Offshore Wind Solutions

Offshore brochure I September 2024

Offshore wind solutions

Engineering that excites

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The design and engineering of offshore substations

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Safety in design

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Combining past and present worlds .S.

Offshore substations

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Pilot for offshore hydrogen production

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Floating offshore substation

SECTIO1:N15

A-A -

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ALE Sofia SCHVDC offshore converter platform

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Neart na Gaoithe HVAC offshore substations

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26 GW Programme IJmuiden Ver

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Borssele Alpha & Beta HVAC offshore substations

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Princess Elisabeth Island

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HelWin Beta offshore converter platform

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Thor HVAC offshore substation

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DolWin Alpha HVDC offshore converter platform

CHEEK PLATE

B

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HVAC offshore substations

20000

A

Horns Rev HVAC offshore substation

10000

10000

2 C.O.G.

45°

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Ostwind 3 and Gennaker East & West C-C

PLATFORM NORTH

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Combining past and present worlds Roots and renewables Although most of our work today is in offshore renewables, our roots are in the oil & gas industry. This experience has provided a solid foundation for developing offshore wind substations, both HVAC and HVDC and, more recently, hydrogen energy solutions such as offshore hydrogen production.

As a result, we have developed additional knowledge and skills to meet the challenges of these new projects: adapting to the evolving offshore wind market, meeting new operator requirements, engaging with new stakeholders, incorporating innovative technologies, and handling a broader engineering scope.

Iv is proud to be one of the first to operate in the offshore wind sector, paticularly in the field of offshore substations. We are proud to have developed and engineered the first HVAC substation Horns Rev. A, as well as the first HVDC offshore converter platform BorWin Alpha. Not only were we among the first in substations, we were also at the forefront of the step up to > 1,000 MW HVAC and to 1,300 MW HVDC. Our dedication to innovation did not stop there. A key milestone was the progression to 2GW-525 kV bi-pole HVDC, which is now being brought to life as 2 GW Standard Design for TenneT for application in the Dutch and German North Sea, highlighting our role in pushing the boundaries of offshore wind energy.

We constantly seek the optimum balance between flexibility, efficiency, sustainability and cost, while never compromising on quality and safety in our designs.

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The design and engineering of offshore substations Smart solutions, powerfull results At the moment, onshore wind energy is the most economical way to produce sustainable energy.

However, in the long term, the use of offshore wind farms offers significant benefits.

An offshore location provides ample space for the facility, higher wind speeds than on land and unobstructed areas. The energy generated by wind farm turbines is collected at an offshore substation, where it is transformed to a higher voltage for transportation to shore via large export cables.

Iv has gained a lot of experience in the design and engineering of HVDC offshore converter platforms and HVAC offshore substations over the last couple of years, excecuting many wind energy projects in close cooperation with our partners.

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Safety in design Our core principle Our overall HSE project design objectives are to engineer a safe, reliable and operable facility for the entire service life of the installations. Throughout the design, we constantly ask ourselves and each other, “Can we make our design safer?” We view this as a responsibility towards our clients, stakeholders and their personnel.

Our ‘safety in design’ principle is always developed to at least comply with the applicable legislative codes and standards as a minimum. We are committed to going above and beyond the requirements. We actively encourage every member of our team to critically assess and challenge our chosen solutions to ensure we are adopting the safest practices possible.

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Offshore substations SEAGREEN

