The National Thermal Power Corporation (NTPC) Limited has recently announced a call for Expression of Interest (EOI) for selling fly ash, aiming to achieve 100% utilization of this byproduct from the Middle East and other designated plants. Utilization of fly ash is a key focus area for NTPC in line with its commitment towards environment-friendly practices.
Understanding Fly Ash
Fly Ash is a byproduct created from burning coal in thermal power generation. The name “fly ash” comes from its method of transportation away from the combustion chamber by exhaustion gases. It is then collected from these gases using electrostatic precipitators or bag filters, devices commonly used for air pollution control.
Composition and Properties of Fly Ash
The composition of fly ash includes significant amounts of silicon dioxide (SiO2), aluminium oxide (Al2O3), ferric oxide (Fe2O3) and calcium oxide (CaO). While it physically resembles Portland cement, it is chemically different. Unlike Portland cement that contains calcium silicates, calcium aluminate and calcium aluminoferrite, fly ash exhibits unique cementitious properties, meaning it hardens when mixed with water.
Uses and Risks of Fly Ash
Fly ash is widely utilized in various industries such as concrete and cement products, road base, metal recovery, and mineral filler, amongst others. However, fly ash particles are also known as toxic air pollutants which can cause severe health issues, including heart disease, cancer, respiratory diseases and stroke. When combined with water, fly ash can leach heavy metals into groundwater, pollute soil and negatively affect the root development system of trees.
Fly Ash Utilisation by NTPC
NTPC has collaborated with cement manufacturers across India to supply fly ash, promoting its use in building construction. The corporation has set up fly ash brick manufacturing plants at its coal-based thermal power plants. These bricks are utilized exclusively for plant and township construction activities. As per the directives of MoEF&CC, NTPC stations are required to keep at least 20% of the total fly ash produced in reserve for issuing free of cost to fly ash brick, block, and tile manufacturers.
Growth of Fly Ash Utilisation
Over the past five years, the utilization of fly ash in India has grown by an impressive 80%. In addition, various state governments, starting with Maharashtra, have launched their fly ash utilization policies. The Pradhan Mantri Awas Yojana (Urban) has emphasized the use of innovative and environment-friendly construction technologies, such as fly ash bricks.
NTPC’s Role and Mission
NTPC Ltd., a central Public Sector Undertaking (PSU) under the Ministry of Power, aims to provide reliable power and related solutions in an economical, efficient and environment-friendly manner. The company became a Maharatna in May 2010 and is currently India’s largest power generating company. It continues to champion innovative and sustainable practices, including the complete utilization of fly ash.
