Didcot Power Station
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Didcot power station (Didcot B Power Station) is an active
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
power plant that supplies the National Grid. A combined coal and oil
power plant A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid. Many pow ...
, Didcot A, was the first station on the site which opened in 1970 and was demolished between 2014 and 2020. The power station is situated in
Sutton Courtenay Sutton Courtenay is a village and civil parish on the River Thames south of Abingdon-on-Thames and northwest of Didcot. Historically part of Berkshire, it has been administered as part of Oxfordshire since the 1974 boundary changes. The 201 ...
, near
Didcot Didcot ( ) is a railway town and civil parish in the ceremonial county of Oxfordshire and the historic county of Berkshire. Didcot is south of Oxford, east of Wantage and north west of Reading. The town is noted for its railway heritage, Di ...
in
Oxfordshire Oxfordshire is a ceremonial and non-metropolitan county in the north west of South East England. It is a mainly rural county, with its largest settlement being the city of Oxford. The county is a centre of research and development, primarily ...
, England. Additionally Didcot OCGT is a gas-oil power plant, originally part of Didcot A and now independent that continues to provide emergency backup power for the National Grid. A large section of the boiler house at Didcot A Power Station collapsed on 23 February 2016 while the building was being prepared for demolition. Four men were killed in the collapse. The combined power stations featured a
chimney A chimney is an architectural ventilation structure made of masonry, clay or metal that isolates hot toxic exhaust gases or smoke produced by a boiler, stove, furnace, incinerator, or fireplace from human living areas. Chimneys are typic ...
, demolished in 2020, which was one of the tallest structures in the UK, and could be seen from much of the surrounding landscape. It had previously had six
hyperboloid In geometry, a hyperboloid of revolution, sometimes called a circular hyperboloid, is the surface generated by rotating a hyperbola around one of its principal axes. A hyperboloid is the surface obtained from a hyperboloid of revolution by defo ...
cooling tower A cooling tower is a device that rejects waste heat to the atmosphere through the cooling of a coolant stream, usually a water stream to a lower temperature. Cooling towers may either use the evaporation of water to remove process heat and ...
s, three of which were demolished in 2014 and the remaining three in 2019. RWE Npower applied for a certificate of immunity from English Heritage, to stop the towers being listed to allow their destruction. In February 2020, the final chimney of Didcot A was demolished.


Didcot A


History

Didcot A Power Station was a coal and gas-fired power station designed by architect
Frederick Gibberd Sir Frederick Ernest Gibberd (7 January 1908 – 9 January 1984) was an English architect, town planner and landscape designer. He is particularly known for his work in Harlow, Essex, and for the BISF house, a design for a prefabricated council ...
. Construction of the 2,000 MWe power station for the
Central Electricity Generating Board The Central Electricity Generating Board (CEGB) was responsible for electricity generation, transmission and bulk sales in England and Wales from 1958 until privatisation of the electricity industry in the 1990s. It was established on 1 Januar ...
began during 1964, and was completed in 1968 at a cost of £104m, with up to 2,400 workers being employed at peak times. The station began generating power on 30 September 1970. It was located on a site, formerly part of the
Ministry of Defence {{unsourced, date=February 2021 A ministry of defence or defense (see spelling differences), also known as a department of defence or defense, is an often-used name for the part of a government responsible for matters of defence, found in states ...
Central Ordnance Depot. A vote was held in Didcot and surrounding villages on whether the power station should be built. There was strong opposition from
Sutton Courtenay Sutton Courtenay is a village and civil parish on the River Thames south of Abingdon-on-Thames and northwest of Didcot. Historically part of Berkshire, it has been administered as part of Oxfordshire since the 1974 boundary changes. The 201 ...
but the yes vote was carried, due to the number of jobs that would be created in the area. The main
chimney A chimney is an architectural ventilation structure made of masonry, clay or metal that isolates hot toxic exhaust gases or smoke produced by a boiler, stove, furnace, incinerator, or fireplace from human living areas. Chimneys are typic ...
was tall with the six
cooling tower A cooling tower is a device that rejects waste heat to the atmosphere through the cooling of a coolant stream, usually a water stream to a lower temperature. Cooling towers may either use the evaporation of water to remove process heat and ...
s each. The cooling towers were arranged in two groups of three; these were located to the north west and to the south of the main building. The original design was for eight cooling towers but the consultant architect Frederick Gibberd proposed that the number be reduced to six to mitigate the visual impact of the station. The consequent limitation in cooling capability reduced the overall thermal efficiency of the power station.
English Heritage English Heritage (officially the English Heritage Trust) is a charity that manages over 400 historic monuments, buildings and places. These include prehistoric sites, medieval castles, Roman forts and country houses. The charity states that i ...
declined to give
listed building In the United Kingdom, a listed building or listed structure is one that has been placed on one of the four statutory lists maintained by Historic England in England, Historic Environment Scotland in Scotland, in Wales, and the Northern Irel ...
status to Didcot A Power Station in 2013. Though it recognised there were some interesting features, for example the "carefully designed" setting and Gibberd's detailing, there were better examples elsewhere. The station ceased operation on 22 March 2013.