1,500 MW

CANADA BERWICK BANK

1,150 MW

EMPIRE WIND

800 + 1,200 MW

NEART NA GAOITHE

VINEYARD WIND

2 X 225 MW

800 MW

UNITED STATES

SOFIA

1,320 MW

SOUTH COAST

1,300 MW

MARWIN

420 MW

ATLANTIC OCEAN

IJMUIDEN VER BÉTA

IRELAND

2,000 MW

UNITED KINGDOM

POSHYDON

1,250 MW

NSE HYDROGEN

500 MW

GREATER GABBARD

2 X 252 MW

PRINCESS ELISABETH ISLAND

3,400 MW

Engineering that excites 10

THOR

1,050 MW

HORNS REV B

209 MW

DENMARK

NORTH SEA OSTWIND 3

HORNS REV A

300 MW

160 MW

BORKUM RIFFGRUND 2

450 MW

HELWIN BETA

BORWIN ALPHA

GENNAKER EAST + WEST

680 MW

460 MW

400 MW

GERMANY

IJMUIDEN VER GAMMA

2,000 MW

DOLWIN ALPHA

800 MW

NETHERLANDS BORSSELE ALPHA + BETA

2 X 700 MW

THORNTON BANK

325 MW

BELGIUM

HVAC • THOR • GENNAKER EAST + WEST • OSTWIND 3 • NEART NA GAOITHE • PRINCESS ELISABETH ISLAND • BORSSELE ALPHA + BETA • BORKUM RIFFGRUND 2 • GREATER GABBARD • THORNTON BANK • HORNS REV A • HORNS REV B

HVAC STUDY • BERWICK BANK • EMPIRE WIND • MARWIN • SEAGREEN • VINEYARD WIND

HVDC • SOFIA • DOLWIN ALPHA • HELWIN BETA • BORWIN ALPHA • IJMUIDEN VER BÉTA • IJMUIDEN VER GAMMA

HVDC STUDY • IJMUIDEN VER • SOUTH COAST

HYDROGEN • POSHYDON (PILOT) • NSE HYDROGEN (PILOT)

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Client Rijksdienst voor Ondernemend Nederland (RVO) Platform operator Neptune Energy Facts Type: PEM electrolyser Nr. of cell stacks: 1 Input power: 1 MW Water consumption: 300 l/h Hydrogen flow: 246 Nm3/hr Hydrogen purity: 99.998% Outlet pressure: 30 barg Footprint: 2 x 40 ft stacked containers Lifting weight: <20 tonnes ( 2 x 20 ft cont) Cable: 9 MVA, 25 kV Production: 400 kg/day

Pilot for offshore hydrogen production The Q13a-A hydrogen pilot project aims to demonstrate green hydrogen production offshore, on a live oil and gas production platform. The lessons learned will help enable large-scale green hydrogen production in the North Sea.

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Off the coast of Scheveningen (The Hague), the first pilot

A logistics, training, and skills gap analysis will also

project for the integration of three working offshore

be carried out, and economic calculations will be

energy systems will take place on the Q13 working

made to determine how the value of hydrogen can

platform, which is already electrified with renewable

be maintained when blended with natural gas. The

energy via a cable to the shore. Energy from wind and

economics of large-scale offshore hydrogen production

demineralised seawater will be converted into green

will also be considered.

hydrogen offshore, according to the wind profile of Eneco’s Luchterduinen wind farm. The green hydrogen

Iv is responsible for the basic and detailed engineering

will be blended with natural gas and transported via

of the necessary adaptions to the platform to

existing pipelines, allowing the existing infrastructure to

accommodate the electrolyser system, Iv is involved

be shared. The platform is expected to be in production

in the risk assessment and mitigation, and provides

by the end of 2024.

offshore expertise. Iv also provided the list of offshore requirements for the containers containing the

Iv is working with several partners in the PosHYdon

electrolyser, the seawater desalination system and the

consortium to create a safe environment for handling

power conversion system.

hydrogen (and oxygen) on a live oil and associated gas platform.

For the hydrogen production system to be tested on land, only a few adaptations are needed: power supply,

Technical limitations of co-production of hydrogen and

sufficient space for the system, supply of (sea)water,

North Sea gas, seawater desalination, power fluctuations

disposal of brine, hydrogen use/release, oxygen release,

and electrolyser performance will be addressed. The

permits to test, and permits to construct. Iv prepared

other partners in the consortium are responsible for

a conceptual design document describing the system

identifying and addressing the requirements related to

interfaces and further requirements for adaptations and

permitting, certification, and entry specifications.

modifications to be carried out onshore.

