C-Power / Thornton Bank

Wind Project Site

Title: C-Power / Thornton Bank

Status:

In Operation

Project Manager:

C-Power

Turbine Developer:

Senvion

Foundation Manufacturer:

THV Seawind

Website:

External Link

Construction Start:

February 1, 2008

Operation Start:

July 1, 2009

Info Last Updated:

April 16, 2025

Contact:

MUMM Scientific Service
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Details

Technology:

Fixed Offshore Wind

Project Scale:

Commercial Farm

Turbine Model:

Senvion REpower 5M (6), Senvion 6.2M126 (48)

Hub Height:

90-120 m, 85-117 m

Rotor Diameter:

126 m

Number of Turbines:

Capacity per Turbine:

6 × 5 MW, 48 × 6.15 MW

Installed Capacity:

325.2 MW

Support Structure:

Monopile, Gravity Foundation, Jacket Foundation

Inter-Array Cables:

33 kV

Export Cables:

Buried Seafloor Cables

Export Cable Voltage:

150 kV, 170 kV

Number of Export Cables:

Cable Landfall:

Horizontal Directional Drill

Physical Site:

Shallow Water (<60m)

Water Depth:

12 to 27.5 m

Distance from Shore:

27 km

Country:

Belgium

Description

C-Power, also known as Thornton Bank Offshore Wind Farm, is the oldest offshore wind farm in Belgium and has a capacity of 325 MW. The project is located in the North Sea, 30km from West Flanders, Belgium and features a total of 54 turbines. The development of the C-Power wind farm took almost 10 years from the award of the first permits and concessions to the construction, and occurred in three distinct phases.

The wind farm was developed by C-Power and its structural partners: the consortium THV Seawind (joint venture between Dredging International and Fabricom), Senvion (formerly known as REpower), ABB, and the Port of Ostend.

Location

C-Power is located in the Exclusive Economic Zone of the Belgian Continental Shelf. The wind farm was built on the Thornton sand bank, located around 30 km off the coast of Belgium, across an area of 19.84km².

The wind farm area is divided into two sub-areas, Sub area A (southwestern part) and Sub area B (northeastern part). Sub area A consists of 30 turbines, while Sub area B has 24 turbines.

The two sub-areas are separated by a channel defined around the Interconnector gas conduct and the Concerto South 1 telecommunication cable. Water depth in the region ranges from 12 m to 27 m. The nearest port to C-Power is the Port of Ostend in Belgium, located approximately 30 km from the wind farm on the Belgian coast. The C-Power Thornton Bank wind farm's export cables make landfall on the Belgian coast, near Zeebrugge. The cables connect to the Elia substation "Sas Slijkens" upon reaching land.

Licensing Information

8 July 2016: Minister responsible for the marine environment, Environmental permit
23 January 2014: Minister responsible for the marine environment, Environmental permit
6 May 2013: State Secretary for Energy, Domain concession
3 February 2010: State Secretary for Energy, Domain concession
25 April 2008: Minister responsible for the marine environment, Environmental permit
10 May 2006: Minister responsible for the marine environment, Environmental permit
1 September 2005: Applicant, Environmental permit
14 April 2004: Minister responsible for the marine environment, Environmental permit
27 June 2003: State Secretary for Energy, Domain concession

Project Timeline

2013: Project completion with 54 turbines
2012-2013: Phase 3 - Addition of 18 turbines (6.15 MW each), jacket foundations, second 150 kV export cable, offshore transformer station (110.7 MW total)
2010-2012: Phase 2 - Installation of 30 turbines (6.15 MW each) with jacket foundations and inter-array cables (184.5 MW total)
2007-2009: Phase 1 - Construction of pilot phase with 6 turbines (5 MW each), gravity-based foundations, 33 kV cables, first 150 kV export cable (30 MW total)
2003: Consent granted to develop Thornton Bank offshore wind project

Key Environmental Issues

C-Power began a comprehensive Environmental Impact Study in 2003. In this study, independent marine scientists studied the impact of C-Power’s offshore wind farm on sea birds, sea mammals, fish, and benthic organisms and analyzed possible safety risks and the visual impact from the seashore.

Based on this report, the MUMM (Management Unit of the Mathematical Models of the North Sea) developed an Environmental Impact Assessment (EIA) of the project. The conclusion of both the EIS and EIA were that the impact of the project on the marine environment was minor.

C-Power has participated in a marine environment monitoring program since 2008. The monitoring program compares the expected environmental effects of the wind farm with the empirically observed impacts in and around the Thornton Bank. The monitoring is carried out by MUMM or third parties and the results are published on a yearly basis and are available on the MUMM website.