Operation

The station used four 500 MWe generating units. In 2003 Didcot A burnt 3.7 Mt of coal. The station burned mostly pulverised
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dea ...
, but later also co-fired with
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
. Didcot was the first large power station to be converted to have this function. In addition, a small amount of
biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...
, such as sawdust, was burned at the plant. This was introduced to try to depend more on renewable sources following the introduction of the
Kyoto Protocol The Kyoto Protocol was an international treaty which extended the 1992 United Nations Framework Convention on Climate Change (UNFCCC) that commits state parties to reduce greenhouse gas emissions, based on the scientific consensus that (part ...
and, in April 2002, the
Renewables Obligation The Renewables Obligation (RO) is designed to encourage generation of electricity from eligible renewable sources in the United Kingdom. It was introduced in England and Wales and in a different form (the Renewables Obligation (Scotland)) in Scot ...
. It was hoped that biomass could replace 2% of coal burnt. In 1996 and 1997,
Thales UK Thales Group () is a French multinational company that designs, develops and manufactures electrical systems as well as devices and equipment for the aerospace, defence, transportation and security sectors. The company is headquartered in Paris' ...
was awarded contracts by Innogy (now Npower) to implement the APMS supervisory and control system on all of the four units, then enabling optimised emissions monitoring and reporting.For more information, see
Advanced Plant Management System The Advanced Plant Management System (APMS) is a SCADA solution developed in partnership by RWE npower (UK), npower and Thales Group, Thales UK. Based on a real-time application platform, APMS is a monitoring and control system for any large indust ...
, th
Didcot A Case study on the APMS website
or the article about the implementation of the Moore's Quadlog Safety PLC in Didcot .
Between 2005 and 2007 Didcot installed overfire air systems on the four boilers to reduce emissions of nitrous oxide. This ensured compliance with the
Large Combustion Plant Directive The Large Combustion Plant Directive (LCPD, 2001/80/EC) was a European Union directive which required member states of the European Union to legislatively limit flue gas emissions from combustion plant having thermal capacity of 50 MW or grea ...
. Some ash from Didcot A was used to manufacture building blocks at a factory on the adjacent
Milton Park Milton Park is a mixed use business and technology park in Oxfordshire, England, operated by MEPC plc. It is just south of the village of Milton, about west of Didcot. It is on the site of a former Ministry of Defence depot between the A34 ...
and transported to
Thatcham Thatcham is an historic market town and civil parish in the English county of Berkshire, centred 3 miles (5 km) east of Newbury, 14 miles (24 km) west of Reading and 54 miles (87 km) west of London. Geography Thatcham straddles t ...
(near Newbury, Berkshire) for the manufacture of Thermalite aerated breeze blocks using both decarbonized fly and raw ash, but most was mixed with water and pumped via a pipeline to former quarries in
Radley Radley is a village and Civil parishes in England, civil parish about northeast of the centre of Abingdon, Oxfordshire, Abingdon, Oxfordshire. The parish includes the Hamlet (place), hamlet of Lower Radley on the River Thames. It was part of B ...
.


