BL reported that power major NTPC Limited is finding that this year’s coal is not yielding as much energy to generate electricity as last year’s did or as that of the year before. So the utility needs to burn more and more coal to produce a unit of electricity.
In 2008-09, NTPC, the nation’s largest electricity producer with 79 coal fired units across the country, managed to increase its electricity output by 3.7% over the previous year, but had to consume 5.4% more coal than it did previously. It was not an anomaly.
NTPC officials concede that that a steady decline in domestic coal quality has been among the key factors responsible for the mismatch in incremental coal consumption and power generation.
NTPC official said “Power stations are designed for a particular coal quality range for optimum plant efficiency. The key areas of concern include high levels of ash in coal, which goes up to 45% in case of domestic coal and also inconsistency in coal quality, both chemical and physical. Presence of mineral matter in coal has a detrimental impact wear and tear of coal and ash flow paths, combustion chambers, mills, crushers etc. High ash also impacts the plants thermal efficiency.”
According to coal ministry officials, Indian coal has always had a problem on account of high ash content. Besides the inherent ash problem, there is dilution in the quality of coal due to the over reliance of open cast mining over underground mining in recent years. Stones and other inert material happen to get scooped up along with the coal.
According to power ministry estimates, during the early 1960s, the calorific value of domestic coal was around 5,900 kilocalories per kilogram. By the 1970s, this had gone down to around 5,250 kilocalories per kilogram, which dipped further to around 4,200 kilocalories per kilogram in the Eighties. This came down to around 4,000 kilocalories per kilogram in the Nineties then to the current levels of around 3,500 kilocalories per kilogram. Imported coal from countries such as Indonesia, Australia and South Africa, in comparison, has an average calorific value of around 6,500 kilocalories per kilogram.
