations to improve reliability and cost. High-voltage AC transmission allowed hydroelectric power to be conveniently moved from distant waterfalls to city markets. The advent of the steam turbine in central station service, around 1906, allowed great expansion of generating capacity. Generators were no longer limited by

6150-458: The Admiralty took over managing the long-distance routes out of Falmouth, while services to and from Ireland and the continent were increasingly put out to commercial tender. Eventually, in 1837, the Admiralty took over control of the whole operation (and with it the remaining Post Office vessels). Subsequently, contracts for carrying mail began to be awarded to new large-scale shipping lines :

6273-752: The British Isles (the nations of which had been unified under Oliver Cromwell as a result of the Wars of the Three Kingdoms ), stating that 'there shall be one General Post-Office, and one office stiled the Postmaster-Generall of England and Comptroller of the Post-Office'. The Act also reasserted the postal monopoly for letter delivery and for post-horses; and it set new rates both for carriage of letters and for 'riding post'. During

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6396-534: The Commonwealth, what had been a weekly post service to and from London was increased to a thrice-weekly service: letters were despatched from the General Letter Office in London every Tuesday, Thursday and Saturday evening, while the inbound post arrived early in the morning on Mondays, Wednesdays and Fridays. Usually the recipient of the post paid the fee (and had the right to refuse to accept

6519-518: The Crown). At Dover merchant ships were regularly employed to convey letters to and from the continent . A similar system connected Holyhead and Milford to Ireland (and by the end of the 16th century a packet service had been established on the Holyhead to Dublin route). Private citizens could make use of the post-horse network, if they could afford it (in 1583 they had to pay twopence per mile for

6642-572: The Drakensberg, Ingula Pumped Storage Scheme . The power generated by a power station is measured in multiples of the watt , typically megawatts (10 watts) or gigawatts (10 watts). Power stations vary greatly in capacity depending on the type of power plant and on historical, geographical and economic factors. The following examples offer a sense of the scale. Many of the largest operational onshore wind farms are located in China. As of 2022,

6765-611: The GPO (in particular the Hull Telephones Department (now privatised) and the telephone system of Guernsey ). The GPO took over the company on 1 January 1912; transferring 1,565 exchanges and 9,000 employees at a cost of £12,515,264. The GPO installed several automatic telephone exchanges from several vendors in trials at Darlington on 10 October 1914 and Dudley on 9 September 1916 ( rotary system ), Fleetwood (relay exchange from Sweden), Grimsby (Siemens), Hereford (Lorimer) and Leeds (Strowger). The GPO then selected

6888-516: The GPO came to be viewed less as a revenue-raising body and more as a public service . The Post Office Savings Bank was introduced in 1861, when there were few banks outside major towns. By 1863, 2,500 post offices were offering a savings service . Gradually more financial services were offered by post offices, including government stocks and bonds in 1880, insurance and annuities in 1888, and war savings certificates in 1916. In 1909 old age pensions were introduced, payable at post offices. In 1956

7011-493: The Middle East uses by-product heat for the desalination of water. The efficiency of a thermal power cycle is limited by the maximum working fluid temperature produced. The efficiency is not directly a function of the fuel used. For the same steam conditions, coal-, nuclear- and gas power plants all have the same theoretical efficiency. Overall, if a system is on constantly (base load) it will be more efficient than one that

7134-454: The Peace had been ordered to arrange appointment of two to three foot-posts in every parish for the conveyance of letters), though in practice precise details were often left to the local postmaster. On the return journey to London, bags of letters would be picked up from each post-house on the way, and taken to the General Letter Office to be sorted for despatch. With the establishment of

7257-670: The Post Master General obtained a court judgement that telephone conversations were, technically, within the remit of the Telegraph Act. The General Post Office then licensed all existing telephone networks. The effective nationalisation of the UK telecommunications industry occurred in 1912 with the takeover of the National Telephone Company which left only a few municipal undertakings independent of

7380-463: The Post Office.) The expansion of the service beyond the main post-roads was in no small part due to the enterprise of the Deputy post-masters themselves, who were allowed to profit from branch services which they established and operated. In this way, the network of 'by-posts' greatly expanded in the 1670s: in 1673 Blome could write that 'there is scarce any Market-Town of note [which does not have]

7503-494: The Postmaster General. Alongside money orders, postal orders were introduced in 1881, which were cheaper and easier to cash. Postal orders and money orders were vital at this time for transactions between small businesses, as well as individuals, because bank transfer facilities were only available to major businesses and for larger sums of money. In 1840 the Uniform Penny Post was introduced, which incorporated

