Combustion of coal in thermal power plants generates fly ash – fine particles of burned fuel emitted from boilers. Fly ash is known to cause groundwater pollution. Due to its light-weight, it can become airborne and cause air pollution. Since heavy metals in coal do not burn, their concentration in fly ash increases to ten times that in the original coal (United States Geological Survey, 1997). Disposal of fly ash also requires large quantities of land, water, and energy. In fact, more than 65,000 acres of land in India is occupied by ash ponds (Raja, Manisekar, & Manikandan, 2013).
In India, this problem is further complicated due to the presence of low-grade coal. Ash content in Indian coal is 30-45 percent compared to 10-15 percent in imported coal (Central Electricity Authority, 2018). Thus, fly ash presents a major land usage, health, and environmental challenge.
Nearly 78 percent of Haryana’s total installed power generation capacity is thermal of which 92 percent is coal-based (Central Electricity Authority, 2018). In the first half of 2017-18, Haryana produced 9.6 lakh tonnes of fly ash (Central Electricity Authority, 2018). This is comparable to the total cotton production in the same period in the state. Thus, fly ash management is a formidable challenge for the government.
Figure 1: Rajiv Gandhi Thermal Power Station at Khedar in Hisar, Haryana; Source – DNA India, HPGCL (DNA, 2018)
In recent years, there has been a shift in outlook on fly ash. Instead of being viewed as a waste material, it has emerged as a resource material in various industries.
In this note, we begin by examining various technologies that use fly ash as a resource material. This is followed by a snapshot of government efforts towards the sustainable use of fly ash. In the end, we examine a list of recommendations by Central Electricity Authority that could help develop Haryana as the model state for fly ash utilisation (FAU).
Fly Ash Technology and its Applications
Fly ash consists of spherical silt-sized particles. These small glass spheres improve fluidity and workability of fresh concrete (US Federal Highway Administration, 2017). It also improves the stiffness, strength, and wear resistance of materials. Fly ash technology has various applications.
- FAL-G bricks: FAL-G is a blend of fly ash (Fa), lime (L), and gypsum (G) which upon hydration yields a strong non-porous building material. FAL-G bricks are lighter, stronger and require less water in their manufacture. Compressive strength and modulus of elasticity of FAL-G bricks increase with age (Jayasudha, Radhakrishna, & Niranjan, 2013). They also provide higher fire insulation. Therefore, FAL-G is an effective replacement for burnt clay bricks (ibid.)
- Geopolymers: Geopolymers are inorganic polymers containing long chains of silicon, aluminium, and oxygen. Fly ash is used as a cementitious binder in the manufacture of geopolymers. The spherical shape of fly ash particles helps increase the workability of cement and reduces water demand (US Federal Highway Administration, 2017). Geopolymers are a ready alternative to Portland cement in the construction industry. Portland cement has high environmental costs. Production of Portland cement for concrete accounts for nearly five percent of global CO2 emissions (Jeyasehar, Salahuddin, & Thirugnanasambandam, 2013). Apart from the construction industry, geopolymers have a wide range of applications in aeronautics, fire protection, hazardous waste management, and ceramics.
- Soil stabilisation: Fly ash helps in improving the strength characteristics of the soil. It is also helpful as a drying agent to reduce moisture and to control shrink-swell properties of the soil (US Federal Highway Administration, 2017). An NTPC trial reveals that fly ash application helped increase the yield of cereal crops by 15-20 percent, sugarcane by 20-30 percent, and plantation crops by 30 percent (Arivazhagan, et al., 2011)
- Construction of embankments: Shear strength, high compressibility, low permeability and uniformity in particle size make fly ash a suitable material for construction of embankments (US Federal Highway Administration, 2017). The cost of construction is also significantly lower.
- Nuclear waste remediation: Recent research advocates the use of fly ash for treatment of hazardous waste. It is a cheaper alternative to natural zeolites (Crespo, 2015).
Therefore, fly ash has a wide range of applications. This has driven both central government and state government in Haryana to monitor fly ash emissions and direct them to suitable industries.
Existing Efforts Towards Fly Ash Utilisation in India and Haryana
In the first half of 2017-18, India produced nearly 8.5 crore tonnes of fly ash. This is nearly twice the amount of steel produced in the country in the same period. 60 percent of this fly ash was utilised (Central Electricity Authority, 2018). Only 43.5 percent of thermal power stations in the country showed FAU of more than 90%. Figure 2 shows major modes of FAU in the first half of 2017-18 throughout the country (Central Electricity Authority, 2018). Cement production is the most important avenue for fly ash followed by reclamation work, bricks and tiles manufacture and mine filling.
A central government notification issued in 2009 prescribed targets of FAU in a phased manner for all coal or lignite based thermal power stations (ibid.). The target is to achieve 100 percent FAU in the country. Various measures have been taken by the central government in this regard.
- ASH TRACK App: The application would connect coal-based power plants, i.e., link fly ash producers to potential fly ash users within a radius of 300 km of each other. This would provide cement and brick manufacturers with a ready input source. The application is estimated to manage 200 million tonnes of fly ash annually (Vikaspedia, 2018).
