Coal and Mining Sector

Fly ash generation and Disposal


From UPSC perspective, the following things are important :

Prelims level: composition of fly ash

Mains level: environmental pollution

fly ashContext

  • India depends heavily on coal for power generation. This creates the problem of fly-ash generation and its proper disposal, usage.
  • The National Green Tribunal (NGT) noted September 19, 2022 that there was an urgent need to augment the utilisation and disposal of fly ash in Chhattisgarh.

What is fly ash?

  • Fly ash is a by-product of coal combustion. It contains Aluminium Silicate, SiO2, CaO, oxides of iron, magnesium and toxic metals like lead, arsenic, cobalt, and copper.
  • It can travel to far places. India is growing to double its power generation in the next decade and with coal being the biggest source of fuel for power generation, the problem of fly ash is going to increase too.

fly ash Environmental Problems with fly ash

  • A large quantity of fly ash dumped into poorly designed and maintained ash ponds. About a billion tonnes of this toxic ash lie dumped in these ponds, polluting land, air, and water.
  • All the heavy metals found in fly ash—nickel, cadmium, arsenic, chromium, lead, etc—are toxic in nature. They leech into the surrounding soil and can enter food-chains.
  • Fly ash gets easily ingested through respiration, which causes many diseases such as asthma, neurological disorders.
  • Suspended fly ash in the air acts as a global warming agent and heats the earth’s surface.
  • Fly ash settles on leaves and crops and reduces crop productivity.
  • It pollutes the groundwater.
  • There is a reduction in recharging of groundwater due to fly ash filled mine voids.
  • Reduces visibility by creating dense fog in the winter season.

fly ashIssues with fly ash management

  • The government mandates that all coal power plants (CPPs) reach 100% utilization of fly ash.
  • Along with it, CPPs should give a certain amount of fly ash free of cost for MSMEs to manufacture bricks, tiles and rest of the fly ash should be sold to other industries.
  • CPPs will have to maintain fly ash ponds to reduce its suspension in air.
  • But all these steps for utilization areas are problematic as they do little to mitigate these risks.
  • The pricing of fly ash is increasingly becoming a contentious issue that is hampering its gainful utilization.
  • The current approaches to evaluating risks with fly ash disposal are very limited, and they may underestimate the true risks
  • In spite of initiatives taken by the government, several nongovernmental and research and development organizations for fly ash utilization, the level of fly ash utilization in the country is quite low at only 38% which is less than the global standards.
  • Hence, rather than being utilized, fly ash is being stored despite warnings from regulators.
  • Deposition in storage places has negative influences on water and soil because of their mineral composition as well as morphology and filtration properties.
  • Ash-handling units are the biggest consumers of water in CPPs. The government advocates the designed ash-to-water ratios as approximately 1:5 for fly ash, but the observed ratios have been around 1:20.
  • Certain states have discouraged the use of blended cement and fly ash bricks in public works.

fly ashThe above issues can be addressed by

  • Greater regulatory oversight and price control,
  • Revision of cement blending standards,
  • Research in improving fly ash quality,
  • Reducing the cost of transportation,
  • Provisions for overcoming information asymmetries,
  • Incentivising use in brick kilns for producing fly ash bricks,
  • Overall sensitization of key decision-makers on the matter.
  • Instead of dumping it on ash ponds, can be used for construction due to its reuse as pozzolan, and replacement of portland cement by hydraulic cement
  • Due to its grain size distribution, enhanced strength permeability, it can be used to construct embankments at road construction, concrete dams like GHATGHAR DAM
  • Strong penalties for those production units who do not use proper filtration devices
  • Moving to renewable energy production away from coal-based thermal production.


  • Utilization of Fly Ash is not only possible but also essential. In this context “Fly Ash Mission of Government of India” is a slow but steady start, the pace of which needs to be ramped up. An honest effort is required by the concerned stakeholders to improve the perceptions of fly ash-based cement or concrete; increase its use, particularly for government works; and impart scientific knowledge about fly ash, its uses, and possible impacts.

Mains question

Q. What is fly ash? Discuss the environmental challenges it poses. Suggest how to address the situation.


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