Pipeline infrastructure Electricity infrastructure Data infrastructure Water infrastructure Waste infrastructure Communication

Oxygen

Platform power

System

Sea water

Brine

Hydrogen Oil/Natural gas

H2 RO

Electrical

Existing infrastructure

Sea water

PEM 1 MW

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Client Internal R&D project Technical data Dimensions:

85 x 85 x 30 m

Weigth Topside: Floater:

approx.11,000 mT 10,000 mT

Water depth Over 150 m

Floating offshore substation Worldwide, the best wind conditions for generating wind energy are often found at sea in areas with deeper water. The question is: how can this be achieved as effciently, reliably, and cost-effectively as possible?

At water depths beyond 150 metres, the costs of the renowned ‘bottom-founded’ offshore structures (such as transformer and converter platforms and wind turbines that are anchored to the seabed via a structure) increase exponentially, making floating solutions an interesting alternative. Iv and Nevesbu jointly developed a concept for an offshore substation. A concept with potential!

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Iv and Nevesbu are consistently carrying out innovative

The main challenge is the transition from a static

studies. In light of the forthcoming energy transition,

bottom-founded substation to a dynamic, floating

Nevesbu began investigating which unique floating

substation. Wind turbines must be capable of operating

applications could be devised to provide a solution.

in conditions up to Beaufort 8, which means that the

Many concepts for floating turbines already exist, but

floating substation must continue to function when

not for a floating substation. We formed a joint initiative

contending with waves of 8 to 12 metres. Existing high

because Iv has already designed many offshore wind

voltage (HV) equipment, however, is not suitable for

substations, and Nevesbu has unique expertise in

high accelerations. To guarantee motions are kept to a

floating structures. The challenges presented with this

minimum, motion analyses were carried out to calculate

type of floating solution include the lifespan of the

how different models behave at sea in strong winds with

dynamic power cables and the allowable motions of the

high waves. These analyses are based on the roughest

transformers, rectifiers, and associated systems. Floating

seas in the world, such as the North Atlantic Gulf Region,

an offshore substation weighing roughly 10,000 tonnes

the Bay of Biscay and the sea near Santa Barbara,

with minimal motions is a complex challenge, but our

California. If the concept is suitable for these waters, it

studies show that it is possible.

can certainly also be applied in calmer waters.

In Europe, the Mediterranean, North Sea, Bay of Biscay,

The floating offshore substation concept is designed to

and the Aegean Sea, in particular, are deepwater areas

operate in water depths in excess of 150 metres and with

that are very suitable for generating wind energy.

minimal vertical motions in sea conditions. The deck area

Especially in the area above Scotland and the United

is 85 by 85 metres and is positioned approximately 20

Kingdom towards Norway and Denmark, there are

metres above the water’s surface. When the substation

almost continuous strong winds. The concept that Iv and

is installed at sea, it will be held in position with the help

Nevesbu have developed is therefore designed for the

of so-called ‘tendons’ that are vertically anchored to the

harsh weather conditions that are characteristic of these

seabed. The floating structure is designed to minimise

areas. The concept also minimises the impact on marine

the vertical motions, which also reduces the loads on

life.

the export cables suspended below the platform. Tuning the motion behaviour of the platform for different water

Some essential principles for the design of the floating

depths and wave conditions is also relatively simple.

offshore substation are: the concept must conform to the set requirements for wind energy at sea, it must not be too heavy in steel weight and must not be complex in terms of fabrication. Safety and reliability must also be guaranteed. It must be possible to guarantee a very high availability, and the platform must have a lifespan of at least 30 years. In addition, the social costs of supplying sustainable electricity must remain affordable, and the solution itself should therefore not be too expensive in terms of costs.

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Client Seatrium. (formerly Sembcorp Marine Offshore Platforms) Technical data Dimensions Topside:

Jacket: Weight Topside: Jacket:

80 x 43 x 45 m (excl. helideck) (lxwxh) 58 x 39 x 44 m (lxwxh) 11,000 mT 4,350 mT

Water depth 28,5 metres below sea-level Field power capacity: 1.4 GW

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No of offshore substations:

1

No of WTG’s:

100

Sofia HVDC offshore converter platform One of the largest wind farms in Europe, the Sofia Offshore Wind Farm, will be realised 195 km off the coast of North East England, in the area known as Doggersbank. With 100 wind turbines covering a total area of 593 km2, totaling a capacity of 1.4 GW and an innovative high voltage direct current (HVDC) converter platform, this wind farm will supply approximately 1.2 million British homes with sustainable energy in the future.

