Why Is Fly Ash Bad For The Environment

Health and Environmental Hazards of Fly Ash

• All the heavy metals found in fly ash—nickel, cadmium, arsenic, chromium, lead, etc—are toxic in nature. Its minute, poisonous particles accumulate in the respiratory tract, and cause gradual poisoning.
• A 2013 study found that the emission of particulate matter from coal power plants (CPPs) resulted in 80,000–1,15,000 premature deaths in India in 2011–12, of which approximately 10,000 were children under the age of five. Around 20 million cases of asthma and respiratory ailments could be directly linked to exposure to fly ash (Conservation Action Trust 2013).
• For an equal amount of electricity generated, fly ash contains a hundred times more radiation than nuclear waste secured via dry cask or water storage4 (Hvistendahl 2007). The breaching of ash dykes and consequent ash spills occur frequently in India, polluting a large number of waterbodies (Bhushan et al 2015).
• These events are treated as issues of national concern in other countries (Dodge 2014), but are considered business-as-usual in India.

Fly Ash Pollution Effects

• The Expert Appraisal Committee (EAC), Ministry of Environment, Forest and Climate Change (MoEFCC), has noted the environmental hazards due to leaching and spills from several CPPs (Jain 2014).
• For example, the destruction of mangroves, drastic reduction in crop yields, and the pollution of groundwater in the Rann of Kutch from the ash sludge of adjoining CPPs has been well documented (Bahree 2014).

Status of Fly Ash as a Usable Waste Product

• In 1999–2000, fly ash was removed from the “hazardous industrial waste” category and reclassified as “waste material” by the Central Pollution Control Board (CPCB). It has since become a saleable commodity.
• The MoEFCC has provided regular notifications regarding the safe disposal of fly ash and its alternative uses, such as, as a substitute for topsoil in making bricks.A notification by the MoEF in November 2009 mandates that all CPPs reach 100% utilisation within five years of the notification.

Fly Ash Pollution Effects

• It also provided for the use of fly ash and fly ash-based products in all lowland reclamation and construction activities within a hundred kilometres of a plant, and at least 25% use of fly ash for the stowing of mines within 50 km of the facility.
• At least 20% of the dry electrostatic precipitate (ESP) fly ash has to be made available free, to micro, small and medium enterprises engaged in manufacturing bricks, tiles, and blocks.
• The remaining quantity of fly ash is eligible to be sold by the power plants to other industries such as the cement and brick industries, and the proceeds must go into fly ash infrastructure development and sales promotion activities until 100% utilisation is achieved (MoEF 2009).

Issues with Existing Utilisation

• Both the dry and wet methods of disposing of fly ash, that leave it in contact with the environment, are not without risk. The EAC has regularly stated that some of the current utilisation areas are problematic as they do little to mitigate these risks. On 6 December 2010, it observed:
• Regarding use of fly ash in agriculture … that fly ash is reported to contain about 48 elements including radioactive elements and toxic heavy metals (in mild doses) … unless scientific study rules out long term adverse health impacts, as such, this method of fly ash disposal shall not be resorted to.
• Yet, FAU in agriculture has increased more than threefold since the notification, to 2.9 Mt.On 12 December 2011, the EAC noted thatdue to weathering action heavy metals or radioactivity content increases manifold when fly ash is left open in fields.
• It was, therefore, of paramount importance that a detailed study … be carried out before advocating promotion of fly ash for utilisation in agriculture, reclamation of low lying areas [or] as mine void filling. (Dharmadhikary 2014)
• Between 2011 and 2015, FAU in reclamation and land-filling increased from 15 Mt to 24 Mt. It is clear that dumping of fly ash in open spaces does little to overcome or even reduce the threat it poses to the environment.