Environmental protests

On the morning of Thursday 2 November 2006, 30
Greenpeace Greenpeace is an independent global campaigning network, founded in Canada in 1971 by Irving Stowe and Dorothy Stowe, immigrant environmental activists from the United States. Greenpeace states its goal is to "ensure the ability of the Earth t ...
trespassers invaded the power station. One group chained themselves to a broken coal-carrying conveyor belt. A second group scaled the 650 ft high chimney, and set up a 'climate camp'. They proceeded to paint " Blair's Legacy" on the side of the chimney overlooking the town. Greenpeace asserted that Didcot Power Station was the second most polluting in Britain after Drax in North Yorkshire, whilst
Friends of the Earth Friends of the Earth International (FoEI) is an international network of environmental organizations in 73 countries. The organization was founded in 1969 in San Francisco by David Brower, Donald Aitken and Gary Soucie after Brower's split with ...
describe it as the ninth worst in the UK. A similar protest occurred early on 26 October 2009, when nine climate change protesters climbed the chimney, and eleven chained themselves to the coal delivery conveyors; the latter group were cut free by police after five hours, but the former waited until 28 October before coming down again — all twenty were arrested, and power supplies continued uninterrupted. The power station was installing improved security fencing at the time.


2013 closure

Didcot A opted out of the
Large Combustion Plant Directive The Large Combustion Plant Directive (LCPD, 2001/80/EC) was a European Union directive which required member states of the European Union to legislatively limit flue gas emissions from combustion plant having thermal capacity of 50 MW or grea ...
which meant it was only allowed to run for up to 20,000 hours after 1 January 2008 and had to close by 31 December 2015 at the latest. The decision was made not to install flue gas desulphurisation equipment which would have allowed continued generation. Studies did continue into whether there was a possibility that Didcot A might be modernised with new super-clean coal burning capabilities; with RWE partly involved in the study, however in September 2012 RWE Npower announced that Didcot A using its current coal burning capabilities would close at the end of March 2013. On 22 March 2013, Didcot A closed and the de-commissioning process began. In 2007, Didcot was identified as a possible site for a new nuclear power station but, as of August 2019, nothing further had been heard of the proposal.


Demolition

The three southern cooling towers of Didcot A were demolished by explosives on Sunday 27 July 2014 at 05:01 BST. There had been a campaign to move the time of the demolition to 6a.m. or later to enable local people to watch the demolition more conveniently, but RWE refused. Despite the early morning demolition, many thousands of people turned out to watch from vantage points, as well as those who watched the towers come down via a live Internet stream and the event trended on Twitter with the hashtag #DidcotDemolition. The three remaining cooling towers were demolished by explosion early on 18 August 2019. The chimney was demolished at 07:30 GMT on 9 February 2020.


