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Making Ash Disappear
The Indian government has been pushing for a target of 1.5 billion tonnes of coal production annually by 2020, most of which will be used in the electricity sector. In this context, current issues—status, policies, regulations, and bottlenecks—regarding the disposal of fly ash generated by thermal power plants are examined. Scenarios of ash generation and utilisation are presented. Blending fly ash in cement is the most environmentally sustainable and financially attractive method of its utilisation. Finally, key technical, regulatory, pricing, logistical, and behavioural issues that need to be urgently addressed to reach complete fly ash utilisation are discussed.
It is unanimously suggested that coal, which has been the dominant source of fuel for power generation in India (almost three-fourths is currently coal-based), will continue to be a critical source for generating baseload electricity. In 2012, approximately 442 million tonnes (Mt) of coal was used to generate 737 terawatt-hours (TWh) of electricity. Various estimates indicate that electricity generated from coal is expected to grow twofold to threefold by 2030. However, burning coal results in the generation of fly ash, a residual waste product that is harmful for human health and the environment. In 2011–12, 145 Mt1 of fly ash generation was reported in India (CEA 2014a). To put this figure in perspective, the municipal solid waste generated in India in 2012 amounted to 46.5 Mt.
Table 1 provides key statistics regarding the generation and utilisation of fly ash, as reported by the Central Electricity Authority (CEA). It is also estimated that over half of India’s requirement of building stock in 2030 is yet to be built. India is the second-largest producer of cement in the world,2 but its per capita consumption remains low—at around 200 kg3— compared to the world’s average. Various growth projections for the cement industry indicate that per capita consumption will increase threefold by 2030. The cement industry utilised 43 Mt of fly ash in the production of Portland Pozzolana Cement (PPC) in 2015. The pozzolanic and hydraulic properties of fly ash enable its use as a substitute for clinker in the production of cement. Approximately 65% of the cement produced in India in 2012 was PPC, with an average blending of fly ash of 27% by weight. With ample availability of fly ash, lower production costs, and functional similarities with Ordinary Portland Cement (OPC), PPC will continue to be the dominant form of cement produced in India in the future.
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