Electricity interconnectors are becoming an increasingly important part of the infrastructure needed to support the energy transition. By enabling electricity to flow between regions and countries, they can strengthen security of supply, improve grid resilience and help balance increasingly renewable power systems by moving surplus generation to markets where supply is tighter.
The scale of the market is already significant. Westwood data indicates around 40,000 km of interconnector cable requirements associated with projects expected online between 2025 and 2035, excluding Mainland China. This compares with around 54,800 km of offshore wind cable requirements over the same period, comprising 59% export and 41% infield cable. Interconnector cable requirements are therefore equivalent to almost two-thirds of those associated with offshore wind.
At the same time, the market is becoming more ambitious. Projects are growing in scale, cross-border links account for an increasing share of planned development and new concepts are emerging that combine electricity trading with offshore wind connections.
However, the rapid expansion of the project pipeline should not be mistaken for guaranteed build-out. Interconnectors are capital-intensive infrastructure projects with long development timelines and can face significant regulatory, financing, commercial and geopolitical risks.
Westwood has therefore assessed the unsanctioned pipeline to understand not only what is planned, but which projects have the strongest prospects of progressing.
Ambition is increasingly cross-border, but sanctioned projects remain domestic
Europe sits at the centre of the current interconnector build-out, supported by a longstanding policy drive towards greater integration of national electricity markets. The EU has set an electricity interconnection target of at least 15% by 2030, while growing renewable generation is increasing the need for flexibility between electricity systems.
This is reflected in Westwood’s unsanctioned pipeline. Cross-border projects account for 69% of developments yet to reach cable contract award.
Figure 1: Sanctioned and Unsanctioned Interconnector Projects by Project Type. Source: Westwood WindLogix.
Yet the picture is almost reversed among projects that have progressed further. Westwood considers an interconnector as sanctioned once a cable contract has been awarded, and 78% of sanctioned projects are domestic. Interconnector ambition is therefore becoming increasingly international, but the projects that have progressed furthest remain overwhelmingly domestic.
Sanctioned activity is heavily concentrated in Western Europe, which accounts for 90% of projects that have reached cable contract award. Greece is particularly prominent, accounting for almost half of sanctioned Western European project involvements. Its geography creates a clear requirement for subsea connections between its island and mainland electricity systems, while coordinated investment and access to public funding have helped turn this requirement into contracted projects. Since 2017, IPTO has invested €3.1 billion in electricity infrastructure, while individual developments have also benefited from European financing. The €524 million Western and Southern Cyclades interconnection, for example, received €157 million of EIB financing alongside a further €108 million from the EU Recovery and Resilience Facility.
Figure 2: Selected Sanctioned Greek Interconnector Projects. Source: Westwood WindLogix.
Greece illustrates how a clear grid requirement, TSO-led investment and access to public financing can help projects progress through procurement, despite continued exposure to cost increases and schedule delays. Replicating that progress becomes more complicated when infrastructure crosses national borders and requires multiple regulatory, political and commercial frameworks to align.
What is stopping projects from progressing?
Westwood assessed unsanctioned projects across development maturity, commercial progress, funding and key project risks, assigning each a Probable, Possible or Risked rating. The results point to considerable uncertainty. Only 14% of the pipeline is currently rated Probable, while 57% is Possible and 29% is Risked.
Risk is particularly concentrated among international developments: 94% of Risked-rated projects are cross-border. However, cross-border development does not in itself determine project viability, with around 63% of Probable-rated projects also crossing national borders.
Figure 3: Unsanctioned Interconnector Projects by Overall Rating and Project Type. Source: Westwood WindLogix.
Instead, the distinction lies in whether strategic support has translated into tangible development progress. MaresConnect, Malta-Sicily Interconnector 3 and Sarawak-Singapore demonstrate relatively strong momentum through combinations of permitting activity, technical development, public or TSO backing and commercial progress.
At the other end of the spectrum, different combinations of risk can stall development. Aquind, a proposed UK-France interconnector, remains exposed to significant legal and permitting challenges, while Australia-Asia Powerlink continues to face financing and delivery risks given its scale. The Great Sea Interconnector between Israel and Cyprus, meanwhile, has recently progressed through regulatory and cost-allocation processes but remains at an early stage and is exposed to geopolitical uncertainty in the eastern Mediterranean.
Physical project characteristics provide a more mixed picture. Capacity alone does not show a clear relationship with project rating, suggesting that larger-capacity projects are not necessarily more exposed to delivery risk. Cable requirements, however, show a more distinct pattern. Median manufactured subsea cable requirements increase from 332 km for Probable projects to 450 km for Possible and 620 km for Risked projects. This suggests that projects with greater cable requirements tend to sit further towards the riskier end of the pipeline, although regulatory, commercial, financing and political maturity remain important differentiators.
Figure 4: Median Manufactured Subsea Cable Requirements by Project Rating. Source: Westwood WindLogix.
Complexity could increase further as interconnector models evolve. Hybrid projects such as LionLink aim to combine cross-border electricity trading with offshore wind connections, potentially reducing infrastructure requirements and supporting a more integrated North Sea grid. However, regulatory frameworks were largely designed for generation and interconnection separately, creating new questions around how costs and benefits should be shared between countries.
The challenge for the cross-border pipeline is therefore not a lack of strategic rationale, but converting that rationale into coordinated regulation, financing and commercial commitments.
Cable demand builds through the 2030s, but timelines remain uncertain
The unsanctioned pipeline points to a significant increase in project delivery through the 2030s. However, the composition of this pipeline also changes over time. Looking at underlying cable requirements, near-term demand is supported by domestic projects, while longer-term demand becomes increasingly dependent on cross-border developments.
Figure 5: Unsanctioned Project Pipeline by Expected Online Year and Rating. Source: Westwood WindLogix.
This shift increases uncertainty around the longer-term delivery profile. Cross-border projects typically require coordination across multiple regulatory, political and commercial frameworks, creating greater potential for expected online dates, and therefore associated cable demand, to move.
Even projects with strong institutional and policy support can experience schedule changes. GRITA 2 (Greece – Italy), for example, has seen its expected commissioning move from 2031 to 2033, with IPTO citing cost-benefit recalculation requirements from the Italian side.
The current online-year profile should therefore be viewed as an indication of where demand could emerge rather than a firm delivery schedule. The scale of planned development is significant, but the timing of longer-term cable requirements will increasingly depend on the progress of cross-border projects.
Conclusion
Interconnectors will play an increasingly important role as electricity systems accommodate more renewable generation and become more interconnected. Yet Westwood analysis shows a clear gap between ambition and execution. Cross-border projects dominate planned development, while domestic projects dominate those that have reached cable procurement, and international developments account for almost all the highest-risk projects.
The opportunity is substantial, but the current pipeline is unlikely to be delivered exactly as it stands. How much of today’s predominantly cross-border pipeline can make the transition from ambition to procurement – and how quickly – will ultimately determine the scale and timing of the next wave of interconnector build-out.
Giulia Cannatelli, Analyst – Energy Transition
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