Case for Blending Fly Ash

• Fly ash utilisation in cement, bricks, and concrete binds the ash, and hence its toxic elements do not escape into the environment. The cement industry has consistently utilised about 25% of the fly ash generated by CPPs.
• It will continue to be the primary driver for FAU on account of the high anticipated growth in cement production, and the health and environmental risks posed by other areas of utilisation.
• This will not only help tackle these risks associated with the other methods of fly ash disposal, but also promote resource efficiency by conserving limestone, coal, and electricity for cement manufacturers, and reducing the land and water requirements of the CPPs.

Fly Ash Disposal Problems

Fly Ash Projections of Production

• The growth in cement production is highly correlated with India’s gross domestic product (GDP), with an average elasticity of 1.23 and a compounded annual growth rate (CAGR) of 9.6% between 2006 and 2012.5
• Coal consumption for electricity generation has been growing at nearly 5% in the same period. Both coal-based electricity and cement are crucial inputs to economic growth; their substitutability is limited due to various factors, discussions regarding which are beyond the scope of this article.
• Private think-tanks and public institutions have tried to estimate figures for the production of cement, and use of coal for the generation of electricity by 2030. M Tables 3 and 4 summarise the projections made in these studies.
• For the purposes of quantitative analysis, 951 Mt of cement production6 and 1,340 Mt of coal in electricity generation7 by 2030 have been considered. At an average ash content in coal of 33%, this implies that the annual fly ash generation by 2030 will be approximately 437 Mt.
• If the current trends in FAU were to continue, overall FAU will increase from 61% in 2013 to 71%, or 310 Mt, in 2030, with cement’s share in utilisation, as a percentage of total fly ash generated, increasing from 25% to 35% by 2030.
• While cement’s fly ash requirement will grow fourfold, to 151 Mt in 2030, approximately 128 Mt of fly ash will still remain unutilised.8 This will require an additional 2,300 hectares (ha) of land and 1.3 billion cubic metres (bcm) of water for ash ponds, exacerbating the existing problems concerning fly ash disposal.

Toxicity Of Fly Ash

• In order to illustrate the gains in resource efficiency from greater fly ash blending in cement, two scenarios are developed: the 27/65 scenario and the 35/80 scenario.9 The 27/65 scenario is a business-as-usual scenario in which the percentage of fly ash blended in cement is constant until 2030.
• The 35/80 scenario denotes greater fly ash blending by weight in PPC cement, and a greater share for PPC in overall cement production by 2030.
• Existing Bureau of Indian Standards (BIS) regulations permit up to 35% of fly ash blending in PPC. If PPC were to be blended at the BIS threshold, and the share of PPC in overall cement production increases to 80%, fly ash demand increases by 59 Mt in 2030 compared to the 27/65 scenario.
• Assuming all of this demand is met with the 128 Mt of unutilised fly ash, significant benefits accrue to cement manufacturers and CPPs beyond the reduction in environmental damage and risks to human health. These are described below.
• Benefits to cement manufacturers: The cement sector accounts for 9% of India’s industrial energy use (Krishnan et al 2012) and 7% of India’s total emissions (WBCSD and IEA 2013). The energy costs (35%–40%) and raw material costs (20%–25%) comprise 55%–65% of the total costs for the industry.
• In the 35/80 scenario, increased blending leads to a reduction in the specific energy consumption (SEC) of cement production by 9%.10 Given that the Indian cement industry is one of the most efficient in the world,11 and that the target SEC reductions for cement plants are around 4%–6% under the Perform, Achieve and Trade (PAT)12 scheme of the Bureau of Energy Efficiency (BEE), such potential savings from a single measure are significant.
• Further, since fly ash directly replaces clinker, this implies savings in the use of limestone, the primary raw material for clinker.13 Overall, this translates into savings of 122 Mt of limestone (₹36 billion), 12 Mt of thermal coal (₹43 billion) and 9 TWh of electricity (₹51 billion) for the cement industry in 2030.
• These savings constitute a reduction of ₹143 for every tonne of cement produced—a 50-kilogramme bag costing ₹12814 can be made cheaper by ₹7 per bag.
• This is important not just for the competitiveness of the cement industry, but also for energy and materials security within the cement sector. In the past, Coal India Limited and Singareni Collieries Company Limited managed to supply less than 50% of the industry’s coal requirements (Department Related Parliamentary Standing Committee on Commerce 2011).
• According to the Indian Bureau of Mines, the total cement-grade limestone reserves in India in 2010–11 was 90 Mt, which are estimated to last 35–41 years based on expected growth and consumption patterns (DIPP 2011). Many cement manufacturers have reported 15–20 years of captive reserves (Department Related Parliamentary Standing Committee on Commerce 2011).
• Another study estimated that known limestone reserves will be exhausted around 2025–30; this can theoretically be extended up to 2047 with 100% blending in cement (Indo–German Environment Partnership 2013).
• Moreover, one million tonnes of limestone extraction generates on average 1.04 Mt of waste, degrades approximately 10 ha of land, and causes significant water stress (Indo–German Environment Partnership 2013), which requires that the limestone be used efficiently.
• The saving of 122 Mt of limestone in the 35/80 scenario, discussed above, therefore translates into 127 Mt of avoided waste and 1,220 ha of land saved from degradation in 2030.
• In the 35/80 scenario, carbon dioxide (CO2) emissions by the cement industry reduce (by 9%) to 629 kg CO2 /tonne of cement, leading to a reduction of 59 Mt of CO2 emissions.
• Given the significant share of cement production in India’s total emissions, it is only fair that it contributes its share in greenhouse gas mitigation, especially in light of India’s Nationally Determined Contribution under the Paris Agreement on climate change.
• Benefits to coal powered plants: Approximately 35% of the land and 40% of the water required by CPPs stems from the handling and disposing of fly ash.
• Additional FAU in the 35/80 scenario will lead to a land saving of 1,053 ha for CPPs. At a nominal price of ₹100/sq m, this translates into over ₹1 billion of avoided investment cost.

