Stand-by unit could have saved Mumbai from power outage, says Tata Power

Tata Power Company has blamed Tuesday's power outage in Mumbai on non-utilisation of stand-by power generation plant because of its higher production cost even as the Maharashtra government has ordered an investigation into the power crisis, following tripping of a Tata Power unit.

Several parts of Mumbai plunged into darkness following the outages. The ruling Congress-NCP combine believes it to be a conspiracy to turn people's ire towards the state government during Ganeshotsav.

Chief minister Prithviraj Chavan has asked principal secretary, energy, to conduct the probe and fix responsibility in seven days and also suggest short and long-term measures to prevent such failures. Moreover, state assembly polls are due to be held in October.

According to Tata Power, Mumbai has a peak power demand of 3,350 MW and on 2 September the system was working at 2,950 MW in the morning, which is 400 MW lower than the peak demand, due to the fair weather. Mumbai is connected with generating stations of Tata Power and RInfra. Between these stations, the generation capacity of 2,500 MW is available for Mumbai.

According to Tata Power, however, power from a standby plant, Unit 6, which is a 500 MW unit that runs on oil, would have solved the issue.

This plant, according to Tata Power Company, ''has been kept on cold standby because the power cost from this unit is high, as the variable cost itself is upwards of Rs12 - Rs13 per unit depending on the cost of oil. Procurers do not want this power to continuously flow in the system, so that the consumer does not have to bear high cost of oil based power.''

On Tuesday, the company said, while Unit 5 of 500 MW, which operates on special coal, tripped at 9:45 am due to some technical problem and the load went out, Tata Power picked up available load from hydro stations.

The company also asked some of its high tension customers to run their standby sets, which they had in their own premises. Thus the gap of about 200 MW was bridged and thereafter an impending shortage of 300 MW was experienced.

According to Tata Power, this 300 MW shortage could have been met through imports from other states if transmission lines were in place to feed imported power.

Against Mumbai's peak electricity consumption of 3,350 MW, the transmission system is designed to carry about 1,450-1,500 MW. The transmission line operates as an integrated system and not as a company property. ''You cannot differentiate one power line from another by company ownership. Everybody's transmission line is controlled by SLDC and not by individual companies. The SLDC decides which transmission systems have to be enhanced and planning of grid is under their domain.''

Maharashtra discom, which is the neighboring system to Mumbai, however, was in a very comfortable position to supply this 300 MW as it was raining everywhere in Maharashtra and they were backing down their demand and said that they could take 300 MW. However, the Transmission system was saturated and it was not possible to carry extra load; as they were already operating at the precarious point. Thus this 300 MW shortage continued until the system could meet full demand 12 hours later at about 9:00 PM when load shedding was finished.

Meanwhile, Tata Power said the unit which was on cold standby has come back and is operational since Wednesday night.

However, the company said while power generation remains coal-constrained, Mumbai must have its own generation to save it from future power outages.