Grain was built on a site for the nationalised Central Electricity Generating Board. The architects were Farmer & Dark with Donald Rudd and Partners. It was built by several contractors including John Laing Construction, the Cleveland Bridge Company, N. G. Bailey, Babcock & Wilcox and GEC Turbine Generators Ltd beginning before 1975. It opened in 1979. 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. 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, at, 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. Grain adjoins the site of the BPKent oil refinery, which closed in 1982. The station burned oil to drive, via steam turbines, two alternators. There were four boilers rated at 592 kg/s, steam conditions were 538°C, with 538°C reheat. 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 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. 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. 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. 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.
Electricity output
Electricity output for Grain power station over the period 1979-1987 was as follows. 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.
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. 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.