Fly Ash Utilization In India

• The CEA has noted that even beyond the MoEFCC’s stipulations, there is a pressing need to reduce the area needed for ash dykes, and to conserve land through greater FAU.
• Indian power plants are amongst the highest consumers of water in the world, and many have been known to face crises of water availability, particularly in the water-stressed regions of Maharashtra, Gujarat, and Rajasthan. Ash-handling units are the biggest consumers of water in CPPs (FICCI and HSBC 2012; CEA 2012; TERI 2010).
• The CEA advocates the designed ash-to-water ratios as approximately 1:5 for fly ash and 1:8 for bottom ash, but the observed ratios have been around 1:20 (FICCI and HSBC 2012).
• The average specific water consumption (SWC) of CPPs is around 5.75 kg/kWh for power plants that use wet cooling systems (Ali 2014), whereas the CEA’s norms for new plants stipulate a maximum of 3 kg/kWh of water consumption from the second year of operation.
• The dry collection of utilisable electrostatic precipitator (ESP) ash15 not only enhances the lime reactivity of ash, making it suitable for cementitious applications, but can also reduce the water requirement significantly.
• If all the utilisable fly ash is collected and transported in dry form, the water requirement for pond ash can be reduced by 67%,16 implying a 27% reduction in the SWC of CPPs. In 2030, 2.94 BCM of water can be saved this way, which would result in savings of ₹2.94 billion at the modest price of ₹1 per kilolitre.
• Moreover, electrical pumping of ash slurry constitutes about 25% of the auxiliary consumption in CPPs (CEA 2012). Dry collection of ESP can reduce auxiliary consumption by approximately 8%, freeing up to ₹50 billion worth of electricity for sale.17 Finally, the sale of the additional 59 Mt of fly ash demanded by the cement industry in the 35/80 scenario will also generate additional revenues of ₹5.9 billion.18
• Overall, this implies a reduced risk of land and water pollution from CPPs and a reduction in the cost of coal-based power, even after investing in dry collection methods and other means to improve the fly ash quality for use in cement, concrete, or brick industries.

