What is Fly Ash?
Fly ash is the waste byproduct formed by the combustion of coal in furnaces.
- In India, the availability of fly ash is significant as India has some of the largest coal reserves in the world. Indian coal has a high ash content and a low calorific value.
- In India, around 73% of the power plants are thermal-based, and amongst them, 90% are running on coal. Until ten years ago, fly ash was treated as waste all over the world, but now it has been developed as an environmental savior.
Since the amount of fly ash generated through these plants is huge, they have the potential to be reused along with other building materials.
Utilized
- It is predicted that 50% of the fly ash in upcoming years will be used for the generation of alternative building materials.
- The cement and concrete industry accounts for 50% of fly ash use, of which the total use currently stands at 30 tons (28%).
- Other areas where fly ash is being used are as a filling material for low-lying areas (17%), for roads (15%), and for brickworks (2%)
Future
Target: 100% Fly Ash Utilization Across All Sectors
- Government mandates for infrastructure projects.
- Strict penalties for non-compliance by power plants.
Innovation & New Technologies
- Geopolymer cement for net-zero emissions.
- Advanced fly ash composites for structural applications.
- Use of AI & automation in fly ash supply chains.
Scaling Up Adoption in Private Sector
- Builders & contractors encouraged to use fly ash-based materials.
- Policy support for startups in fly ash-based industries.
Problem
Current Scenario
The remaining 90% of particles in flue gas consist of tiny particles known as fly ash. If not collected, these particles can be released into the atmosphere.
Power plants use devices like baghouses, scrubbers, and electrostatic precipitators to capture fly ash, but these methods may not catch all particles.
Why the Remaining Fly Ash Is a Problem?
- Fly ash varies in physical and chemical composition based on the fuel burned. Most particles are extremely fine, typically smaller than 100 microns. Those that escape collection can contain acidic, toxic, or radioactive materials that may contaminate air, soil, and groundwater. Prolonged exposure to such particles can increase the risk of cancer, respiratory illnesses, and cognitive issues.
- Handling fly ash is also challenging, as nearly half is repurposed for products like concrete and asphalt, while some is sent to landfills. Its fine nature makes it susceptible to becoming airborne during transport, posing risks to safety and productivity for bulk material handlers. Many operators seek solutions to better control fugitive fly ash.
The EPA has found that prolonged exposure to these pollutants can increase the risk of cancer, respiratory diseases, and cognitive impairments.
Case Studies
Delhi Metro Project
- Used fly ash-based concrete, reducing cement consumption by 30%.
- Resulted in lower carbon emissions and stronger structures.
NTPC’s Fly Ash Utilization Initiative
- 70% fly ash utilization in cement, roads, and mine backfilling.
- Set up fly ash supply chains for construction industries.
Fly Ash Roads in Chhattisgarh & Maharashtra
- Highways built using fly ash are more durable and cost-effective.
- Reduced natural resource consumption (sand and gravel).