2016 collapse

On 23 February 2016, a large section of the former boiler house at Didcot A power station collapsed while the building was being prepared for demolition. One person was killed outright and three people were listed as missing presumed dead. Four or five people were injured, three seriously. Additionally, around 50 people were treated for dust inhalation. The rubble from the collapse was high and unstable, which along with the instability of the remaining half of the building hampered search efforts. The collapse occurred at around 16:00
GMT Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London, counted from midnight. At different times in the past, it has been calculated in different ways, including being calculated from noon; as a cons ...
, and
Thames Valley Police Thames Valley Police is the territorial police force responsible for policing the Thames Valley, covering the counties of Berkshire, Buckinghamshire and Oxfordshire. It the largest non-metropolitan police force in England and Wales, covering a ...
declared a "major incident" shortly thereafter. Initial reports of an explosion were ruled out by police after being reported in the media for several hours following the incident. The boiler house was a
steel frame Steel frame is a building technique with a "skeleton frame" of vertical steel columns and horizontal I-beams, constructed in a rectangular grid to support the floors, roof and walls of a building which are all attached to the frame. The developm ...
d building with the boilers suspended from the superstructure and above ground level to allow for their expansion. At the time of the collapse it was being prepared for
explosive demolition In the controlled demolition industry, building implosion is the strategic placing of explosive material and timing of its detonation so that a structure collapses on itself in a matter of seconds, minimizing the physical damage to its immedia ...
on 5 March, a process which involved cutting the structure to weaken it. On 17 July 2016, what remained of the structure was demolished in a controlled explosion. The bodies of the three missing men were still in the remains at that time. A spokesman said that due to the instability of the structure, they had been unable to recover the bodies. Robots were used to place the explosive charges due to the danger and the site was demolished just after 6 o'clock in the morning (BST). The families said that they wanted their dead relatives back in one piece, not hundreds of pieces but the demolition company highlighted the inherent danger of rescue operations citing that "legally you could not justify humans going back in." The search for the missing men continued the day after the controlled demolition. On 31 August 2016, it was confirmed that a body had been found in the rubble and the search had been paused to allow specialist teams to recover the body. On 3 September the body was identified as Christopher Huxtable from Swansea. On 8 September 2016 police confirmed they had found the body of one of the remaining two missing men. On 9 September, the body was formally identified as that of missing workman Ken Cresswell. The last missing worker was found on 9 September. He was identified as John Shaw from Rotherham. In 2018, Coleman and Company who were doing the demolition announced they were stepping down from the demolition, they were replaced by Brown and Mason.


2019 Pylon fire

During the demolition of the three remaining cooling towers on 18 August 2019, debris from one of the collapsing towers hit a nearby pylon, causing it to explode and catch fire. The substation was shut down to allow the fire to burn out without intervention. Several people received minor burns but did not require medical attention. Up to 40,000 homes lost electricity until power was restored two hours later.


Rail services

Like many power stations built at the time, Didcot was served by a rail loop which is a branch from the
Great Western Main Line The Great Western Main Line (GWML) is a main line railway in England that runs westwards from London Paddington to . It connects to other main lines such as those from Reading to Penzance and Swindon to Swansea. Opened in 1841, it was the or ...
. This allowed weekly coal and oil trains to service the Power Station. Rail facilities included a west-facing inlet connection and an east-facing station outlet connection to the GWML, hopper lines No. 1 and No. 2, and injectors for fly ash on a dust and ash disposal loop. The loop has not been used since the station's closure in 2013 and the track has been partially lifted for construction of a new warehouse on the site of the old coal pits. Initially the coal was supplied from the Nottingham coalfields then latterly from South Wales or Avonmouth when the Northern coal pits were closed. The service from South Wales was usually operated by one Class 66 locomotive pulling 25 EWS Coal Cars. The service ran from Avonmouth in Bristol, down the main line, reversing at Didcot Parkway and into the power station. The connections to the main line were severed in mid-2018 in association with the Oxford area remodelling.


Technical specifications

The technical specifications below were correct as at time of commissioning; later modifications may have changed these.


Turbine

Manufacturer: C.A. Parsons & Co, Ltd H.P. cylinder steam:
Inlet 158.6 bar (2,300 lb/sq.in.) at 565 deg. C
Exhaust 42.0 bar (610 lb/sq.in.) at 365 deg. C I.P. cylinder steam:
39.0 bar (565 lb/sq.in) at 565 deg. C Condenser Vacuum:
-965 mbar (28.5 Hg)


Generator

Manufacturer: C.A. Parsons & Co, Ltd
Maximum continuous rating: 500 MW at 23,500 volts
Phase current: Three phases at 14,450 amps each
Efficiency: 98.63%
Stator cooling: Demineralised water
Rotor cooling: Hydrogen


Boiler

Manufacturer:
Babcock & Wilcox Ltd Babcock International Group plc is a British aerospace, defence and nuclear engineering services company based in London, England. It specialises in managing complex assets and infrastructure. Although the company has civil contracts, its main b ...