The Sofia HVDC converter platform, to be installed at the heart of the wind farm, will be one of the largest and most powerful offshore HVDC converter platforms currently in existence or under construction.

A 25-metre-high telecom mast will be placed on the top

The water-cooling system allows lower temperatures to

deck of the topside. This telecom mast will provide a

be achieved in the air conditioning system, and smaller

direct connection to the satellite dish on land. However,

ducts to be designed, which in turn require less space.

the challenge here is that when the platform was ready, it was transported by ship around the Cape of Good

The cutting of the first steel for the fabrication of the

Hope in Africa. The platform will convert electricity from

platform took place in August 2021.

66 kV alternating current (AC) to 320 kV direct current (DC). Two export cables of approximately 220 km in

The construction of the wind farm began in early 2021,

length, which together form a single high voltage direct

with the construction of the onshore substation in

current circuit, will transport the power from the wind

Lackenby. The offshore installation has already taken

farm to the onshore substation in Lackenby.

place, and the platform is expected to be operational by 2026.

When converting alternating current to direct current, heat is produced, which must be cooled. The HVAC system (i.e. heating, ventilation, and air conditioning), that is required for cooling the HV system demands a lot of space. Iv has therefore applied a new cooling concept for the Sofia HVDC converter platform.

Conventionally, the cooling system is subcontracted to an HVAC contractor to design the system and supply the components.

For this project, Iv is responsible for the HVAC system, including designing it, purchasing the necessary components, and the integrating it with the process systems.

For the Sofia HVDC converter platform, an HVAC system has been chosen that uses cold water to cool the condenser rather than air. Cooling with cold water has the advantage that the highest design temperature of the seawater used is lower than the temperature of the outside air. Furthermore, the heat transfer of water is better than that of air, allowing the system to be more compact.

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Client EDF Energy Renewables (EDF-ER) Technical data Dimensions OSS Topside (lxwxh): 36 x 26 x 20 m Jacket: Weight OSS Topside: Jacket: Water depth Variation between

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height 41 m + height of the buckets 12 m 1200 mT 1261 mT (-)28.6 m and (-)29.8 m

Field power capacity:

450 MW

No of offshore substations:

2

No of WTG’s:

54 x 8.4 MW

Accommodation:

12 POB

Neart na Gaoithe HVAC offshore substations Iv was awarded the contract to provide the detailed engineering and procurement services for the two Neart na Gaoithe (NnG) alternating current (AC) offshore substations. NnG is a 50:50 JV owned by EDF Renewables UK and ESB. As a subcontractor of HSM, Iv provided the detailed design and procurement of all piping, auxiliary and HVAC equipment, as well as the integration of the high voltage equipment.

Structural workshop drawings for both platforms were also produced

by Iv. HSM has joined forces with General Electric Grid System (GEGS) for the engineering, fabrication, load-out and commissioning of this wind park development in the North Sea near the Scottish coast.

The Neart na Gaoithe (‘strength of the wind’ in Gaelic)

platform power, communications, and platform

offshore wind farm consists of a total of 54 Wind Turbine

operations, with a dedicated area (the cable deck, part

Generators (WTGs), located approximately 15.5 km from

of the substructure) for the pull-in of the inter-array sea

Fife Ness and 29 km from the East Lothian coastline. It

cables and export cable. On the main deck, the MT is

covers an area of 105 km . Each WTG has a capacity of

installed in the centre, with the GIS installed on either

8.4 MW, resulting in a total capacity of 450 MW being fed

side. To improve the overall schedule and allow for the

back to the two HVAC offshore substations by inter-array

full completion, installation, and commissioning of the

sea cables.

HV Equipment before lifting onto the main structure, the

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GIS modules are built separately from the main structure.