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7626-770: The Research Section of the Telegraph Office, which had its origins in innovative areas of work being pursued by staff in the Engineering Department. In the 1920s a dedicated research station was set up by the GPO seven miles away in Dollis Hill ; during the Second World War the world's first electronic computer, ' Colossus ', was designed and constructed there by Tommy Flowers and other GPO engineers. The Telegraph Office

7749-455: The UK. The responsibility for the 'electric telegraphs' was officially transferred to the GPO in 1870. Overseas telegraphs did not fall within the monopoly. The private telegraph companies that already existed were bought out. The new combined telegraph service had 1,058 telegraph offices in towns and cities and 1,874 offices at railway stations. 6,830,812 telegrams were transmitted in 1869 producing revenue of £550,000. London's Central Office in

7872-581: The United States, Ferranti and Charles Hesterman Merz in UK, and many others . 2021 world electricity generation by source. Total generation was 28 petawatt-hours . In thermal power stations, mechanical power is produced by a heat engine that transforms thermal energy , often from combustion of a fuel , into rotational energy. Most thermal power stations produce steam, so they are sometimes called steam power stations. Not all thermal energy can be transformed into mechanical power, according to

7995-481: The benefit of the conveyance of letters to and fro'; he went on to list, County by County, both the 'Stages' on the post-roads (of which there were over 140) and the Post-towns on the branch roads (which by then numbered over 380 in total), where members of the public were able to leave letters with a Post-Master 'to be sent as directed'. Before long moves were made to incorporate the by-posts (and their income) into

8118-552: The cooling machinery. These screens are only partially effective and as a result billions of fish and other aquatic organisms are killed by power plants each year. For example, the cooling system at the Indian Point Energy Center in New York kills over a billion fish eggs and larvae annually. A further environmental impact is that aquatic organisms which adapt to the warmer discharge water may be injured if

8241-463: The country. The 1850s also saw the widespread introduction of red-painted post boxes where the public could deposit their outgoing mail. Few other organisations (either of state or of commerce) could rival the early Victorian Post Office in the extent of its national coverage. Its counters began to be relied upon for providing other government services (e.g. the issuing of licences of various types); and increasingly (and significantly) in this period,

8364-417: The early 17th century.) Each post-house on the road was staffed by a postmaster , whose main responsibility was to provide the horses; he would also provide a guide to accompany the messenger as far as the next post house (and then see to the return of the horses afterwards). In practice most post-houses were established at roadside inns and the innkeeper served as postmaster (in return for a small salary from

8487-411: The energy carried by ocean waves , tides , salinity , and ocean temperature differences . The movement of water in the world's oceans creates a vast store of kinetic energy , or energy in motion. This energy can be harnessed to generate electricity to power homes, transport and industries. The term marine energy encompasses both wave power —power from surface waves, and tidal power —obtained from

8610-546: The establishment of the Penny Post, the only location where letters could be posted in London was the General Letter Office in Lombard Street .) The receiving-houses were often found in public houses, coffee houses or other retail premises. Deliveries were made six or eight times a day in central London (and a minimum of four times a day in the outskirts). The innovation was a great success, and within two years

8733-409: The evening, thus improving the system load factor and reducing the cost of electrical energy overall. Many exceptions existed, generating stations were dedicated to power or light by the choice of frequency, and rotating frequency changers and rotating converters were particularly common to feed electric railway systems from the general lighting and power network. Throughout the first few decades of

8856-507: The extra charges. In 1680 William Dockwra and Robert Murray founded the 'Penny Post', which enabled letters and parcels to be sent cheaply to and from destinations in and around London. A flat fee of a penny was charged for sending letters or parcels up to a pound in weight within an area comprising the City of London, the City of Westminster and the Borough of Southwark ; while two-pence

8979-417: The first decade of nationalized telegraphy created two levels of service. High-status circuits catering to the state, international trade, sporting life, and imperial business. Low-status circuits directed toward the local and the provincial. These distinct telegraphic orbits were connected to different types of telegraph instruments operated by differently gendered telegraphists. 1909 saw the establishment of

9102-412: The guides from one post house to the next in a cotton-lined leather bag (although this method was only available for royal, government or diplomatic correspondence). The guides at this time were provided with a post horn , which they had to sound at regular intervals or when encountering others on the road (other road users were expected to give way to the post riders ). At the start of the 16th century

