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Longannet Power Station
Longannet, near Kincardine, Fife, Scotland, UK
associated engineer
Not known
date  1966 - 1969
UK era  Modern  |  category  Power Generation  |  reference  NS952854
Longannet is the third largest power station in Europe and the location for the UKís first carbon capture plant attached to a working coal-fired power station. It occupies 89 hectares of reclaimed land on the north bank of the Firth of Forth in Scotland.
The power station opened in 1969 and was fully operational by 1973. Its net output of 2,304MW is generated from four generating units. Each consists of one boiler and two 300MW turbo generators.
Coal supplies came from the adjacent Longannet Colliery until its closure in 2002. Now coal arrives by road and rail ó up to 4.5 million tonnes per year. There is site storage for 2 million tonnes of it. The coal is conveyed to 32 pulverising mills, which can each reduce 40 tonnes per hour to powder. This burns like a gas in the boilers, which produce high-pressure steam to turn the turbine shafts that are linked to the generators. Cooling water for the condensers is extracted from (and returned to) the Firth of Forth, through 12 intakes.
Electrostatic precipitators remove fine coal dust (fly ash) from the boiler exhaust gases before they are expelled from the 183m tall chimney. Coarser ash particles are collected from the bottom of the boiler.
In the late 1980s, equipment was installed to remove hazardous sulphur trioxide from the fly ash, and the electrostatic precipitators were refurbished. Large quantities of ash are produced ó up to 4,350 tonnes per day. It is piped to settlement lagoons on Preston Island, which were once salt pans, as part of land reclamation along the Firth of Forth and some is used by ScotAsh in construction projects.
In 1994, the station received European funding to retrofit one of the generating units with equipment to reduce the emissions of nitrogen oxides, carbon dioxide and sulphur dioxide. This was achieved by injecting natural gas into the boiler. In 1996 the remaining three units were retrofitted, reducing the stationís emissions of nitrogen oxides by 40 percent. These works should extend the useful life of Longannet Power Station until 2020 or 2025.
In 2003, Longannet was identified as Scotland's principal source of pollution. In 2006, it was claimed that more than 20 million fish were killed and discarded annually by the screening process for cooling water extraction.
In line with UK government advice, some power is generated by burning biomass ó dried pellets of treated sewage sludge, with a similar calorific value to brown coal. This practice has been ruled illegal since 28th December 2005, under the EU Waste Incineration Directive, but continues.
Longannet burns 48 percent of Scotlandís waste sludge annually (52,800 tonnes), while the remainder is applied to the land (55,000 tonnes) or is taken to landfill (2,200 tonnes). Sludge could be burned legally if the facilities were upgraded to comply with the directive.
A prototype carbon capture unit was commissioned on 29th May 2009, and successful testing was completed on 29th November 2009. It uses amines to remove around 90 percent of the carbon dioxide from flue gases, and can process 1,000 cubic metres of gas per hour. The waste carbon dioxide is liquefied and stored underground (beneath the sea).
The unit is a scaled-down version of a full carbon capture plant, 12.2m long and 2.6m high, weighing 30 tonnes. Improvements to the equipment as a result of testing reduced the energy requirement by around one third, compared with a reference plant. A commercial scheme could be operational by 2014.
Longannet is owned and operated by Scottish Power.
Architect: Robert Matthew, Johnson Marshall & Partners
Boiler supply: Foster Wheeler
Burner supply: ABB Combustion Ltd
Turbine and generator supply: General Electric
Carbon capture prototype (2009): Aker Clean Carbon
Research: ECPK

Longannet Power Station