Table of Contents
| Project at a Glance | |
| Project Name | Hornsea One Offshore Wind Farm |
| Project Type | Greenfield |
| Project Location | Off the coast of Yorkshire, UK, southern North Sea |
| Sector | Energy |
| Subsector | Wind Energy |
| Project Value | USD 4.54 Billion |
| Project Status | Commissioned |
| Project Developer/Coordinator | Orsted |
| Capacity | 1.2 GW |
| Project Start Date | 2016 |
| Project Completion Date | 2020 |
| Turbine System | Siemens Gamesa SWT-7.0-154 |
Overview
Ørsted AS developed the Hornsea 1 Wind Farm, a USD 4.54 billion greenfield project located off the Yorkshire coast in the southern North Sea. Commissioned in 2020, it features a capacity of 1.2 GW and employs Siemens Gamesa 7 MW turbines to generate clean, renewable energy. As one of the largest offshore wind farms globally, Hornsea One is a milestone in the UK's renewable energy sector, actively contributing to the nation's carbon reduction efforts and exemplifying a commitment to sustainability.
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Background
Hornsea Project One, located off the Yorkshire coast in the Hornsea Zone of the southern North Sea, is a significant offshore wind farm venture. Established as a 50:50 joint venture between Orsted (formerly DONG Energy) and Global Infrastructure Partners, it marks a substantial investment in offshore wind energy.
In 2018, Orsted divested its 50% shares among Global Infrastructure Partners, Greencoat UK Wind and The Renewables Infrastructure Group having ownership stakes of 50%, 29.7%, 12.5%, and 7.8% respectively.
Orsted's expertise in offshore wind development drives this project alongside its partner. The project is part of a larger initiative, including Hornsea Two (under construction) and Hornsea Three (under construction), collectively aiming to add over 3 GW of capacity to the region.
Following a final investment decision in February 2016, Hornsea Project 1 began generating power in February 2019, with full operations commenced by early 2020. The wind farm, with a lifespan of around 25 years, is expected to power approximately one million homes in the UK and create up to 2,300 job opportunities.
Project Timeline

Hornsea 1 Location
Hornsea 1 is located 120 km off the Yorkshire coast in the Southern North Sea, United Kingdom. The project is developed in the Hornsea zone and covers 407 square kilometers.

Source: Orsted
Technical Specifications
The technical specifications of the Hornsea One Offshore Wind Farm encompass both onshore and offshore infrastructure. The onshore facilities, situated in North Killingholme, North Lincolnshire, feature essential components such as a substation, underground cables, core buildings, compounds, low-voltage electricity equipment, communication cables, and associated roadways, pathways, drainage systems, and landscaping.
Notably, the onshore substation, constructed with Powercrete for optimal thermal conductivity, serves as a crucial hub for transferring electricity from the offshore wind farm to the national grid substation.
Offshore, the wind farm spans a sizable area of 32,200 square meters and incorporates various critical components, including transformers, reactors, high-voltage gas-insulated switchgear systems, static VAR compensators (SVCs), or static synchronous compensators (STATCOMs), and harmonic filters.
The offshore cable system plays a vital role, with cables making landfall at Horseshoe Point, south of Grimsby, and connecting to underground onshore cables through transition joint bays. This extensive cable network spans approximately 40 kilometers underground, linking the landfall site to the onshore substation in North Killingholme.
In March 2021 the agreement for the sale of Hornsea's transmission assets to Diamond Transmission Partners Hornsea One (DTP). Under this agreement, DTP, a collaborative venture between Mitsubishi's Diamond Transmission Corporation and Chubu Electric Power, acquired key assets, including the onshore substation, export cables, offshore reactive compensation systems (RCS), and three offshore substations.
Operational continuity will be ensured through a long-term agreement for operations and maintenance services provided by Orsted, further cementing the project's commitment to reliability and efficiency.