- Use in Government Programmes: Fly ash has been used in the construction of roads under Pradhan Mantri Gram Sadak Yojana (PMGSY) and other construction work under Mahatma Gandhi National Rural Employment Guarantee Scheme (MGNREGS). In 2017-18, nearly 6300 km of road was constructed using green technologies (Press Information Bureau, 2018).
- Tax Cut: Goods and Services Tax (GST) rates of fly ash and its products have been reduced to 5 percent from an initial 18 percent.
Haryana has been one of the frontrunners in FAU in India. It has achieved 100 percent FAU as prescribed by the central government notification of 2009 (Central Electricity Authority, 2018). By the first half of 2017-18, the state had achieved an FAU level of 104 percent. This means the state used more fly ash than was produced by its thermal power plants. The Panipat thermal power station has exceeded its target and achieved a 133 percent FAU level. The Hisar thermal power station has achieved a FAU level of 86.5 percent (ibid.). Thus, Haryana’s performance in FAU has been impressive.
Figure 2: The pie chart shows the major modes of FAU throughout the country Data source – Central Electricity Authority
(Central Electricity Authority, 2018)
The Way Forward
Along with Delhi and Rajasthan, Haryana is one of the three states that has achieved its target of 100 percent FAU. Successive governments in Haryana have implemented policies for fly ash collection at power plants and its usage in construction. However, there exists a significant scope for improvement in the diversity of its applications. According to Ash Track, 99 percent of fly ash in Haryana is used in cement manufacture (Ash Track, 2018). Use of fly ash in road construction, brick manufacture and reclamation work is negligible. Haryana must take up research in geopolymers as well as usage of fly ash for soil stabilisation. In its report on FAU, the Central Electricity Authority has given a list of recommendations on efficient fly ash use (Central Electricity Authority, 2018). These recommendations are summarised below.
- FAU in agriculture and wasteland development is below expectations. A study conducted by NTPC in Hisar showed that fly ash application led to a 32 percent increase in the yield of wheat and pearl millet crops (Arivazhagan, et al., 2011).
- There is a need for technological advancement in the collection of dry fly ash from thermal power plants. More efficient electrostatic precipitators must be used to ensure complete collection.
- New emerging areas such as Light Weight Aggregates, Geopolymers, and Coal Beneficiation must be developed for better utilisation of fly ash.
- There is a need to sensitise state Public Work Departments (PWDs) towards accommodating fly ash in their construction plans from as early as the project formulation stage. PWDs may partner with the relevant thermal power plant in order to ensure a continuous availability of fly ash.
- The use of fly ash in backfilling of open cast and underground mines has a large potential for FAU that has not been met. Similarly, the use of fly ash in the construction of roads, embankments, and flyovers needs to be stepped up.
The state government in Haryana must pursue these recommendations in order to achieve better and more efficient use of fly ash. This could be instrumental in establishing Haryana as the model state for FAU. As the energy needs of the state increase, a push towards renewable sources is necessary while minimizing the impact of non-renewable sources of energy. Efficient fly ash utilization is an excellent way to achieve the latter.
Arivazhagan, K., Ravichandran, M., Dube, S., Mathur, V., Khandakar, R., Yagnanarayana, K., . . . Narayan, R. (2011). Effect of coal fly ash on agricultural crops. National Thermal Power Corporation.
Ash Track. (2018). Ash utilization.
Central Electricity Authority. (2018). All India installed capacity of power stations. Central Electricity Authority.
Central Electricity Authority. (2018). Report on fly ash generation and at coal based thermal power stations and its utilization in the country. New Delhi: Central Electricity Authority.
Crespo, I. (2015, January 19). Scientific highlights. Retrieved from nmi3: Click Here
DNA. (2018, May 10). Haryana govt announces Rs 20 lakh ex-gratia to Khedar thermal plant victims. Retrieved from DNA India: Click Here
Jayasudha, R. K., Radhakrishna, & Niranjan, P. S. (2013). Properties of FAL-G masonry blocks. International Journal of Research in Engineering and Technology, 384-389.
Jeyasehar, C. A., Salahuddin, M., & Thirugnanasambandam, S. (2013). DEVELOPMENT OF FLY ASH BASED GEOPOLYMER CONCRETE PRECAST ELEMENTS. Ministry of Environment and Forests.
Press Information Bureau. (2018, April 16). PMGSY well on its way to achieve March 2019 target. Retrieved from Press Information Bureau: Click Here
Raja, R. S., Manisekar, K., & Manikandan, V. (2013). Study on mechanical properties of fly ash impregnated glass fiber reinforced polymer composites using mixture design analysis. Elsevier, 499-510.
United States Geological Survey. (1997). Radioactive Elements in Coal and Fly Ash: Abundance, Forms, and Environmental Significance. United States Geological Survey.
US Federal Highway Administration. (2017, June 27). Fly ash facts for highway engineers. Retrieved from US Federal Highway Administration: Click Here
Vikaspedia. (2018). ASH TRACK App. Retrieved from Vikaspedia: Click Here