Thermal power production has a high pollution quotient. In addition to lead, leather and chemical industries, conventional power production companies are the major sources of air, soil, and water pollution. The residual matter of power production is responsible for long term environmental contamination. Fly ash is one of the major residuals of coal based thermal power plants (TPPs). It requires large area of land for disposal and it often leads to toxicity in ground water. Also vehicles carrying fly ash are meant to be covered as it can lead to air pollution if it mixes freely with air.
The trend of using fly ash for different products is on the rise in India. Fly ash bricks (FABs) are gaining popularity in different regions in India. Additionally, fly ash has emerged as a major input for the cement sector.
Indian coal has high ash content (35%-45%) and low calorific value (around 4000 kcal/kg) and as a result, the amount of fly ash generated for Indian coal is relatively higher. 84% of Indian thermal power plants (TPPs) are run by coal. About 120 coal-based TPPs in India are producing more than 112 million tonnes (MT) of fly ash per year.
A report titled ‘Fly Ash in India: Generation vis-à-vis Utilisation and Global Prospective’ by Research India Publications says, “During 2014-15 in India, in 132 thermal power stations, 257 MT coal was consumed. Fly ash generation was 84 MT while only 47 MT was utilised and that can be counted as 56% of the generated ash.”
Fly ash is an important ingredient of the cement industry that accounts for 50% fly ash utilisation at around 30 MT (28%) in India. Low lying area fill (17%), roads and embankments (15%), dyke raising (4%), brick manufacturing (2%) and agriculture are the other important uses of fly ash. In the cement industry, fly ash is used because of its resilience and concrete qualities.
FABs in real estate
Fly ash is used to make FABs that is used in the real estate and construction sectors. FABs are more durable than clay bricks. As per The Energy and Resources Institute (TERI) guidelines, a certified green home has to use lowest carbon materials (like FABs) instead of traditional clay bricks. FABs are also sturdy and earthquake resistant.
Debashis Bhattacharya, Director, Superstruct Infracon Private Limited, a company that is in the business of making FABs informed BE, “The major challenges are from the TPPs as we are not being able to procure fly ash from them. Instead TPPs are exporting it for profit. Currently, we are running our organisation depending only on the quota we have obtained from Damodar Valley Corporation (DVC) which is of 15,000 tonnes. Though the central government has previously ordered that all TPPs are bound to provide their fly ash free of cost to manufacturers of FABs, it has been hardly followed in India for last five years. Also because of the huge labour and contractor involvement in the traditional clay made red-brick business, they are not willing to give it up and move towards FABs easily.”
Bhattacharya added, “Some Kolkata based real estate developers namely PS Group, Srijan Group, Mani Group were using FABs but they are now using fly ash blocks (which are less resilient) because of poor availability of FABs.”
Indian fly ash is exported to the Middle East and Afghanistan from the west coast (Gujarat) and to Bangladesh from the east coast (West Bengal). Bhattacharya added, “Indian TPPs are communicating with foreign vendors and are organising auctions to set better prices. They are charging as high as `500 per tonne of fly ash. Though India has its own demand for fly ash for the domestic cement and the real estate markets, many TPPs are exporting fly ash because of profitability. This trend is hampering FAB producers like us.”