India's top three
The three highest rated coal-based power plants in India in the study by CSE are CESC, Budge Budge, in West Bengal; JSWEL, Toranagallu in Karnataka; and Tata, Trombay, in Maharashtra. While these plants follow certain best practices, their overall environmental performance is average when compared to the global best. Since the plants are subcritical, their efficiencies were nowhere near those of the latest ultrasupercritical plants. While their water use was relatively good, air pollution control and ash handling were a mixed bag with improvements needed.
CESC- BUDGE BUDGE POWER PLANT
It is a 750 MW capacity (three 250 MW capacity units) power plant located in densely populated Pujali town of South 24 Paraganas district in West Bengal and has an average age of 11 years.Although it uses subcritical technology designed for 37 per cent efficiency—far below that of the global best ultrasupercritical (usc) technology—its operating performance is commendable. The plant availability averaged 93 per cent during the last three years (2010-13), indicating very good maintenance. plf at 87 per cent was far better than the Indian average. In fact, it used to be even higher but has dropped in recent years because of low demand from the area.
Second, the plant has maintained efficiency of 35.7 per cent—although the efficiency is just above the Indian average, it is only 1.4 percentage points below its design,reflecting good operating practices. The plant has shown steady efficiency improvement during the assessment period.
The most remarkable feature of the plant is its efficient water use despite abundant water supply from the River Hooghly. The plant consumes only 2.2 cubic metres of water per MWh power generation—seven cycles of concentration (coc) in its cooling towers means low water use; a zero liquid discharge system (zld) ensures water discharged from various uses is recycled back; fly ash is handled dry; boiler water is treated in an advanced system to allow reuse and reduce losses.
Its 100 per cent fly ash utilisation record is also positive,especially since 76 per cent of total ash is used for cement and bricks.The plant sells its fly ash to cement manufacturers in Bangladesh. The plant has adopted many good practices for handling ash, including pneumatic storage in silos,pneumatic transport into barg- es and high concentration slurry disposal. However, its high concentration ash disposal in an “emergency” pond was found problematic with high fugitive emission. It is the only plant in India to have installed a de-watering system for disposal of bottom ash,which is largely used for filling of low-lying areas.
The company was in compliance with water pollution and waste management. Unlike most of the plants in the sector,the plant meets strict PM norms of 50-75mg/Nm3 except in some incidences where high stack PM emissions were recorded by the state pollution control board.