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Partnering with WREN, questionnaires are sent to offshore wind energy developers around the world who are involved in environmental monitoring. This page provides contextual project information and highlights environmental monitoring, providing links to available data and reports. Content is updated annually.

London Array

London Array

Contents

Wind Project Site

Title: London Array
Status:
Operating
Project Manager:
RWE Renewables (RWE)
Turbine Developer:
Siemens
Construction Start:
Operation Start:
Info Last Updated:
Contact:
Lynn Austin
(login for email address)
Website:
External Link

Details

Technology:
Fixed Offshore Wind
Project Scale:
Commercial Farm
Turbine Model:
SWT-3.6-120
Hub Height:
80 m
Rotor Diameter:
120 m
Number of Turbines:
175
Capacity per Turbine:
3.6 MW
Installed Capacity:
630 MW
Support Structure:
Monopile
Inter-Array Cables:
33 kV
Export Cables:
AC, Buried Seafloor Cables
Export Cable Voltage:
150 kV
Number of Export Cables:
4
Cable Landfall:
Trenched
Physical Site:
Shallow Water (<60m), Marine, Hard-Bottom Habitat
Water Depth:
1.5-25 m
Distance from Shore:
20 km
Country:
United Kingdom

Description

At the time of its inauguration in 2013, RWE’s London Array offshore wind farm was the largest offshore wind farm in the world. It occupies and area of 107 square kilometres and has a capacity of 630 MW. Its 175 Siemens 3.6 MW turbines generate enough clean electricity to power around 500,000 British homes while displacing around 900,000 tonnes of CO2 a year.

Location

The London Array offshore wind farm is located 20km off the Kent coast in the Outer Thames Estuary. It is maintained and operated from the Port of Ramsgate and has a grid connection point of Cleve Hill.

Project Timeline

  • April 2023: Tenth Year in Operation
  • April 6, 2013: Fully Commissioned
  • October 2012: Construction Completed and power production began
  • July 1, 2011: 2 Offshore Substations installed
  • July 2009: Construction Started
  • August 2007: London Array project team was established
  • December 18, 2006: Offtake Conditionally Secured
  • June 2005: Applied for planning consent

Licensing Information

  • May 2009: Department of Energy and Climate Change (DECC), Formal Approval for phase 1
  • December 2008: Swale Borough Council, approval for the Cleve Hill substation
  • August 2007: United Kingdom NationalGrid, Onshore application
  • December 2006: FEPA, Offshore work consented

Key Environmental Issues

As part of the planning and licensing process for London Array, a series of environmental studies were carried out and reported on. The findings were summarised in the Environmental Statement (non-technical summary).

Various ecological mitigation measures were identified and agreed to safeguard the integrity of the project site. These measures are detailed in the Ecological Mitigation and Management Plan.

A three-year post-construction benthic monitoring programme was completed. This programme involved collection of grab and trawl samples at nearly 300 locations followed by all the associated microbenthic and Particle Size Distribution (PSD) sample analyses to test for potential impacts within the wind farm and in areas near the turbines themselves. A detailed analysis of datasets spanning the pre- and post-construction periods was subsequently conducted to validate the predictions made during the Environmental Impact Assessment

Environmental Papers and Reports

Additional London Array data can be found on the Marine Data Exchange.

Environmental Monitoring: London Array

ID Phase Stressor & Receptor Design and Methods Results Publications Data
2080210 Baseline Fish Beam and Trawl Surveys 
Otter and beam trawl pre-construction juvenile and adult fish surveys were undertaken in spring 2010 for the London Array Offshore Wind Farm development.  		Complete 
During the otter trawl surveys, a total of 21 species were caught, 19 within the wind farm site and 15 at control locations. The thornback ray was the species caught in the greatest numbers.

During beam trawl surveys, a total of 17 fish species were caught, 8 at control locations and 15 withing the wind farm site. Solenette and Dover sole were the most abundant species in the locations. 		Brown & May Marine 2010

2010, Brown and May Marine Ltd., London Array Offshore Wind Farm, Spring 2010 Pre-Construction Fish Survey 
2080212 Baseline Fish Otter and Beam Trawling and Sample Analysis 
A commercial demersal trawl with a 100mm cod-end liner was used for sampling. The juvenile fish/epibenthic survey was undertaken using a 2-metre scientific beam trawl. The survey was undertaken from the 20th to the 25th March 2010.  		Complete 
A total of 21 species were caught in the otter trawl, 19 within the wind farm site and 15 at control locations. Thornback ray was the species caught in the greatest numbers.

A total of 17 fish species were caught in the beam trawl, eight at control locations and 15 within the wind farm site. Solenette and Dover sole were the most abundant species. One elasmonbranch species, the lesser spotted dogfish, was caught at both the wind farm and control locations. 		Brown & May Marine 2010

2010, Brown and May Marine, London Array, Spring Fish Survey 
2080211 Baseline Invertebrates GPS Surveys 
Surveys of the main biotope boundaries were carried out using a Garmin GPS system with a quoted accuracy of +/- 10m. The survey was carried out on the morning of Tuesday 28th September, on a moderately large spring tide 		Complete 
In this survey, areas within/adjacent to the mussel beds appeared to very closely match the biotope LMU.Smu.HedMac (Hediste and Macoma balthica on littoral sandy muds). 		Centre for Marine and Coastal Studies Ltd (CMACS) 2004 No data publicly available.
2080205 Baseline Physical Environment Benthic Surveys 
Trawl (beam and otter) surveys were completed April 21-27, 2003, July 7-15, 2003, December 6-11, 2003, and February 20-26, 2004. On each occasion trawls were carried out at 43 locations around the study area and 17 locations along the cable route options.