9225-503: The horse, plus fourpence per stage for the guide), but it was primarily designed for the relaying of state and royal correspondence, or for the conveyance from one place to another of individuals engaged on official state business (who paid a reduced rate). Private correspondence was often sent using common carriers at this time, or with others who regularly journeyed from place to place (such as travelling pedlars ); towns often made use of local licensed carriers, who plied their trade using

9348-483: The inhabitants of the nation. At that time there were 182 Deputy Post-Masters (or 'Deputies') in England [and Wales], most of whom were stationed at the 'Stages' or stops which lay along the six main post-roads; and under them were sub-Post-masters , based at market towns which were not on the main post-roads but to which the service had been extended. (The sub-Post-masters, unlike the Deputies, were not employed by

9471-529: The item if they did not wish to pay); the charge was based on the distance the item had been carried so the Post Office had to keep a separate account for each item. After the Restoration , the Post Office Act 1660 ( 12 Cha. 2 . c. 35) was passed (the previous Cromwellian Act being void), confirming the arrangements in place for the Post Office, and the post of Postmaster General, and emphasizing

9594-406: The kinetic energy of large bodies of moving water. Offshore wind power is not a form of marine energy, as wind power is derived from the wind , even if the wind turbines are placed over water. The oceans have a tremendous amount of energy and are close to many if not most concentrated populations. Ocean energy has the potential of providing a substantial amount of new renewable energy around

9717-556: The largest power plants terawatt-hours (TW·h). It includes the electricity used in the plant auxiliaries and in the transformers. Net generation is the amount of electricity generated by a power plant that is transmitted and distributed for consumer use. Net generation is less than the total gross power generation as some power produced is consumed within the plant itself to power auxiliary equipment such as pumps , motors and pollution control devices. Thus General Post Office#Headquarters The General Post Office ( GPO )

9840-536: The latter's accession to the throne as King James II , this income became part of the hereditary revenues of the Crown ; and subsequently, under the growing scrutiny of HM Treasury , the postal service came increasingly to be viewed as a source of government income (as seen in the Post Office (Revenues) Act 1710 , which increased postal charges and levied tax on the income in order to finance Britain's involvement in

9963-575: The lease on to the King's gunpowder manufacturer, Daniel O'Neill ; after the latter's death, his widow the Countess of Chesterfield served out the remainder of the original seven-year term (so becoming the first female Postmaster General). Meanwhile, under the terms of a 1663 Act of Parliament, the 'rents, issues and profits' of the Post Office had been settled by the King on his brother, the Duke of York, to provide for his support and maintenance. Following

10086-500: The length of journey required it). Under Edward IV , however, a more efficient system was put in place (albeit temporarily) to aid communications during his war with Scotland : a number of post houses were established at twenty-mile intervals along the Great North Road , between London and Berwick , to provide the king's messengers with fresh horses for each stage of the journey; in this way they were able to travel up to

10209-425: The light to run a heat engine. A solar photovoltaic power plant converts sunlight into direct current electricity using the photoelectric effect . Inverters change the direct current into alternating current for connection to the electrical grid. This type of plant does not use rotating machines for energy conversion. Solar thermal power plants use either parabolic troughs or heliostats to direct sunlight onto

10332-517: The mail bags from one post-house to the next; the postmaster at the next post-house would then record the time of arrival, before transferring the bags to a new horse, ridden by a new post-boy, for the next stage of the journey. On the outbound journey from London, the mail for each Stage (and its associated Post-towns) was left at the relevant post-house. Arrangements for its onward delivery varied somewhat from place to place. Witherings had envisaged using 'foot-posts' for this purpose (in 1620 Justices of

10455-516: The medieval period, nobles generally employed messengers to deliver letters and other items on their behalf. In the 12th century a permanent body of messengers had been formed within the Royal Household of King Henry I , for the conveyance of royal and official correspondence. The messengers delivered their messages in person, each travelling on his own horse and taking time as needed for rest and refreshment (including stopping overnight if

10578-524: The messengers appointed by the said Thomas Witherings', thus establishing a monopoly, which (under the auspices of the Royal Mail ) would remain in place until 2006. Under the Commonwealth the Post Office was farmed to John Manley and John Thurloe , successively. In 1657 an Act of Parliament entitled Postage of England, Scotland and Ireland Settled set up a postal system for the whole of

10701-506: The national network: 'Riding Surveyors' were appointed in 1682, to travel with the post and scrutinise the Deputies' income and activity at each Stage (particularly in relation to by-letters); in later years the Surveyors served as the GPO's inspectorate , tasked with maintaining efficiency and consistency across the network (until they were finally disbanded in the 1930s). It was usual for each postmaster to employ post-boys to ride with