Contractors Involved
| Company | Role | Notes |
| Siemens Gamesa Renewable Energy SA | Wind Turbine Supplier | Supplied 174 Siemens 7MW turbines |
| Balfour Beatty | Onshore Substation Construction | - |
| Atkins | Engineering Design (Offshore Substations) | Provided design services for 3 offshore substations |
| Fugro Geoconsulting | Site Investigation | Used Greatship Manisha and Bucentaur vessels |
| RPS | Environmental Impact Assessment (EIA) | Led EIA for all 3 projects |
| A2SEA | Wind Turbine Installation (Partial) | - |
| CHC Group | Aviation Services (Initial Phase) | - |
| ABB | High-Voltage Cable System | Supplied 220kV cable system |
| Babcock International Group | Remote Control System (RCS) Construction | - |
| Wartsila | Switchboards & Distribution Boards (Offshore Substation) | - |
| Bladt Industries & Semco Maritime | Substation Topsides | Order placed in May 2016 |
| EEW Special Pipe Constructions (EEW SPC) | Transition Pieces (124) | Supplied to Bladt |
| EEW Offshore Structures, Britain (EEW OSB) | Transition Pieces (86) | Manufactured pieces from Bladt & EEW SPC |
| Wilton Engineering | Transition Pieces (20) | - |
| SPIE UK | Transition Piece Installation (20) | Contract awarded in February 2019 |
| Mech Tool Engineering | Suspended Internal Support Structures (SIPS) | Manufactured for EEW OSB |
| DEME (Tideway subsidiary) | Cable Installation (Design & Build) | Design and build contract for cables |
| JDR | Subsea Power Cables (Supply) | Supplied 242 km of cables |
| NKT | Subsea Power Cables (Manufacture) | Manufactured cables at Cologne & Karlskrona facilities |
| Royal Boskalis Westminster | Foundation Transport & Installation | Contract won in October 2016 |
| DeepOcean 1 UK | Array Cable Installation & Trenching | Contract secured in November 2016 |
| Siem Offshore Contractors (SOC) | Inner Array Grid Cable System Transport & Installation (Partial) | Contract secured in November 2016 |
| Dragados Offshore | Substation Jackets | Procured and fabricated jackets, piles for substations & RCS |
| LOC Renewables | Marine Warranty Surveying (MWS) | - |
| Seaproof Solutions | Inter-Array Cable Protection Systems (CPS) | Supplied a total of 372 CPS |
| Spectrum Offshore | Survey Work (Rix Leopard vessel) | - |
| BD Systems | Internal Hydrocarbon Blast Walling & Doors (Offshore) | Design, engineering & delivery in February 2017 |
| SeaRoc Group | SeaHub Unmanned Communication Units | - |
| ALE & Conbit (subsidiary) | Offshore Engineering, Transportation & Installation (Transition Pieces) | ALE for engineering, transportation etc., Conbit for specialist engineering services |
| Manor Renewable Energy | Temporary Power Package | Supplied generators, vessels & personnel for turbine installation in November 2018 |
| Seaway Offshore Cables | Inner Array Grid Cable System Engineering, Transport & Installation | - |
| RINA | Lightning Protection & Earthing Design (Onshore Substation) | - |
| Hanson UK | Powercrete Supply (Onshore Substation Construction) | - |
| ABP Mer | Seabed Mobility & Level Change Investigation | Investigated wind farm & export cable corridor |
| SAL | Monopile & Transition Piece Transport | Transported 174 monopiles and 68 transition pieces |
| DNV GL | Lenders' Technical Due Diligence | Completed in September 2018 |
Project cost
The estimated cost for the development of Hornsea Project One amounts to at least USD 4.54 billion. Ørsted initially entered a joint venture with SMart Wind for the project in December 2011, securing a partial ownership stake. This partnership included an option for Ørsted to acquire the remaining 66.66% ownership upon receiving consent from the Secretary of State for Energy and Climate Change. Upon the granting of consent in December 2014, Ørsted exercised its option on February 4th, 2015, subsequently becoming the sole proprietor of the project.
Environmental Impact
The Hornsea Project One offers the benefit of clean energy generation but raises concerns about ecological disruption. While it's expected to significantly reduce greenhouse gas emissions, the project's construction and infrastructure pose potential threats to marine life.
Underwater noise and seabed disturbance from construction activities could harm benthic communities and displace fish. Collisions with wind turbines threaten birds, particularly migratory species. Additionally, historical shipwrecks or submerged cultural heritage sites on the seabed could be damaged. Further surveys are needed to assess these risks in detail.
The project acknowledges the need for mitigation measures, including careful construction planning, habitat restoration, and monitoring programs. Consulting DEFRA's EIA guidelines and the project's Environmental Statement can provide a more comprehensive picture of the environmental impact and proposed mitigation plans.
Current Status & Future Outlook
Hornsea Project One wind farm, operational from 2020, provides clean energy for roughly 1 million households in the UK. Currently co-owned by a consortium led by Orsted, the project's future outlook suggests continued operation for 20-25 years. As offshore wind technology advances, there's potential for future upgrades to enhance power generation capacity at Hornsea One.
Summary
The Hornsea One Offshore Wind farm is a significant greenfield project located off the coast of Yorkshire, UK. It was commissioned in 2020 and has a capacity of 1.2 GW. The project, developed by Orsted, utilizes Siemens Gamesa turbines to generate clean, renewable energy. It is one of the largest offshore wind farms in the world and contributes to the UK's carbon reduction efforts. The project has faced environmental concerns regarding its impact on marine life, but mitigation measures have been implemented. The wind farm is currently operational and expected to continue operating for 20-25 years, with potential for future upgrades.
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