Cockenzie Coal Power Plant is a coal-fired power station in East Lothian, Scotland, capable of co-firing biomass. It is situated on the south shore of the Firth of Forth, near the town of Cockenzie and Port Seton, 8 mi (13 km) east of the Scottish capital of Edinburgh. The Cockenzie Coal Power Plant has dominated the local coastline with its distinctive twin chimneys, since it opened in 1967. Initially operated by the nationalised South of Scotland Electricity Board, it has been operated by Scottish Power since the privatisation of the industry in 1991. In 2005 a WWF report named Cockenzie as the UK's least carbon-efficient power station, in terms of carbon dioxide released per unit of energy generated. The 1,200 megawatt power station is set to close by 2016, but there are plans to replace the current station with a Combined Cycle Gas Turbine (CCGT) power station.

Since 1991, the Cockenzie Coal Power Plant has been owned by the privatised Scottish Power utility group. It recently surpassed its originally intended lifespan. It is now run as a 'marginal station', guaranteeing seasonal and peak supply and non-availability of other power stations. For this reason considerable investment has been made to improve start-up times to maximise generating opportunities in the deregulated electricity generation market. Since 2001, the station has exported electricity to Northern Ireland via an undersea power link.

CCGT replacement

The Cockenzie Coal Power Plant must close by 31 December 2015, so Scottish Power are currently considering replacing it with a Combined Cycle Gas Turbine (CCGT) power station. If the station is built, it will require a 17 km (11 mi) gas pipeline from East Fortune, to supply it with fuel.

Coal transportation

Coal was originally supplied to the station directly from the deep mines of the neighbouring Lothian coalfield, but these have since been exhausted or closed. Subsequently coal has been supplied from open cast mines in the Lothians, Fife, Ayrshire and Lanarkshire.

The power station was the first to use the new "merry-go-round" system of coal deliveries by rail. This system uses hopper wagons which carry around 914 tonnes of coal each. This coal is delivered to the station's coal store, which has the capacity to hold up to 900,000 tonnes of coal. The coal store is situated on the opposite side of B1348 road between Prestonpans and Cockenzie and Port Seton, to the rest of the station. Coal is transported from the coal store to the station's boiler house by a conveyor belt. It is then weighed, sampled and screened, before being pulverised in a pulverising mill. It is then blasted into the station's furnaces with preheated air, to heat the station's boilers.

Water use

The water used in the station's boilers is taken from the local water supply, but is purified in the station's water treatment plant. In the boilers, the water is super heated to a temperature of 556 °C, before it is piped to the station's turbogenerators. It hits the turbine blades, causing the turbine shaft to rotate at 3,000 rmp. This is connected to a generator, which generates electricity at 17 kilovolt (kV). The steam is reheated and then fed to intermediate and low pressure turbines.

After use, the steam is then condensed back into water, using a cooling medium; water from the Firth of Forth. 30 million gallons of water are used for cooling purposes every hour. It is then discharged back into the Firth of Forth.

Ash use and removal

The burning of coal in power stations generates a lot of ash and dust. The station's electrostatic precipitators capture fly ash from the flue gases, preventing them from entering the atmosphere. Bottom ash is also produced by the station. Ash from the station is sold through the ScotAsh company, a joint venture between Scottish Power and Blue Circle. It is used in the construcion industry and in products such as grout and cement. Any remaining ash is piped to the large lagoons in the nearby town of Musselburgh, where it is capped and planted, and used as a nature reserve.

Electricity distribution

The electricity is initially generated at 17 kV. This is stepped up via a transformer to 275 kV for distribution on the National Grid. The electricity is not just distributed to Scotland, but England too, which it is connected to via a double circuit overhead line, operating at 275 kV and 400 kV, to Stella near Newcastle upon Tyne.


The Cockenzie Coal Power Plant occupies a 24 hectare site. It generates electricity using four 300 megawatt (MW) generating units, for a peak supply of 1200 MW.

Cockenzie Coal Power Plant
Country Scotland
Locale Cockenzie
Status Operational
Commission date 1967
Operator(s) South of Scotland Electricity Board
Scottish Power

Power station information
Primary fuel Coal
Secondary fuel Biomass

Power generation information
Installed capacity 1,200 MW