Hornsea 1 OFTO

Offshore GridOperationalGB1,200 MW220 kV561 km

Basic Information

Also known as:Hornsea One OFTO, Hornsea Project One OFTO, Diamond Transmission Partners Hornsea One OFTO, Hornsea One Offshore Transmission Owner, TR6 Hornsea One OFTO

Status:Operational

Capacity:1,200 MW

Transmission Model:Developer Build & Transfer

Owners:

Chubu Electric Power Co., Inc.(49%)

Mitsubishi HC Capital(31%)

DTUK BLK Bidco Holdings Limited (ultimate controller BlackRock)(20%)

Project Company:

Diamond Transmission Partners Hornsea One Limited

Type:offshore grid

Expected Life:25 years

Website:www.diamondtransmissionpartners.com

Description:

Hornsea One OFTO is the offshore transmission link that conveys electricity from the Hornsea Project One offshore wind farm to the onshore GB transmission network. The connection transmits c.1,218 MW of alternating‑current power collected at three offshore substations and routed via a reactive compensation station (RCS). The transmission system uses...

Supply Chain (0)

Project Timeline (0)

No lifecycle events recorded yet.

Route

	North Sea	North Sea	Southern North Sea	North Sea	North Lincolnshire
Landfall	N/A	N/A	N/A	N/A	—
Grid Connection	—	—	—	—	Killingholme 400kV substation (National Grid)

North Sea

Landfall:N/A

Grid:—

North Sea

Landfall:N/A

Grid:—

Southern North Sea

Landfall:N/A

Grid:—

North Sea

Landfall:N/A

Grid:—

North Lincolnshire

Landfall:—

Grid:Killingholme 400kV substation (National Grid)

Financial

£1,174.9M€1,692.8M adj.€2.51k/MW-km

www.ofgem.gov.uk (Mar 2021)

CAPEX:£1,174.9M

Adjusted to 2025¹:€1,692.8M

Cost Intensity¹:€2.51k per MW-km

Estimate Date:Mar 2021

Source:www.ofgem.gov.uk

Notes:

OFTO final transfer value / assessed costs for Hornsea One transmission assets (includes onshore substation, export cables, offshore reactive compensation station and three offshore substations).

¹ Cost inflated in local currency then converted to euros (where applicable).

Cable Specifications

Offshore substation (GB 1) to Reactive Compensation Station (RCS)

3 × 220 kV HVAC · 1218 MVA · 84 km

System:3 × 220 kV HVAC

Power rating:1218 MVA

Route length:84 km(84 subsea)

Central Offshore Substation to Reactive Compensation Station (RCS)

1 × 220 kV HVAC · 84 km

System:1 × 220 kV HVAC

Route length:84 km(84 subsea · 0 land)

Burial depth:

Project documents describe the export/transfer cables in the Hornsea 1 transmission system as buried offshore export cable circuits; specific nominal or target burial depths for the inter-platform inter‑substation links are...

Offshore substation (GB 3) to Reactive Compensation Station (RCS)

1 × 220 kV HVAC · 84 km

System:1 × 220 kV HVAC

Route length:84 km(84 subsea · 0 land)

Interlink: Offshore Platform (GB 1) – Central Offshore Substation

34 kV HVAC

System:34 kV HVAC

Route length:0 km land

Burial depth:

Ofgem and project documentation describe the offshore export and transmission circuits (including interlinks between offshore substations) as buried subsea cable circuits; however no target or achieved burial depths for the...

Interlink: Central Offshore Substation – Offshore Platform (GB 3)

220 kV HVAC

System:220 kV HVAC

Export cable circuit A: Reactive Compensation Station (RCS) – Killingholme substation

Horseshoe Point, Lincolnshire, United Kingdom

1 × 220 kV HVAC · 400 MVA · 103 km

System:1 × 220 kV HVAC

Power rating:400 MVA

Route length:103 km(65 subsea · 38 land)

Burial depth:

Sources describe the export circuits as buried offshore and buried onshore but give no detailed target depths. Ofgem and project documents refer to 'three buried offshore export cable circuits' and...

Export cable circuit B: Reactive Compensation Station (RCS) – Killingholme substation

Horseshoe Point, Lincolnshire, United Kingdom

1 × 220 kV HVAC · 400 MVA · 103 km

System:1 × 220 kV HVAC

Power rating:400 MVA

Route length:103 km(65 subsea · 38 land)

Export cable circuit C: Reactive Compensation Station (RCS) – Killingholme substation

Horseshoe Point, Lincolnshire, United Kingdom

1 × 220 kV HVAC · 400 MVA · 103 km

System:1 × 220 kV HVAC

Power rating:400 MVA

Route length:103 km(65 subsea · 38 land)

Stations

Offshore Platform (GB 1)

Hornsea Project One (offshore), United Kingdom

1200 MW 220 kV · offshore

Rating:1200 MW · 220 kV

Location:offshore

Type:HVAC Collector Station

Central Offshore Substation

Hornsea Project One - Central Offshore Substation, United Kingdom

1218 MW 220 kV · offshore

Rating:1218 MW · 220 kV

Location:offshore

Type:HVAC Collector Station

Offshore Platform (GB 3)

Hornsea Project One offshore substation (Hornsea 1, southern North Sea), United Kingdom

220 kV · offshore

Rating:220 kV

Location:offshore

Type:HVAC Collector Station

Reactive Compensation Station (RCS)

Hornsea Zone (Southern North Sea), United Kingdom

220 kV · offshore

Rating:220 kV

Location:offshore

Type:Reactive Compensation

Killingholme substation

Killingholme (North Killingholme), Lincolnshire, United Kingdom

1218 MW 400 kV · onshore

Rating:1218 MW · 400 kV

Location:onshore

Type:HVAC Collector Station