Scottish and Southern Energy (SSE) is building the 840MW Keadby-2 combined-cycle power plant in Keadby, North Lincolnshire, UK.

Estimated to cost £350m ($442m), the gas-fired power plant will be owned and operated by SSE. It is being developed on a site adjacent to SSE's existing 735MW Keadby-1 combined-cycle gas-fired power station.

The ground-breaking ceremony for the project was held in October 2018, while main civil works were started in April 2019.

Scheduled to commence operations in 2022, the Keadby-2 power plant will have an operational life of 25 years.

Keadby-2 combined-cycle power plant make-up

Keadby-2 combined-cycle power plant will consist of one 50Hz version of Siemens HL-class SGT-9000HL gas turbine with associated boilers and a single exhaust stack, one condensing steam turbine unit, and a heat recovery steam generator (HRSG).

It will further include up to 16 hybrid cooling towers, a water treatment plant, control room and administrative block, and ancillary buildings.

Siemens HL-class gas turbine features

Siemens SGT-9000HL 50Hz four-stage air-cooled gas turbine comes with 567MW single-cycle power output and features advanced can-annular combustion system, multi-layer thermal barrier coating on blades and vanes, and advanced 3D blading for higher aero-efficiency in the compressor.

It is derived from Siemens’ proven HL-class gas turbine design, which has completed more than 650,000 operating hours with 99.5% reliability.

With a ramp-up rate of 85MW/min, the SGT-9000HL 50Hz gas turbine provides more than 63% efficiency in combined-cycle operations.

The nitrogen oxide (NOx) emissions of the turbine are below two parts per million (ppm).

Keadby-1 power plant history and details

Erected on the site of a former coal-fired power station, the existing 735MW Keadby-1 gas-fired combined-cycle power plant was commissioned in 1996.

It was originally developed and owned by Keadby Generation, a 50:50 joint venture between Scottish Hydro Electric and NORWEB. Scottish Hydro Electric bought NORWEB’s 50% stake in 1997 to become the sole owner of the plant.

Scottish Hydro Electric, however, subsequently was merged with the English public electricity supplier Southern Electric to become Scottish and Southern Energy (SSE) in December 1998.

The Keadby-1 gas-fired power plant consists of two GE Frame 9FA gas turbines of 250MW rated capacity each, one 260MW steam turbine, and a HRSG.

SSE mothballed the Keadby-1 plant because of low power prices in March 2013, but resumed the operations in December 2015.

Gas supply and electricity transmission for Keadby-2

The Keadby-2 power plant will be supplied with natural gas from National Grid’s gas transmission system through a new pipeline connected to the existing gas compound at Keadby-1. National Grid has confirmed sufficient supply of gas for the new power plant.

The electricity output from Keadby-2 will be fed into National Grid’s electricity transmission system via an overhead transmission line connected to the Grid’s existing 400kV substation  located immediately north-west of Keadby-1 power plant.

Contractors involved in Keadby-2 power project

Siemens was awarded the turnkey engineering, procurement, and construction (EPC) contract for the 840MW Keadby-2 combined-cycle power plant in June 2018. The contractual scope includes supply of SGT-9000HL gas turbine and a 15-year service agreement, which is Siemens’ first such long-term service contract for an HL-class gas turbine in Europe.PJ Carey, a civil engineering firm based in the UK, is the civil construction contractor for the project. It is responsible for the construction of turbine buildings, cooling tower, and auxiliary structures, apart from building a ring road around the project site.

Britcon, a civil engineering firm based in Scunthorpe, is engaged for site development works, while CLS Civil Engineering, a local contractor, was responsible to demolish the existing structures from the erstwhile coal-fired power plant to prepare the ground for construction.

Environmental Resources Management (ERM), a global environmental consulting company based in the UK, was involved in the environmental impact assessment (EIA) of Keadby-2 power project.

Mayer Brown was engaged to carry out the traffic and transport impact assessment of the Keadby-2 power plant.