The Union Government recently issued a draft amendment notification regarding the eco-friendly utilisation of ash (fly ash and bottom ash), which are by-products of coal and lignite thermal power plants (TPPs). The draft mandates 100% utilisation of fly ash and promotes sustainable practices while conserving topsoil. Fly ash, which makes up about 80% of the total ash generated, consists of fine, powdery particles that are carried away with flue gases. Bottom ash, accounting for approximately 20% of the total ash in a TPP, is a coarse, gravel-like residue that settles at the bottom of a coal furnace.
A 2020 report by the Centre for Science and Environment (CSE), a New Delhi-based non-profit environmental policy think tank, found that only about 50-60% of the total fly ash generated by the power sector is currently utilised.
Various media reports and experts associated with TPPs have noted that the usage of ash is quite uneven. Some TPPs manage to utilise as much as 98% of their fly ash, while the majority utilise around 50%. Less than adequate utilisation of fly ash is prevalent in clustered TPP areas, where multiple power plants exist in districts such as Korba, Talcher and Nagpur. In these clusters, the utilisation level is often below 40%. One of the significant challenges in using ash is its transportation.
Fly ash is now being primarily used in industries such as cement, brick, ready-mix concrete, and for constructing roads and flyover embankments. While the industry sees profitable opportunities for fly ash in industrial applications, they find it uneconomical for use in abandoned mining fill sites.
Fly ash poses adverse environmental and health impacts due to its hazardous nature. Improper disposal and non-utilisation can result in severe air and water pollution. In addition to lime, silica and alumina, fly ash contains toxic heavy metals such as lead, mercury, arsenic and hexavalent chromium, all of which are known carcinogens. The presence of fly ash also diminishes the fertility of nearby agricultural lands, and residents living within a 5 km radius often report respiratory disorders due to emissions.
In addition to health and environmental impacts, several significant coal ash pond accidents have occurred across the country over the last 15 years, affecting both utility thermal plants and captive power plants. Minor incidents involving fly ash occur regularly but often go unreported.
The new draft recognises the concerns raised by various stakeholders regarding the implementation of the Ash Utilization Notification of 2021. The notification requires all mines — regardless of whether they are operated by the government, public, or private sector — to backfill voids or stow both operating and abandoned mines located within a 300 km radius (by road) of coal or lignite thermal power plants with fly ash.
In the first year of a two-year cycle, non-compliance with the requirement to utilise at least 80% of total ash will result in a fine of H1,000 per ton. If ash remains unutilised throughout the entire three-year cycle, violators will face an environmental compensation charge of H1,000 per ton for the quantity of utilised ash.
However, financial penalties have not been effective as many TPPs failed to meet the 100% utilisation rate and continue to pollute their surroundings. A notable case is the North Chennai Thermal Power Station, which has faced persistent issues with fly ash pollution, including a significant leak in August 2020 that flooded a nearby village. Residents reported problems with ash slurry entering their homes and adverse health effects due to pollution. River and borewell samples revealed heavy metal contamination. In 2017, the National Green Tribunal warned the TPP of a potential shutdown due to non-compliance, and a committee was established to monitor the situation. Despite a penalty of H8.34 crore in January 2020, pollution persisted.
To improve monitoring, the Central Pollution Control Board (CPCB) and the Central Electricity Authority (CEA) will develop an online portal for real-time tracking of ash utilisation within the next six months. The CEA is responsible for monitoring ash utilisation and ensuring TPPs comply with these provisions on a quarterly basis.
The new draft notification eliminates the mandatory requirement to mix at least 25% fly ash with sand for backfilling open cast and underground mines. It also removes the provision requiring at least 25% fly ash to be mixed with overburden.
Overburden (OB) in mining refers to the rock, soil and materials above an ore body or coal seam removed to access resources. This material, often regarded as waste, is typically dumped about 5 km from the site of mining, forming large mounds. Over time, rainfall can cause erosion and slope instability, potentially leading to landslides or mudslides in mining areas. Incorporating fly ash with overburden helps create a binding effect that mitigates erosion and reduces rainwater infiltration.
“The draft doesn’t specify the amount of fly ash to be mixed with OB or materials like sand used for filling the mines,” stated Dr Vimal Kumar, Founder and Mission Director of Fly Ash at the Ministry of Science & Technology, Government of India. He added, “The draft notification creates space for speculation and manipulation regarding whether to mix a small amount or a large quantity of fly ash with overburden or other materials in the backfilling of used mines.”
The notification indicates that the CEA, in collaboration with the CPCB, will formulate a plan for managing ash waste. Previously, the CPCB was tasked with initiating consultations with the CEA and chairing a stakeholder committee that included multiple ministries — Coal, Road Transport and Highways, Ports, Shipping and Waterways, Micro, Small and Medium Enterprises, and the Department for Promotion of Industry and Internal Trade — along with the CPCB and CEA.
This change in leadership reflects a shift in the government’s approach toward fly ash, moving from managing pollution to developing it as an industrial product. TPPs are now viewing fly ash as a profitable venture, as its industrial applications have surged. The demand for fly ash has increased in various sectors, including roads, embankments, highways, cement and concrete, and in the brick, block, and tile industries.
However, the new notification does not address the issue of cluster power plants where ash ponds are created. These clusters generate significant amounts of ash, yet their utilisation remains limited. Transporting ash for mine backfilling or alternative uses is often uneconomical for these TPPs. “A major focus of this draft is on the management of ash from single TPPs or urban TPPs, which are already implementing usage strategies. However, it is silent on the challenges faced by cluster TPPs,” commented a CPCB scientist who wished to remain anonymous. “Transporting fly ash is costly, and no TPP is interested in it.” This silence leaves a significant gap in the comprehensive management of ash generated by cluster power plants.