10824-507: The network of post towns served by the General Post, and at the same time did much to reform its workings. In 1772 the Court of the King's Bench ruled that letters ought to be delivered directly to recipients within the boundaries of each post town at no additional cost. Often a messenger with a locked satchel would be employed by the postmaster to deliver and receive items of mail around town; he would alert people to his presence by ringing

10947-548: The new arrangement, the King commanded 'all his postmasters, upon all the roads of England, to have ready in their stables one or two horses [...] to carry such messengers, with their portmantles , as shall be imployed in the said service', and they were forbidden from hiring out these horses to others on days when the mail was due. Furthermore, it was enjoined that (with a few specific exceptions) 'no other messenger or messengers, footpost or footposts, shall take up, carry, receive or deliver any letter or letters whatsoever, other than

11070-479: The ocean or a lake, river, or cooling pond instead of a cooling tower. This single pass or once-through cooling system can save the cost of a cooling tower and may have lower energy costs for pumping cooling water through the plant's heat exchangers . However, the waste heat can cause thermal pollution as the water is discharged. Power plants using natural bodies of water for cooling are designed with mechanisms such as fish screens , to limit intake of organisms into

11193-436: The packet ship services. Since the 1780s these had been run on behalf of the Post Office by private contractors, who depended on supplementary income from fee-paying passengers in order to make a profit; but in the 19th-century steamships began to lure the passengers away. At some considerable cost the Post Office resolved to build and operate its own fleet of steam vessels, but the service became increasingly inefficient. In 1823

11316-557: The past, but almost all modern turbines being produced today use a three-bladed, upwind design. Grid-connected wind turbines now being built are much larger than the units installed during the 1970s. They thus produce power more cheaply and reliably than earlier models. With larger turbines (on the order of one megawatt), the blades move more slowly than older, smaller, units, which makes them less visually distracting and safer for birds. Marine energy or marine power (also sometimes referred to as ocean energy or ocean power ) refers to

11439-674: The plant shuts down in cold weather . Water consumption by power stations is a developing issue. In recent years, recycled wastewater, or grey water , has been used in cooling towers. The Calpine Riverside and the Calpine Fox power stations in Wisconsin as well as the Calpine Mankato power station in Minnesota are among these facilities. Power stations can generate electrical energy from renewable energy sources. In

11562-406: The power themselves, in which case the generation output is classified into gross generation , and net generation . Gross generation or gross electric output is the total amount of electricity generated by a power plant over a specific period of time. It is measured at the generating terminal and is measured in kilowatt-hours (kW·h), megawatt-hours (MW·h), gigawatt-hours (GW·h) or for

11685-559: The power transmission of belts or the relatively slow speed of reciprocating engines, and could grow to enormous sizes. For example, Sebastian Ziani de Ferranti planned what would have reciprocating steam engine ever built for a proposed new central station, but scrapped the plans when turbines became available in the necessary size. Building power systems out of central stations required combinations of engineering skill and financial acumen in equal measure. Pioneers of central station generation include George Westinghouse and Samuel Insull in

11808-483: The privilege of being badged and designated as Royal Mail Ships (RMS). In 1838 the Money Order Office was established, to provide a secure means of transferring money to people in different parts of the country (or world), and to discourage people from sending cash by post. The money order system had first been introduced as a private enterprise by three Post Office clerks in 1792, with the permission of

11931-422: The public and economic benefits of a General Post system: "Whereas for the maintenance of mutual correspondencies, and prevention of many inconveniences happening by private posts, several public post-offices have been heretofore erected for carrying and recarrying of letters by post to and from all parts and places within England, Scotland, and Ireland, and several posts beyond the seas, the well-ordering whereof

12054-460: The rest of the realm). Witherings was required to extend the new system to other post roads 'as soon as possibly may be' (beginning with the routes to Oxford and Bristol, and to Colchester, Norwich and Yarmouth); and provision was also made for the establishment of 'bye-posts' to run to and from places not directly served by the post road system (such as Lincoln and Hull). The new system was fully and profitably running by 1636. In order to facilitate

12177-661: The road, which was the monopoly of the gas companies. The customers included the City Temple and the Old Bailey . Another important customer was the Telegraph Office of the General Post Office , but this could not be reached through the culverts. Johnson arranged for the supply cable to be run overhead, via Holborn Tavern and Newgate . In September 1882 in New York, the Pearl Street Station

