The Trans Borneo power grid, also known as Sarawak to West Kalimantan Link, is a 275kV transmission line that is currently under construction in the island of Borneo, Malaysia. It is being developed by Sarawak Energy Berhad (SEB), Malaysia’s state-owned energy company and P.T. Perusahaan Listrik Negara (Persero), Indonesia’s state-owned power utility.

The project is part of the Association of Southeast Asian Nations Power Grid (ASEAN APG) initiative, which is aimed at encouraging economic use of energy resources for mutual benefit. It also aims to enhance power system security and open up opportunities for energy trading.

The Trans Borneo power grid project will enable Sarawak to export additional electricity to West Kalimantan thereby generating additional income for SEB. It will also help to diversify West Kalimantan’s energy generation portfolio by retiring inefficient oil-based power plants, while reducing CO2 emissions in the Borneo Island.

Trans Borneo power grid location and route

The Trans Borneo power grid is located in the mid-western portion of the Borneo Island, spanning both Malaysia (Sarawak) and Indonesia (West Kalimantan).

The total length of the high-voltage electric power transmission line (HVTL) will be 128.2km. It will extend over 45.6km on the Malaysian side from the Mambong substation to Serikin on the Malaysian/Indonesian border. It will pass through the Kuching and Bau districts.

On the Indonesian side, the transmission line will traverse 82.6km from the Malaysian/Indonesian border south to Bengkayang in the northern portion of West Kalimantan province. The line passes through five sub districts including Jagoi Babang, Seluas, Sanggau Ledo, Ledo, and Lumar of Bengkayang district.

On the West Kalimantan side, additional 150kV HVTL lines will run 90km from Bengkayang to Ngabang and 55km from Ngabang to Tayan. The lines will pass through three districts including Bengkayang, Landak, and Sanggau) and eight sub districts including Bengkayang, Teriak, Banyukehulu, Menyuke, Ngabang, Tayan Hilir, Balai, and Jelimpo.

Trans Borneo power grid infrastructure

The double-circuit transmission cables are supported by self-supporting steel lattice towers placed approximately 340m apart. A total of 201 towers will be constructed on the West Kalimantan side and 144 towers on the Sarawak side.

The tower base is approximately 5mx5m, with each of the four tower legs supported by foundations designed for the soil conditions at the site.

A right-of-way (RoW) with a width of 40m (2mx20m) is being implemented in Sarawak for the transmission line. The West Kalimantan side has 30m and 20m RoW for the 275kV and 150kV HVTLs respectively.

Construction details

On the Sarawak side, SEB began land acquisition process in 2012. Tower erection and cable stringing construction works started in September 2013 on Sarawak and West Kalimantan.

The project was initially expected to be completed by Q1 2015 but has faced delays in funding due to obstructions by activists against the project development.

Trans Borneo power grid substations

The project includes the construction of a new substation at Benkayang and extension of the existing substation at Mambong in Sarawak along with associated infrastructure.

On the Malaysian side, the expanded Mambong substation will consist of two units each of 275kV line and transformer bays, 275/150kV transformers with 250MVA capacity each and one 150/20kV transformer bay with a 25MVA transformer.

In addition, the project will include four 150kV line bays, capacitor bank, control building with 20kV indoor switchgear, computer-based substation control system, protection and metering equipment, telecommunication facilities, AC/DC supply and other access.

The West Kalimantan side the transmission line will feature three new substations. A 275/150/20kV substation will be constructed at Bengkayang in Magmagan village in Lumar sub district. It will feature four 275kV bays, five 150kV bays, auto-transformer and a control building with 20kV indoor switchgear.

The Bengkayang substation will be connected to both the 275kV regional interconnection HVTL from Mambong in Sarawak and the 150kV HVTL from Bengkayang to Ngabang.

In addition, 150kV/120kV substations will be developed in Ngabang and Tayan, Indonesia. The Ngabang substation will be connected via the 150kV HVTL with both the Bengkayang and Tayan substations. The Tayan substation will be connected with the Ngabang substation via the 150kV HVTL and to the substations in Sanggau and Siantan.

Project financing

The project is funded on the Indonesian side by a sovereign loan from Asian Development Bank (ADB) and a loan from Agence Française de Développement (AFD).

P.T. Perusahaan Listrik Negara (Persero) will provide the remaining funding. The Malaysian side of the project is funded by a non-sovereign loan from ADB and Sarawak Electricity and Supply Corporation (SESCO).

Contractors involved

Fichtner Engineering and Consulting prepared the Trans-Borneo power grid development and energy trading study that established the feasibility of the 275kV double circuit transmission line.