Growth in offshore wind is increasing demand for subsea cables, larger installation vessels and more resilient supply chains, creating new pressure points for project delivery through 2030 and beyond. Two new reports from TGS | 4C indicate that while near-term supply remains broadly manageable in some markets, longer-term constraints are emerging as projects become larger, more complex and increasingly infrastructure-intensive.
TGS | 4C’s Q1 Supply & Demand Offshore Wind Vessels and Transmission & Cables Outlook reports point to structural changes across the offshore wind sector. Demand is becoming more concentrated around large-scale projects and critical offshore infrastructure, with implications for vessel availability, cable manufacturing capacity, installation schedules and project costs.
Demand for subsea cables continues to increase as offshore wind deployment accelerates and interconnector activity expands. Installed offshore wind cables have increased six-fold over the past decade, rising from 9,000 km in 2015 to 55,500 km in 2025. The analysis forecasts a further 117,640 km of cables will be installed for offshore wind projects between 2026 and 2040.
Subsea interconnectors and high-voltage cables installed between neighbouring countries and regions are expected to increase by 60,700 km during the same period.
The Supply and Demand: Offshore Wind Vessels Q1 2026 report also highlights a shift towards larger and more capable vessels, particularly in installation and support segments. While vessel supply in Europe is expected to remain broadly manageable in the near term, longer-term bottlenecks are forecast in key regions, especially in Asia-Pacific, where demand linked to larger turbine installations is expected to exceed available capacity.
The report forecasts supply and demand across major offshore wind vessel segments, including foundation installation vessels, wind turbine installation vessels, heavy operation and maintenance vessels, crew transfer vessels, walk-to-work vessels, cable lay vessels and commissioning service operation vessels.
The continued growth in offshore wind is increasing pressure on manufacturing capacity, installation capabilities and project schedules.
Cost pressures are also increasing, with structural inflation affecting cable contracts. The research indicates that high-voltage direct current turnkey contract costs are 30% higher than 2024 estimates, while high-voltage alternating current contract costs have increased by 35%. Rising raw material prices, particularly for copper, together with supply chain constraints and strong demand, continue to increase project costs.
