Grain Power Station

Grain Power Station is a CCGT power station and former oil-fired power station in Kent, England, with operational capacity of 1,275 megawatts (1,710,000 hp) owned by Uniper (formerly E.ON UK).

Grain Power Station
CountryEngland
LocationIsle of Grain
Kent
Coordinates51.445181°N 0.715028°E / 51.445181; 0.715028
StatusDecommissioned and demolished
Construction began1971 (Oil station)
2007 (Gas station)
Commission date1979 (Oil station)
2010 (Gas station)
Decommission date2012 (Oil station)
Owner(s)Central Electricity Generating Board
(1979–1990)
PowerGen
(1990–2002)
E.ON UK
(2002–2016)
Uniper
(2016–present)
Operator(s)As owner
Thermal power station
Primary fuelOil-fired
Tertiary fuelNatural gas
Site area100 hectare
ChimneysOne (244 metres)
Cooling towersNone
Cooling sourceRiver / sea water
Combined cycle?Yes
Cogeneration?Yes
Power generation
Units operational5 (2 oil, 3 gas) 660 MW
Make and modelAlstom (CCGT)
Units decommissionedAll
Nameplate capacity1,320 MW (1,770,000 hp) (oil) and 1,275 MW (1,710,000 hp) (gas)
Annual net outputSee text
External links
Websitewww.uniper.energy/en/what-we-do/where-we-operate/united-kingdom.html
CommonsRelated media on Commons

grid reference TQ886753

History

Grain was built on a 250-acre (100 ha) site for the nationalised Central Electricity Generating Board. The architects were Farmer & Dark with Donald Rudd and Partners.[1] It was built by several contractors including John Laing Construction (Civils), the Cleveland Bridge Company (Steel Frame & Cladding), N. G. Bailey (Electrical), Babcock & Wilcox (Boilers) and GEC Turbine Generators Ltd (steam turbines) beginning before 1975.[2] It opened in 1979.[3] The principal buildings were the main boiler house - turbine house block, an attached central control wing, a detached range of offices, the chimney and a gas turbine power station. The buildings are steel framed and reinforced concrete construction. The main boiler house - turbine house block was nearly half a kilometre long. The larger buildings had curved eaves and slightly pitched roofs, an attempt to reduce the visual impact of the site.[1]

Grain power station was located on the Isle of Grain, where the River Medway flows into the Thames Estuary. The station had the second tallest chimney in the UK,[4] at 244 metres (801 ft), visible from a wide area of North Kent and parts of South Essex. The chimney was built by specialist contractors Bierrum and Partners Ltd; Drax Power Station has the tallest chimney, at 259 metres or 850 feet. This chimney was demolished at 11am on 7 September 2016.[3] Grain adjoins the site of the BP Kent oil refinery, which closed in 1982. The station burned oil to drive, via steam turbines, two 690 megawatts (930,000 hp) (gross power output – but 30 megawatts (40,000 hp) was used on-site, leaving 660 megawatts (890,000 hp) for export to the Grid) alternators. There were four boilers rated at 592 kg/s, steam conditions were 538°C, with 538°C reheat.[5] The station was capable of generating enough electricity to supply approximately 2% of Britain's peak electricity needs.

The station was originally designed to have a total capacity of 3,300 megawatts (4,400,000 hp) from five sets of boiler/turbine combinations. The two remaining oil-fired generating units were mothballed by Powergen in 2002 and 2003, but almost immediately the company began to consider reopening the plant as electricity prices increased rapidly. It was operated by E.ON UK who also operated the nearby Kingsnorth coal-fired station, now also decommissioned.

The plant did not meet the emissions requirements of the Large Combustion Plant Directive and was required to close by 2015.[6]

However, due to the rising costs of maintaining the plant, E.ON UK, the owners of Grain Oil power station, announced that Grain was to be mothballed and the site closed by 31 December 2012.[7] Grain Oil power station generated no further electricity but was maintained as standby capacity for the grid.

In April 2014 the dismantling process at the site began, being carried out by Brown and Mason Ltd; it was expected to take around 2 years to complete. On 10 May 2015, three buildings on the site were destroyed. Three of the five boiler houses were demolished by explosives on Sunday 2 August 2015. The 244m-high chimney was demolished on 7 September 2016.[8] Until 2014, BBC Radio Kent maintained an Outside Broadcast reception antenna on top of the chimney. The chimney is now officially the largest structure to ever be demolished in the United Kingdom beating the New Brighton Tower which won the title almost one hundred years ago.[9]

Electricity output

Electricity output for Grain power station over the period 1979-1987 was as follows.[10]

Grain gas turbine plant annual electricity output GWh.

Grain power station annual electricity output GWh.

The load factor in 1984/5 was greater than 100 per cent. Rotational capability plant was being operated at Grain, Ince and Littlebrook oil-fired power stations; this was in the context of the 1984-5 miners strike.

New combined cycle gas turbine plant

A new 1,275MW plant consisting of three natural gas-fired combined cycle gas turbine units capable of generating enough electricity to supply around one million homes has been constructed on the site. Construction work by Alstom started in May 2007, finished in May 2010, and cost £580 million. One of the gas turbines was first fired on 2 June 2010. The overall efficiency was expected to be 72%.

The power station is able to transfer up to 340MW of heat energy recovered from the steam condensation to run the vaporisers in the nearby liquefied natural gas terminal, allowing for a reduction in carbon emissions of up to 350,000 tonnes a year.[11]

It has three GT26 gas turbines. The whole scheme is designed to three Alstom KA26 Single-Shaft Combined Cycle Power Plant Power Blocks; these include a STF30C reheat steam turbine, a heat recovery steam generator and a TOPGAS hydrogen-cooled turbogenerator each.[12]

References
  1. Royal Commission on the Historical Monuments of England (1995). The Power Stations of the Lower Thames. Swindon: National Monuments Record Centre.
  2. "A – Z list of Bridges Built by Cleveland Bridge Company". Newcastle University. Archived from the original on 27 May 2003. Retrieved 18 April 2011.
  3. "Giant chimney demolished at former power station". ITV News. 7 September 2016. Retrieved 20 September 2020.
  4. "Grain Power Station - Flue gas stack illustration". Skyscraper Page.
  5. Handbook of Electricity Supply Statistics 1989. London: The Electricity Council. 1990. p. 4. ISBN 085188122X.
  6. "Large combustion plant directive". E.ON UK. Archived from the original on 3 January 2010.
  7. "E.ON UK announces oil-fired Grain-A power station to be mothballed and the site closed by 31 December 2012". E.ON UK. Archived from the original on 28 April 2017.
  8. "Chimney at Grain Power Station to become tallest concrete structure ever demolished next week". Kent Online. 30 August 2016. Archived from the original on 31 August 2016. Retrieved 5 September 2016.
  9. "Landmark Kent power station chimney blown up in demolition of UK's tallest concrete structure". Archived from the original on 22 June 2018.
  10. CEGB Statistical Yearbooks (1979-1987). CEGB, London.
  11. "Grain CHP". E.ON UK. Archived from the original on 2 January 2010. Retrieved 27 October 2009.
  12. TOPGAS Archived 6 January 2011 at the Wayback Machine
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