Revolution in offshore wind energy

Skyscrapers at sea

“Imagine turbines taller than the Shard (Europe’s tallest skyscraper, at 310m) being towed from Port Talbot to locations around the UK coast,” says Rose Richardson, project manager in our ports and maritime business.

Port Talbot in south Wales is home to the UK’s largest steelworks, founded early last century and now owned by Indian industrial conglomerate Tata. The vast complex is served by a port that was built to import raw materials for steelmaking. Today the port is owned and operated by Associated British Ports (ABP).

ABP’s port at Port Talbot is ripe for transformation into a manufacturing and integration hub for the next generation of offshore wind turbines.

Away from land, the wind blows more strongly and consistently than on or near shore, so it can drive larger turbines. Shallow offshore locations have already been leased, and now the Crown Estate, which manages the seabed within UK territorial waters, is starting to lease areas where the water depths are too great for conventional direct fixing. So turbines will be mounted on semi-submersible floating foundations.

Wind energy developers therefore require new manufacturing and assembly facilities to produce and launch the foundations. And that creates an opportunity to rethink the entire turbine assembly process.

Offshore wind farms are currently built by transporting components – foundations, towers, nacelles and rotor blades – individually to site. Assembling them at sea, on a fixed foundation, requires specialist (and very expensive) ships, barges and lifting equipment. The speed and safety of work is highly dependent on weather and sea conditions. Now there is a better way – and it will be used at Port Talbot.

Vasi Maier: designing a first-of-its-kind port for floating wind turbines

A soaring need

The UK government’s energy security strategy, published in 2022, set the goal of building 5GW of floating offshore wind capacity by 2030. Up to 125GW of offshore wind capacity will need to be built by 2050 to facilitate decarbonisation of the UK’s electricity supply.

The world’s largest wind turbine to date has 16MW capacity, but a factory to produce 20MW turbines is now being built in Poland. It is expected that 25MW turbines will be available within this decade and machines as big as 30MW could follow. The rotor tips of a 20MW turbine will sweep the sky 300m above sea level.

Just in the Celtic Sea, an installation rate of 25 to 50 turbines per year will be needed to help meet the UK’s energy ambitions.

Floating foundations

The use of floating foundations – needed for the new, larger turbines destined for use in greater water depths – makes it possible to integrate turbines in the controlled environment of a harbour, instead of transporting all the components to a fixed foundation at sea.

Close to land, wind speeds are lower, and a breakwater provides a calm harbour, even when waves are crashing outside. With foundations moored securely against a dock wall and cranes standing on solid ground, lifting towers, nacelles and blades becomes comparatively straightforward.

As the size of turbines increases – with larger, heavier components to transport, lift and fix – simplifying the construction process using quay mounted equipment has clear advantages.

Once fully assembled, turbines can be towed to the location of a new wind farm, anchored in position and connected to a ready installed transmission cable.

Floating foundations have been used for offshore oil rigs for decades. But where oil rigs were few and far between even at the height of oil production, a foundation will be required for every one of these new turbines.

“By 2030, floating offshore wind turbines will be moving into the commercial mainstream. Hundreds will be needed. We want that to be the catalyst for transformation of Port Talbot – the port, the town, its community and the environment,” says Julian Walker, ABP’s chief commercial officer.

During stormy months, installing offshore wind farms is difficult, so production is likely to work to a cycle. Foundations will be manufactured year round and stored throughout the winter. During more settled summer months, turbines will be erected on the foundations and then towed offshore.

What will the foundations look like?

Designs for steel foundations of the type that could be fabricated and assembled at the port at Port Talbot are typically triangular in plan, with a cylindrical buoyancy body at each corner. Buoyancy bodies will be connected by steel trusses.

The buoyancy bodies will be ballasted with water. This will help keep the foundation stable, in combination with water resistance provided by large flanges or damping pads at the base of each body, and the catenary sag of anchor chains.

Foundations of different sizes will be built to support different capacity turbines.

Representation and dimensions of a steel semi-submersible floating foundation for a wind turbine

Green energy hub

Developing the port of Port Talbot as a hub for floating offshore wind is a multiple stage programme for ABP. Over several years, it will transform the port into a hub for the emerging green energy industry.

We are working to turn initial concepts into a detailed solution that can be tendered and built. We are also working as estate-wide infrastructure masterplanner for subsequent phases.