The two offshore substations are connected via an interconnector. Each one is connected to the onshore

The offshore substations are normally unmanned.

support station via an export cable, which then connects

However, a shelter (12 POB) will be provided for

to the onshore station to the Scottish grid system. The

emergencies. Furthermore, the substations are equipped

project will supply renewable energy to around 375,000

with lifting trunnions, a pedestal crane, laydown areas,

Scottish homes and will offset over 400,000 tonnes of

W2W platforms, a heli-lift area, and other facilities

CO2 emissions each year.

to accommodate the installation work and future maintenance services.

The offshore substation configuration consists of a receiving end connected to the 66 kV GIS. The main

The engineering phase started in June 2019. On 15

transformer (MT) transfers the power to the export cable

January 2020, the first steel was cut. The loading of

at 220 kV.

the offshore substations took place in the summer of 2022, and the substations were fully commissioned and

Each offshore substation consists of two deck levels. The

handed over to EFD in Q1 of 2023.

cellar deck houses the auxiliary systems for control,

Layout of the Neart na Gaoithe development.

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Client TenneT TSO b.v.

Field power capacity 2 GW Export voltage 525 kV DC Special features design Standard platform design for 2 GW connection

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2 GW Programme IJmuiden Ver On 26 February 2020, Iv signed the contract with TenneT TSO b.v. to carry out the Front End Engineering and Design (FEED) for the world’s first 525 kV offshore grid connection. The FEED is part of the development of a new standard design for two network connections to the IJmuiden Ver wind farms, located in the North Sea.

The two high voltage direct current (HVDC) offshore platforms, Alpha and Beta, will have a capacity of two gigawatts (GW) and will be the world’s first HVDC platforms based on 525 kV. This voltage level is just one example of HV technologies that have never before been applied offshore.

With this innovatively high level of voltage, the platforms will be suitably equipped to supply green electricity to around four million households. This would be enough to supply around half of all private households in the Netherlands with sustainable electricity.

The technology required for this capacity has never been applied before, making this project unique. Throughout the entire design process, trade-offs will be made with regard to the lowest ‘Levelised Costs of Energy (LCOE)’ and the enhancement of nature. It is Iv’s and TenneT’s intention that nature should benefit from this project. Therefore, environmental measures have been integrated as fundamental conditions into the design criteria of the HVDC platforms.

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Borssele Alpha & Beta HVAC offshore substations

Client TenneT TSO b.v.

Technical data Borssele Alpha

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Dimensions Topside (lxwxh): Jacket (lxwxh):

58 x 32 x 25 m 28 x 27 x 55 m

Weight Topside: Jacket:

3700 t 2900 t

Borssele Beta Dimensions Topside (lxwxh): Jacket (lxwxh):

58 x 32 x 26 m 37 x 35 x 57,5 m

Weight Topside: Jacket:

3700 t 2950 t

Piles:

61 m each

Field power capacity:

2 x 700 MW each

The offshore high voltage substations Borssele Alpha and Beta are required to link the wind farms built offshore in the Dutch North Sea. The Borssele Alpha project, followed by the Borssele Beta project, are the first large-scale grid connections to be constructed under the National Energy Agreement for offshore wind farms in the Netherlands.

HSM Offshore has taken on the engineering,

The Borssele Alpha offshore substation was delivered

procurement, construction, transport, installation,

during the summer of 2019. The Borssele Beta offshore

connection, and testing of the offshore substation

substation, which is almost identical to the Alpha

under an EPCI contract. Iv is the subcontractor for this

platform, was delivered in July 2020.

project and is responsible for the design, engineering, and procurement support, including the integration of the TenneT-supplied high voltage components and the balance of plant materials.

The detailed design and engineering includes both the steel jackets with skirt pile foundations and the liftinstalled topsides.

Iv is responsible for the procurement of all necessary services, materials, and equipment, as well as the onshore and offshore commissioning of all systems for the jackets and topsides, including the TenneT-supplied HV equipment. Iv also manages the interfaces with the other parts of the network connection, such as the 66 kV wind farm and 220 kV export cable connections.