Monitoring has shown that thousands of organisms are developing on and around the foundations and that fish are increasingly attracted to the Thornton Bank. The MUMM has also identified an increase in the seabird population. Wind farms offer an additional resting-place as well as a new food-abundant area to seabirds. For most species, the dreaded rotor blades of the wind turbines do not constitute any danger. Most seabirds avoid wind farm sites anyway, and of those species that are drawn to it, some fly so high that the radius of the blade hardly ever interferes with their flight height pattern.

Metadata Documents

Thornton Bank Offshore Wind Farm Annual Report 2023 (Magnus 2024)
Thornton Bank Offshore Wind Farm Annual Report 2022 (Magnus 2023)
Thornton Bank Offshore Wind Farm Annual Report 2021 (Magnus 2022)
Thornton Bank Offshore Wind Farm Annual Report 2020 (Magnus 2021)
Thornton Bank Offshore Wind Farm Annual Report 2019 (De Conseth 2020)
Thornton Bank Offshore Wind Farm Annual Report 2017 (De Conseth 2019)
Environmental Impacts of Offshore Wind Farms in the Belgian Part of the North Sea: Marking a Decade of Monitoring, Research and Innovation (Degraer et al. 2019)
Seabird monitoring at the Thornton Bank offshore wind farm: Lesser black-backed gull distribution in and around the wind farm using GPS logger data (Vanermen et al. 2018)
Thornton Bank Offshore Wind Farm Annual Report 2016 (Dumon 2017)
Thornton Bank Offshore Wind Farm Annual Activity Report 2011 (C-Power 2016)
Wind Farm Thornton Bank Phase 1: Annual Environmental Report 2009 (C-Power 2016)
Thornton Bank Offshore Wind Farm Annual Report 2012 (C-Power 2016)
Wind Farm Thornton Bank Phase 1: Annual Environmental Report 2010 (C-Power 2016)
Thornton Bank Offshore Wind Farm Annual Report 2015 (Van Laere 2016)
Early Development of the Subtidal Marine Biofouling on a Concrete Offshore Windmill Foundation on the Thornton Bank (Southern North Sea): First Monitoring Results (Kerckhof et al. 2010)
Seasonal variation and vertical zonation of the marine biofouling on a concrete offshore windmill foundation on the Thornton Bank (southern North Sea) (Kerckhof et al. 2010)
Monitoring of Hydrodynamic and Morphological Changes at the C-Power and Belwind Offshore Windfarm Sites - A Synthesis (Van den Eynde et al. 2010)
Early colonisation of a concrete offshore windmill foundation by marine biofouling on the Thornton Bank (southern North Sea) (Kerckhof et al. 2009)
Bouw en exploitatie van een windmolenpark op de Thorntonbank in de Noordzee: Milieueffectenbeoordeling van het project ingediend door de n.v. C-Power (Management Unit of the North Sea Mathematical Models (MUMM) 2004)

