Inside Europe’s Race to Build a Supergrid Beneath the Sea

Prysmian and Nexans drive Europe’s offshore energy surge with major subsea cable expansions

23 Oct 2025

Europe’s push to harness offshore wind is reshaping its energy backbone. Across the continent, vast webs of high-voltage cables are being laid beneath the sea to link wind farms to the grid. The result is a new industrial scramble, partly financial and partly logistical, to build the infrastructure of Europe’s clean-energy future.

Two companies dominate the race. Prysmian Group and Nexans are expanding fast through acquisitions, partnerships and factory upgrades. Nexans has pledged about €90m to boost its offshore-wind and interconnection capacity, while Prysmian secured €450m in financing from the European Investment Bank to enlarge its high-voltage submarine-cable production. Both firms aim to meet surging demand as governments accelerate offshore connections and cross-border interconnectors.

According to Europe’s network of transmission-system operators, grid expansion is gathering pace, though estimates of new subsea length vary widely. “Subsea connectivity is becoming a backbone of Europe’s energy transition,” notes a senior analyst at Aurora Energy Research. That optimism is reflected in a wave of capital spending and in fiercer competition for long-term grid contracts.

Regulators are trying to keep up. In Britain, Ofgem has tightened oversight of fault reporting and reliability standards, and recently approved funding for a cable link between Scotland and north-east England. Such scrutiny helps reassure investors but adds to the industry’s already heavy paperwork.

Beneath the optimism lie constraints. Manufacturing slots for high-voltage cables are booked years ahead, while the ships that lay them are few. Shortages could drive up costs and delay projects. Still, consolidation among suppliers may eventually ease bottlenecks and speed up innovation in monitoring, repair and recycling technologies.

What began as a scatter of national schemes is becoming a continental network, a step toward an integrated offshore supergrid. Europe’s subsea cable boom is not just another phase of its energy transition. It is the connective tissue that will determine how far and how fast that transition runs.