Key facts: London Array location
The London Array Offshore Wind Farm is located more than 20km (12 miles) from the Kent and Essex coasts in the outer Thames Estuary. The site is one of three areas within the estuary that the Government earmarked for offshore wind farm development. The map below shows the wind farm’s position relative to the coast:
In total the London Array site covers an area of around 245km2 on and between two sandbanks, Long Sand and Deep Knock and in waters up to 25m deep. Phase One covers an area of 100km2.
The site is bounded to the west by Black Deep, the main approach to the Port of London, and to the south by the approaches to Fisherman’s Gat. The water depth increases quite quickly to the east of the site, into an area used by shipping. However, there are no major shipping channels within the wind farm site itself, and Long Sand and Deep Knock provide natural barriers along two sides.
The turbines are arranged in rows and columns aligned according to the prevailing south-westerly wind. They are placed 650m to 1,200m apart and connected to each other and to the offshore substations by array cables buried in the seabed.
Why the outer Thames Estuary?
There are several reasons why this location was chosen. Its main advantages include:
- High wind speeds
- Variable water depths
- Nearby ports to enable construction, operation and maintenance
- Suitable ground conditions
- A suitable electricity network connection
- Local power demand (south east England has the UK’s highest electricity demand). Using the electricity locally reduces transmission losses.
Before we gained permission to build at the offshore site, we had to undertake extensive environmental surveys to assess the wind farm’s potential impact on the local area. Our original location plans were amended after the RSPB raised concerns about protecting the Red-Throated Diver, a seabird that overwinters in the outer Thames estuary.
A new onshore substation has been built at Cleve Hill near Graveney, about 1km south of the Thames Estuary. To build the site, we cut a plateau into the north face of Cleve Hill, around 6.4m above sea level. To connect the substation to the offshore wind farm, we needed to drill horizontally through the sea wall.
Cleve Hill is an ideal site as it’s located next to the existing Canterbury-Kemsley 400kV overhead line on the north side of Cleve Hill. Due to the large amount of electricity that London Array will generate, the power must be fed directly into the 400kV network. Cleve Hill offered the only site that satisfied our key environmental and technical criteria: it needed no new overhead power lines or soil deliveries for landscaping, and has little visual impact on its immediate neighbours.
The Port of Ramsgate, on the east Kent coast, is London Array’s base for construction and operations and maintenance. Ramsgate was chosen both because of its existing facilities and the potential to build on these to meet our needs.
We completed the temporary construction base in summer 2010 and our construction team moved into the site in the autumn.
Construction on our permanent operations and maintenance base started in September 2010 and the team moved in towards the end of 2011. The building incorporates a number of environmentally-friendly features, such as a green roof and its own Combined Heat and Power (CHP) plant.