Record power generation at Nathpa-Jhakri project
Rakesh Lohumi
Tribune News Service

Shimla, March 19
While power generation at smaller projects in the region has been affected due to lack of rain and snow this year, the country’s largest 1,500-MW Nathpa-Jhakri hydroelectric project has achieved a record generation during the year that crossed 6,500 million units today.

With a daily generation of 8 million units, the project is well on its way to achieve the “excellent” target of 6,600 million units for the first time since it was commissioned in 2003. Last year, 6,449 million units were generated during the entire year, surpassing the “very good” target of 6,397 million units. In the preceding year, only 5,947 million units were generated and the project had not even achieved a “good target” of 6,100 million units.

The project was designed to generate 6,950 million units for a maximum silt level of 5,000 ppm (parts per million). It was based on the hydrological data as per which there were to be only four such days when the silt level will be higher than the permissible limits.

However, the number of such days was actually much higher and the project had to be shut down repeatedly during peak season as the silt, which mostly comprised extremely hard quartz particles, caused extensive damage to the turbines.

The Union Ministry of Power lowered the maximum silt level to 4,000 ppm to save the machinery from silt damage and the target was scaled down to 6,600 million units. The number of high silt days for which the project could be shut down was raised from four to 11.

However, the battle against silt was won by taking steps like raising the height of the dam at Nathpa from 1,485 m to 1,495.5 m, coating the vulnerable parts of turbines with tungsten carbide-based material and ensuring better reservoir management, general manager of the project NC Bansal said.

The 10-m increase in the height of the dam more than doubled the length of the reservoir to 3.1 km, which helped in higher sedimentation of particles, allowing operation of the project at higher levels of silt.