Context and Chronology

Project teams have long foregrounded turbines while export systems sat in the background; that practice now masks concentrated downside that scales with distance and capacity. Subsea high-voltage direct current links solve a real electrical challenge when circuits carry gigawatts over long corridors, but that technical fit creates a single-point exposure that can remove very large blocks of generation in one fault. Regulators, system planners, and insurers are already signaling higher exposure; European operating surveys and sector reviews show fault frequencies and repair durations that, when aggregated across lifespan and route length, produce non-trivial expected failures.

Empirical performance data point to a fault band of roughly 0.07–0.10 faults per 100 km‑years and typical export repair durations near 60 days, numbers that convert rapidly into life‑of‑asset exposure for long routes. A 150 km export corridor over 25 years generates thousands of km‑years of exposure, implying multiple expected faults under those rates and turning the ‘‘rare but big’’ scenario into a planning reality. When a single export outage removes a 1 GW block at ~50% capacity, lost megawatt‑hours and foregone market revenue become measurable line items in lender stress tests and insurer loss modelling.

Project delivery traces most failures to manufacturing and installation defects rather than pure weather impacts; that shifts responsibility into procurement, installation supervision, and factory QA domains. Fast scaling of offshore projects — larger arrays, longer links, and higher capacity per circuit — raises the stakes by increasing consequence per event and extending repair logistics over harsher windows. Classic optimism bias in megaprojects masks tail risk; using outside‑view methods reduces the temptation to underestimate contingency and schedule uplifts for cable‑heavy portfolios.

Practical mitigation is straightforward but often costly: invest in deeper route characterization, stricter component qualification, strategic spares, guaranteed jointer and vessel access, and architecture choices that avoid concentration of generation behind single circuits. Treating the export package as a nested megaproject changes contract design, insurance terms, and bank covenant triggers; it also forces system planners to consider redundancy and distributed routing where feasible. Absent these changes, concentrated HVDC exposures will change how portfolios are financed, how national grids count firm capacity, and how insurance markets price long‑distance offshore generation.