Maximum continuous rating: 422 kg/s (3,350,000 lb/hr)
Efficiency: 90.76%
Steam at superheater: 165.5 bars (2,400 lb/sq.in.) at 568 deg. C.
Steam at reheater outlet: 40.3 bars (585 lb/sq.in.) at 568 deg. C.
Feed water temperature: 256 deg. C.
Type of firing: Front face, 48 burners
Dimensions of furnace:
29.6 m (97 ft) wide
9.1 m (30 ft) deep
45.7 m (150 ft) high


Circulating water system

Number of cooling towers: 6
Cooling tower capacity: 11.4 cubic meters per second (150,000 gal/min.) each
Cooling tower dimensions:
Height: 114 m (375 ft)
Diameter: base 91 m (300 ft), top 54 m (176 ft)
Thickness: 0.6m (23 in.) tapering to 0.2m (7 in.)
Total evaporation in six towers: 59 x 103 cubic meters/day (13m gal/day)
Water temperature fall in tower: 10 deg. C
Condenser water flow: 17.0 cubic meters per second (225,000 gal/min)
Water temperature rise in condenser: 10 deg. C
Circulating water pump capacity: 18.2 cubic meters per second (240,000 gal/minute)
Make-up water taken from the River Thames (max): 45m gal/day
Water returned to the River Thames: 32m gal/day


Coal plant

Manufacturer: Babcock-Moxey Ltd.
Train capacity: 1,016 tonnes (1,000 tons), 32.5 tonnes (32 tons) per wagon
Quantity of coal used per day (max): 18,289 tonnes (18,000 tons)


Main chimney

Dimensions: high
Base Diameter:
Number of flues: 4
Gas at exit: 97 km/h (60 mph) at 100 deg. C.


Motor powers

Induced draught fan motor: 1,710 kW (2,290 h.p.)
Forced draught fan motor: 1,200 kW (1,600 h.p.)
Circulating water pump motor: 6,150 kW (8,250 h.p.)
Feed pump motor: 6,410 kW (8,600 h.p.)


Didcot B


History

Didcot B is the newer sibling initially owned by
National Power National power is defined as the sum of all resources available to a nation in the pursuit of national objectives. Assessing the national power of political entities was already a matter of relevance during the classical antiquity, the middle ages ...
, constructed from 1994-7 by Siemens and National Power's in house project team, and uses a (
combined cycle A combined cycle power plant is an assembly of heat engines that work in tandem from the same source of heat, converting it into mechanical energy. On land, when used to make electricity the most common type is called a combined cycle gas turb ...
) gas turbine type power plant to generate up to 1,440 MWe of electricity. It opened in July 1997.


Specification

It consists of two 680 MWe modules, each with two 230 MW SGT5-4000F (former V94.3A) Siemens
gas turbine A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directi ...
s and two
heat recovery steam generator A heat recovery steam generator (''HRSG'') is an energy recovery heat exchanger that recovers heat from a hot gas stream, such as a combustion turbine or other waste gas stream. It produces steam that can be used in a process (cogeneration) or u ...
s, built by
International Combustion International Combustion Limited was a major engineering business based in Derby offering products for the nuclear engineering industry. International Combustion Australia Limited was a separate non-affiliated company. History The Company was foun ...
(since 1997 known as ABB Combustion Services), and a
steam turbine A steam turbine is a machine that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Charles Parsons in 1884. Fabrication of a modern steam turbin ...
.


2014 fire

On 19 October 2014 just after 8pm, three of the mechanical wooden cooling towers serving one of the steam turbines at Didcot B caught fire. Two of the fifteen fan-assisted cooling towers in the row were completely destroyed, one was seriously damaged, and one suffered light damage. The cause was probably an electrical fault in one of the cooling fans. RWE n power managed to get half the plant back into operation on 20 October 2014 whilst the other half would remain out of action until the four damage cooling towers were repaired. The station returned to full operation in 2015.


