The blackout on October 12 exposes the weakness in Mumbai's power supply system
At 10.01 am on October 12, demand for power in Mumbai Metropolitan Region reached 2,600 MW. That is marginally higher than the peak demand of about 2,400 MW that all the seven states in the North East put together have.
That was the time when the third of the four transmission lines that bring power to MMR, tripped and shut down. Soon, the fourth line also tripped. Over the weekend, the first line was already under repair. And early morning on Monday, the second line too was shut down due to over-voltage.
If the breakdown of the power infrastructure that meets energy requirement of India's financial capital was alarming, here is something that should ring the alarm bells even louder - the MMR's peak power demand is much higher, at 3,600 MW.
Something equally worrying is that the present state government, and the previous one, had been 'sensitised' about the stress Mumbai's power infrastructure was already under. "And it's not that the administration is not doing anything about it. But there are several challenges to expanding Mumbai's own generation capacity, or to add more lines, to the present four, that brings power from external grids," said an industry executive.
The four lines that shut down are critical to filling the deficit in Mumbai's power supply.
The city's own generation capacity comes from Tata Power's plant in Trombay, with additional back-up from its three hydro units located in Pune district. The second source of supply is from the Dahanu plant of Adani Electricity Mumbai Ltd (AEML).
In the past, this internal capacity was enough to 'island' the city from any disruption in the grid. The islanding system in Mumbai was developed by Tata Power in 1981. It has worked efficiently in the past.
A 2018 report by Western Region Power Committee says the system has helped Mumbai stay immune to major grid disturbances – which otherwise affected other parts of the state and country - 27 times, since 1981.
How does an islanding work? A Mint story, quoting Tata Power officials explains. In case of a blackout because of tripping in a major grid, a micro-grid goes into an ‘intentional islanding,’ mode. Under this, the micro-grid disconnects the local circuit from the bigger grid, and the entire power demand is met locally. Apart from Mumbai, Kolkata is also said to have an islanding mechanism.
But on October 12, the load on the system was too high and led to the shut down of Tata Power's unit. The Adani supply was just enough to ensure vital amenities such as hospitals -though not all - and airports continued functioning.
The two problems
The blame could be put on MSETCL, or Maharashtra State Electricity, which is in charge of the transmission lines. "This could have been avoided if proper maintenance was done. This includes regular checking of the transmission lines by deploying helicopters or drones," said an industry expert.
"If technology is not available, then physical patrolling is needed to check for loose ends that should be immediately repaired," the expert added.
But finding fault in MSETCL alone will not solve Mumbai's power woes.
"Over the last 10 years, the peak demand in Mumbai has more than doubled. But neither the internal generation capacity nor the ability to source more power from the outside grid, has increased accordingly," said an industry executive.
The four lines that bring power from the grid are not enough, say experts. "There should be at least four more lines to avoid such a situation. So that even if there is a failure on a few lines, which is bound to happen technically, there should be enough resources to restore power supply," said the industry executive.
Interestingly, the present state government led by Shiv Sena, and even the last headed by the BJP, has been considering ways to add transmission lines. "But it has been delayed because there is a space crunch in Mumbai," says an official.
The second challenge is in increasing the islanding capability. Sources told Moneycontrol that here too, space is the problem and the only possible solution could be for Tata Power to increase its capacity in Trombay. "Talks are expected to be held between government officials and the company in the coming days," said an executive.That the issue has taken a political tone, has added one more layer to an already complicated issue. And because the energy problems of the nation's financial capital dent India's ranking on the ease of doing business, the Prime Minister's Office is also said to be involved in finding a solution to Mumbai's power woes.