The major components

An offshore wind farm breaks down into a handful of major systems: the turbines, the steel foundations that hold them, the subsea cables that move the power, and the heavy electrical equipment that steps it up and sends it ashore. Each has its own supply story.

Wind turbine generators

The turbine is the most visible part of a wind farm and the most concentrated in supply. In offshore waters outside mainland China, a small group of Western manufacturers still dominates, Siemens Gamesa (Germany, Spain, Denmark), Vestas (Denmark) and GE Vernova (United States), while Chinese makers such as Mingyang and Goldwind dominate their home market and are beginning to push into Europe. Chinese OEMs now lead the global ranking overall, but that is driven by their vast home market; in offshore waters outside China, Western OEMs still supply the large majority. The two are often conflated.

Blades and composites

Turbine blades are glass and carbon fibre composites over a structural core. The carbon fibre in the load-bearing spar is a concentrated supply chain in its own right: high-performance grades are dominated by Japanese producers, Toray (including its US Zoltek arm), Teijin and Mitsubishi, with Hexcel (US) and SGL (Germany) also present, while lower-cost large-tow capacity, the type favoured for wind blades, is expanding rapidly in China through Sinopec and CNBM. Blades themselves are made by TPI Composites and LM Wind Power, plus Vestas and Siemens Gamesa in-house.

Foundations and steel

Most offshore turbines stand on steel monopiles, large-diameter welded tubes driven into the seabed, with jackets used in deeper water. Monopile fabrication is European-led and the market is currently tight, with manufacturers reporting capacity booked years ahead. Beneath the fabricators sits the steel itself: the specialist heavy plate used for monopiles, thermomechanically rolled grades such as S355ML, comes from a small number of European mills, while commodity steel feedstock is more globally traded.

Subsea cables

Two kinds of cable matter: array cables linking turbines to the offshore substation, and export cables carrying aggregated power to shore, increasingly as high-voltage direct current (HVDC) for longer distances. The market is moderately concentrated, with a European top tier and strong Asian suppliers. The raw conductor, copper and aluminium, is globally traded; the bottleneck is manufacturing and installation capacity, not the metal, though copper cost is a growing pressure.

Main electrical, transformers, switchgear and converters

Power leaves the turbines at medium voltage, is stepped up at an offshore substation, and sent ashore. The heavy electrical equipment, large power transformers, high-voltage gas-insulated switchgear (GIS), and HVDC converters, is supplied by a very small group of global firms, with specialist yards fabricating the platforms that house it. This is one of the most concentrated tiers in the entire chain. When the UK grid operator awarded its HVDC converter framework, it named just four eligible suppliers.

Control systems and electronics

A wind farm is also a distributed control system. Unlike the items above, this is a shared global electronics supply chain, not specific to offshore wind, the same components run factories, ships, grids and data centres, so the picture is qualitative rather than wind-specific. Programmable logic controllers (PLCs), intelligent electronic devices (IEDs) and protection relays come from the established industrial automation names, Siemens, ABB, Schneider, Rockwell, SEL and GE among them. Servers, switches and firewalls come from the usual IT majors but are physically assembled across Asia, and semiconductors underneath are concentrated in a small number of Asian foundries.

The offshore-specific wrinkle is ruggedisation. Equipment on a substation topside or inside a nacelle has to survive salt, vibration, wide temperature swings and, in places, hazardous-area conditions. That tends to draw on a narrower pool of marine and hazardous-area-rated components, conformal-coated boards, wide-temperature parts, higher ingress-protection ratings, which is a smaller, more specialist segment than commercial-grade kit, and can carry longer lead times as a result.

Critical raw materials beneath the components

Below the finished components sits a layer of raw materials, and this is where the sharpest dependencies appear. The umbrella term used in EU and UK policy is critical raw materials: the inputs whose supply is concentrated enough, and important enough, to pose a strategic risk.

Rare earth elements, the magnet metals

Direct-drive turbine generators use powerful permanent magnets, and those magnets depend on four rare earth elements: neodymium and praseodymium, with dysprosium and terbium added to hold magnetism at high temperature.

The name is misleading. Rare earth elements are not geologically rare, they are reasonably abundant in the Earth’s crust. What makes them critical is that they are rarely found in concentrated deposits, and that extracting, separating and refining them is technically difficult, capital-intensive and environmentally demanding. The dependency is about processing capability, not scarcity in the ground, which is exactly why the supply chain has concentrated in one country rather than tracking where the rock happens to be. That distinction shows up clearly in the numbers: China’s share of mining is large, its share of refining and magnet-making far larger, and the gap between the two is the whole story.

The risk is not theoretical. China introduced export controls on several rare earth elements and magnets in April 2025, and a wider set in October 2025 (since suspended, with a review due in late 2026), causing real short-term disruption to manufacturers outside China and a lasting price premium on non-Chinese magnets.

The other critical inputs

Rare earths get the headlines, but they are not the only constraint, and the magnet itself is mostly iron, not rare earth metal.

Where the dependencies really sit

Put the picture together and the exposure is uneven. The West is reasonably self-sufficient in some tiers and deeply dependent on a small number of suppliers, sometimes a single country, in others.

The short version: foundations, cables and turbine assembly are reasonably secure for Western projects. The exposure is concentrated in the things hardest to substitute quickly, the magnets, the transformer steel, and the chips, all of which route back through a small number of suppliers and, in the case of rare earths, overwhelmingly through one country.

Supply chain look ahead

The picture above is today’s. It is also changing. Governments and industry on both sides of the Atlantic are spending heavily to loosen the tightest dependencies, above all in rare earth magnets, transformers and electrical steel. The direction of travel is clear; the pace is not, and almost none of it is guaranteed.

Rare earths and magnets, the build-out beyond China

This is where the most determined effort is going, because it is the sharpest dependency. Both the EU and the US are trying to stand up rare earth processing and magnet-making capacity outside China, the refining and magnet stages where China’s share is highest.

Transformers and electrical steel, capacity being rebuilt

The transformer shortage has triggered the largest wave of new factory investment in decades, concentrated in the US but also in Europe. Hitachi Energy has committed more than $1bn across US sites, Siemens Energy is building its first US large-power-transformer plant in Charlotte, North Carolina (production expected around 2027), and Eaton has committed $340m to a South Carolina facility on a similar timeline. The constraint is easing, but slowly: demand has more than doubled since 2019 and analysts still expect multi-year deficits even as the new plants come online. Electrical steel sits underneath this, new transformer capacity only helps if the grain-oriented steel to feed it scales too, which is the slower-moving half of the problem.

Turbines and cables, the patterns to watch

Two shifts matter for the rest of the chain. First, Chinese turbine makers, already dominant at home, are pushing into European and other international waters; whether they win significant share outside China is one of the defining questions for the turbine supply chain this decade. Second, cable manufacturers are adding factory capacity to relieve the current bottleneck, though new high-voltage cable plants, and the vessels to install them, take years to come online, a topic for the ports and vessels page.