12300-555: The roof of the Telegraph Office in St. Martin's Le Grand. The development of radio links for sending telegraphs led to the Wireless Telegraphy Act 1904 , which granted control of radio waves to the General Post Office, who licensed all senders and receivers. This placed the Post Office in a position of control over radio and television broadcasting as those technologies were developed. By 1900 house-to-house mail delivery

12423-455: The royal proclamation instructed him to establish 'a running post, to run night and day', initially between London and Edinburgh, London and Holyhead and London and Plymouth, 'for the advancement of all His Majesty's subjects in their trade and correspondence'. (A similar system, running between London and Dover, had already been established by Witherings as part of his administration of the foreign posts, and he himself had proposed its extension to

12546-777: The same power plant. Natural draft wet cooling towers at many nuclear power plants and large fossil-fuel-fired power plants use large hyperboloid chimney -like structures (as seen in the image at the right) that release the waste heat to the ambient atmosphere by the evaporation of water. However, the mechanical induced-draft or forced-draft wet cooling towers in many large thermal power plants, nuclear power plants, fossil-fired power plants, petroleum refineries , petrochemical plants , geothermal , biomass and waste-to-energy plants use fans to provide air movement upward through down coming water and are not hyperboloid chimney-like structures. The induced or forced-draft cooling towers are typically rectangular, box-like structures filled with

12669-442: The start of the 21st century the Post Office became a public limited company (initially called 'Consignia plc'), which was renamed ' Royal Mail Group plc' in 2002. In 2012 the counters business (known as ' Post Office Limited ' since 2002) was taken out of Royal Mail Group, prior to the latter's privatisation in 2013. The privatised holding company (Royal Mail plc) was renamed International Distributions Services plc in 2022. In

12792-512: The storage is used for peaking power , where water in the upper reservoir is allowed to flow back to a lower reservoir through a turbine and generator. Unlike coal power stations, which can take more than 12 hours to start up from cold, a hydroelectric generator can be brought into service in a few minutes, ideal to meet a peak load demand. Two substantial pumped storage schemes are in South Africa, Palmiet Pumped Storage Scheme and another in

12915-556: The telecommunications and postal sides were split prior to British Telecommunications ' conversion into a totally separate publicly owned corporation the following year as a result of the British Telecommunications Act 1981 . In 1986 the Post Office Counters business was made functionally separate from Royal Mail Letters and Royal Mail Parcels (the latter being rebranded as ' Parcelforce '). At

13038-448: The time. Operators feed more fuel into load following power plants only when the demand rises above what lower-cost plants (i.e., intermittent and base load plants) can produce, and then feed more fuel into peaking power plants only when the demand rises faster than the load following power plants can follow. Not all of the generated power of a plant is necessarily delivered into a distribution system. Power plants typically also use some of

13161-474: The two key innovations of a uniform postal rate, which cut administrative costs and encouraged use of the system, and adhesive pre-paid stamp. Packets (weighing up to 16 ounces (450 g)) could also be sent by post, the cost of postage varying with the weight. The reforms were devised and overseen by Rowland Hill , having been initially proposed in Parliament by Robert Wallace MP . A book post service

13284-512: The world's first public coal-fired power station , the Edison Electric Light Station , was built in London, a project of Thomas Edison organized by Edward Johnson . A Babcock & Wilcox boiler powered a 93 kW (125 horsepower) steam engine that drove a 27-tonne (27-long-ton) generator. This supplied electricity to premises in the area that could be reached through the culverts of the viaduct without digging up

13407-537: The world's first public telegraph company, was established in the UK and developed a nationwide communications network. Several other private telegraph companies soon followed. The Telegraph Act 1868 granted the Postmaster General the right to acquire inland telegraph companies in the United Kingdom and the Telegraph Act 1869 conferred on the Postmaster General a monopoly in telegraphic communication in

13530-415: The world. Salinity gradient energy is called pressure-retarded osmosis. In this method, seawater is pumped into a pressure chamber that is at a pressure lower than the difference between the pressures of saline water and fresh water. Freshwater is also pumped into the pressure chamber through a membrane, which increases both the volume and pressure of the chamber. As the pressure differences are compensated,

13653-652: The year 2008–2009 was 49.17 percent. After more than forty years the Power Plant was shut down permanently on March 31, 2017. It will be replaced with a single Supercritical unit of 660 MW, also run by the TANGEDCO . The replacement does not have clearance yet. The plant is opposed by the residents who fear that the new plant will degrade the air quality and lead to a loss of fishing livelihoods. Power plant Many power stations contain one or more generators , rotating machine that converts mechanical power into three-phase electric power . The relative motion between

