The country’s dependence on coal for meeting its energy needs has resulted in the generation of huge quantities of ash over the years. However, ash utilisation levels have remained dismal. Of the total installed capacity of over 330 GW, nearly 60 per cent is coal based, the majority of which comprises domestic coal with a high ash content of 30–35 per cent. It is estimated that thermal power plants (TPPs) generate 200 million tonnes (mt) of ash annually, which is likely to reach 300 mt by 2022. Around 90 per cent of ash generated by power plants is in the form of fly ash and the remaining is bottom ash or pond ash.
Between 2009-10 and 2015-16, fly ash generation increased from 123.5 mt to 177 mt, recording a compound annual growth rate of 6.25 per cent. However, fly ash utilisation has not registered any significant increase and remained in the range of 55-62 per cent over these years. In 2015-16, the fly ash utilisation rate stood at 61 per cent, and dipped to 57 per cent in the first half of 2016-17.
In order to mitigate the environmental hazards posed by fly ash, the Ministry of Environment, Forest and Climate Change (MoEFCC) has issued various notifications on fly ash utilisation. The first notification was issued in 1999, which has been amended many times. The latest amended notification, dated January 25, 2016 stipulates 100 per cent utilisation of fly ash by TPPs by December 2017. Earlier, in 2009, the MoEFCC had prescribed ash utilisation targets in a phased manner over a period of five years till 2014. However, only one-third of the TPPS were able to meet the target. Out of 151 TPPs surveyed by the Central Electricity Authority (CEA), only 54 power stations achieved the fly ash utilisation targets as of 2015-16.
According to the latest amendment, the TPP owner would have to bear the entire cost of ash transportation up to a radius of 100 km from the TPP. For distances of more than 100 km and up to 300 km for road construction projects or for the manufacture of ash-based building products, the owner would share the cost equally with the user/construction agency. In addition, the notification states that it is mandatory to use fly ash-based products for all government schemes such as the Pradhan Mantri Gram Sadak Yojana, the Mahatma Gandhi National Rural Employment Guarantee Scheme and the Swachh Bharat Abhiyan.
Fly ash is collected through electrostatic precipitators installed in power plants while bottom ash falls through the furnace grating and is collected in a hopper. The pozzolanic property of fly ash makes it an excellent resource material for the construction industry. It can be used for the manufacture of cement, bricks, concrete blocks and high density interlocking blocks. These can be used in conjunction or as an alternative to conventional bricks by the construction industry. Another fly ash-based product is lightweight aggregate, which proves an excellent alternative to natural quarried aggregate. Fly ash aggregate is about 25 per cent lighter than natural aggregate and provides greater flexibility to builders during construction. It allows easier placing, compacting and finishing. Fly ash can also be used as a partial replacement to cement. Fine fly ash particles are collected from the banks of the electrostatic precipitators for this purpose. Meanwhile, bottom ash is frequently used in the construction of roads.
In 2015-16, about 177 mt of ash was produced by 151 TPPs, of which about 108 mt was utilised in various applications. The maximum amount (about 25 per cent) of ash was utilised in the manufacture of cement and concrete. About 8.35 per cent was used to make bricks and tiles, nearly 7 per cent for the reclamation of low-lying areas, about 6 per cent for the raising of ash dykes, and 5.8 per cent for the backfilling of mines. The remaining was utilised for constructing embankments of roads and flyovers (2.83 per cent), for agricultural purposes (1.25 per cent) and in other areas (4.6 per cent).
According to the CEA, Andhra Pradesh, Chhattisgarh, Madhya Pradesh, Maharashtra, Odisha, Uttar Pradesh and West Bengal crossed the 10 mt mark of fly ash generation in 2015-16. Uttar Pradesh generated the maximum volume at 24.6 mt but its utilisation levels were dismal at 45 per cent. Meanwhile, Delhi, Haryana and Punjab achieved a fly ash utilisation level of over 100 per cent and Gujarat, Jharkhand, Rajasthan and West Bengal achieved a fly ash utilisation level of over 90 per cent.
In the first half of 2016-17, the best performing states in terms of fly ash utilisation were Delhi (167 per cent), Gujarat (106 per cent), Haryana (150 per cent), Jharkhand (99.9 per cent) and Rajasthan (101 per cent).
As far as utilities are concerned, of the 71 power generation utilities surveyed by the CEA in 2015-16, 20 utilities achieved a fly ash utilisation level of 100 per cent or more. Broadly, the private utilities fared better as compared to their public counterparts. Among state generation utilities, Jharkhand, Odisha and Uttar Pradesh were the worst performers with ash utilisation levels ranging from 10 per cent to 35 per cent. NTPC Limited, the country’s largest generator, recorded an ash utilisation level of 41 per cent in 2015-16.
In the first half of 2016-17, the best performing utilities included Adani Power (Mundra), CESC Limited, Gujarat State Electricity Corporation Limited, Haryana Power Generation Corporation Limited, JSW Energy and Rajasthan Rajya Vidyut Utpadan Nigam Limited with over 100 per cent ash utilisation. Meanwhile, Chhattisgarh State Power Generation Company Limited, Uttar Pradesh Rajya Vidyut Utpadan Nigam Limited, Odisha Power Generation Corporation Limited and Telangana Power Generation Corporation Limited recorded low ash utilisation levels of 10-30 per cent.
New initiatives and the way forward
The Ministry of Power (MoP) has outlined certain initiatives to monitor fly ash generation by TPPs and ensure compliance with environmental directives. To this end, the TPPs are required to upload the details of fly ash available with them on a monthly basis. A quarterly report of this data needs to be also submitted to NITI Aayog.
In addition, the MoP is developing a mobile application to connect fly ash generators and users. The proposed application will have details about the fly ash availability at TPPs, the location of plants and the facility to apply online for issues/supply of ash.
Going forward, concerted efforts are needed by all states to improve fly ash utilisation. The state governments need to promote fly ash utilisation in government construction programmes by including fly ash bricks in tender specifications, developing ash parks in designated industrial parks, and establishing storage facilities and quality testing procedures for ash-based products. The Maharashtra government has taken a lead in this regard and approved a policy for 100 per cent utilisation of fly ash generated by power plants for construction activities. Recently, Mahagenco Ash Management Services Limited invited brick kiln owners to set up their units near its TPP in Koradi. Further, the CEA has suggested that TPP operators should conduct awareness programmes on the use of fly ash for the manufacture of bricks and cement in rural areas in the plant vicinity as a part of their corporate social responsibility.
Besides, there is significant potential for ash utilisation in the manufacture of bricks, building products and construction material for roads/highways, which needs to be exploited further. The concerned agencies, including the National Highways Authority of India and housing development authorities, need to be sensitised about the utilisation of fly ash so that it can be factored in at the tendering stage itself.
In addition, TPP operators are looking at making technical modifications to ensure the collection, storage and disposal of fly ash in dry form. The key driver for this is the new environmental norm that restricts water consumption at existing and new power plants.
As per the Centre for Fly Ash Research and Management, ash generation is projected to increase to 500 mt by 2022 and further to 1,000 mt by 2032 while the utilisation levels are projected to be 45 per cent and 65 per cent, if the current ash management practices continue. In order to achieve 100 per cent utilisation, there is a need for stricter compliance monitoring by the authorities along with committed efforts by TPP owners and other stakeholders.