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Princess Elisabeth Island

Client Elia Location 45 KM off the Begium Coast Technical data Dimensions

6 hectares

Weight 9,000 metric tonnes (all modules combined) Special features 2 x 1,050 MW AC Modules 2 x 700 MW AC Modules Facility Module Garage 2x Diesel Generator skids General island electrical infrastructure All modules will be placed on an artificial island Field power capacity:

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3,400 MW

The HSI Joint Venture, consisting of HSM Offshore Energy, Smulders, and Iv, has been awarded the contract for the development of Princess Elisabeth Island—the world’s first artificial energy island off the Belgian coast, commissioned by transmission system operator Elia.

Iv is responsible for designing four high-voltage substations for Princess Elisabeth Island: two with a capacity of 1,050 megawatts each and two with a capacity of 700 megawatts. The total capacity amounts to approximately 3.5GW, sufficient to meet the annual energy needs of more than three million households.

In addition to designing the four high-voltage substations, Iv is also responsible for the facilities module and garage design. The design, which includes the development of the layout and 3D model of all transmission assets on the energy island, will be carried out from Iv’s office in Papendrecht. For prefabrication, Smulders will use its Belgian facilities, while HSM will use its facilities in Schiedam. Final assembly of the modules will take place at the HSM Offshore Energy yard in Schiedam and at the Smulders yard in Vlissingen.

The project includes 330 km of 220-kV HVAC cables, divided into two contracts of 165 km each. Additionally, the island will feature five HVAC substations equipped with transformers and gas-insulated switchgear (GIS).

A unique aspect of this project is that the island will combine high-voltage direct current (HVDC) and alternating current (HVAC) for the first time. Princess Elisabeth Island will also serve as a hub for future hybrid interconnectors, efficiently combining offshore wind energy transmission with cross-border electricity exchange.

The high-voltage electrical equipment market is currently under pressure due to high demand and rising material costs, which has influenced the tender process.

Despite these challenges, the contracts were awarded on competitive terms, aligning with current market conditions.

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Client TenneT TSO b.v./Siemens Dimensions Topsides (lxwxh): Jacket (lxwxh):

100 x 43 x 75 m 63 x 42 x 48 m

Weight Topsides: Jacket:

10,4000 T 4,700 T

Power generation 680 MW Water depth 24 m

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HelWin Beta offshore converter platform HelWin Beta is an offshore high voltage direct current converter platform. This means the incoming alternating current from the wind farms is converted into direct current by the converter platform. The converted current is then transported via inter-array sea cables and land cables to a converter station onshore, where it is changed back into alternating current. This conversion process minimises energy losses during the transport of energy from offshore wind farms to shore. The HelWin Beta platform has been installed in the German part of the North Sea in a water depth of 23 metres, and 55 kilometres off the coast of Germany.

TenneT Offshore, the operator of the project, has

During the process of energy conversion, a significant

selected Siemens as the main contractor for the entire

amount of heat is released in the transformers and

offshore link. Siemens granted Heerema Fabrication

converters. To cool down this equipment, the platform

Group (HFG) the contract for the construction of the

has a large water cooling system and an HVAC system,

platform, with Iv responsible for the engineering and

connected to the water cooling system.

design of the topsides. The jacket has been engineered and designed by HFG Engineering. As engineer, Iv is also

The water cooling system sends fresh cooling water

responsible for the procurement of the non-high-voltage

through circulation pumps to the equipment,

equipment.

maintaining a controlled temperature of 18 to 25°C. The heated water returning from the equipment is cooled by

Iv’s Consult division will provide the workshop drawings

seawater heat exchangers. In order to do this, seawater

for HFG. HelWin Beta is designed as an unmanned

is pumped up, passed through the heat exchangers, and

platform, normally operated remotely when there are

then discharged back overboard.

no personnel on board. The HelWin Beta platform will be operated from the control centre of the electricity

The maximum capacity of HelWin Beta is 680 megawatts,

network in Lehrte or from the land station in Büttel.

enough to supply over 500,000 households with energy.

