North India's Hydel Generation Dips, Despite Heavy Rain

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Researched by Industrial Info Resources India (New Delhi, India)--Although heavy rainfall over the past weeks in Northern India has raised the reservoir levels considerably, power generation from hydel resources continues to be hampered, as the rain caused a multifold increase in the silt levels in major rivers in the region. Three hydropower plants in Himachal Pradesh were forced to undergo a preventive outage last week due to high silt levels in the Sutlej and Ravi rivers, triggering an incidental power shortage in the northern states.

State-owned NHPC Limited's (BSE:533098) (Faridabad, Haryana) 300-megawatt (MW) Chamera-II hydropower station and Satluj Jal Vidyut Nigam Limited's (BSE:533206) (SJVNL) (Shimal, Himachal Pradesh) 1,500-MW Nathpa Jhakri and Jaiprakash Hydro-Power Limited's (BSE:532627) (Noida, Uttar Pradesh) 1,000-MW Karcham Wangtoo power stations were shut down after silt levels exceeded the threshold 5,000 parts per million level. The three power stations feed 2,800 MW to the country's northern grid, mainly catering to the states of Punjab, Haryana, Chandigarh, Himachal Pradesh, Delhi, Jammu and Kashmir, Rajasthan, Uttar Pradesh and Uttarakhand.

The Nathpa Jhakri and Karcham Wangtoo power stations underwent outages on August 20, 2012, after the silt level in the Sutlej River was found to be 13,000 parts per million, way beyond the threshold silt level for the safe running of machines. The Chamera-II power station, located on the Ravi River, underwent a forced outage after recording an exponential increase in silt levels in the river.

Hydropower-generation has been hampered in northern India during this peak rainy season, as the region has received below-normal rainfall. The situation, however, improved by the end of the first week of August 2012. Almost all of the northern Indian states have recorded moderate-to-heavy rainfall during the last two weeks.

Silting is a major problem faced by hydropower stations in Himachal Pradesh. The erosion of hydroturbine components affects the efficient operation of hydropower plants. The problem is more prominent in power stations that are of run-of-the-river. The problem aggravates if the silt contains a higher percentage of quartz, which is highly corrosive. The sedimentary rocks in the Himalayan Mountains contain a high concentration of quartz, which is drained by the rivers originating from the mountain. Both the Satluj and Ravi rivers originate from the same mountain range. Every year, a rise in the silt level during heavy rains causes the power plants to shut down their operations, leading to a power crisis in the region. To combat the challenge of silting, Nathpa Jhakri Power Plant has been equipped with the high-capacity Desilting Arrangement, which is touted to be the largest desilting chamber in the world.

The silt levels in these rivers are is expected to fluctuate more, as the meteorological data indicates very high rainfall in the low and mid hills of the state during the next few days.

Notably, this is the second occasion within a month's time when India has witnessed a major power crisis. On July 30 and July 31, 2012, India faced a severe power outage as the country's Northern, Eastern and Northeastern grids collapsed, leaving more than 600 million people without electricity.

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