Water is a crucial resource for the power generation, playing a vital role in processes such as steam generation, cooling, and other operational needs.
For Tenaga Nasional Berhad (TNB), ensuring a stable water supply is fundamental to operational efficiency, plant reliability, and long-term business sustainability.
As climate change accelerates and water demand rises, water stress assessments help power producers understand their exposure to scarcity risks - particularly in regions facing reduced rainfall, over-extraction, or declining water quality.
Why Water Stress Assessment Matters to TNB
At TNB, water stress assessment serves three strategic functions:
Identify Vulnerable Assets
Pinpoint power plants operating in high water-stress regions.
Enable Targeted Risk Mitigation
Develop site-specific solutions to ensure operational continuity.
Enhance ESG Transparency
Support regulatory compliance and strengthen environmental disclosures.
This approach reflects TNB’s broader ESG and climate resilience strategy, aligned with the UN Sustainable Development Goals (SDGs).
Understanding BWS Levels
Water stress is typically evaluated using the Baseline Water Stress (BWS) index, which represents the ratio of total annual water withdrawals to available renewable water supply.
The higher the ratio, the greater the competition for limited water resources - and the higher the stress level:
| BWS Score | Stress Level | |
|---|---|---|
| <10% | Low |  |
| 10% - 20% | Low-Medium |  |
| 20 - 40% | Medium-High |  |
| 40% - 80% | High |  |
| >80% | Extremely High |  |
Table 1: The BWS Score Range
Assessing Water Stress At TNB Power Plants
TNB’s thermal plants rely on water for cooling and steam processes, which gives them comparatively higher water needs than solar power plants. By comparison, hydropower plants consume relatively little water but are highly dependent on its availability, as their generation is directly tied to river flows and reservoir levels. Using World Resources Institute (WRI) Aqueduct data, TNB assesses each plant's exposure to water stress:
| No | Thermal Power Plants | Baseline Water Stress | |
|---|---|---|---|
| 1 | SJ Sultan Azlan Shah (Manjung 1-5) (TNB Janamanjung Sdn. Bhd. & TNB Manjung Five Sdn. Bhd.) | Low (<10%) | |
| 2 | SJ Tuanku Muhriz (Jimah East Power Sdn. Bhd.) | Low (<10%) | |
| 3 | S.J Sultan Salahudin Abdul Aziz, Kapar (Kapar Energy Venture Sdn. Bhd.) | Low (<10%) | |
| 4 | SJ Prai (TNB Prai Sdn. Bhd.) | Low (<10%) | |
| 5 | S.J Jambatan Connaught (TNB Connaught Bridge Sdn. Bhd.) | Low (<10%) | |
| 6 | Southern Power Generation Sdn. Bhd. | Low (<10%) | |
| 7 | S.J Gelugor | Low (<10%) | |
| 8 | S.J Tuanku Jaafar | Low (<10%) | |
| 9 | S.J Putrajaya | Low (<10%) | |
Table 2: TNB’s Thermal Power Plants BWS Scores
| No | Scheme | Hydropower Plants | Baseline Water Stress | |
|---|---|---|---|---|
| 1 | SSJ Kenyir | S.J Kenyir | Low |
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| 2 | S.J Hulu Terengganu | Low |
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| 3 | SSJ Sungai Perak | S.J Pergau | Low |
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| 4 | S.J Temenggor | Low |
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| 5 | S.J Bersia | Low |
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| 6 | S.J Kenering | Low |
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| 7 | S.J Chenderoh | Low |
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| 8 | S.J Sg. Piah | Low |
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| 9 | SSJ Cameron Highlands | S.J Sultan Yusof (JOR) | Low |
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| 10 | S.J Sultan Idris (WOH) | Low |
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| 11 | S.J Ulu Jelai | Low |
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Table 3: TNB’s Hydropower Plants BWS Scores
| No | Solar Power Plants | Baseline Water Stress | |
|---|---|---|---|
| 1 | TNB Sepang Solar | Low (<10%) |
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| 2 | TNB Bukit Selambau Solar 1 & 2 | Low Medium (10%-20%) |
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Table 4: TNB’s Solar Power Plants BWS Scores
Most of TNB’s power plants are situated in areas with Baseline Water Stress (BWS) scores below 10%, reflecting minimal competition for water resources. The only plants in a relatively higher band are the Bukit Selambau Solar 1 & 2, with a BWS reading between 10% and 20%, which is still classified as low to medium stress.
For context, the CDP (formerly the Carbon Disclosure Project) uses a 40% threshold based on WRI’s Baseline Water Stress data to identify areas of high-water stress. Subsequently, all TNB’s power plants fall well below this level, indicating that their water demand remains within the available resources at each location.
This achievement demonstrates careful site selection and strong resource-management practices, aligned with the company’s broader ESG and climate objectives. However, current low stress levels may change over time due to climate variability, weather fluctuations, and increasing regional demand.
To sustain responsible operations, TNB will continue monitoring water use, practicing diligent resource management, and enhancing water efficiency measures, supported by new technologies to strengthen overall water stewardship.
Strategic Responses and ESG Implications
Understanding and addressing water stress risks is a key component of TNB’s ESG commitment and long-term climate resilience strategy. It supports SDG 6 (Clean Water and Sanitation) and SDG 13 (Climate Action).
Key mitigation strategies include:
- Expansion of rainwater harvesting systems at key sites
- Improvement in infrastructure to use less water
- Strengthening data tracking on water management
By proactively addressing water stress risks, TNB enhances the resilience of its operations while demonstrating leadership in sustainable energy generation.