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Power Ministry has asked the Central Electricity Authority (CEA) to create a standard operating procedures (SoP) for blending of domestic and imported coal used at thermal power plants (TPPs). The development comes as coal supply at TPPs comes under pressure due to high electricity demand.
The pressure on domestic supply for the key commodity forced the government to increase the percentage of imported coal in the domestic mix to 10 per cent from 4 per cent in December 2021.
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The increased supply to power sector was despite huge outstanding dues from a number GENCOS. The highest outstanding is from Maharashtra to the tune of ₹ 2,608.07 crore.Sources said that Power Ministry in consultation with States decided to task the CEA for creating an SoP to blend imported coal with domestic supplies. The blending process followed at NTPC and Damodar Valley Corporation (DVC) will be analysed to devise a pan-India mechanism.
“NTPC, which will import around 20 million tonnes of coal in FY23, formula suggests that 10 per cent blending of imported coal gives 15 per cent more heat. Besides, in terms of heat content, this makes 1 tonne of coal (blended) worth 1.5 tonnes (of Indian coal),” explained one of the sources.
Coal blending
India imports coal from Indonesia, South Africa and Australia. The gross calorific value (GCV) of imported coal is in the range of 5700-6300 kCal per kg while that of domestic coal ranges from 2900-4200 kCal per kg.
Generally, Indian power boilers are designed for high ash Indian coal and the furnace is also higher (height) by around 20 per cent compared to boilers for imported low ash coal.
The average ash content of coal supplied to Gencos is in the range of 35-45 per cent. The inferior quality of coal (high ash content), not only pollutes the environment but also leads to high cost for operations & maintenance (O&M) and ash disposal.
Experts point out that coal characteristics that affect boiler design are ash content, volatile matter, moisture content, fixed carbon, gross calorific value (GCV), Hardgrove Grindability index (HGI), coal reactivity and ash fusion characteristics.
TPPs follow various methodologies for blending of foreign and domestic coal such as separate layering of both in a stockyard or blending in beds. Besides, blending on conveyors by silo, blending by ground hoppers or emergency reclaim hoppers and blending of two streams of coal on conveyor belt are also used for mixing.
Coal imports
Coal imports by power sector declined from 69.22 mt in FY20 to 45.47 mt in FY21. As per CareEdge, during April 2021-February 2022, coal import by power sector decreased further to 24.2 mt from 42.4 mt during the corresponding period of previous year.
Coal prices of South African thermal, a global benchmark, have been on an upward trajectory since December 2021 and the ongoing tension between Russia-Ukraine has impacted the international coal prices even more.
The global benchmark has crossed its all-time high price at $199.7 per tonne and has peaked at around $295 per tonne as of March 2022. The continuous rise in coal prices is discouraging coal imports which are pressurising domestic coal producers to increase supply to fulfil the coal demand in the country, CareEdge added.
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