TNB announced on 7 September that it had received through its wholly owned subsidiary, TNB Power Generation (TNB Genco), a Letter of Notification from the Ministry of Energy and Natural Resources to develop the project at Mukim Ulu Nenggiri in the state’s southern district of Gua Musang.
“The project will enhance energy security for the nation and bring about a positive socio-economic impact for Malaysia, the State of Kelantan and the local communities”, the company said.
The project is a strategic national hydroelectric project to complement TNB’s mission to support the Government’s ambition to increase the share of renewable energy in its capacity mix to 31 per cent by 2025 and 40 per cent by 2035 under its power generation plan. It will reinforce the security of supply in Peninsular Malaysia, particularly to the eastern region, while also bringing additional benefits to the State of Kelantan in terms of flood mitigation, cleaner water supply and raw water supply for irrigation.
TNB Genco has incorporated a wholly owned project company named TNBPG Hydro Nenggiri Sdn. Bhd (THNSB) to undertake the project. THNSB will sign a 30-year Power Purchase Agreement (PPA) with the offtaker, TNB.
The construction work is estimated to take five years, with commissioning scheduled to take place by June 2027. The project will include three dams: the main dam, a saddle dam and a re-regulating dam. The main dam will be an 88 m-high RCC structure with a gated radial spillway. The saddle dam will be a composite dam, comprising a 329 m-long RCC section and a 109 m-long embankment dam, both of which will have a maximum height of 56 m. The re-regulating dam will be a concrete gravity structure with a maximum height of 29 m.
The project entails some technical innovations. The saddle dam will be located on cavernous limestone, which has required extensive grouting works to seal potential leakage paths beneath the dam. The re-regulating dam has a unique stepped spillway design which smooths out large flow fluctuations from the main powerhouse. This allows the project to be optimized to generate valuable peaking energy without impacting the downstream community by releasing large flow fluctuations. The reservoir created will inundate an area of about 5400 ha. The intake structure for the surface power station will be located in the main dam and will be constructed of concrete, with a steel trashrack to prevent debris being drawn into the turbines and gates to shut off the flow. The station will be equipped with two 150 MW units that will generate average annual output of around 600 GWh, for export to the main 275 kV transmission grid.
Approximately 1100 people will require resettling, and the project scope includes the construction of two new townships with associated infrastructure such as roads, electricity reticulation, water and sewerage. Rubber plantations will also be established to provide income for the resettled people.
The project has been under development for around 35 years. In 1986 a feasibility study was undertaken to investigate the possibility of the Nenggiri hydro project. In 2005, TNB engaged SMEC to update the project’s feasibility study. SMEC carried out several studies, which culminated in a decision by TNB in 2016 to begin the design of the project. TNB engaged SMEC in July 2016 to provide engineering services for the project, including tender design, detailed design, assistance with tender evaluation, project management, supervision of construction, and commissioning.
Initial approval to develop the project was received from Suruhanjaya Tenaga, the energy regulator, in 2012. In September 2019, the Federal Government agreed for TNB to proceed with the project. The project also received recommendation from Majlis Perancangan Fizikal Negara (MPFN), the National Physical Planning Council, in June 2020.
Currently, TNB has received all the required approvals to construct the project, including the environmental impact assessment, social impact assessment, heritage impact assessment, wildlife management plan and environmental management plan (EMP).
Peninsula Malaysia has an installed hydro capacity of 2578 MW, accounting for 9.8 per cent of total licensed capacity, of which 2558 MW is owned and operated by TNB.