Why the Asean Power Grid’s future lies in subsea cables
Some of the world’s longest subsea power cables could be laid in the region, if vision can translate to action
South-east Asian countries have long traded electricity via land-based power cables. But achieving the Asean Power Grid (APG) – a decades-old vision to link up the bloc’s power systems – calls for a deep dive into the ocean.
Subsea interconnectors will be vital to realise the APG. These are high-voltage power cable systems laid on or under the seabed, transmitting electricity from one country to another.
Vikings ahoy!
Today, the world’s longest subsea interconnector runs 630 km between the UK and Denmark. It is part of the Viking Link, a network of high-voltage direct current (HVDC) cables that allows both countries to exchange power from sources such as offshore wind.
Source: National Grid
If the Viking Link seems massive, South-east Asia could take subsea interconnectors to a whole new scale.
The region already has several overland interconnectors, mostly used by Laos to export electricity to its neighbours – including Singapore, via Thailand and Malaysia, as part of a breakthrough APG project.
The APG envisions many more interconnectors, including those that could connect Singapore to Cambodia, Vietnam, Sarawak in East Malaysia, and the Riau Islands and Sumatra in Indonesia.
Singapore aims to import 6 gigawatts (GW) of low-carbon electricity by 2035, meeting about one-third of its energy demand then.
To obtain an import licence, companies will first need to receive conditional approval from Singapore’s energy regulator, followed by a conditional licence.
The Energy Market Authority (EMA) has thus far granted conditional approvals to projects that seek to import 6.25 GW of clean energy from destinations such as Cambodia, Vietnam and even as far away as Australia.
EMA has also granted conditional licences to six projects that could bring in 3 GW of clean energy from Indonesia.
Conditional approvals
These seven projects could bring 6.25 GW of clean energy into Singapore
| Country of export | Companies | Import capacity |
|---|---|---|
| Australia | Sun Cable | 1.75 GW |
| Vietnam | Sembcorp Utilities | 1.2 GW |
| Malaysia (Sarawak) | Sembcorp Utilities, Sarawak Energy | 1 GW |
| Cambodia | Keppel Energy | 1 GW |
| Malaysia | Southern Solar Alliance | 0.6 GW |
| Indonesia | Shell Eastern Trading, Vena Energy | 0.4 GW |
| Malaysia (Linggiu Reservoir, Johor) | Sembcorp Utilities | 0.3 GW |
Source: Data compiled by BT
Conditional licences
These six projects could import 3 GW of clean power into Singapore from Indonesia
| Companies (export from Indonesia) | Import capacity |
|---|---|
| Singa Renewables (TotalEnergies and Royal Golden Eagle) | 1 GW |
| Pacific Medco Solar Energy (PacificLight Renewables, Medco Power Global, Gallant Venture) | 0.6 GW |
| Adaro Solar International* | 0.4 GW |
| Equator Renewables Asia | 0.4 GW |
| Keppel Energy | 0.3 GW |
| Vanda RE (formed by Gurin Energy, Gentari International Renewables) | 0.3 GW |
*Adaro has since changed its name to Alamtri Resources
Source: Data compiled by BT
With such projects in the works, the market for subsea power cables is “expanding steadily”, said Sandra Seah, a partner at law firm Bird & Bird with expertise in energy.
She noted that ZTT Group, a Chinese advanced manufacturing player, “has stepped up its game” with major manufacturing and research bases in the region for medium-voltage and high-voltage subsea power cables.
Cable installers – who specialise in the transportation, installation and protection of subsea power cables – “are also becoming more active in the Asean market”, said Seah.
Ambitious leap
Realising these projects will be a big leap. The region currently only has one subsea interconnector: between Plentong in Johor, Malaysia and Singapore’s Woodlands.
Established in 1983 and upgraded in 2022, the link supports bidirectional electricity flows of up to 1 GW. It spans just 2 km, a fraction of the UK-Denmark Viking Link, according to data compiled by the International Energy Agency (IEA).
