ASEAN’s Subsea Power Connectivity Ambition Needs a Jolt

Subsea interconnections play an important role in realising the ASEAN Power Grid (APG), a regional initiative aimed at achieving cross-border power connectivity among ASEAN countries. Seven of the 18 priority interconnections identified in the ASEAN Interconnection Masterplan Study (AIMS) III involve subsea links (technically eight when counting all of Indonesia’s domestic connections). But there remains a critical need to improve technical and industrial capacity in subsea power systems.

The bloc has recently stepped up efforts to put vision into action. In October 2025, ASEAN energy ministers endorsed the Terms of Reference for the ASEAN Subsea Power Cable Development Framework, covering legal and regulatory, technical, commercial, and financial components. On 7 October, the ministers noted the substantial progress made in developing the framework and agreed to expedite discussions. At the same time, preparatory work to develop certain subsea infrastructure has already commenced. Notably, initial steps have been undertaken to facilitate Singapore’s target of importing 6 gigawatts (GW) of low-carbon electricity from neighbouring countries by 2035. This includes connections beyond those in AIMS III (Table 1).

There are, however, challenges to realising the vision of a connected electrical network. ASEAN currently has limited experience in developing, operating and maintaining long-distance, high-capacity and cross-border submarine power systems. Existing subsea links that can serve as references are primarily domestic, such as Indonesia’s Java–Bali link, or the Mindanao–Visayas and Luzon–Visayas links in the Philippines. The only operational cross-border subsea electricity link is the modest 4km cable connecting Plentong in Malaysia and Woodlands in Singapore.

The challenges become even more significant when constraints in the cable supply chain are taken into account. Manufacturing high-voltage submarine power cables requires specialised factories and lengthy fabrication processes. Currently, only a handful of global firms can produce High-Voltage Direct Current (HVDC) cables. Major manufacturers are based in Europe and Northeast Asia. No operational facility in Southeast Asia can independently produce long-distance HVDC submarine cables at the scale required to meet regional ambitions.

At the same time, global demand for subsea cables is rising. A June 2026 study estimates the value of the global submarine power-cable market, including offshore-wind cables, at USD17.8 billion in 2025 and projects it to reach USD35.9 billion by 2033. Key manufacturers such as NKT, Prysmian and Nexans have their manufacturing slots booked until 2030. Together, they control 60 per cent of global capacity.

Without expanding manufacturing capacity, acquiring subsea power cables will therefore entail lengthy lead times for Southeast Asia. A study released by the US Agency for International Development and the ASEAN Centre for Energy in January 2025 noted it could take 10–12 years. This supply constraint is a critical bottleneck given the large cable quantities required for some of the proposed interconnections. For instance, depending on the route selection, the proposed Australia–Singapore link is projected to require two 3,200km subsea cables. This exceeds the current annual worldwide plant capacity .

Without expanding manufacturing capacity, acquiring subsea power cables will therefore entail lengthy lead times for Southeast Asia.

Securing the physical cables is only the first hurdle. Cables must be transported, installed, maintained and repaired. If cables are sourced from European suppliers, shipping them to Southeast Asia will add considerable lead time. Furthermore, cable installation requires highly specialised vessels, particularly given Southeast Asia’s distinct geographical challenges, such as varying combinations of shallow and deep waters, seismic activity and steep seabed slopes. Globally, only a few cable-laying vessels currently have the capacity to handle long and heavy HVDC cable systems. The vessel limitation could further prolong project installation timelines and hamper critical maintenance and emergency repairs.

Left unaddressed, these constraints risk causing budget overruns and project delays across ASEAN power connectivity initiatives. Coupled with a lack of technical expertise, they can also lead to subsea cable infrastructure which cannot operate at full capacity and loses its electrical load over long distances. This will compound the financial and regulatory hurdles that have already stalled some cross-border electricity trade projects.

The appropriate response is not to postpone subsea interconnection until ASEAN can manufacture its own high-voltage cables or have adequate specialised vessels. Instead, ASEAN countries should strategically leverage the first generation of proposed APG subsea projects to enhance local manufacturing and installation capacities through a phased approach, while simultaneously building the infrastructure.

Policy Implications

Foreign developers and contractors should be incentivised to directly engage local stakeholders. For instance, governments can offer carefully-designed financial incentives to these entities when they partner with local firms or engineers in project design, installation, operation, or maintenance. This will help to facilitate collaborative knowledge transfer.

Local firms and the expansion of foreign manufacturers into Southeast Asia should be supported through regulatory arrangements that provide certainty and a streamlined system of permits. Commercial frameworks should ensure predictable risks and revenue, while governance mechanisms should facilitate coordinated planning.

Providing scholarships for Southeast Asians to study subsea power systems would help to build long-term local expertise. Additionally, ASEAN should explore strategic technical partnerships with grid operators and research institutions in advanced partner countries. This includes the EU, Japan, China and the Republic of Korea. Instead of short-term training, Southeast Asian engineers in the subsea power sector can be seconded to institutions with deep operational expertise in large-scale HVDC transmission.

ASEAN’s proactive steps toward subsea power integration are commendable. However, without addressing capacity gaps, including physical cable and installation infrastructure, the ambition is prone to high project costs, delayed completion and prolonged maintenance and repair bottlenecks.

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