Cement, Energy & Environment

- • • In ~ Waste to Wealth & Waste Recycling -·· ·- -· ... ,. Initiatives by power generation companies Only 55-56 per cent of fly ash is absorbed in segments such as cement manufacturing, road construction , land reclamation and mine filling, among others. Environmental regulations require much higher utilization levels. Stricter enforcement by the pollution control boards, along with ash utilization conditions for upcoming plants is contributing towards better adherence to ash disposal norms. At the same time, power generation companies face major challenges related to logistics and evacuation arrangements in the fly ash disposal process. There is also an issue of low off take by entities which enter into contracts with power stations for sourcing fly ash. Among other applications, mine filling appears to be a feasible option to increase ash utilization levels. This is likely to gain ground with upcoming captive coal mine development. The following is a review of some of the key initiatives in fly ash utilization by some major power generation companies. NTPC As of 2011-12, NTPC Limited's fly ash utilization stood at 55 per cent. Cement and land development are the two key areas of utilization. A key step has been the setting up of dry ash evacuation and storage systems at all projects sites. This helps in the efficient bulk transfer of ash to end-users. These systems are supplemented by rail-loading facilities at power plants. For instance, at NTPC's Rihand power station, the rail loading facility is provided to enable bulk transportation to end-users' locations through the railway network. Some of the major areas of fly ash utilization include road embankment construction and filling works, building construction works and concrete works. Notably, all NTPC stations have fly ash– based brick manufacturing plants. These bricks are also used in in-house civil works. Steps have also been taken to use bottom ash as a replacement for sand in civil projects. For example, at the Dadri power project, bottom ash was utilized as a drainage layer in the ash mound and as a filling material in road embankment construction. Also, demonstration projects established that bottom ash was suitable for stowing of underground mines. Fl y ash has been effectively utilized in the manufacturing of Portland Pozzolana Cement (PPC). NTPC has signed agreements with cement manufacturers for fly ash supply at the Dadri, Unchahar, Farakka and Tanda stations. In select power stations such as those at Badarpur, Ramagundam, Kahalgaon Unchahar, it is supplied at a price due to the high demand. Studies and projects have also been undertaken to expand the scope of ash utilization: • • • Showcase projects of fly ash utilization in the agriculture sector were taken up at all power stations. These involved local farmers and agricultural institutions. Preliminary results in this regard have been encouraging. Studies have been carried out for assessing the suitability of fly ash for railway embankments. The design of the railway embankment, developed by the Central Road Research Institute (CRRI), was validated by centrifugal model tests at the Indian Institute of Technology, Bombay. The use of fly ash in bituminous road surfacing was taken up through CRRI. The demonstration stretch will be constructed at the NTPC Dadri and Badarpur power project locations. MaJor modes of nv ash uUiisallon l%1 RedamabOo of low lying area 9 Source: Central ElectricityAuthority Mahagenco Maharashtra State Power Generation Company Limited's (Mahagenco) ash utilization level has been 55 per cent. Enhancing this has been a concern for the generation company, especially in the context of dependence on coal for upcoming power projects. To be sure, a formal utilization programme was initiated way back in 1999 for maximizing ash utilization. Currently 32 I