Goals include:

• Facilities for assembling the floating foundations from component parts and erecting the turbines. In time the aspiration is to fabricate all foundation components on site.
• Generation of onshore wind energy to meet local electricity demand.
• Import infrastructure for ammonia, which will be used to produce hydrogen, as a green fuel source in heavy transport and industry.
• Production of sustainable aviation fuel from imported ethanol.

Further benefits will come from plans to restore and create natural habitats on site, as well as to provide enhanced access to the impounded dock and river for recreational use.

Investment in quayside infrastructure will attract other parts of the offshore wind industry supply chain, it is hoped. “It would make sense to co-locate production of mooring systems,” says Mott Macdonald technical lead Peter Mallin.

Transformation of the port is part of the wider Celtic Freeport economic regeneration plan, which also covers the Port of Milford Haven, some 100km to the west. The two ports provide complementary port facilities, access to energy and industrial infrastructure, and substantial development potential. The freeport vision includes a west Wales enterprise hub that attracts innovation and creates new employment.

Success will see the port of Port Talbot, and the town too, shift decisively onto a new economic pathway, triggering the growth of a new supply chain, creating several hundred highly skilled jobs, and opening new export opportunities.

With a potential build rate of up to 50 foundations a year, ABP’s port could launch 150 turbines in three years, generating as much electricity as the Hinkley Point C nuclear power station now under construction on the opposite side of the Bristol Channel. (Note: Artist’s impressions not to scale; more accurate representations will be produced as the project evolves.)

With a potential build rate of up to 50 foundations a year, ABP’s port could launch 150 turbines in three years, generating as much electricity as the Hinkley Point C nuclear power station now under construction on the opposite side of the Bristol Channel. (Note: Artist’s impressions not to scale; more accurate representations will be produced as the project evolves.)

Sizing up the opportunity

We are “providing the engineering to support the vision,” says Rose, “developing designs for the project’s first phases and mapping the technical considerations and inputs required for later phases.

“Pretty much every aspect of this project is groundbreaking – there aren’t examples you can look at for reference, although we can transfer knowledge and experience from other sectors. This project is also unusual in being so multidisciplinary.”

Rose Richardson: master planning a pioneering green energy hub

In-house expertise is complemented by our partnership with consultant Royal Haskoning, author of the industry roadmap on building UK port infrastructure to support offshore floating wind , which is published by industry body RenewableUK.

Simon Power, Mott MacDonald’s lead for infrastructure masterplanning, has been working through the project’s functional, spatial and connectivity requirements. “Developing Future Port Talbot will be a multi-year programme. Infrastructure masterplanning is helping ABP to understand and decide what is needed straight away and what’ll be required later.”

Masterplanning addresses a very long list of questions. It includes the optimal locations and space required for foundation fabrication and assembly facilities, onshore wind turbines, energy storage, road and rail access and office accommodation.

Corridors need to be protected for future potential HVDC electricity cables, hydrogen and carbon capture and storage operations.

And the site’s connection to the electricity grid has to be assessed with a view to changing demand and the supply of surplus renewable energy.

“Masterplanning is essential for testing the level of ambition, which sets the pace of development and in turn determines which technical inputs will be required, when,” says Simon.

Preparing for production

“Port Talbot is one of only a few harbours in the UK that is both capable of handling large cargo vessels and that has the capacity to accommodate a major new industry,” says Peter.

“Pretty much every other potentially suitable port is busy – there’s not enough room to assemble, launch and manoeuvre structures the size of a floating foundation. This port can provide the required quayside length and has around 170ha of port land on which to place fabrication, assembly, turbine integration and maintenance facilities.”

Design studies and modelling are in progress to determine the future configuration of the port, including potential land reclamation and quay alignment.

Harbour depth is critical. The largest anticipated floating foundations could have a total height of 56m; with turbines mounted and part ballasted, they will float high but still require a depth of 15m for manoeuvring within the port and towing out to sea. (When in location and under operation, the buoyancy bodies will be ballasted, causing them to sit another 15m deeper in the water and further improving stability.)

Port Talbot's tidal harbour currently has a maximum depth of 22m at the highest tides but only 11.2m at the lowest. Work may be needed to address this, but operations will be planned to take advantage of the large high-water window.

Meanwhile we are also working on other green port and energy hub projects for ABP, including the masterplan for expansion of the ABP and Siemens Gamesa blade manufacturing facility at Green Port Hull 2 and the feasibility study for potential green energy developments at ABP’s Port of Barrow.