On road to em-power-ment

While the summer shows every sign of being a scorcher this year, the power cuts could be shorter—at least in Delhi and 10 states in northern India.

While the summer shows every sign of being a scorcher this year, the power cuts could be shorter—at least in Delhi and 10 states in northern India. After three years of interrupted functioning and repeatedly throwing the region out of gear, the 1,500 MW Nathpa-Jhakri Hydel project in Himachal Pradesh finally seems ready to generate power without any hitches.

Located on the Sutlej river, 145 km from Shimla, many of the unit’s problems stemmed from silting. The bursting of the Pareechu lake and the subsequent flash floods meant that Sutlej’s silt content shot up. While the project is designed for a maximum 4,000 pmm (particles per million) capacity, it touched the 25,000 ppm mark in June and July last year, forcing the plant to shut down for 30-35 days. Power generation resumed only after the monsoon, when the silt level came down. Low water discharge also forced the plant to close for a few days.

Now, however, there are reasons to be sanguine. A number of corrective steps have been taken and the results are already showing. The project is generating 24-25 million units of power every day, against a target of 15 million units this month. If things go well, the unit is expected to hit its full capacity of 36 million units in another month.

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Says H.K. Sharma, CMD, Satluj Jal Vidyut Nigam: “This year, we are prepared to make a significant contribution to bridge the power shortfall in the country.”

So what’s prompting the turnaround? First, the height of the Nathpa dam—the water storage reservoir—has been raised from the existing 1,485 mt to 1,495 mt. This will ensure that it will provide sufficient water even in the lean months. “Now the unit can run to its capacity even if there is no requisite water discharge in the river,” says Sharma.

A solution to contain the silt inflow has also been found. Instead of the silt directly hitting the turbines, it will be stopped by the high dam and later settle down in the large reservoir, whose size will also be increased from 158 to 343 hectares. “However, this measure will be effective only if the silt is marginally high. If it exceeds 10,000-12,000 ppm, we will have to shut down. But it should be a rare occurrence,” says Sharma.

Besides, the turbines, which were damaged by the heavy silt content, have been provided with a tungsten carbide coating (TCC), which helps in enhancing the life of the turbines. Now instead of closing down the project every week for flushing of silt deposits, the exercise will be repeated only after a fortnight. “All these measures were suggested by an expert committee, which was set up by the Ministry of Power after the problem of high silt cropped up last year,” says Sharma.

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The SJVN has also installed eco-sensors to monitor the silt level in the river, which will enable the unit to be shut down the moment a warning is received. The work on treatment of the project catchments to check silt inflow has also been initiated by SJVN after it identified nearly 30 vulnerable points upstream. There is a problem though: at least 70 per cent of the catchment area lies in China.

Even so, there is hope that power outages will soon be a thing of past.