The HelWin Beta platform is designed as a ‘daughter’

The wind turbines in the connected farms will provide

platform of the ‘mother’ platform HelWin Alpha.

power as 33 kV AC. The turbines are connected to socalled HVAC transformer platform in the middle of the wind farm, which transform the energy to 155 kV AC. From there, the energy will be delivered to the HelWin Beta transformer platform. The energy is then first converted to 320 kV HVAC and thereafter to 320 kV DC.

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Client RWE Thor Wind Farm Technical data Dimensions Topside (lxwxh): Jacket (lxwxh):

41 x 32 x 25 m 35 X 35 x 50 m

Weight Topside:

max. 2,900 T

Water depth 28 m Field power capacity:

1,050 MW

Thor HVAC offshore substation Situated in the Danish North Sea, near Thorsminde, Thor is set to become Denmark’s largest wind farm, with a capacity of approximately 1,000 MW. This project is the first of three initiatives envisioned under the country’s 2018 Energy Agreement, aiming to supply sustainable energy to over 1.5 million households. Iv, in partnership with HSM Offshore Energy, is entrusted with the role of designing and integrating the offshore substation.

This offshore substation is essential for the efficient transmission of electricity generated by the farm’s 72 wind turbines to the mainland, thereby solidifying Thor’s role in Denmark’s renewable energy strategy.

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Central to this initiative is the implementation of two main 66/275 kV HVAC transformers and associated equipment, engineered to revolutionise the efficiency and environmental impact of offshore wind farms. The Thor offshore substation, one of the most powerful HVAC substations under construction, will transform 66 kV AC generated by the wind turbines into 275 kV AC and weighs less than 3,000 mT. Upon completion, the Thor offshore wind farm will mark Denmark’s shift towards a greener future, significantly reducing reliance on fossil fuels and and increasing the use of clean, renewable energy. Led by RWE, this project reflects the necessary investment and focus on developing green energy technologies.

Expected to be operational in 2027, Thor highlights Denmark’s commitment to sustainable energy. It also demonstrates the technical expertise and innovation needed to make renewable energy a key part of global energy systems.

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Client TenneT TSO b.v./ABB Technical data Dimensions Topside (lxwxh): 62 x 43.3 x 40 m (excluding helideck) Jacket (lxwxh): 45 x 42 x 44 m Weight Topside: Jacket:

11,000 T 4,000 T

Water depth 27m Accommodation 24 persons Input 8 cables of 155 kV AC Output 2 x 320 kV DC Throughput 800 MW Power generation 2 x 3050 kV A / 10 kV Diesel

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DolWin Alpha HVDC offshore converter platform TenneT Offshore GmbH is the electrical network operator of the HVDC platforms in the German sector of the North Sea and the client for the design, manufacturing and installation of the HVDC platforms.

ABB Offshore Wind Connections is the main contractor for the entire DolWin project, which consists of the DolWin Alpha offshore HVDC converter platform, an onshore transformer substation in Dörpen (Germany) for the connection to the German electricity grid, and all the interconnecting onshore and offshore cables. Heerema Fabrication Group in Zwijndrecht (the Netherlands) was contracted by ABB to design and construct the converter platform, including its support facilities, with Iv commissioned to provide the design.

The DolWin Alpha converter platform consists of a jacket with a large topside and is equipped with an auxiliary and emergency generator, helideck, and an accommodation quarters. The legs are supported by six foundation piles driven approximately 55 metres into the seabed.

The DolWin Alpha converter platform houses an 800 megawatt HVDC converter substation. The key components of the HVDC substation comprise a 155 kilovolt Gas Insulated Switchgear (GIS) for connecting the AC cables to the wind farm, main transformers of 155 kilovolts/320 kilovolts, and a 400 kilovolt rated GIS for linking and protecting the main step-up transformers.

The substation and all its supporting systems have a minimum service life of 30 years.