Towards Full Fly Ash Utilisation

• As the FAU increases from 71% to 84%, driven by increased demand from the cement industry in the 35/80 scenario, we find that significant benefits accrue to both the consumers and producers of fly ash. However, even in the 35/80 scenario, 100% FAU will not be realised before 2047.
• This is a cause for serious concern. Below, we examine the technical, regulatory, pricing, logistical, and behavioural issues that can accelerate the march towards 100% FAU in an environmentally safe manner.
• Technical and regulatory issues: In July 2000, the BIS revised the maximum and minimum blending standards for PPC19 from 10% to 15%, and 25% to 35%, respectively.
• The physical and chemical properties need to conform to the standards mentioned in IS: 3812 (I)–2003 (NTPC 2010; European Cement Research Academy 2009). While the BIS is in line with the American ASTM 618 standards on blended cement, the European EN 197 and South African SANS 50197 standards allow the blending of fly ash up to 55%.
• Indian fly ash is primarily of the calcareous or class C variety, implying that it possesses not only pozzolanic, but also hydraulic (self-cementing) properties. In contrast, European fly ash is of a silicious or class F variety, implying an absence of hydraulic properties.

Fly Ash Utilization In India

• Class C fly ash is obtained from lower grades of coal such as lignite and sub-bituminous coal, whereas class F fly ash is obtained from anthracite and bituminous varieties.
• Class C fly ash has certain advantages and disadvantages compared to class F fly ash (Benson and Bradshaw 2011; European Cement Research Academy 2009). While Indian class C fly ash may provide greater early strength development and a reduced initial setting time, its major disadvantages are:
•  low lime reactivity (2.0–7.0 mpa);
•  low glass content (15%–45%);
•  high carbon content;
•  varying blaine or fineness levels (30 m to 10 mm); and  high variability in composition (WBCSD 2010; DIPP 2011).
• Studies have shown that blending levels can be safely increased by 10–15 percentage points through mechanical, chemical, thermal, and electromagnetic means without compromising on the mechanical properties or the durability of PPC (WBCSD 2010).
• Newer technologies such as ash improvement technology and Ceratech can enable fly ash to displace Ordinary Portland Cement completely (Jacques 2014). The National Council for Cement and Building Materials (NCCBM) conducted initial studies on increased fly ash blending, and the results have been encouraging.
• However, it has been unable to conclude these studies due to the lack of funds (Department Related Parliamentary Standing Committee on Commerce 2011; DIPP 2011).
• In light of the above, NCCBM must be allocated funds on a priority basis by the government to conduct research on improving the quality of fly ash, grading fly ash generated by different technologies and types of coal, and feasible blending ratios for the cement industry.
• CPPs must provide for dry collection and handling of ESP ash since wet collection reduces lime reactivity, and mixing with bottom ash adds carbon to a significant degree. They must also invest in safe and innovative ways of handling and packaging fly ash such as the mechanised bagging (PTI 2014).
• Moreover, as per the latest MoEFCC notification, receipts from the sale of fly ash must be invested in lowering the quantity and improving the quality of fly ash generated, through efficient coal blending, controlled coal combustion techniques, coal washing, etc.21
• Finally, the BIS must update the blending standards, which have not been revised since 2000. Up to 45%–50% fly ash blending can provide PPC of a strength equivalent to OPC 33. Lastly, standards for composite cements should also be developed for the co-use of fly ash with blast furnace slag and other clinker-substituting materials.
• Pricing and logistics: The pricing of fly ash is increasingly becoming a contentious issue that is hampering its gainful utilisation. It has been repeatedly emphasised that there is opacity around the disposal process.
