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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.

Alpha Ventus

Alpha Ventus Wind Farm

Contents

Wind Project Site

Title: Alpha Ventus
Status:
Operating
Project Manager:
Deutsche Offshore - Testfeld und Infrastructur
Turbine Developer:
Adwen Offshore, Senvion
Foundation Manufacturer:
Aker Solutions, OWEC Tower
Construction Start:
Operation Start:
Info Last Updated:
Contact:
Maren Engelhardt
(login for email address)
Website:
External Link

Details

Technology:
Fixed Offshore Wind
Project Scale:
Commercial Farm
Turbine Model:
Adwen AD 5-116 (x6), Senvion 5M (x6)
Hub Height:
90-92 m
Rotor Diameter:
116-123 m
Number of Turbines:
12
Capacity per Turbine:
5 MW
Installed Capacity:
60 MW
Support Structure:
Tripod Foundation, Jacket Foundation
Inter-Array Cables:
33 kV
Export Cables:
AC, Buried Seafloor Cables
Export Cable Voltage:
110 kV
Number of Export Cables:
1
Cable Landfall:
Trenched
Physical Site:
Shallow Water (<60m), Marine, Soft-Bottom Habitat
Water Depth:
30 m
Distance from Shore:
45-60 km
Country:
Germany

Description

The Alpha Ventus wind farm is the first German offshore wind farm and thus has the longest operational experience of all German offshore wind farms. It is owned by Deutsche Offshore – Testfeld und Infrastructur GmbH & Co. KG, which was formed by the three utilities EWE, E.ON, and Vattenfall. In 2019, RWE AG took over the shares of E.ON. The farm consists of 12 5 MW turbines for a total of 60 MW, including six Senvion 5MW turbines on jacket foundations designed by OWEC Tower and six Adwen AD 5-116 turbines on tripods designed by OWT. Alpha Ventus went into operation in April of 2010. The wind farm is located off the coast of Germany on the North Sea near the island of Borkum, with the twelve turbines laid out in a 4x3 grid covering 4 square kilometers of ocean. The entire area of the wind farm is closed to general shipping and fishing.

Within the wind farm, the electricity is routed from the wind turbines to the offshore substation using 33 kV submarine cables. To do this, around 16 kilometers of cable were buried at least 60 centimeters deep in the seabed. In the offshore substation, the electricity is increased to 110 kV and then transported to the mainland via an approximately 60 km long submarine cable that also runs via the island of Norderney. There the electricity is fed into the Hagermarsch substation and from there it is transferred to the German transmission network. The transmission system operator TenneT TSO GmbH is responsible for the offshore grid connection.

In May 2025, the Alpha Ventus consortium decided to decommission the wind farm and will work in close cooperation with relevant authorities over the next few years to develop a plan. This will mark the first time an offshore wind farm is decommissioned and dismantled in Germany.

Location

Alpha Ventus is located in the North Sea 60 kilometers off the coast of Germany, 45km north of the island of Borkum. The farm is controlled from the operations room of EWE Offshore Service & Solutions GmbH in Oldenburg.

Exact locations of each turbine can be found on RAVE’s data webpage. Request to access the data.

Project Timeline

  • May 2025: Alpha Ventus Consortium decided to decommission
  • April 2010: Farm officially opened and became commercially operational
  • November 2009: Construction completed
  • September 2009: Installation begins of additional six turbines
  • August 2009: First six turbines operational
  • July 2009: First turbine installed
  • June 2009: Jacket foundations installed
  • April 2009: Tripod foundations installed
  • July 2008: Construction begins on substation
  • February 2008: Baseline surveying for Marine Mammals
  • 2001: Permit for construction approved by Federal Maritime and Hydrographic Agency

Key Environmental Issues

Alpha Ventus is home to the research institute RAVE (Research at Alpha Ventus), which tackles open issues in offshore wind energy, and boasts the research platform FINO 1, 400 m to the west of the wind farm. Fraunhofer IWES coordinates RAVE projects. Since 2009, an extensive measurement program has been part of RAVE. Four of the twelve turbines of the Alpha Ventus wind farm have been equipped with extensive measurement technology. The marine ecosystem – marine mammals, fish, bottom creatures, sea, resting and migratory birds – were recorded for the first time two years before the start of construction and examined in detail during construction and operation. 

Environmental Papers and Reports

Environmental Monitoring: Alpha Ventus

ID Phase Stressor & Receptor Design and Methods Results Publications Data
2074347 Baseline Marine Mammals Aerial and Boat Based Surveys, Passive Acoustic Monitoring
Three methods were used: line-transect observation by aerial and vessel surveys, and passive acoustic monitoring (PAM) via porpoise detectors (PODs). Surveys were done before construction, during construction, and during operation.  		Complete 
Porpoise activities close to the windfarm were lower in the first two years after construction and then returned to and even exceeded the level of the baseline survey by 2012. 		Diederichs et al. 2014 No data publicly available.
2074382 Construction, Operations Habitat Change

Physical Environment 		Van Veen Grab Samples
Van Veen grab samples taken annually over four years beginning in 2008 in order to study the benthic community and seafloor sediment characteristics. 		Complete
Predominant sediment composition was fine sand, followed by medium sand. This was consistent across all 4 years of sampling. 		Teschke et al. 2023

Teschke et al. 2022
2074383 Construction, Operations Habitat Change

Physical Environment 		Seabed and Fouling Sampling
Seabed and fouling samples were taken from turbine foundations and surrounding seafloor from three wind farms between 2003 and 2012. 		Complete
The water depth was the most important structuring factor for fouling communities while seasonal effects were driving most of the observed changes in soft-sediment communities. 		Coolen et al. 2022 No data publicly available.
2074381 Operations Avoidance

Fish 		Hydroacoustic Surveys, Net Catches, Fish Stomach Content Analysis
The effects of Alpha Ventus on pelagic fish were investigated though hydroacoustic surveys, sampling with net catches, fish stomach content analysis. 		Complete
A relative decline in the abundance of pelagic fish was observed during construction at Alpha Ventus. 		Krone and Krägefsky 2013 No data publicly available.
2074384 Operations Noise

Marine Mammals 		Static Acoustic Monitoring, Visual Monitoring
Monitoring was conducted between 2008 and 2011 to explore the effect of pile driving on harbour porpoises. 		Complete
Lowest densities of observed porpoises occurred during construction in 2009. Strong avoidance response is correlated with pile driving. 		Dähne et al. 2013 No data publicly available.
2074386 Operations Noise

Marine Mammals 		Passive Acoustic Monitoring
In May 2009 a closed bubble curtain surrounding a monopile was used during pile driving at Alpha Ventus and hydro sound measurements were recorded. 		Complete
The bubble curtain’s mitigation effect is strongly dependent on tide and related flow speed and direction. For future applications, there is strong need to direct the bubbles in such a way that their lateral drift is minimized. 		Raimund et al. 2012 No data publicly available.
2078164 Operations Noise

Marine Mammals 		Study of operational underwater sound emission of 5MW offshore wind energy converters
Signals were collected with 5 hydrophones and acceleration sensor s above and below water. Measurements were taken 3x/day for a period of 300 seconds each and took place between 2008 and 2011. 		Complete
Overall in the wind farm it became quieter with increasing power, especially with increasing wave height. The reason is that the background noise was of the same order of magnitude as the turbine noise, the background noise decreased with increasing wind and more than compensated for the increase in turbine noise. 		Radecke and Benesch 2012 No data publicly available.