VIJAYAWADA: While the procurement of power from power exchanges has resulted in significant savings for the distribution companies (discoms), it has created a problem for APGENCO's thermal power generating units, which have stocked coal anticipating high demand during summer.
With majority of the coal stock left unused in the last couple of months, officials of Dr Narla Tatarao Thermal Power Station (Dr NTTPS), Vijayawada, have written to APGENCO explaining that the quality of the coal has been deteriorating, and requested it to take the units in reserve shut down to service at the earliest.
Due to the COVID-19 lockdown, the demand has seen a drastic fall during April and May. The discoms started purchasing power from spot markets at much lower prices. With this, the thermal units were kept in reserve shutdown. However, anticipating high demand during summer, the three thermal power stations — Dr NTTPS, Rayalaseema Thermal Power Plant (RTPP), Kadapa, and Sri Damodaram Sanjeevaiah Thermal Power Plant (SDSTPP), Krishnapatnam — had stocked 13 lakh - 15 lakh metric tonnes (MT) of coal.
For the record, out of 3,410 MW capacity of Dr NTTPS and RTPP, only 370 MW and 302 MW generation happened in April and May respectively. This led to most of the coal being stocked without utilisation. APGENCO officials explained that stocking coal for longer duration would result in deterioration of it gross calorific value (GCV).
The engineers of Dr NTTPS, Vijayawada, have written to APGENCO raising the same issue. Noting that 4.98 lakh MT of coal has been stocked since months, they said that the coal sample studies they conducted showed that the GCV fell 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 rise in specific coal consumption and thereby rise in variable cost to some extent,” the letter said.
Concluding that specific coal consumption will rise by 0.117 kg/KWhr, which results in a rise of variable cost of Rs 0.47 per unit, they requested to permit to take the units in reserve shutdown into service at the earliest.
"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.
As of Friday, only one unit each of Dr NTTPS and RTPP, and two units of SDSTPP are being used, an official noted. As a solution, the engineers suggested that all the three thermal power plants’ units be brought back into 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.