M A I N   N E W S

Nathpa project shut down as level of silt increases
Rakesh Lohumi
Tribune News Service

Shimla, August 14
The abnormally high turbulence of the Sutlej during the season is creating all sorts of problems for the country’s largest hydroelectric venture, the 1,500 mw Nathpa Jhakri Project, which has suffered a loss of over Rs 300 crore in the current financial year so far.

The project, which has been operating at one-third of its installed capacity, was shut down again this morning as the level of silt crossed 11,000 ppm (parts per million). The year has been bad for the project. The project has not functioned, smoothly except in the first three weeks of June during which it also achieved the highest ever generation of 37.7 million in a day. April and May were not very encouraging as the winter prolonged and there was not enough discharge into the river to run more than two or three units. A minimum discharge of 450 cumecs(cubic metre per second) is required for operating all the units but the discharge remained between 220 and 290 cumecs.

It was only in June that the mercury rose and the snow started melting briskly to raise the discharge to 700 cumecs and finally to over 1,100 cumecs. However, the Sutlej Jal Vidyut Nigam managed to run only for a few days as the level of the silt suddenly rose on June 24 thus forcing it to slow down the project. Thereafter, the Parechu flood which hit the region on June 26 and since then it has either remained shut or functioned at a very low capacity. During the flood the level of the silt crossed one lakh ppm mark and has mostly remained beyond the permissible limit of 5,000 ppm.

Till date the total loss of generation has been 1,250 mu (million units) and the nigam is not likely to achieve the target of 6,950 mu for the year as the peak generation period (May 15 to September 15) is almost over. Even if the level of the silt goes down over the next few days there is not much time to makeup for the lost generation. Once the mercury dips in September the melting of snow will be slow down and there won’t be enough discharge in the river to run the project at full capacity.

Apart from the loss of generation the high level of silt has been causing much damage to the turbines, which will require crores of rupees for repair. The nigam had coated three units with tungsten carbide to protect them from erosion. The coated units have suffered very little damage as compared to the uncoated ones. The nigam plans to coat all units before the next season so that it should run at full capacity.