• “No information is available in [the] public domain about the amount of stock of fly ash, the amount of generation at each location and the amount of fly ash disposed of to various sectors”.
• It is also alleged that “power houses … have started charging heavy prices from the cement factories … under the garb of administrative charges … otherwise, they had to incur heavy expenditure in dumping their fly ash” (Department Related Parliamentary Standing Committee on Commerce 2011).
• Further, there is evidence of political interference in the process, leading to exorbitant prices being charged, to the detriment of the producers and consumers of fly ash (Institute for Solid Waste Research and Ecological Balance 2009).
• It must be acknowledged that these observations are from those who largely feel that fly ash is a waste product that should be treated like a commodity only after its utilisation reaches 100%.
• The MoEFCC has instead taken a balanced approach to the issue by allowing its sale on the condition that the proceeds go into development and promotion activities for FAU until 100% utilisation is achieved.
• Preliminary investigation into the matter echoes the above concerns. Table 5 reproduces the fly ash price at the NTPC’s Vidyut Vyapar Nigam’s (NVVN) stations.
• Since proper documentation on collection and disposal costs is not available, the reasons for such large variations in prices are difficult to ascertain. The question also arises as to why prices at certain stations are indexed to cement prices.
• Moreover, an account of whether the revenues from the sale of fly ash are being utilised in the prescribed manner is also missing.
• The weighted average fly ash price obtained from Table 5 is ₹207/tonne.22 On the other hand, the average limestone price has been around ₹223/tonne (Indiastat 2015).
• This shows that the price advantage of fly ash as a substitute material is on the wane. As prices reach parity, fly ash may risk losing its price advantage over limestone. This will likely lead to a cost-push inflation in cement prices due to the paucity of limestone reserves relative to the industry’s needs.
• Also, indexing the fly ash price to the price of cement ultimately works by eroding the competitive advantage of PPC. Given its high share in overall cement production, this will further lead to a general escalation in cement prices, and ultimately reflect on the general price indices.
• In light of these issues, the following suggestions may help to improve transparency and reduce the costs of fly ash disposal by CPPs. The average revenue requirement calculations of CPPs must account for avoided costs, additional revenues generated, and utilisation of these revenues.
• There have been instances of lack of transparency in these matters leading to legal disputes between the generating and distribution companies (CERC 2013). This will help remove the opacity around fly ash utilisation in CPPs, and allow for cost reductions to be passed on to the consumer.
• It will also pave the way for fly ash pricing mechanisms to be disclosed, scrutinised, and subject to regulatory oversight.
• Next, while the cement industry’s captive power plants could be allowed to use all of their fly ash generated locally in the cement unit, CPPs supplying power to the grid must ensure that 20% of their fly ash is provided free to the brick industry as stipulated by the MoEFCC, which has not happened in various instances (Institute for Solid Waste Research and Ecological Balance 2009; National Green Tribunal 2014).
• This is particularly important since the transportation of fly ash often turns out to be prohibitively expensive. Small-scale brick manufacturers in Delhi have to pay ₹100/tonne as transportation costs for fly ash procured for free (MSME Development Institute 2010).
• J K Cement has reported that its transportation costs (including fly ash) have increased by 60% in the last decade (Department Related Parliamentary Standing Committee on Commerce 2011).
• Around 65% of cement-related freight is transported by road. The task force on the cement industry for the Ninth Five Year Plan had set an ambitious target of 60% share for the railways, which was revised to 50% by the working group on power for the Twelfth Five Year Plan (DIPP 2006, 2011).

