Grain Power Station
| Company type | Power station |
|---|---|
| Industry | Electricity generation |
| Predecessor | Oil-fired Grain power station (1979–2012) |
| Founded | 1979 |
| Headquarters | Isle of Grain, Kent , England, United Kingdom |
| Products | Electricity |
| Owner | Uniper (previously E.ON UK) |
Grain Power Station is a combined cycle gas turbine (CCGT) facility located in Kent, England, currently owned by Uniper (previously known as E.ON UK). It replaced a now-demolished oil-fired power plant with a capacity of 1,320MW that was in operation from 1979 until 2012.
Oil-fired power station
The original Grain power station was developed on a site designated by the nationalised Central Electricity Generating Board. The architectural design was led by Farmer & Dark in collaboration with Donald Rudd and Partners. Major contractors included John Laing Construction (civil engineering), Cleveland Bridge Company (steel framework and cladding), N. G. Bailey (electrical installations), Babcock & Wilcox (boiler systems), and GEC Turbine Generators Ltd (steam turbine manufacturing). The location was chosen in 1971, with construction commencing in 1975 and the plant becoming operational by 1979.
The facility's primary structures consisted of the boiler and turbine house complex, a central control wing, administrative offices, a chimney stack, and an additional gas turbine power station. The buildings incorporated steel frames combined with reinforced concrete; the boiler-turbine block stretched nearly 500 metres featuring curved eaves and pitched roofs designed to minimize visual intrusion.
Situated at London Thamesport on the Isle of Grain, where the River Medway flows into the Thames Estuary, the station boasted the UK's second-tallest chimney at , which was visible across North Kent and parts of South Essex. Constructed by Bierrum and Partners Ltd, it was only exceeded in height by the chimney at Drax Power Station.
Positioned next to the former BP Kent Refinery, which ceased operations in 1982, the power station utilized oil combustion to generate steam driving two alternators (gross output), exporting electricity after meeting internal demand. Four boilers operated with steam flow rates of 592 kg/s at temperatures of 538 °C, including reheating at the same temperature. This installation contributed approximately 2% of the UK's peak electricity requirements.
Originally designed to deliver capacity through five boiler and turbine units, two oil-fired units were placed on standby by Powergen between 2002 and 2003. Due to increasing electricity prices, reopening these units was reconsidered. Managed by E.ON UK alongside the now-retired nearby Kingsnorth Power Station, Grain also housed four open cycle gas turbines rated at 113MWth each, running on gas oil for black start capability and emergency power generation.
Closure and demolition
The station did not comply with emissions limits set by the Large Combustion Plant Directive and was slated for closure by 2015. However, rising maintenance expenses prompted E.ON UK to mothball the facility and fully shut down operations by 31 December 2012. Although generation ceased, the oil-fired plant remained available as reserve grid capacity throughout 2013.
Decommissioning commenced in April 2014 under Brown and Mason Ltd, with an anticipated timeline of about two years. On 10 May 2015, three buildings on-site were demolished, followed by controlled explosions demolishing three out of five boiler houses on 2 August 2015. The chimney, standing as the tallest concrete structure ever demolished in the UK at , was felled on 7 September 2016. This surpassed the previous record held by the New Brighton Tower in Wallasey, Cheshire, which was dismantled between 1919 and 1921. Until its removal in 2014, BBC Radio Kent maintained an external broadcast antenna atop this chimney.
Electricity generation
The electricity production at Grain power station from 1979 through 1987 is summarized below.
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During the period of the UK miners' strike (1984–85), the load factor for 1984/85 surpassed 100%, indicating elevated operational demand. To ensure continuous power supply, the flexible plants at Grain, Ince, and Littlebrook oil-fired stations were heavily deployed.
Grain CCGT power station
Also referred to as Grain power station or Grain CHP power station.
Overview
Situated on the Isle of Grain in Kent, this combined cycle gas turbine (CCGT) facility has a capacity of 1,275MW across three natural gas-fired units, sufficient to supply electricity to approximately one million households. E.ON obtained planning approval in 2006, with Alstom overseeing construction from May 2007 until May 2010 at an estimated cost of £500 million. The initial turbine began operation in June 2010, achieving an anticipated efficiency rate of around 72%.
Operating in combined heat and power (CHP) mode, the station channels up to 340MW of waste heat to vaporisers at the adjacent liquefied natural gas terminal, resulting in carbon dioxide emission reductions estimated at up to 350,000 tonnes per year.
Plant description
The facility incorporates three Alstom GT26 gas turbines arranged within KA26 single-shaft combined cycle units. Each unit consists of an STF30C reheat steam turbine, a heat recovery steam generator (HRSG), and a TOPGAS hydrogen-cooled turbogenerator. The GT26 turbines operate as lean-premix, low-NOx systems, specifically optimized to use natural gas delivered through a 3.5 km pipeline linked to the National Transmission System.
Exhaust from these turbines is utilized to produce steam within the HRSGs, which then powers triple-pressure reheat steam turbines mounted on the same shaft as the gas turbines. Steam condensation and recycling are facilitated by a once-through seawater cooling arrangement that draws water from the River Medway. This system reuses intake and outfall structures originally built for the previous oil-fired plant. The cooling water flow rate is 226,008 m³/h, with a maximum temperature increase of 18 °C; biofouling is controlled through an electro-chlorination treatment.
Generated electricity is elevated in voltage and transmitted into the National Grid via the existing 400 kV substation. Plant control and monitoring are centralized through an ABB 800xA automation platform.
Due to challenging soil conditions—comprising alluvial deposits over London Clay—up to 3,000 foundation piles were installed during construction to support heavy machinery, following a similar approach used for the nearby BP Kent refinery established in the 1950s.
Combined heat and power
When operating in combined cycle mode, the units achieve an overall efficiency of 58.6%, which rises to 72.6% under combined heat and power (CHP) operation. In CHP mode, condenser water is directed to the Grain LNG terminal to assist in vaporizing liquefied natural gas (LNG), transferring up to 341 MW of thermal energy and cutting carbon emissions by as much as 350,000 tonnes annually. The condensers are separated from seawater circuits and connected to the LNG terminal’s submerged combustion vaporisers (SCV) through two pipelines measuring 2.5 km in length and 1.4 m in diameter for supply and return flows. The SCVs operate with warm closed-loop demineralised water at supply temperatures of 42.5 °C and return temperatures of 15 °C, with flow rates ranging from 330 to 2,980 kg/s. Both material selection and water chemistry are carefully managed to prevent stress corrosion cracking within the stainless steel tube bundles of the SCVs.
Development
The plant operator aims to achieve carbon neutrality at Grain by 2035. Investigations are underway into replacing natural gas with hydrogen fuel and introducing carbon capture and storage (CCS) technologies involving post-combustion CO₂ capture. Captured carbon dioxide would potentially be transported via pipeline or ship to depleted offshore gas reservoirs for long-term storage.
Incidents
On 18 February 2022, amid Storm Eunice, one of the chimney stacks collapsed, causing a temporary shutdown of the power station for safety reasons.