13776-478: Was calculated in London and entered into a book, which went with the letters on the road, indicating the amounts due from each postmaster for the letters delivered into his care. At first the new postal network was not especially well publicised; but in his 1673 publication Britannia , Richard Blome sought to remedy this by describing in some detail the geographical disposition of the new 'general Post-Office' , which he called an 'exceeding great conveniency' for

13899-413: Was charged for items posted or delivered in the surrounding 'country' area (which included places such as Hackney, Newington, Lambeth and Islington). The Penny Post letter-carriers operated from seven main sorting offices around London, which were supplemented by between four and five hundred 'receiving houses' in all the principal streets in the area, where members of the public could post items. (Prior to

14022-436: Was demonstrated that a mail coach departing from Bristol at 4pm would regularly arrive in London at 9 o'clock the following morning: a day and a half quicker than the post horses. As a result, the conveyance of letters by mail coach, under armed guard, was approved by Act of Parliament. Mail coaches were similar in design to the passenger-carrying stage coaches , but were smaller, lighter and more manoeuvrable (being pulled by

14145-454: Was established by Edison to provide electric lighting in the lower Manhattan Island area. The station ran until destroyed by fire in 1890. The station used reciprocating steam engines to turn direct-current generators. Because of the DC distribution, the service area was small, limited by voltage drop in the feeders. In 1886 George Westinghouse began building an alternating current system that used

14268-549: Was established in 1695 (although the post-road to Edinburgh continued to be managed from London); in 1710 the Scottish and English establishments were united by statute . By virtue of the same Act of Parliament (the Post Office (Revenues) Act 1710 ), the functions of the 'general letter office and post office' in the City of London were set out, and the establishment of 'chief letter offices' in Edinburgh, Dublin, New York and

14391-540: Was extended to Scotland and Ireland, and across parts of the British Empire . The GPO was abolished by the Post Office Act 1969 , which transferred its assets to the Post Office , so changing it from a Department of State to a statutory corporation . Responsibility for telecommunications was given to Post Office Telecommunications , the successor of the GPO Telegraph and Telephones department. In 1980,

14514-492: Was far from reliable, so in the 1630s Thomas Witherings set about establishing a regular Dover-Calais packet service. By the end of the century additional packet services had been established between Harwich (off the Yarmouth post road) and Helvoetsluys , between Dover and Ostend / Nieuport , and between Falmouth and Corunna . The packet services were generally arranged by contract with an agent, who would commit to provide

14637-408: Was introduced in 1837, and these began to be widely used enabling mail to be sorted in transit; TPO operation was greatly aided by the invention in 1852 of a trackside ' mail-bag apparatus ' which enabled bags to be collected and deposited en route . By the 1860s the Post Office had contracts with around thirty different rail companies. The development of marine steam propulsion inevitably affected

14760-417: Was introduced in 1848, and parcel post in 1883; that same year the term 'letter-carrier' was replaced with ' postman ' in the GPO's official nomenclature. By the 1850s the postal system was described as having become 'universal all over the three kingdoms: no village, however insignificant, being without its receiving-house'. In 1855 a network of 920 post offices and 9,578 sub-offices were in place around

14883-434: Was only after much lobbying that a 'cross-post' between Bristol and Exeter was authorised, in 1698; previously mail between the two cities had to be sent via London). In 1720 Bath postmaster Ralph Allen , who had a vision for improving the situation, took over responsibility for the cross-posts (i.e. routes connecting one post road to another) and bye-posts (connecting to places off the main post roads). He greatly expanded

15006-554: Was slightly damaged by a German bomb in 1917 and in 1940, was set alight during the London Blitz , destroying much of the interior. It reopened in 1943. By the 1950s, the volume of telegraph traffic had declined and the Telegraph Office closed in 1963. In 1984 the new British Telecom Centre was opened on the site. The Post Office commenced its telephone business in 1878, however the vast majority of telephones were initially connected to independently run networks. In December 1880,

15129-494: Was the state postal system and telecommunications carrier of the United Kingdom until 1969. Established in England in the 17th century, the GPO was a state monopoly covering the dispatch of items from a specific sender to a specific receiver (which was to be of great importance when new forms of communication were invented); it was overseen by a Government minister , the Postmaster General . Over time its remit

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