Didcot OCGT


History

Didcot OCGT is an Open Cycle Gas Turbine that was originally part of Didcot A built in 1968 that uses four open-cycle gas turbines which are each powered by a pair of
Rolls-Royce Avon The Rolls-Royce Avon was the first axial flow jet engine designed and produced by Rolls-Royce. Introduced in 1950, the engine went on to become one of their most successful post-World War II engine designs. It was used in a wide variety of ai ...
engines to generate 100MW of electricity. The site was made separate from the Didcot A station as part of the decommissioning process being retained to provide a strategic emergency backup for the National Grid providing a fast-responding source of additional electricity in periods of high demand.


Specification

Didcot OCGT uses four open cycle gas turbines which are gas-oil fired with combustion gases from all four units combined into a single 101m chimney that has a distinctive blue top.


Ownership

Following
privatisation Privatization (also privatisation in British English) can mean several different things, most commonly referring to moving something from the public sector into the private sector. It is also sometimes used as a synonym for deregulation when ...
of the
CEGB The Central Electricity Generating Board (CEGB) was responsible for electricity generation, transmission and bulk sales in England and Wales from 1958 until privatisation of the electricity industry in the 1990s. It was established on 1 Januar ...
in the early 1990s, Didcot A passed into the control of what became
National Power National power is defined as the sum of all resources available to a nation in the pursuit of national objectives. Assessing the national power of political entities was already a matter of relevance during the classical antiquity, the middle ages ...
, who also started construction of Didcot B. Following demerger the plant passed to Innogy plc (in 2000) and following the takeover of Innogy by RWE in 2002 ownership passed to
RWE npower Npower Limited is a British supplier of gas and electricity to businesses. It has been a subsidiary of E.ON UK since January 2019. The company was formerly known as Innogy plc and was listed on the London Stock Exchange and was a constituent ...
.


Architectural reception

Didcot A won a Civic Trust Award in 1968 for how well it blended into the landscape, following its construction. It was voted Britain's third worst
eyesore An eyesore is something that is largely considered to look unpleasant or ugly. Its technical usage is as an alternative perspective to the notion of landmark. Common examples include dilapidated buildings, graffiti, litter, polluted areas, and e ...
in 2003 by '' Country Life'' readers. British poet
Kit Wright Kit Wright (born 17 June 1944 in Crockham Hill, Kent) is the author of more than twenty-five books, for both adults and children, and the winner of awards including an Arts Council Writers' Award, the Geoffrey Faber Memorial Prize, the Hawthornd ...
wrote an "Ode to Didcot Power Station" using a parodic style akin to that of the early romantic poets and
Marina Warner Dame Marina Sarah Warner, (born 9 November 1946) is an English historian, mythographer, art critic, novelist and short story writer. She is known for her many non-fiction books relating to feminism and myth. She has written for many publicatio ...
, who made a 1991 BBC documentary about the station, described the cooling towers as having "a sort of incredible furious beauty". Artist Roger Wagner painted ''Menorah'', a crucifixion scene featuring the towers of Didcot power station.


See also

*
List of tallest buildings and structures in Great Britain This list contains all types of structures in height or more, which is the accepted criterion for a building to qualify as a skyscraper in the United Kingdom. Entries in ''italics'' denote approximate figures. Structures taller than 300 ...
*
Energy use and conservation in the United Kingdom Energy in the United Kingdom came mostly from fossil fuels in 2021. Total World energy supply and consumption, energy consumption in the United Kingdom was 142.0millionTonne of oil equivalent, tonnes of oil equivalent (1,651TWh) in 2019. In 20 ...
*
Energy policy of the United Kingdom The energy policy of the United Kingdom refers to the United Kingdom's efforts towards reducing energy intensity, reducing energy poverty, and maintaining energy supply reliability. The United Kingdom has had success in this, though energy int ...


References


External links


Power Stations Visits — Didcot A



APMS: Advanced Plant Management System

Architectural views


{{RWE Buildings and structures in Oxfordshire History of Berkshire Power stations in South East England Environmental protests in the United Kingdom RWE Explosions in England
Power stations A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid. Many pow ...
1964 establishments in England 2016 disasters in the United Kingdom