Severn Power is a £600m, 800MW CCGT power station near Newport in South Wales. Originally owned by Welsh Power, the plant was acquired by DONG Energy in 2009.
Using brownfield land and existing grid connection infrastructure, the new CCGT has been built on the footprint of the former Uskmouth A coal-fired power station and operates next to the 360MW coal-fired Uskmouth power plant (formerly called Uskmouth B). The plant started production in November 2010, after a three year construction period and four months of commissioning.
The plant is 58% efficient and is air-cooled to limit the impact on the local environment.
It takes its gas supplies from a new pipeline connected to the local distribution network owned by Wales and West Utilities. The development created more than 650 high-value jobs during construction and 45 longer-term jobs. The development will create more than 650 high-value jobs during construction and 45 longer-term jobs.
Power plant design
The plant is a Siemens built combined-cycle plant. It has two generating units, each consisting of a gas turbine, a waste heat recovery boiler and a steam turbine.
Siemens’ combined-cycle plants have pre-engineered power plant design, with flexible solutions from power island to complete turnkey plant. The 50 or 60Hz plants come in single-shaft or multi-shaft arrangement, with power generation capacity from 10MW to above 1,000MW. Combined-cycle power plants use the hot exhaust gas of a gas or oil-fired gas turbine to generate steam in a separate water/steam cycle. The hot steam is expanded into a steam turbine, providing power to drive a generator. In a multi-shaft arrangement, the gas and steam turbines are each connected to a generator. In a single shaft, gas and steam turbines drive the same generator.
Power plants in Uskmouth
There has been a power plant on the banks of the Usk for 47 years. The old Uskmouth A coal-fired power station was demolished in 2002. The new plant has been built on the ‘A’ site, alongside Uskmouth Power which is already owned by Welsh Power.
The new plant is expected to increase the UK’s dwindling plant margin (spare capacity at peak demand, which should be a minimum of 20% to maintain secure supplies). The CCGT station is flexible, altering its output to meet changes in daily and seasonal demand.
Uskmouth B has been refurbished, with investment in environmental improvements to meet new legislative requirement. The £120m refurbishment was completed and the station fully commissioned in early 2001, making it the cleanest coal-fired power station in the UK.
Unfortunately, the station went into receivership after only a year of commercial operation. During the period of care and maintenance that followed, the station ran briefly in the winter of 2003–2004.
Project helps UK increase plant margin
The new plant is expected to increase UK’s dwindling plant margin (spare capacity at peak demand, which should be a minimum of 20% to maintain secure supplies). The CCGT station is flexible, altering its output to meet changes in daily and seasonal demand.
The location, as well as reducing the level of transmission losses created by the current generation shortfall, will add to the stability of the UK National Grid.
The site has 96 hectares of land and a 1,250MW connection to the National Grid, presenting opportunities for further development. The new facility could in future supply heat as a byproduct to improve efficiency, and also be upgraded to store carbon dioxide emissions.
Uskmouth power – recoverew water plant
Make-up water for the high-pressure boilers of Uskmouth B is piped from Nash wastewater treatment plant as tertiary treated effluent. It must be treated on site to reach ultra-pure water quality.
To meet Uskmouth’s requirements, Veolia Water designed and built a plant consisting of ultrafiltration and base exchange softening pre-treatment followed by three reverse-osmosis units, with three mixed-bed demineralisation units (two regenerable and one cartridge unit for use during the regeneration of the mixed bed plants).