A grab sampling survey was carried out during the summer of 2004. 		Complete 
The most abundant taxa included: Magelona johnstoni, Bathyporeia elegans, Nephtys cirrose, Spiophanes bombyx, and Mysella bidentata.  		Centre for Marine and Coastal Studies Ltd (CMACS) 2005

2003-2004, CMACS Ltd., London Array Offshore Wind Farm, Benthic Sampling using Beam Trawls, Otter Trawls and Day Grabs in the Thames Estuary during 2003 and 2004
2080207 Construction Displacement

Birds 		Aerial Bird Surveys 
The London Array Offshore Wind Farm site was surveyed eight times, once a month between November and February, during the winters of 2010/11 and 2011/12 using digital high resolution still imagery.

2012/2013 aerial surveys were carried out during the second winter. The site plus a buffer around the wind farm in the Outer Thames estuary was surveyed four time (once per month in November, December, January, and February) during the winter of 2012/2013. A control zone was surveyed with the same frequency over the same period. 		Complete 
The most abundantly counted species included: diver species, small gull species, gannet, kittiwake, guillemot/razorbill, and auk species.

Divers abundance increased across both survey zones throughout the winter of 2010/11. Numbers of divers were lowest in November 2010.

In 2012/2013 the majority of divers recorded were red-throated divers. The remainder were recorded as black-throated and great northern divers. High concentrations of divers were recorded in the norther part of zone 1 as well as along the north-east border of zone 1 in January and February 2013. 		APEM Ltd 2012, APEM Ltd 2013 No data publicly available.
2080206 Construction Displacement

Birds, Marine Mammals 		Aerial Surveys 
Aerial surveys of the proposed London Array Ltd. Offshore wind farm site, and associated control zones, for birds and marine mammals was undertaken between November 2009 and May 2010. 		Complete 
The findings of the four surveys demonstrate that the London Array area is used by a number of species throughout the winter season. Red-throated diver and other bird species were most abundant in January 2010 and least abundant in April 2010.

Marine mammals were recorded in three out of four surveys. 		APEM Ltd 2010

2009-2010, APEM, London Array, Aerial Ornithology Survey 
2080208 Operations Displacement

Birds 		Aerial Surveys 
Aerial surveys were conducted during 2013 and 2014 at the London Array Offshore Wind Farm site and a buffer around the wind farm. 		Complete 
The majority of divers recorded were red-throated divers and the remainder were recorded as black-throated divers and great northern divers. Total diver numbers peaked in December 2013 with 5,748 estimated to be present. 		APEM Ltd 2016 No data publicly available.
2080209 Operations Habitat Change

Birds, Fish, Marine Mammals, Physical Environment 		Trawl, Grab, and Aerial Surveys 
The benthic grab sampling survey was undertaken July 16-31, 2014.

A commercial otter trawl fish survey was conducted in November 2013 and April 2014.

High-definition aerial surveys to record the presence of birds and marine mammals were conducted during the winter period from November 2013 – February 2014. 		Complete 
A total of 291 distinct species were recorded during the 2014 grab sampling survey. The most abundant species were the bivalvue mollusc, Abra alba and polychaete worm, Magelona johnstoni.

A total of 24 species of fish and shellfish were caught in the November 2013 otter trawl and a total of 23 fish and shellfish species were caught during the April 2014 otter trawl.

During the bird surveys, a total of 14 bird species, 2 bird species groups, a single species of marine mammal, and a marine mammal group were recorded. 		MarineSpace Ltd 2015

2013-2015, MarineSpace Ltd., London Array, Year 1 Post-construction Monitoring Report 
2083837 Operations Cetaceans, Marine Mammals, Pinnipeds Boat-based and Acoustic Surveys
A visual and acoustic vessel-based survey was conducted for the presence and distribution of cetaceans within the Thames Estuary, including transects around London Array, from 22nd to 28th April 2022. The survey incorporated 868 km of effort, of which 629 km included acoustic effort using a towed hydrophone array. 		Complete
There were 31 detections of porpoise groups and 16 sightings; of these encounters, seven were ‘matched’ (i.e. both seen and heard). There were also 26 seal sightings, of which 10 were ‘definite’ grey seals and four were ‘definite’ common seals. 		Zoological Society of London and Marine Conservation Research 2022 No data publicly available.
2083838 Operations Marine Mammals, Pinnipeds Boat-based and Aerial Surveys
In August 2024, over several days, surveys were conducted by both observing the seals from boats along the estuary and joining training flights with the Royal Air Force to cover the Greater Thames Estuary coastline and sandbanks between Suffolk and Kent, both located within the wind farm area. The surveys were conducted during low tide when the sandbanks were exposed. Only seals resting on the sandbanks were recorded, those in the water were excluded for this survey. 		Ongoing
During the 2024 seal survey 431 harbour seals and 714 grey seals were counted laying out on sandbanks along the Thames. The final report highlighting these results is still in prep. 		No data publicly available.