While the purchase of electricity from power exchanges has resulted in significant savings for distribution companies (discommodity companies), it has created a problem for APGENCO ‘s thermal generating units, which have stored coal in anticipation of high demand during the summer.
With most of the coal stock left unused in the last few months, officials of Dr. Narla Tatarao Thermal Power Station (Dr. NTTPS), Vijayawada, wrote to APGENCO explaining that the quality of the coal had deteriorated and requested that the reserve units be shut down as soon as possible.
As a result of the COVID-19 lockdown, demand fell sharply in April and May. Discoms began buying power from spot markets at much lower prices. As a result, the thermal units were kept in reserve shutdown. However, expecting high demand during the summer, the three thermal power stations – Dr NTTPS, Rayalaseema Thermal Power Plant (RTPP), Kadapa, and Sri Damodaram Sanjeevaiah Thermal Power Plant (SDSTPP), Krishnapatnam – had stored 13 lakh-15 lakh metric tons ( MT) of coal.
Out of the 3,410 MW capacity of Dr. NTTPS and RTPP, only 370 MW and 302 MW were generated in April and May, respectively. This has contributed to much of the coal being stored without being used. APGENCO officials clarified that storing coal for a longer period of time would result in the degradation of its gross calorific value (GCV).
The engineers of Dr. NTTPS, Vijayawada, wrote to APGENCO raising the same issue. Noting that 4.98 MT of coal has been stored for months, they said that the coal sample studies they performed showed that the GCV had decreased by 375 kcal / kg. “Due to drop in GCV and fixed carbon, rise in ignition temperature and percentage content, more quality of coal is to be burnt to achieve the same heat. This eventually results in a rise in specific coal consumption and thereby rise in variable cost to some extent,” the letter said.
Concluding that the specific consumption of coal would increase by 0.117 kg / KWh, which would result in an increase in the variable cost of Rs 0.47 per unit, they requested permission to bring the units in reserve shutdown into service as soon as possible.
“If we don’t use the available stocks at the earliest, the coal quality dips further, which will eventually lead to higher variable cost of thermal power generation. So, the savings done by discoms will be negated by the losses that APGENCO may incur,” an engineer explained. Sources said RTPP officials are also expected to write to APGENCO citing the same issue.
Just one unit of Dr. NTTPS and RTPP and two units of SDSTPP are used, an official noted. As a solution, the engineers suggested that all three thermal power plants be returned to service immediately.
“APGENCO has about 15 lakhs MT of coal, which is enough for over 30 days for all three stations. If the units are run for a month, then we can use the coal. Later, we can balance market procurement and coal stocking,” one official suggested.
APGENCO, along with APSEB Engineers’ Association and APSEB Assistant Executive Engineers’ Association, had made a representation to Energy Secretary Nagulapalli Srikant on the issue on May 28.