Phase	Stressor & Receptor	Design and Methods	Results	Publications	Data
Construction, Operations	Habitat Change Birds	Displacement Monitoring Ship-based seabird counts and advanced statistical modeling (BACI and INLA) to assess seabird interactions with offshore wind farm infrastructure.	Complete Species-specific responses: Northern gannet, common guillemot, and razorbill showed 60-98% avoidance of wind farm area. Herring and great black-backed gulls demonstrated 3.8-6.6 times higher densities. Spatial analysis revealed 45-78% common guillemot displacement.	Degraer et al. 2019	No data publicly available.
Construction, Operations	Habitat Change Invertebrates	Artificial Hard Substrate Colonization Monitoring SCUBA-based in situ sampling of biofouling on offshore wind turbine foundations. Subtidal and intertidal sampling at multiple depths from 2008-2010.	Complete Rapid colonization with 49-75 taxa identified, including 4 non-indigenous species. Distinct vertical zonation observed with three ecological zones: intertidal, transitional barnacle-Jassa zone, and extensive subtidal zone. Dominant species included Telmatogeton japonicus, Jassa herdmani, and Electra pilosa.	Kerckhof et al. 2010, Kerckhof et al. 2010, Kerckhof et al. 2009	No data publicly available.
Operations	Habitat Change Birds	Avian Impact and Migration Monitoring Multi-technique approach including ship and aircraft surveys, radar tracking, visual observations, and collision risk assessments. Focused on understanding bird migration patterns, behavioral adaptations, and potential collision risks during different seasons.	Ongoing Preliminary investigations revealed variations in bird species interactions with wind farm infrastructure. Identified potential resting and migration route modifications for seabirds and migratory species. Ongoing assessment of collision risks and behavioral adaptations.	Management Unit of the North Sea Mathematical Models (MUMM) 2004	No data publicly available.
Construction, Operations	EMF Fish	Impact Assessment Literature review and in-situ electromagnetic field measurements around marine cables. Evaluation of potential effects on sensitive marine species.	Ongoing Limited potential impacts identified. Rare cartilaginous fish species in the area reduce likelihood of significant electromagnetic field interactions.	Management Unit of the North Sea Mathematical Models (MUMM) 2004	No data publicly available.
Operations	Habitat Change Marine Mammals	Behavioral Monitoring Occasional marine mammal observations, potential use of PODs (Porpoise Detectors) during construction and initial operational phases.	Ongoing Minor and temporary effects expected. Occasional observations to be integrated with seabird monitoring reports.	Management Unit of the North Sea Mathematical Models (MUMM) 2004	No data publicly available.
Construction, Operations	Habitat Change Marine Mammals, Physical Environment	Annual Environmental Monitoring Period: January-December 2009, 2010, 2011, 2012 Comprehensive environmental assessment of Thornton Bank Offshore Wind Farm using multi-method approach, including hydrodynamic measurements, bathymetric surveys, sedimentation and erosion monitoring, cable route assessment, and electromagnetic field measurements.	Complete Monitoring revealed progressive wind farm development from 6 to 30 operational turbines, reaching 215 MW total capacity by 2012. No significant environmental impacts were detected, with minor incidents carefully documented and stringent safety standards consistently maintained throughout the project phases.	C-Power 2016, C-Power 2016, C-Power 2016, C-Power 2016	No data publicly available.
Operations	Habitat Change Physical Environment	Multibeam Bathymetric Analysis and Annual Environmental Monitoring Period: January-December 2011-2015, 2016, 2017, 2019, 2020 Long-term morphological assessment using multibeam surveys, scour depth measurements, and temporal tracking of bathymetric changes. Adapted monitoring protocols in response to COVID-19 pandemic challenges.	Complete Analysis revealed scour depths up to 2m, with distinct foundation area responses: Area B foundations reached morphological equilibrium, while Area A foundations continued to exhibit evolving scour patterns. Depth-dependent scour characteristics were identified, providing insights into seabed transformation around offshore wind infrastructure.	Van Laere 2016, Dumon 2017, De Conseth 2019, De Conseth 2020, Magnus 2021	No data publicly available.
Construction, Operations	Noise Physical Environment	Underwater Noise Monitoring In-situ noise level measurements under various weather conditions. Literature review of potential impacts.	Ongoing Limited knowledge of operational phase noise effects. Occasional observations to be integrated with existing monitoring reports.	Management Unit of the North Sea Mathematical Models (MUMM) 2004	No data publicly available.
Operations	Habitat Change Birds, Fish, Marine Mammals, Physical Environment	Annual Environmental Monitoring and Reporting Period: January-December 2021, 2022, 2023 Comprehensive multi-receptor environmental assessment using diverse monitoring techniques including fish deterrence tests, seabird surveys, marine mammal monitoring (C-pods), hard substrate and fish fauna sampling, water sampling, cable surveys, bathymetric foundation assessments, and meteorological parameter tracking.	Complete Systematic environmental evaluation detected no significant adverse impacts, with any minor incidents promptly documented and effectively managed.	Magnus 2022, Magnus 2023, Magnus 2024	No data publicly available.
Operations	Habitat Change Birds	Lesser Black-backed Gull Distribution and Behavior Tracking GPS tracking of 133 lesser black-backed gulls from Zeebrugge and Ostend colonies using UvA-BiTS trackers. Multi-year analysis (2014-2017) examining spatial and temporal variations in bird behavior around Thornton Bank offshore wind farm.	Complete Birds showed complex interactions with wind farm: preference for outer turbine foundations, decreased flight activity inside wind farm, and wind speed-dependent behavior. 95% of offshore records within 38 km of colony. Significant variation in roosting, flight heights, and wind farm entry based on wind conditions.	Vanermen et al. 2018	No data publicly available.
Operations	Habitat Change Birds	Bird Flight Characteristics Analysis of flight heights, directions, and behaviors using GPS tracking data. Examined rotor height flight proportions, wind and tidal influences on bird movement.	Complete Overall 37% of bird flights at rotor height (31-157m), increasing to 49% inside wind farm. Flight heights strongly influenced by wind velocity, ranging from 30m at low wind speeds to sea level during high winds. Diurnal and seasonal variations in flight patterns observed.	Vanermen et al. 2018	No data publicly available.
Construction, Operations	Habitat Change Fish, Invertebrates	Ecological Community Assessment Comprehensive multi-year monitoring using grab sampling, beam trawling, and underwater photography to assess colonization of artificial hard substrates and soft sediments. Sampling conducted seasonally with increasing intensity during initial colonization phases.	Ongoing Initial findings revealed rapid colonization of artificial substrates, with 49 species identified within 3.5 months. Observed development of distinct ecological zones and potential "reef effect" with increased biodiversity around wind farm foundations.	Management Unit of the North Sea Mathematical Models (MUMM) 2004	No data publicly available.