Fly Ash Pollution Effects

• In order to increase the share of rail transport, there needs to be an explicit commitment from the Railway Board to rationalise tariffs through suitable legislation, increase the number and capacity of wagons, and provide for specialised wagons that can transport high volume, low-effect waste products like fly ash.
• This must be complemented by appropriate policy directives from state pollution control boards, and the maintenance of a database of fly ash stock and flow (MoEFCC 2015). There is also a proposal to increase the carrying capacity of multi-axle vehicles from nine tonnes to 13 tonnes (DIPP 2011), which should be considered.
• According to the report of the working group on cement industry for Twelfth Five Year Plan, one litre of fuel can carry 24 tonne-kilometres by road, 85 tonne-km by rail and 105 tonne-km by inland water transport.
• Therefore, research and discussion must take place on how to best exploit the approximately 4,500 km of inland waterways in an intermodal manner (DIPP 2011).
• Issues of perception and behaviour: Cement companies fetishise the “strength” of their product, often by conflating strength with “purity” or high clinker ratios. As stated earlier, this reasoning is not borne out technically.
• Indian PPC conforms to BIS 1489 (I) three-day, seven-day and 28-day standards, yet 1-day strength is the usual principle for agreements in the marketplace (European Cement Research Academy 2012). Moreover, certain states have discouraged the use of blended cement in public works.
• Many government construction agencies and public sector undertakings have chosen clay bricks despite the availability of fly ash bricks and PPC (Institute for Solid Waste Research and Ecological Balance 2009).
• Since the pozzolanic reaction is slower, fly ash-based concrete may show lower early strength and an increased initial setting time. However, as per the BIS, PPC is suitable for all generalised applications as OPC 33.
• In fact, the use of fly ash-based concrete can offer significant benefits by:
•  reducing the water requirement by 6%–18% (NTPC 2014);
•  blocking bleeding channels, thereby resisting sulphate attacks and improving durability;
•  providing additional cementitious (C-S-H) bond with lime, thereby reducing chances of corrosion;
•  reducing heat of hydration and hence brittleness; and
• improving workability and providing higher long-term strength (Federal Highway Administration and American Coal Ash Association 2003).

Fly Ash Disposal Problems

• On the part of fly ash producers, while organisations such as NTPC have undertaken promotional measures such as films, workshops, advertisements, exhibitions, and the dissemination of other information for FAU, they tend to promote an understanding of fly ash as a benign byproduct of coal combustion, as “a type of soil” (Mathur 2010).
• Such promotional activities tend to understate the hazards of fly ash and ignore its potential to cause damage to flora and fauna. This is invariably done to suggest its suitability for use in agriculture, mine and void filling, and it contradicts the MoEFCC’s own observations on the matter.
• Therefore, 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.

Conclusions

• As India tries to close the gaps in its energy and physical infrastructure, it needs to do so in an equitable, cost-effective, and resource-efficient manner, since competing demands for, and the limited availability of natural resources will pose hard constraints on economic growth.
• Fly ash is a unique problem in this context—it is a social and economic bad, its impacts are asymmetric across economic groups, and yet it offers an opportunity for capitalists to exploit it economically in a socially desirable way. With this realisation, the MoEFCC has provided regular notifications over the past 15 years regarding its “utilisation.”
• But 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, have impeded the flow of fly ash to its most value-adding use.
• Public policy on the issue will need to tackle these challenges on the one hand, while limiting asymmetric damage to wage earners and petty agriculturalists on the other.
• It is in this context that the use of fly ash in cement-related applications remains an understudied topic. This article attempts to build a case for greater FAU through a quantitative examination of the future of cement and coal-based electricity production, and the former’s ability to absorb fly ash from CPPs.
• The implications of greater fly ash blending for the cement industry are savings of coal, electricity, and limestone; lower greenhouse gas emissions; and, ultimately, lower production costs.
• A reduced reliance on mined resources also limits the ecological footprint from mining. For CPPs, greater FAU in cement implies reduced land and water dependence, a decline in auxiliary consumption (therefore, more electricity available for sale), and additional revenues from the sale of fly ash.
• However, it is most desirable to limit fly ash production through greater deployment of renewable energy sources, using better coal and combustion techniques, etc, since cement-related industries alone will not be able to absorb all the fly ash generated in the future.
• At the same time, the key requirements for overcoming the barriers to higher FAU are greater regulatory oversight and price control, revision of cement blending standards, research in improving fly ash quality, reducing cost of transportation, provisions for overcoming information asymmetries, and overall sensitisation of key decision-makers on the matter.