The fly ash produced as a by-product of coal combustion in the boiler poses environmental challenges, and its efficient, sustainable utilisation has been of paramount importance to the power industry. According to latest Central Electricity Authority (CEA) data available for 2016-17, almost 169 million tonnes (mt) of fly ash was generated by thermal power plants (TPPs) in India.
While the government has been promoting 100 per cent fly ash utilisation through several policy and regulatory stipulations, the ash utilisation level in the country continues to hover at around 60 per cent of overall ash generation. Currently, only a few utilities have been able to comply with the environment ministry’s January 2016 notification, which had stipulated 100 per cent utilisation of ash by December 2017. A key initiative for promoting ash utilisation levels by the Ministry of Power (MoP) recently, has been the launch of a web-based monitoring system and a fly ash mobile app, which would act as an interface between producers and consumers (road contractors, cement plants), providing details such as plant-wise ash availability and utilisation status.
A look at the key trends in ash generation and utilisation, the policy initiatives to promote ash utilisation, and issues and concerns for power producers and end-use industries…
The Ministry of Environment, Forest and Climate Change (MoEFCC) issued the first directive for promoting fly ash utilisation in the country back in September 1999. This was subsequently amended with notifications issued in 2003, 2009 and 2016, setting targets for fly ash utilisation and promoting its use by construction agencies. The ministry, in a notification dated January 25, 2016, stated on the complete utilisation of fly ash by thermal power plant (TPP) by end December 2017. In addition, it was specified that power plant developers would bear the entire cost of ash transportation up to a radius of 100 km. For distances of more than 100 km and up to 300 km for road construction projects or for ash-based building products, the developer would share the cost equally with the user/construction agency. The notification also made it 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.
Earlier, in 2009, the ministry had chalked out the timeline for gradually achieving 100 per cent ash utilisation by TPSs. TPSs in operation before the date of the 2009 notification (that is, November 3, 2009) needed to achieve the target of fly ash utilisation in five successive years (50 per cent in the first year, 60 per cent in the second year, 75 per cent in the third year, 90 per cent in the fourth year and 100 per cent in the fifth year). Meanwhile, TPSs commissioned after the notification were required to achieve the fly ash utilisation target of 50 per cent in the first year, 70 per cent in the second year, 90 per cent in the third year and 100 per cent in the fourth year, depending on their date of commissioning.
Taking cognisance of the need to ensure greater utilisation of fly ash, the MoP has directed the states to prepare a roadmap to achieve the prescribed targets at respective state power plants. The government has also reduced the goods and services tax (GST) rates on fly ash and its products to 5 per cent.
Apart from this, last year, NITI Aayog constituted a committee for minimising fly ash generation and promoting its utilisation. As per the committee’s directions, the web-based application for ash management was launched by the power ministry wherein each TPP needs to upload ash data electronically on a monthly basis latest by the 7th of every month. This would include data such as the number of ash ponds available, the quantum of fly ash generated and disposed of the balance fly ash stock available, etc. Meanwhile, the mobile app for ash management, ASH TRACK, will help to establish a link between fly ash users and power plant executives for obtaining fly ash for use in various areas.
According to the CEA, in the decade 2007-08 to 2016-17, while the generation of fly ash grew at a compound annual growth rate (CAGR) of 4.19 per cent, ash utilisation grew at a rate of 6.27 per cent. Fly ash utilisation increased from 53 per cent to 63 per cent during the same period.
In 2016-17, fly ash generation across 155 TPPs (aggregating 157 GW of capacity) stood at 169.25 mt, of which around 107.1 mt was utilised. Of the 155 plants, 50 power stations recorded 100 per cent or more utilisation of fly ash; 39 thermal power stations (TPSs) recorded fly ash utilisation of over 100 per cent; 42 power stations recorded ash utilisation of 75 per cent to 100 per cent; 11 recorded ash utilisation of 60 per cent to 75 per cent; and 42 recorded ash utilisation of less than 42 per cent. Regarding compliance with the MoEFCC’s notification of November 3, 2009, during 2016-17, out of 155 TPSs, 56 achieved the set targets.
