Thermal Plant Set To Reduce Pollution, Will Improve Polluted Air Or Not?

The Central Electricity Authority has issued guidelines to address the pollution caused by coal-based thermal power plants. One of the recommendations put forth by the CEA is the use of a high-concentration slurry disposal (HCSD) system to manage fly ash. According to the CEA report – the ash generated from thermal power plants is typically disposed of in well-designed ash ponds, usually in the form of wet slurry. Read More Business News on our website.

CEA Announcement To Control Pollution By Thermal Plants

However, in certain cases, a dry ash disposal system may be more suitable, particularly at specific locations. The HCSD system is being preferred in new projects due to its inherent benefits, such as reducing land and water requirements and preventing groundwater contamination. To promote ash utilization, the CEA guidelines require thermal power projects to have systems in place for 100% dry ash extraction, storage and supply to entrepreneurs interested in utilizing the ash.

The guidelines also specify that each thermal power project should install dedicated dry fly ash silos, capable of storing at least 16 hours worth of ash based on the plant’s installed capacity. These silos should have separate access roads to facilitate ash delivery in accordance with the Ministry of Environment, Forest and Climate Change (MOEF&CC) notification. The HCSD system involves the disposal of fly ash in a high-concentration slurry form with the ash concentration ranging from 60% to 70% by weight. This slurry is pumped using high pressure slurry pumps and conveyed through steel pipes. Flexible pipes are used at the disposal area. Some plants have also successfully implemented centrifugal pumps to transport high concentration slurry over long distances.

Overall, the CEA guidelines aim to mitigate pollution from thermal power plants by implementing efficient and environmentally friendly methods for ash disposal and utilization. The dry ash disposal system differs significantly from the wet disposal system. In the dry ash disposal system, furnace bottom ash (FBA) and pulverized fly ash (PFA) are transported in a moistened state from hydro bins and silos, respectively. This transportation is carried out via fixed belt conveyors located in enclosed gantries.

The ash is then disposed of at ash mound sites using various equipment, including fixed, extendable, shiftable and mobile belt conveyors, a crawler-mounted boom spreader, a crawler mounted bucket wheel reclaim as well as a range of wheeled and crawler-mounted mobile equipment. Currently, this system is in use only at one station, namely the National Capital Thermal Power Station in Dadri. The Central Electricity Authority (CEA) has recommended that all new power plants adopt a high-concentration slurry disposal system for their ash ponds.

According to Anubha Aggarwal, a programme officer in the industrial pollution unit of the CSE (Centre for Science and Environment), our research indicates that even with multiple deadline extensions ranging from five to eight years, there are certain concerning figures. Specifically, 43% of the capacity falling under Category A (which includes plants within a 10 km radius of Delhi-NCR or cities with a population of over one million), 11% of the capacity falling under Category B (within a 10 km radius of critically polluted areas), and 1% of the remaining capacity falling under Category C are unlikely to meet the prescribed standards within the latest deadlines of 2024, 2025 and 2026 respectively.

In India, approximately 73% of the total electrical energy is derived from coal-based sources. Each year, around 271 million tonnes of solid waste or by-product, known as ash, is produced during the combustion of pulverized bituminous, sub bituminous and lignite coal for electricity generation. The coal used in India has a low calorific value of 3500 Kcal/kg and contains a significant ash content ranging from 30% to 60%. 

The coal-based thermal power plants will continue to be the primary source of power in the foreseeable future, the disposal of ash remains a matter of utmost importance due to the increasing environmental concerns of this century.