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Ostwind 3 and Gennaker East & West HVAC offshore substations

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Client 50Hertz Transmission GmbH

Client 50Hertz Transmission GmbH

Client 50Hertz Transmission GmbH

Gennaker East

Gennaker West

Ostwind 3

Technical data Dimensions Topside (lxwxh): Jacket (lxwxh): Piles:

Technical data Dimensions Topside (lxwxh): Jacket (lxwxh): Piles:

48 x 33 x 17 m 40 x 25 x 40 m 104 inch, 75 inch

Technical data Dimensions Topside (lxwxh): Jacket (lxwxh): Piles:

48 x 33 x 20 m 60 x 43 x 65 m 104 inch, 75 inch

Weight Topside 4,800 mT Jacket: 3,100 mT

Weight Topside: Jacket:

4,800 mT 3,100 mT

Weight Topside: Jacket:

4,800 mT 4,500 mT

Water depth 17 m

Water depth 16 m

Water depth 43 m

Field power capacity 450 MW

Field power capacity 450 MW

Field power capacity 300 MW

Transmission 66 kVa AC to 220 kVa AC

Transmission 66 kVa AC to 220 kVa AC

Transmission 66 kVa AC to 220 kVa AC

48 x 33 x 20 m 40 x 33 x 20 m 104 inch, 75 inch

The Ostwind 3 and Gennaker East & West projects, with

These tailored designs, which support the topsides

a combined generation capacity of 1.2 GW, have been

with a six-leg jacket, are engineered to withstand the

designed to significantly boost green energy production

challenging conditions of the Baltic Sea and meet the

in the German Baltic Sea region. These projects will be

environmental noise restrictions during installation. The

overseen by the HSI consortium, consisting of HSM

engineering approach for each substructure is carefully

Offshore Energy, Smulders, and Iv, responsible for the

tailored to the specific site conditions. For example,

engineering, procurement, construction, transport and

Ostwind 3 will be provided with a skirt pile jacket.

installation, and commissioning of the HVAC offshore

The Gennaker locations require an innovative solution

substations and jackets in these 50Hertz Transmission

resulting in a jacket supported by suction buckets.

GmbH projects.

Ostwind 3 is scheduled for offshore completion in Q2 Initially awarded the Ostwind 3 contract, the

2026, followed by the Gennaker East & West projects in

German network operator 50Hertz has expanded its

2027, ready to efficiently transform wind energy from 66

collaboration with our HSI consortium by awarding

kV AC to 220 kV AC. It is Iv’s goal to support 50Hertz in

the EPCI contract for two additional substations for the

setting new benchmarks for the efficiency and reliability

Gennaker wind farm - Gennaker East and Gennaker West.

of offshore power transmission, marking a significant

The Gennaker wind farm is the largest offshore wind

advancement in the transition to green energy.

farm in the Baltic Sea. Ostwind 3 will have a capacity of around 300 MW, whereas both Gennaker projects will have a total capacity of approximately 900 MW, underlining our ongoing partnership to deliver green electricity to over one million households.

These projects not only signify a strategic move towards local manufacturing in the Netherlands, reducing dependencies and strengthening economic resilience, but they also represent engineering innovation that contributes to sustainable development in the local context.

Crucially, the substructures of these projects are designed for efficient transport and installation, using a vertical barge transport method and a crane lift system.

33

Client Eltra Technical data Weight Topside 1100 mT Dimensions 28x19x11 metres Location Horns Rev A, Danish North Sea Capacity 160 MW Water depth 8 metres

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Horns Rev HVAC offshore substation Horns Rev A is the first offshore (transformer) substation ever built and was installed in the world’s first large-scale offshore wind farm ‘Horns Rev 1’, which is located in Danish waters in the North Sea. Horns Rev. HSM was awarded the EPC contract of the topside and jacket. Iv performed the design and engineering and the topside with a capacity of 150 MW and 3 support piles in a water depth of 8 metres. This Tripod was designed with 5 x 36 kV J-tubes and an independent boat landing structure.

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Would you like to know more about the possibilities for your project?

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Fedor van Veen will be pleased to share ideas about your engineering issues. +31 88 943 3300

2 offshore-energy@iv.nl

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