For the APG to truly take off, subsea cables would have to run much longer distances, beating even the Viking Link. For instance, an undersea interconnector from Malaysia to Vietnam could span 700 km.
One from Singapore to Sarawak may run 750 km.
And another from the city-state to Vietnam or to Cambodia may have to cross at least 1,000 km.
The APG is a “step change in ambition for the region”, said Tan Sue-Ern, head of IEA Regional Cooperation Centre.
“Several planned subsea cable projects are significantly more complex than what came before – with cables spanning long distances, crossing multiple jurisdictions, and requiring specialised vessels and expertise for cable installation and repair,” she told The Business Times.
Serious money
US$27 billion is needed from 2025 to 2040 to deliver the APG’s interconnectors
IEA estimated US$27 billion is needed between 2025 and 2040 to deliver the proposed pipeline of energy interconnection projects, inclusive of both overland and subsea cables.
This is more than 10 times the US$2 billion that the region invested in energy interconnectors from the 1970s to 2024, mostly for one-way power export.
Caution: high voltage
Building these long-distance interconnectors will require HVDC cables, as well as specialised vessels to lay them. But the global market for these resources is tight.
Lam Pham, an Asia energy analyst at think tank Ember, noted that Asean still lacks manufacturing capacity for such cables within the region, and is thus “heavily dependent” on established suppliers and installation capacity from elsewhere.
“(With) Asean projects competing for the same manufacturing slots and installation capacity as Europe’s offshore wind industry, (this) is pushing up costs and creating long lead times for new projects,” he said.
Cross-section of a HVDC subsea cable
The interactive cutaway loads as you reach this section.
Illustrative single-core extruded HVDC cable based on the Europacable reference. Layer proportions and colours are schematic.
Sources: Europacable, ZMS Cable
Assaad Razzouk, CEO of Singapore-based renewable power company Gurin Energy, called for centralised procurement of subsea power cables to mitigate supply constraints.
“Governments should give us a hand in procuring these ahead of time, so that as a region, we don’t find ourselves in five years without the ability to… build the Asean grid because the rest of the world gobbled (the cables),” he said at an industry event in August.
Cracking the puzzle
Regulatory clarity is another key piece of the puzzle.
For subsea cable manufacturers to establish production or installation operations in Asean, they will need greater certainty around the project pipeline and government policy, Lam noted.
Seah echoed this, noting that transmission infrastructure is capital-intensive and will only be developed where there is “demonstrable demand”.
Sentiment around the APG is still cautious. In a recent survey of energy professionals, only a quarter expect significant cross-border power trading in the next decade. Over half of respondents believed that a fully integrated regional grid “will remain some way off”.
Wait and see
Responses from 100 energy professionals in Asean on whether the APG will become a reality
Source: Sustainable Energy Association of Singapore
This comes amid obstacles that APG projects face. The Singapore-Indonesia projects, for instance, have run into delays over regulatory uncertainty.
Jakarta requires clean energy exporters to renew permits every five years. But this frequent renewal timeframe leads to a lack of confidence among potential investors and offtakers.
Asean member states have also not formally agreed on a single framework governing subsea cable assets under the APG, and whether ownership will be public or private, noted Seah.
Key development to watch
The status quo could change, as Asean works on its Submarine Power Cable Development Framework.
The framework will cover four aspects around the laying and maintenance of subsea power cables: legal and regulatory, technical, commercial, and governance issues.
In October last year, Asean’s energy ministers reaffirmed the importance of the framework during their annual meeting, calling for “sustained and accelerated progress”.
The completion of this framework will be a key milestone to watch out for.
Asean's diversity of technical standards and political priorities will need to be taken into consideration, said Seah, noting that the region currently uses more than 20 grid codes.
As she put it, the process will take “time and trust”.
Sources: Rystad Energy, International Energy Agency, Sustainable Energy Association of Singapore, data compiled by BT
Graphic: Ho Yan Hao, Nurulshazanani Idris, BT (with AI assistance)