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The massive power outage in Mumbai and its suburbs last week has exposed fault lines in the city’s four-decade-old power islanding system. Even as a committee appointed by the Central
Electricity Authority is probing the outage, it is clear that the energy-guzzling city’s generation and distribution networks need an upgrade. Mumbai practically came to a standstill around
10am on 12 October by the blackout. The outage that lasted from 2 to 15 hours depending on the locality was caused by a cascade of failures that started with the western grid and ended with
the city’s famed islanding network also tripping. The islanding system, built by Tata Power in 1981, is designed to isolate its electricity network from the rest of the western grid during
widespread grid disturbances. Under the system, power plants within the greater Mumbai region continue generating electricity during grid failures, supplying power for rail transport and
essential consumers such as hospitals. Mumbai’s embedded generation capacity is 1,600MW, split between coal, natural gas, and hydroelectric power plants run by Tata Power and Adani Power in
Trombay, Khopoli and Dahanu. However, in the past four decades, Mumbai’s power demand has grown disproportionately to its embedded generation. The demand in the morning of 12 October was
2,400MW, quite lower than the peak demand, which can touch 3,600MW in summer. “The city is building more substations in Vikhroli and Navi Mumbai to create more entry points for power into
Mumbai,” said Dinesh Waghmare, chairman and managing director, Maharashtra State Electricity Transmission Co. Ltd (MSETCL). The city draws surplus power from the MSETCL substation at Kalwa.
“We’re also evaluating the feasibility of building a substation between Dahanu and Boisar but land is not available. Mumbai’s power needs will only keep increasing once the new metro,
monorail and high-speed rail lines are commissioned. The Navi Mumbai airport, Mumbai port trust redevelopment, and new slum rehabilitation projects will all increase demand. We estimate that
demand will touch 5,000-5,500MW by 2023-24, so this can only be met by drawing more power from the western grid,” he said. It is difficult to build more generation units within the city
because of environment and coastal zone regulations. However, depending more on the western grid implies that Mumbai will lose its historical islanding advantage.