State-wise, seven states – Andhra Pradesh, Chhattisgarh, Madhya Pradesh, Maharashtra, Odisha, Uttar Pradesh and West Bengal, generated over 10 mt of fly ash during 2016-17. Uttar Pradesh recorded the highest level of fly ash generation at 28.27 mt. Bihar, Chhattisgarh, Madhya Pradesh, Telangana and Uttar Pradesh utilised less than 50 per cent of the fly ash generated. Meanwhile, Delhi, Gujarat, Haryana, Jharkhand and Punjab achieved a fly ash utilisation levels of over 100 per cent and Rajasthan achieved fly ash utilisation of over 90 per cent.
Utility-wise, out of 76 utilities (for which the CEA received data), 21 utilities achieved a fly ash utilisation level of 100 per cent or more, and 23 power utilities achieved a fly ash utilisation level in the range of 75 per cent to 100 per cent.
Cement is one of the key end-use consumer industries for fly ash, with almost a 23.98 per cent share in total utilisation. Blending fly ash in cement is environmentally sustainable and financially attractive since the pozzolanic and hydraulic properties of ash facilitate its use as a substitute for clinker.
Besides this, fly ash is used in the manufacture of bricks and concrete (8.81 per cent in the end use of fly ash in 2016-17), which binds the ash and prevents it from escaping into the environment. Another use for fly ash is in building roads and embankments, since fly ash is lightweight, compressible and amenable. In the agricultural sector, fly ash helps in the early maturity of crops, improves soil aeration, and conserves plant nutrients and water, without affecting the quality of groundwater. Apart from this fly ash is used in the rubber industry, and in the manufacturing of high water-resistant tiles and wood substitutes.
Various studies are under way to explore new avenues for its utilisation. A recent study has shown that fly ash can be used for mosquito control purposes. It could serve as a carrier for Bacillus thuringiensis israelensis, a bio-pesticide used to kill the larvae of many insects. Currently, plaster of Paris and charcoal are used for this purpose, but the use of fly ash as a carrier material enhances the chances of its ingestion.
Various states are undertaking initiatives for promoting fly ash utilisation. The Odisha government has made it mandatory to use fly ash bricks in buildings in the city area. The Maharashtra government too has adopted a fly ash utilisation policy and is considering making fly ash available free of cost.
To enhance fly ash utilisation from pithead power plants, a trial for the bulk transportation of fly ash to consumption centres was carried out successfully by NTPC Limited with the help of Indian Railways, from Shaktinagar railway station (NTPC Rihand) to Prism Cement’s Satna cement plant in April 2017.
According to estimates published in the Economic and Political Weekly (May 26, 2018), the annual generation of fly ash is expected to reach approximately 437 mt by 2030 and, provided the current trend in ash utilisation continues, its utilisation would reach 71 per cent, or 310 mt. This is based on the assumption that by 2030, 1,340 mt of coal would be used for electricity generation and that the average ash content in coal would be around 33 per cent.
In such a scenario, improving fly ash utilisation practices is imperative for sustainable development. However, a number of issues are hampering this. A key issue pertains to ash pricing. This is especially true for cement factories, which is one of the major ash-consuming industries. Often, power plant developers charge heavy prices from cement factories in the form of administrative charges, as a result of which the price advantage of fly ash over limestone is lost. By indexing the fly ash price to the price of cement, the cost benefit of ash in the cement sector is lost. Apart from this, the use of fly ash as a value-added product has been impeded by imperfections typical of quasi-markets, such as information asymmetry and high transaction costs, vested interests, technical and technological limitations, and the lack of regulatory oversight and political will.
In order to incentivise the utilisation of fly ash and ensure its appropriate pricing, it is recommended that power plant developers account for avoided costs, additional revenues, etc. in their revenue requirement. This will help remove the opacity around fly ash utilisation and allow cost reductions to be passed on to the consumer.
Furthermore, the revision of cement blending standards, research in improving fly ash quality, reducing transportation costs by sharing them between TPPs and end-user industries, and provisions for dry fly ash evacuation and storage are other recommendations for the industry to improve its ash utilisation levels.
To conclude, while a host of avenues for the utilisation of fly ash are available, the most desirable option is to limit fly ash production through the use of better coal, advanced combustion techniques, etc. The overall sensitisation of decision-makers regarding the benefits of ash in end-use industries and its hazardous impact if it is left unutilised will go a long way in creating better market value for the product.