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1. Hydroelectric Power Dams (HEP Dams)


Energy resources are materials or processes in nature that can be used to produce work. Generally, energy resources can be divided into 2 categories, i.e. non-renewable and renewable energy resources. Non-renewable energy resources are resources that cannot be replenished within a short period of time (e.g. oil, natural gas, coal). On the other hand, renewable energy resources are resources that can be replenished within a short time-frame and are usually found in abundance (e.g. hydroelectric power, geothermal, tidal and wind energy). The hydroelectricity is the most widely used type of renewable energy resource, which provides both clean and cheap power generation.

In Sarawak, hydroelectric power is the most promising alternative renewable energy source.  Hydroelectric power generation is particularly highly potential and suitable in Sarawak due to the abundance of water, with an annual precipitation of about 4000mm.   

Other than the high rainfall intensity in this particular state of Sarawak, the availability of suitable hydroelectric power (HEP) dam sites also attributes to the implementation of HEP generation as a long-term sustainable energy measure to cater for the current and future electricity consumption of the State. Hydroelectric power dams are considered non-water consumptive schemes, since the volume of water utilized to generate power are all returned into the natural stream flow downstream of the HEP dams.

In some cases, the implementation of a HEP scheme will have to take into consideration not only the need as a energy source, but only as a potential source for both water supply and/or irrigation, i.e. a multi-purpose dam. Currently there is no implementation of a specifically-designed multi-purpose dam, although in the case of the existing Batang Ai HEP Dam, the water released from the dam has been abstracted for water supply usage from a raw water intake downstream. In addition to providing regulated (controlled) baseflow for water supply, irrigation and navigation, HEP dam can also function as a saline intrusion prevention measures, and for flood mitigation purposes too.  

With the upcoming major developments in Sarawak particularly the SCORE development plan, the implementation of HEP dams has been given much emphasis to cater for the future domestic, commercial and industrial electricity demands in the State.

2. List of the Existing and Proposed HEP Dams in Sarawak

As an overview, the current status on the implementation of HEP Dams in Sarawak are listed as follows:

a) Existing HEP Dam
  1. Batang Ai Dam
b) HEP Dams Under Construction
  1. Bakun Dam
  2. Murum Dam
c) Proposed HEP Dams (planning or feasibility study level)
  1. Balleh Dam
  2. Limbang Dam (feasibility study completed)
  3. Lawas Dam
  4. Baram Dam
  5. Belaga Dam
  6. Mejawa Dam (12km downstream of Bakun Dam)
  7. Punan Bah Dam
  8. Pelagus Dam
3. Brief Description of the Existing and Proposed (Under Construction) HEP Dam Projects

The existing and proposed HEP Dam projects in Sarawak are briefly described and tabulated below:

a) Existing Batang Ai HEP Dam

The existing Batang Ai HEP Dam is currently the only HEP dam in Sarawak.
Picture Above: Existing Batang Ai HEP Dam

The dam is located in Lubok Antu and is a Concrete-Faced Rockfill Dam (CFRD), with a current output of 108 Megawatt (MW). The dam height is approximately 85m and the crest length is about 810m. The Batang Ai HEP Dam is constructed across the Batang Ai river, which is located within the Batang Ai Catchment (catchment area ~ 1200

The full supply level (FSL) is at the elevation level of EL108m, with a reservoir surface area of 85km2 at FSL. Meanwhile, the Minimum Operating Level (MOL) of the HEP dam is at EL98m. The reservoir has a gross storage volume of about 2870 million cubic meter (MCM), and a dead storage of about 1630 million cubic meter (MCM).

The electricity generation from this dam is operated and managed by Sarawak Energy Berhad (SEB).
Picture Above: Batang Ai HEP Dam viewed from the Batang Ai River

b) Proposed Murum Dam       

The proposed Murum Dam which is located in Belaga, is presently under the construction stage. The proposed Murum Dam is a Roller Compacted Concrete (RCC) Dam and is estimated to be able to generate a total output capacity of 944MW.

The proposed HEP dam is to be constructed across Sg. Murum in the Murum Catchment. The Murum Catchment has an approximate area of 2750 km2.

With the proposed dam standing at a height of 141m and a crest length of 473m, the estimated  reservoir gross storage volume is about 12043 million cubic meter (MCM); whereas the dead storage volume is about 6568MCM.

At the Full Supply Level (FSL at EL540m), the reservoir surface area covers a total area of 245 km2. The MOL of the proposed HEP dam is at EL515m.  

c) Proposed Bakun Dam      
Picture Above: Bakun Dam Outlet Tunnel

The proposed Bakun Dam, a Concrete Faced Rockfill Dam (CFRD) located in Belaga is currently under construction. Upon its scheduled completion and commissioning in Year 2010, the proposed HEP Dam is anticipated to have an estimated power generating capacity of 2400MW.

Erected at the height of 205m with a crest length of 814m, the proposed Bakun Dam will be the highest Concrete Faced Rockfill Dam (CFRD) in the world upon completion.

The proposed Bakun Dam is constructed across the Btg. Balui River. With all its tributaries from Btg. Balui, the total catchment area from the Bakun Catchment (at the Upper Rajang Basin) is approximately 14750 km2. The dam reservoir gross storage volume is about 44 billion cubic meter (BCM).

Picture Above: Overview of the Bakun Dam under construction, a CFRD dam

The Full Supply Level of the Bakun Dam stands at 228m high above sea level with an approximate 695km2 of reservoir surface area. The Minimum Operating Level (MOL) is at 195m above sea level. The riparian flow from the dam is estimated to be 1500 cubic meter per second (m3/s).  

Upon the completion, the Bakun Dam is expected to supply electricity to a proposed aluminium smelter plant in Samalaju, Bintulu. Plans are also being made to construct overhead power transmission lines and under-sea cable to transfer the electricity generated to Peninsular Malaysia, and connect to Tenaga Nasional Berhad’s (TNB) power grid.

4. Tabulated Summary of the Existing and Proposed (Under Construction) HEP Dam Projects in Sarawak

Name     of
 Murum Dam
Batang Ai
Bakun Dam
Dam Type
Lubok AntuBelagaBelaga
Capacity (MW)
Crest Length (m)
Dam Height (m)
River Source
Murum River
Batang Ai
Btg. Balui
Catchment Name
Murum Catchment
Batang Ai Catchment
Bakun Catchment (Upper Rajang River)
Catchment Area (km2)
Reservoir Gross Storage (MCM)
Dead Storage (MCM)
6,5681,630 -
Riparian Flow
 - -1,500m3/s
Full Supply Level (FSL), EL(m)
EL540mEL108m228m asl
Minimum Operating Level, EL (m)EL515mEL98m195m asl
Reservoir Area at FSL (km2)24585695


*RCC = Roller Compacted Concrete
CFRD = Concrete Faced Rockfill Dam

5. Proposed HEP Dams (Under Planning Stage)

Currently, there are a total of 7 more HEP Dams which are planned to be built in Sarawak. They are namely:
  1. Limbang HEP Dam
  2. Balleh HEP Dam
  3. Lawas HEP Dam
  4. Baram HEP Dam
  5. Belaga HEP Dam
  6. Mejawa HEP Dam
  7. Punan Bah HEP Dam
The implementation of these HEP dams is in their feasibility study stage at present. For the proposed Limbang HEP Dam, the feasibility study has been completed.