This article was first published on 28 November 2024, and updated on 30 March 2025.

The global energy landscape is undergoing a significant transformation as countries strive to balance economic growth, energy security, and environmental sustainability. For many nations, coal-fired power plants remain a vital component of their energy infrastructure, supporting industrial growth, meeting increasing energy demand, and ensuring economic stability. However, as we navigate the transition toward a cleaner energy future, we recognize the critical need to align the operation of our existing coal plants with environmental stewardship and sustainable practices.

Reducing Coal Generation Capacity

We have made a firm commitment: Our focus is solely on the operation of existing coal-fired power plants, not to build any new coal plants and no longer investing in greenfield coal plants since 2021. We are shifting from fossil fuels to greener sources. This decision underscores our dedication to transitioning toward a low-carbon energy system without expanding our reliance on coal. Instead, we are committed to deliver clean generation through renewable capacity growth, carbon management and coal generation capacity reduction.

Coal Combustion By-product and its Environmental Impact

Ash is the by-product of coal combustion, produced when coal is burned at high temperatures to generate electricity. It consists of fine particles or heavier residue, depending on the type of ash, and can either be disposed of or repurposed for construction applications. These ashes are considered hazardous waste and are strictly regulated under the Environmental Quality (Scheduled Wastes) Regulations 2005.

There are two main types of ash produced from coal burning to generate electricity: fly ash and bottom ash.

Fly ash is a fine, powdery material that rises with flue gases during combustion and is captured using filtration systems such as electrostatic precipitators or bag filters. It contains components like silica, alumina, iron oxide, and traces of unburnt carbon. Fly ash can be reused in construction materials like cement and concrete, where it improves the strength and durability of these products.

In contrast, bottom ash is heavier and settles at the bottom of the furnace. Although it has fewer applications than fly ash, bottom ash can be used in construction for road-based materials and structural fills.

Since fly ash and bottom ash are regulated as per the Environmental Quality (Scheduled Wastes) Regulations 2005 requirement, both types of ashes can cause a significant impact on the environment if not managed and disposed of properly. Fly ash, if released into the atmosphere, can contribute to air pollution, and poses health risks through inhalation. It can also contaminate water sources if it leaches into groundwater. Bottom ash, though less prone to becoming airborne, can still pose a risk through soil and groundwater contamination if not properly contained. Therefore, safely handling both fly ash and bottom ash is essential to prevent environmental harm.

Fly ash and bottom ash from our power generation operations constitute 99% of our total hazardous waste generated. The remaining hazardous waste is mainly used transformers, used lubricating oil, used batteries and e-waste.

Managing Ash the TNB Way, a responsible way

Our approach to handling the coal combustion byproducts such as fly ash and bottom ash reflects our commitment to environmental responsibly through circular economy principles and integration of technology:

1. Recycling and Reuse: Fly ash is repurposed as a key ingredient in cement and concrete production, reducing the demand for virgin raw materials.
2. Safe Storage: When recycling is not feasible, the ash is transported to secure, licensed landfill sites that adhere to environmental standards stipulated by the Department of Environment (DOE).
3. Integration of Technology: Our ASH Management System utilises digital tools to streamline the process, making it easier to manage consignment notes and track the life cycle of the ash.

ASH Management System was designed to monitor and oversee the fly ash and bottom ash that our coal-fired power stations produce. We have implemented this system to ensure safe and efficient ash management in compliance with Malaysia's environmental regulations, particularly the Environmental Quality (Scheduled Wastes) Regulations 2005.

The Consignment Note Monitoring process is a key component of our ASH Management System. Each power station that generates fly ash or bottom ash issues a consignment note, which records ash production, transport, and disposal. This ensures complete traceability from the point of generation to its final disposal or recycling.

We closely monitor all ash produced to ensure it complies with regulatory requirements. This helps to maintain transparency and accountability in how we manage our ash. Through the ASH Management System, we track and document all movements of ash, ensuring that it is safely disposed of at approved landfills or approved recycling facilities.

Ash contributes to the majority of the Scheduled Waste (SW) generated by TNB. As reflected in our internal tracking systems, this significant amount of ash is directed to a landfill or diverted to a recycling facility.

Fly ash has substantial potential for reuse, particularly in construction, and we actively explore opportunities to recycle this material. By using fly ash in the production of concrete and bricks, we can increase the amount of fly ash diverted from landfills, hence promoting a circular economy. In 2024, we collaborated with ten construction or cement companies to make use of the fly ash in the production of concrete and bricks. However, when recycling is not feasible, our system ensures that the ash is transported to secure, licensed landfill sites that adhere to environmental standards stipulated by the Department of Environment (DOE).

Integrating Technology for Efficient Ash Management

Our ASH Management System is vital to our broader strategy to enhance environmental sustainability. The system utilises digital tools to streamline the process, making it easier to manage consignment notes and track the life cycle of the ash. Powerplants are required to submit data electronically, allowing for real-time updates on ash movements. This digital integration ensures that we can monitor every stage of the ash management process efficiently.

Figure 1: Login Page of ASH Management System

The system was designed based on input gathered from coal power stations during the development phase from December 2023 to March 2024. This collaboration ensured that the system met the needs of those directly involved in ash management.

The system's go-live date occurred on 15 May 2024, during which users began inputting data. Any technical issues were addressed, and relevant personnel were trained.

The engagement and rollout phase commenced on 1 September 2024, ensuring all relevant users, including Health, Safety, and Environment (HSE) personnel, became familiar with the system. Since then, the ASH Management System has undergone continuous implementation to ensure long-term efficiency and effectiveness.

Verification and endorsement mechanisms are built into the system to ensure compliance with our internal policies and national regulations. Every step, from waste generation to final disposal, is carefully monitored to prevent environmental risks and maintain operational integrity.

Aligning with Our Scheduled Waste Roadmap Goals

Responsible fly ash management is part of our wider TNB Scheduled Waste Roadmap 2030, which outlines goals for improving waste management, increasing recycling rates, and minimising our operations' overall environmental impact.

Through the ASH Management System, we have taken significant steps to mitigate the environmental risks associated with its production while exploring ways to recycle and repurpose it. We remain focused on positively contributing to Malaysia’s environmental goals as we continue to refine and enhance our processes. In conclusion, TNB has taken great steps to ensure the ash's life cycle is appropriately managed and proper disposal and recycling are conducted. This is in line with TNB's strong drive for sustainability and promoting a circular economy.

Commitment to a Sustainable Energy Future

While coal-fired power plants continue to play a role in meeting current energy demands, our long-term vision is aligned with global decarbonization goals. We are accelerating investments in renewable energy, energy efficiency, and emerging clean technologies to drive the energy transition forward. By operating our existing coal plants responsibly and reducing their environmental impact, we are demonstrating that economic growth and environmental responsibility can coexist.

This balanced approach reflects our commitment to the energy trilemma: delivering affordable, reliable, and sustainable energy. It is a journey that requires collaboration, innovation, and an unwavering focus on our shared future.

Revision History:
30 March 2025: Added data on fly ash and bottom ash constitution, and added details on collaboration with construction or cement companies in 2024.

Back to ESG Stories