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.

Hornsea 1 Wind Farm

Description

Hornsea One, located in the North Sea, comprises 174 turbines and covers an area of 407 square kilometres (157.2 square miles). It was the world's first offshore wind farm to exceed 1 GW in capacity, produces enough green energy to power over one million homes, and features the longest powerline (900 km). With a combined total capacity of 1.2 GW, Hornsea One held the title of the world’s largest wind farm until its sister project, Hornsea 2, came into operation in August 2022.

Hornsea One became fully operational in 2019 and is operated and maintained from Ørsted’s East Coast Hub in Grimsby, England. The offshore wind farm is owned by Ørsted (50%) and Jupiter Offshore Wind Limited (50%). It was initially developed by Smart Wind Ltd, a joint venture between Mainstream Renewable Power and Siemens Project Ventures GmbH and was awarded by the Crown Estate as part of the Offshore Wind Round 3 Programme.

For more information on the Hornsea projects, check out this 60 minutes video!

Location

Hornsea One is located 120 km (74.5645 miles) off the Yorkshire coast in the North Sea. The farm covers 407 square kilometres (157.2 square miles). Hornsea Two is located about 55 miles east of the Port of Grimsby. The landfall site for Hornsea Project One is at Horseshoe Point, Marshchapel.

Licensing Information

  • November 2016: Marine Management Organisation (MMO), Deemed Marine Licences (DML)
  • December 2014: United Kingdom Government, Development Consent Order
  • November 2014: Secretary of State, Final Environmental Impact Assessment (EIA)
  • March 2014: The Planning Inspectorate, Report on the Implications for European Sites (RIES)

Project Timeline

  • 2020: Fully operational.
  • 2019: Hornsea One starts producing power.
  • 2018: Start of offshore construction.
  • 2017: Landfall cable construction begins.
  • 2016-2019: Onshore construction.
  • 2016: Hornsea Zone was disbanded into project-specific Agreements for Leases.
  • 2015: Ørsted Energy takes full ownership of the project.
  • 2014: Hornsea Project One awarded an FID (Final Investment Decision). Development Consent granted by the Secretary of State.
  • 2012-2013: Consultation events in local communities took place to discuss environmental and local impact.
  • 2011: Ørsted Energy acquires 33% stake in the Hornsea One project.
  • 2010: Smart Wind Ltd is awarded the ‘Hornsea Zone’ by the Crown Estate as part of the Offshore Wind Round 3 Programme.

Key Environmental Issues

During construction, a code of construction practice (CoCP) for vessel operators was put in place to protect marine mammals. Vessel operators were not to deliberately approach marine mammals and to avoid abrupt changes in course or speed should a marine mammal approach the vessel.

Per the marine mammal monitoring plan (MMMP), a soft start was required to provide an audible cue to allow marine mammals to flee the area before piling at full hammer energy commenced. A 30-minute soft/slow-start was used for all piling activities. Piling commenced at a maximum of 20% hammer energy with a reduced strike rate. Hammer energy ramped up with a maximum increase up to full hammer energy. The strike rate increased from every six seconds to every four seconds over the soft start.

Metadata Documents

Environmental Papers and Reports

Environmental Monitoring: Hornsea 1 Wind Farm

Phase Stressor & Receptor Design and Methods Results Publications Data
Baseline Fish Trawl Survey
A fish screening assessment took place in the area of Project One and across a wider regional study area in the southern North Sea. Surveys were performed in spring and fall during pre construction though boat-based trawling of the area. 		Complete
Populations of migratory fish species considered in the screening assessment include sea lamprey, twaite shad, allis shad and Atlantic salmon. A single salmon was recorded at the mouth of the Humber Estuary during the spring survey, a single twaite shad was recorded in the northeast of Subzone 1 during the autumn trawl survey. No lamprey were recorded, though these surveys were not specifically designed to target migratory fish species. 		RPS group 2013

No data publicly available.
Baseline Marine Mammals Tagging
Twelve grey seals were tagged at the Donna Nook haul-out. 		Complete
Tracking data showed that the seals transitioned between haul-outs at Donna Nook and Dogger Bank, moving across the Hornsea zone. 		RPS group 2013

No data publicly available.
Baseline Marine Mammals Boat-based observation
Boat-based surveys were performed throughout the lease area over two years of surveying. 		Complete
Grey seal densities average 0.043 animals per square kilometer in the Hornsea Zone plus 10 km buffer, with slightly lower densities recorded in Subzone 1 plus 4km buffer (0.038 animals per square kilometer). 		RPS group 2013

No data publicly available.

Baseline Marine Mammals Boat-based observation
In the summers of 1987 and 1989, four whale observers and one bird observer were located on a cruising ship to record the boat position and any visible species. 		Complete
On average, 14.7 seabirds and 1.2 cetaceans were recorded per 10-minute period. Northern fulmar, Atlantic puffin, white pilot whale, white-sided dolphin, and common dolphin accounted for most sightings. 		Skov et al. 1995

No data publicly available.
Baseline Birds Bird displacement study
Assessment of the displacement effects of Hornsea 1 on birds was performed during the breeding, post-breeding, and non-breeding seasons using pre-existing ornithological data. The assessment focused on Guillemots and Razorbills. 		Complete
Using Natural England’s assumptions, displacement levels of 30% and 40% for guillemot and razorbill birds, respectively, were identified. A mortality rate of 2% of displaced birds is assumed. This displacement and mortality are below the necessary threshold. 		Jenner 2014

No data publicly available.
Baseline Birds Boat survey
Boat-based bird surveys were undertaken to collect data for ornithological characterization of the wind farm area. Year 1 data covers March 2010 to February 2011, and Year 2 data covers March 2011 to February 2012. 		Complete
In winter months British breeding birds are joined by migratory birds from continental Europe and Fennoscandia. Pelagic seabirds may also be present in particular months (gannet, fulmars, auks), and great skua and lesser black-backed gulls use the area as a migration corridor to leave the North Sea. 		RPS group 2013

No data publicly available.
Baseline Birds Satellite tagging
In each of the three years 2010-2012, adult northern gannets (Morus bassanus) from Bempton Cliffs, on the northeast coast of England, were fitted with satellite tags to investigate their foraging ranges during chick-rearing and early post-breeding periods. 		Complete
Tagged birds entered the Hornsea wind farm area during early post-breeding periods before birds dispersed out of the North Sea. Breeding success was high during all three years of study. 		Langston et al. 2013

Seabird Tracking Data