India is endowed with the fifth largest coal reserves in the world1 and meets a majority of its power demand through combustion of coal in thermal power plants (TPPs). Fly ash, a by product of coal based power production, exhibits cementitious properties in varying degrees in accordance with the chemical and physical properties of the mineral impurities in the coal such as clay, feldspar, quartz and shale. This cementitious behaviour makes fly ash an effective substitute to clinker in the production of cement.
India generated 226 MT of fly ash in fiscal year 2019-20, which was utilised through various modes such as cement, mine backfilling, bricks & tiles, reclamation of low lying area, ash dyke raising, roads & flyovers, agriculture, concrete, hydro power sector and others. Table details the quantum of fly ash generation and utilisation in India.
The utilisation of fly ash utilisation has been on the rise from 63% in fiscal year 2016-17 to 83% in fiscal year 2018-19. The Cement Industry is the largest consumer of fly ash in the Country. With the cement companies in India gradually transitioning to greener alternatives such as Pozzolana Portland Cement(PPC) and Pozzolana Slag Cement(PSC). Between 1996 and 2017, the share of PPC in cement production in India has increased from ~19% to 65%.2
|Year||Fly Ash Generation Million Tonnes||Fly Ash Utilised Million Tonnes||Fly Ash Utilisation by Cement Industry Million Tonnes||Fly Ash Utilisation by Cement Industry % of total generation|
Over a period, the Ministry of Environment, Forests and Climate Change (MoEFCC) has issued various notifications on fly ash utilisation, which have helped nudge up the utilisation of fly ash in the Country. While Cement Industry is already the largest consumer of fly ash, there exists potential for additional utilisation through the measures detailed below:
Participation of traders and exporters tend to increase the price of fly ash for the domestic end use industries. Granting first right of refusal of fly ash to priority end user industries such as cement would enable sustainable utilisation of fly ash. Additionally, the use of fly ash in development of value added products (such as blended cement) should be encouraged instead of backfilling closed/abandoned mines.
Implementation of railway sidings, loading, packing and storage infrastructure would enable channelising fly ash from pit head plants (in remote areas) and other fly ash surplus areas in the Country through cost effective railway transportation.
Publishing plant wise and state wise real time data on generation/utilisation of fly ash (current and legacy), monthly planned operations and plant load factor among others would enable end use industries to plan procurement and utilisation of fly ash. The Ministry of Power has developed a web page and a mobile application Ash Track for fly ash generation and utilisation as an interface between TPS and potential users.
Periodic reassessment and revision of standards implemented by the Bureau of Indian Standards (BIS) in accordance with the prevalent international standards would help in increasing the limit for blending for producing Pozzolana Portland Cement (PPC). While the European standard (EN-197) for Pozzolana Cement type IV/B allow addition of siliceous fly ash in the range of 36-55%, BIS allows addition only up to 35%.
Implementation of the Polluter Pays Principle would provide the necessary impetus for an investment in waste management technology, infrastructure (dry fly ash collection, storage and disposal) and transportation of fly ash from surplus to deficient regions within the Country.
Utilisation of PPC in public infrastructure projects such as buildings, highways, roads and flyovers would help spread awareness on blended cements.
India has set an ambitious target to achieve 500 GW of renewable energy by 2030 at COP26. The resulting decarbonisation of grid is set to impact the generation of fly ash in the Country in the upcoming decades. As such, it becomes critical to leverage the legacy fly ash for priority sectors such as cement to foster the production of green blended cements in the distant future.